Patent Publication Number: US-11642485-B2

Title: Outlet connection assembly

Description:
2 CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 17/518,996, filed Nov. 4, 2021, which is a continuation of U.S. application Ser. No. 16/726,304, filed Dec. 24, 2019, now U.S. Pat. No. 11,305,088, which is a continuation of U.S. application Ser. No. 14/392,306, filed Dec. 24, 2015, now U.S. Pat. No. 10,549,060, which is the U.S. national phase of International Application No. PCT/AU2014/050089 filed 24 Jun. 2014, which designated the U.S. and claims the benefit of US Provisional Application Nos. 61/838,971, filed Jun. 25, 2013, and 61/987,245, filed May 1, 2014, each of which is incorporated herein by reference in its entirety. 
     A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
    
    
     3 (B) BACKGROUND OF THE TECHNOLOGY 
     3.1 (1) Field of the Technology 
     The present technology relates to one or more of the diagnosis, treatment and amelioration of respiratory disorders, and to procedures to prevent respiratory disorders. In particular, the present technology relates to medical devices, and their use for treating respiratory disorders and for preventing respiratory disorders. 
     3.2 (2) Description of the Related Art 
     The respiratory system of the body facilitates gas exchange. The nose and mouth form the entrance to the airways of a patient. 
     The airways include a series of branching tubes, which become narrower, shorter and more numerous as they penetrate deeper into the lung. The prime function of the lung is gas exchange, allowing oxygen to move from the air into the venous blood and carbon dioxide to move out. The trachea divides into right and left main bronchi, which further divide eventually into terminal bronchioles. The bronchi make up the conducting airways, and do not take part in gas exchange. Further divisions of the airways lead to the respiratory bronchioles, and eventually to the alveoli. The alveolated region of the lung is where the gas exchange takes place, and is referred to as the respiratory zone. See West, Respiratory Physiology—the essentials. 
     A range of respiratory disorders exist. 
     Obstructive Sleep Apnea (OSA), a form of Sleep Disordered Breathing (SDB), is characterized by occlusion or obstruction of the upper air passage during sleep. It results from a combination of an abnormally small upper airway and the normal loss of muscle tone in the region of the tongue, soft palate and posterior oropharyngeal wall during sleep. The condition causes the affected patient to stop breathing for periods typically of 30 to 120 seconds duration, sometimes 200 to 300 times per night. It often causes excessive daytime somnolence, and it may cause cardiovascular disease and brain damage. The syndrome is a common disorder, particularly in middle aged overweight males, although a person affected may have no awareness of the problem. See U.S. Pat. No. 4,944,310 (Sullivan). 
     Cheyne-Stokes Respiration (CSR) is a disorder of a patient&#39;s respiratory controller in which there are rhythmic alternating periods of waxing and waning ventilation, causing repetitive de-oxygenation and re-oxygenation of the arterial blood. It is possible that CSR is harmful because of the repetitive hypoxia. In some patients CSR is associated with repetitive arousal from sleep, which causes severe sleep disruption, increased sympathetic activity, and increased afterload. See U.S. Pat. No. 6,532,959 (Berthon-Jones). 
     Obesity Hyperventilation Syndrome (OHS) is defined as the combination of severe obesity and awake chronic hypercapnia, in the absence of other known causes for hypoventilation. Symptoms include dyspnea, morning headache and excessive daytime sleepiness. 
     Chronic Obstructive Pulmonary Disease (COPD) encompasses any of a group of lower airway diseases that have certain characteristics in common. These include increased resistance to air movement, extended expiratory phase of respiration, and loss of the normal elasticity of the lung. Examples of COPD are emphysema and chronic bronchitis. COPD is caused by chronic tobacco smoking (primary risk factor), occupational exposures, air pollution and genetic factors. Symptoms include: dyspnea on exertion, chronic cough and sputum production. 
     Neuromuscular Disease (NMD) is a broad term that encompasses many diseases and ailments that impair the functioning of the muscles either directly via intrinsic muscle pathology, or indirectly via nerve pathology. Some NMD patients are characterised by progressive muscular impairment leading to loss of ambulation, being wheelchair-bound, swallowing difficulties, respiratory muscle weakness and, eventually, death from respiratory failure. Neuromuscular disorders can be divided into rapidly progressive and slowly progressive: (i) Rapidly progressive disorders: Characterised by muscle impairment that worsens over months and results in death within a few years (e.g. Amyotrophic lateral sclerosis (ALS) and Duchenne muscular dystrophy (DMD) in teenagers); (ii) Variable or slowly progressive disorders: Characterised by muscle impairment that worsens over years and only mildly reduces life expectancy (e.g. Limb girdle, Facioscapulohumeral and Myotonic muscular dystrophy). Symptoms of respiratory failure in NMD include: increasing generalised weakness, dysphagia, dyspnea on exertion and at rest, fatigue, sleepiness, morning headache, and difficulties with concentration and mood changes. 
     Chest wall disorders are a group of thoracic deformities that result in inefficient coupling between the respiratory muscles and the thoracic cage. The disorders are usually characterised by a restrictive defect and share the potential of long term hypercapnic respiratory failure. Scoliosis and/or kyphoscoliosis may cause severe respiratory failure. Symptoms of respiratory failure include: dyspnea on exertion, peripheral oedema, orthopnea, repeated chest infections, morning headaches, fatigue, poor sleep quality and loss of appetite. 
     Otherwise healthy individuals may take advantage of systems and devices to prevent respiratory disorders from arising. 
     3.2.1 Therapy 
     Nasal Continuous Positive Airway Pressure (CPAP) therapy has been used to treat Obstructive Sleep Apnea (OSA). The hypothesis is that continuous positive airway pressure acts as a pneumatic splint and may prevent upper airway occlusion by pushing the soft palate and tongue forward and away from the posterior oropharyngeal wall. 
     Non-invasive ventilation (NIV) provides ventilatory support to a patient through the upper airways to assist the patient in taking a full breath and/or maintain adequate oxygen levels in the body by doing some or all of the work of breathing. The ventilatory support is provided via a patient interface. Non-invasive ventilation (NIV) has been used to treat OHS, COPD, MD and Chest Wall disorders. 
     Invasive ventilation (IV) provides ventilatory support to patients that are no longer able to effectively breathe themselves and may be provided using a tracheostomy tube. 
     Ventilators may control the timing and pressure of breaths pumped into the patient, and monitor the breaths taken by the patient. The methods of control and monitoring of patients typically include volume-cycled and pressure-cycled methods. The volume-cycled methods may include among others, Pressure-Regulated Volume Control (PRVC), Volume Ventilation (VV), and Volume Controlled Continuous Mandatory Ventilation (VC-CMV) techniques. The pressure-cycled methods may involve, among others, Assist Control (AC), Synchronized Intermittent Mandatory Ventilation (SIMV), Controlled Mechanical Ventilation (CMV), Pressure Support Ventilation (PSV), Continuous Positive Airway Pressure (CPAP), or Positive End Expiratory Pressure (PEEP) techniques. 
     3.2.2 Therapy Systems 
     A therapy system, or a respiratory therapy system, may comprise a Respiratory Pressure Therapy Device (RPT device), an air circuit, a humidifier, a patient interface, and data management. 
     3.2.2.1 Patient Interface 
     A patient interface may be used to interface respiratory equipment to its user, for example by providing a flow of air. The flow of air may be provided via a mask to the nose and/or mouth, a tube to the mouth or a tracheostomy tube to the trachea of the user. Depending upon the therapy to be applied, the patient interface may form a seal, e.g. with a face region of the patient, to facilitate the delivery of gas at a pressure at sufficient variance with ambient pressure to effect therapy, e.g. a positive pressure of about 10 cmH2O. For other forms of therapy, such as the delivery of oxygen, the patient interface may not include a seal sufficient to facilitate delivery to the airways of a supply of gas at a positive pressure of about 10 cmH2O. 
     The design of a patient interface presents a number of challenges. The face has a complex three-dimensional shape. The size and shape of noses varies considerably between individuals. Since the head includes bone, cartilage and soft tissue, different regions of the face respond differently to mechanical forces. The jaw or mandible may move relative to other bones of the skull. The whole head may move during the course of a period of respiratory therapy. 
     As a consequence of these challenges, some masks suffer from being one or more of obtrusive, aesthetically undesirable, costly, poorly fitting, difficult to use, and uncomfortable especially when worn for long periods of time or when a patient is unfamiliar with a system. For example, masks designed solely for aviators, mask designed as part of personal protection equipment (e.g. filter masks), SCUBA masks, or for the administration of anaesthetics may be tolerable for their original application, but nevertheless may be undesirably uncomfortable to be worn for extended periods of time, e.g. several hours. This discomfort may lead to a reduction in patient compliance with therapy. This is even more so if the mask is to be worn during sleep. 
     Nasal CPAP therapy is highly effective to treat certain respiratory disorders, provided patients comply with therapy. If a mask is uncomfortable, or difficult to use a patient may not comply with therapy. Since it is often recommended that a patient regularly wash their mask, if a mask is difficult to clean (e.g. difficult to assemble or disassemble), patients may not clean their mask and this may impact negatively on patient compliance. 
     While a mask for other applications (e.g. aviators) may not be suitable for use in treating sleep disordered breathing, a mask designed for use in treating sleep disordered breathing may be suitable for other applications. 
     For these reasons, masks for delivery of nasal CPAP during sleep form a distinct field. 
     3.2.2.1.1 Seal-Forming Portion 
     Patient interfaces may include a seal-forming portion. Since it is in direct contact with the patient&#39;s face, the shape and configuration of the seal-forming portion can have a direct impact on the effectiveness and comfort of the patient interface. 
     A patient interface may be partly characterised according to the design intent of where the seal-forming portion is to engage with the face in use. In one form of patient interface, a seal-forming portion may comprise two sub-portions to engage with respective left and right nares. In one form of patient interface, a seal-forming portion may comprise a single element that surrounds both nares in use. Such single element may be designed to, for example, overlay an upper lip region and a nasal bridge region of a face. In one form of patient interface, a seal-forming portion may comprise an element that surrounds a mouth region in use, e.g. by forming a seal on a lower lip region of a face. In one form of patient interface, a seal-forming portion may comprise a single element that surrounds both nares and a mouth region in use. These different types of patient interfaces may be known by a variety of names by their manufacturer including nasal masks, full-face masks, nasal pillows, nasal puffs and oro-nasal masks. 
     A seal-forming portion that may be effective in one region of a patient&#39;s face may be in appropriate in another region, e.g. because of the different shape, structure, variability and/or sensitivity regions of the patient&#39;s face. For example, a seal on swimming goggles that overlays a patient&#39;s forehead may not be appropriate to use on a patient&#39;s nose. 
     Certain seal-forming portions may be designed for mass manufacture such that one design is able to fit and be comfortable and effective for a wide range of different face shapes and sizes. To the extent to which there is a mismatch between the shape of the patient&#39;s face and the seal-forming portion of the mass-manufactured patient interface, one or both must adapt in order for a seal to form. 
     One type of seal-forming portion extends around the periphery of the patient interface, and is intended to seal against the user&#39;s face when force is applied to the patient interface with the seal-forming portion in confronting engagement with the user&#39;s face. The seal-forming portion may include an air or fluid filled cushion, or a moulded or formed surface of a resilient seal element made of an elastomer such as a rubber. With this type of seal-forming portion, if the fit is not adequate, there will be gaps between the seal-forming portion and the face, and additional force will be required to force the patient interface against the face in order to achieve a seal 
     Another type of seal-forming portion incorporates a flap seal of thin material so positioned about the periphery of the mask so as to provide a self-sealing action against the face of the user when positive pressure is applied within the mask. Like the previous style of seal forming portion, if the match between the face and the mask is not good, additional force may be required to effect a seal, or the mask may leak. Furthermore, if the shape of the seal-forming portion does not match that of the patient, it may crease or buckle in use, giving rise to leaks. 
     Another form of seal-forming portion may use adhesive to effect a seal. Some patients may find it inconvenient to constantly apply and remove an adhesive to their face. 
     A range of patient interface seal-forming portion technologies are disclosed in the following patent applications, assigned to ResMed Limited: WO 1998/004,310; WO 2006/074,513; WO 2010/135,785. One form of nasal pillow is found in the Adam Circuit manufactured by Puritan Bennett. Another nasal pillow, or nasal puff is the subject of U.S. Pat. No. 4,782,832 (Trimble et al.), assigned to Puritan-Bennett Corporation. 
     ResMed Limited has manufactured the following products that incorporate nasal pillows: SWIFT nasal pillows mask, SWIFT II nasal pillows mask, SWIFT LT nasal pillows mask, SWIFT FX nasal pillows mask and LIBERTY full-face mask. The following patent applications, assigned to ResMed Limited, describe nasal pillows masks: International Patent Application WO2004/073,778 (describing amongst other things aspects of ResMed SWIFT nasal pillows), US Patent Application 2009/0044808 (describing amongst other things aspects of ResMed SWIFT LT nasal pillows); International Patent Applications WO 2005/063,328 and WO 2006/130,903 (describing amongst other things aspects of ResMed LIBERTY full-face mask); International Patent Application WO 2009/052,560 (describing amongst other things aspects of ResMed SWIFT FX nasal pillows). 
     3.2.2.1.2 Positioning and Stabilising 
     A seal-forming portion of a patient interface used for positive air pressure therapy is subject to the corresponding force of the air pressure to disrupt a seal. Thus a variety of techniques have been used to position the seal-forming portion, and to maintain it in sealing relation with the appropriate portion of the face. 
     One technique is the use of adhesives. See for example US Patent publication US 2010/0000534. 
     Another technique is the use of one or more straps and stabilising harnesses. Many such harnesses suffer from being one or more of ill-fitting, bulky, uncomfortable and awkward to use. 
     3.2.2.1.3 Vent Technologies 
     Some forms of patient interface systems may include a vent to allow the washout of exhaled carbon dioxide. The vent may allow a flow of gas from an interior space of the patient interface, e.g. the plenum chamber, to an exterior of the patient interface, e.g. to ambient. The vent may comprise an orifice and gas may flow through the orifice in use of the mask. Many such vents are noisy. Others may block in use and provide insufficient washout. Some vents may be disruptive of the sleep of a bed-partner  1100  of the patient  1000 , e.g. through noise or focused airflow. 
     ResMed Limited has developed a number of improved mask vent technologies. See WO 1998/034,665; WO 2000/078,381; U.S. Pat. No. 6,581,594; US Patent Application; US 2009/0050156; US Patent Application 2009/0044808. 
     
       
         
           
               
            
               
                   
               
               
                 Table of noise of prior masks (ISO 17510-2: 
               
               
                 2007, 10 cmH 2 O pressure at 1 m) 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 A-weighted 
                 A-weighted 
                   
               
               
                   
                   
                 sound power 
                 sound pressure 
               
               
                   
                 Mask 
                 level dbA 
                 dbA 
                 Year 
               
               
                 Mask name 
                 type 
                 (uncertainty) 
                 (uncertainty) 
                 (approx.) 
               
               
                   
               
               
                 Glue-on (*) 
                 nasal 
                 50.9 
                 42.9 
                 1981 
               
               
                 ResCare 
                 nasal 
                 31.5 
                 23.5 
                 1993 
               
               
                 standard (*) 
               
               
                 ResMed 
                 nasal 
                 29.5 
                 21.5 
                 1998 
               
               
                 Mirage (*) 
               
               
                 ResMed 
                 nasal 
                 36 (3) 
                 28 (3) 
                 2000 
               
               
                 UltraMirage 
               
               
                 ResMed 
                 nasal 
                 32 (3) 
                 24 (3) 
                 2002 
               
               
                 Mirage Activa 
               
               
                 ResMed 
                 nasal 
                 30 (3) 
                 22 (3) 
                 2008 
               
               
                 Mirage Micro 
               
               
                 ResMed 
                 nasal 
                 29 (3) 
                 22 (3) 
                 2008 
               
               
                 Mirage SoftGel 
               
               
                 ResMed 
                 nasal 
                 26 (3) 
                 18 (3) 
                 2010 
               
               
                 Mirage FX 
               
               
                 ResMed 
                 nasal 
                 37   
                 29   
                 2004 
               
               
                 Mirage Swift (*) 
                 pillows 
               
               
                 ResMed 
                 nasal 
                 28 (3) 
                 20 (3) 
                 2005 
               
               
                 Mirage Swift II 
                 pillows 
               
               
                 ResMed 
                 nasal 
                 25 (3) 
                 17 (3) 
                 2008 
               
               
                 Mirage Swift LT 
                 pillows 
               
               
                   
               
               
                 (* one specimen only, measured using test method specified in ISO3744 in CPAP mode at 10 cmH 2 O) 
               
            
           
         
       
     
     Sound pressure values of a variety of objects are listed below 
     
       
         
           
               
               
               
             
               
                   
               
               
                   
                 A-weighted 
                   
               
               
                   
                 sound pressure 
               
               
                   
                 dbA 
               
               
                 Object 
                 (uncertainty) 
                 Notes 
               
               
                   
               
             
            
               
                 Vacuum cleaner: Nilfisk 
                 68 
                 ISO3744 at 1 m 
               
               
                 Walter Broadly Litter Hog: B+ 
                   
                 distance 
               
               
                 Grade 
               
               
                 Conversational speech 
                 60 
                 1 m distance 
               
               
                 Average home 
                 50 
               
               
                 Quiet library 
                 40 
               
               
                 Quiet bedroom at night 
                 30 
               
               
                 Background in TV studio 
                 20 
               
               
                   
               
            
           
         
       
     
     3.2.2.2 Respiratory Pressure Therapy (RPT) Device 
     One known type of RPT device used for treating sleep disordered breathing is a positive airway pressure (PAP) device, such as the S9 Series, manufactured by ResMed. Other examples of RPT devices include a ventilator and a high flow therapy device. In some cases, RPT devices such as PAP devices have been known to be referred to as flow generators. Ventilators such as the ResMed Stellar™ Series of Adult and Paediatric Ventilators may provide support for invasive and non-invasive non-dependent ventilation for a range of patients for treating a number of conditions such as but not limited to NMD, OHS and COPD. 
     The ResMed Elisée™ 150 ventilator and ResMed VS III™ ventilator may provide support for invasive and non-invasive dependent ventilation suitable for adult or paediatric patients for treating a number of conditions. These ventilators provide volumetric and barometric ventilation modes with a single or double limb circuit. 
     RPT devices typically comprise a pressure generator, such as a motor-driven blower or a compressed gas reservoir, and are configured to supply a flow of air to the airway of a patient. In some cases, the flow of air may be supplied to the airway of the patient at positive pressure. The outlet of the RPT device is connected via an air circuit to a patient interface, such as those described above. 
     RPT devices typically also include an inlet filter, various transducers, and a microprocessor-based controller. A blower may include a servo-controlled motor, a volute, and an impeller. In some cases a brake for the motor may be implemented to more rapidly reduce the speed of the blower so as to overcome the inertia of the motor and impeller. The braking can permit the blower to more rapidly achieve a lower pressure condition in time for synchronization with expiration despite the inertia. In some cases the pressure generator may also include a valve capable of discharging generated air to atmosphere as a means for altering the pressure delivered to the patient as an alternative to motor speed control. The transducers may measure, amongst other things, motor speed, mass flow rate and outlet pressure, such as with a pressure transducer or the like. The controller may include data storage capacity with or without integrated data retrieval and display functions. 
     
       
         
           
               
            
               
                   
               
               
                 Table of noise output levels of prior RPT devices 
               
               
                 (one specimen only, measured using test method specified 
               
               
                 in ISO3744 in CPAP mode at 10 cmH 2 O). 
               
            
           
           
               
               
               
            
               
                   
                 A-weighted sound power 
                 Year 
               
               
                 RPT Device name 
                 level dB(A) 
                 (approx.) 
               
               
                   
               
               
                 C-Series Tango 
                 31.9 
                 2007 
               
               
                 C-Series Tango with Humidifier 
                 33.1 
                 2007 
               
               
                 S8 Escape II 
                 30.5 
                 2005 
               
               
                 S8 Escape II with H4i Humidifier 
                 31.1 
                 2005 
               
               
                 S9 AutoSet 
                 26.5 
                 2010 
               
               
                 S9 AutoSet with H5i Humidifier 
                 28.6 
                 2010 
               
               
                   
               
            
           
         
       
     
     3.2.2.3 Humidifier 
     Delivery of a flow of air without humidification may cause drying of airways. Medical humidifiers are used to increase humidity and/or temperature of the flow of air in relation to ambient air when required, typically where the patient may be asleep or resting (e.g. at a hospital). As a result, a medical humidifier may be relatively small for bedside placement, and it may be configured to only humidify and/or heat the flow of air delivered to the patient without humidifying and/or heating the patient&#39;s surroundings. Room-based systems (e.g. a sauna, an air conditioner, an evaporative cooler), for example, may also humidify air that is breathed in by the patient, however they would also humidify and/or heat the entire room, which may cause discomfort to the occupants. 
     The use of a humidifier with a RPT device and the patient interface produces humidified gas that minimizes drying of the nasal mucosa and increases patient airway comfort. In addition in cooler climates, warm air applied generally to the face area in and about the patient interface is more comfortable than cold air. 
     Respiratory humidifiers are available in many forms and may be a standalone device that is coupled to a RPT device via an air circuit, is integrated with the RPT device or configured to be directly coupled to the relevant RPT device. While known passive humidifiers can provide some relief, generally a heated humidifier may be used to provide sufficient humidity and temperature to the air so that the patient will be comfortable. Humidifiers typically comprise a water reservoir or tub having a capacity of several hundred milliliters (ml), a heating element for heating the water in the reservoir, a control to enable the level of humidification to be varied, a gas inlet to receive air from the RPT device, and a gas outlet adapted to be connected to an air circuit that delivers the humidified air to the patient interface. 
     Heated passover humidification is one common form of humidification used with a RPT device. In such humidifiers the heating element may be incorporated in a heater plate which sits under, and is in thermal contact with, the water tub. Thus, heat is transferred from the heater plate to the water reservoir primarily by conduction. The air flow from the RPT device passes over the heated water in the water tub resulting in water vapour being taken up by the air flow. The ResMed H4i™ and H5i™ Humidifiers are examples of such heated passover humidifiers that are used in combination with ResMed S8 and S9 CPAP devices respectively. 
     Other humidifiers may also be used such as a bubble or diffuser humidifier, a jet humidifier or a wicking humidifier. In a bubble or diffuser humidifier the air is conducted below the surface of the water and allowed to bubble back to the top. A jet humidifier produces an aerosol of water and baffles or filters may be used so that the particles are either removed or evaporated before leaving the humidifier. A wicking humidifier uses a water absorbing material, such as sponge or paper, to absorb water by capillary action. The water absorbing material is placed within or adjacent at least a portion of the air flow path to allow evaporation of the water in the absorbing material to be taken up into the air flow. 
     An alternative form of humidification is provided by the ResMed HumiCare™ D900 humidifier that uses a CounterStream™ technology that directs the air flow over a large surface area in a first direction whilst supplying heated water to the large surface area in a second opposite direction. The ResMed HumiCare™ D900 humidifier may be used with a range of invasive and non-invasive ventilators. 
     4 (C) BRIEF SUMMARY OF THE TECHNOLOGY 
     The present technology is directed towards providing medical devices used in the diagnosis, amelioration, treatment, or prevention of respiratory disorders having one or more of improved comfort, cost, efficacy, ease of use and manufacturability. 
     A first aspect of the present technology relates to apparatus used in the diagnosis, amelioration, treatment or prevention of a respiratory disorder. 
     Another aspect of the present technology relates to methods used in the diagnosis, amelioration, treatment or prevention of a respiratory disorder. 
     Another aspect of the present technology is directed to a connection assembly for a respiratory therapy system. The connection assembly may comprise: an outlet assembly, said outlet assembly including an outlet housing and a swivelling disc located on said outlet housing, said outlet housing comprising a void and an annular section; and a cable having a first end to connect to an electrical connector and a second end to connect to at least one electrical component of the respiratory therapy system, said cable having a slack portion, wherein said swivelling disc is rotatable relative to said outlet housing between a first position and a second position, and wherein the slack portion of the cable extends from the void and wraps around the annular section as the swivelling disc is rotated from the first position to the second position. 
     In examples, (a) said swivelling disc may include a first pair of stop surfaces and said outlet housing may include a second pair of stop surfaces to limit the rotation of the swivelling disc relative to the outlet housing, (b) each pair of stop surfaces may be arranged to limit the rotation of the swivelling disc relative to the outlet housing to less than 360°, (c) each pair of stop surfaces may be arranged to limit the rotation of the swivelling disc relative to the outlet housing to greater than 180°, (d) the first pair of stop surfaces may be located on either side of and adjacent to a receiver opening in the swivelling disc that receives the cable, (e) the outlet housing may include an inner wall, said second pair of stop surfaces may be located on the inner wall and said inner wall may be configured to rotatably receive said swivelling disc, (f) the void may be defined, at least in part, by the inner wall and an outer wall of the outlet housing, (g) a distance between the inner wall and the outer wall of the outlet housing and across the void may be in the range of about 2 mm to about 5 mm, (h) the cable may comprise a flexible circuit board or a ribbon cable, (i) the cable may have a substantially rectangular cross-section, and a major side of the substantially rectangular cross-section may be oriented in parallel to an axis of rotation of the swivelling disc, (j) the swivelling disc may include an electrical connector receiver to receive the electrical connector, and the electrical connector may be electrically connectable to the cable within the electrical connector receiver, (k) the electrical connector receiver may include an opening to receive the electrical connector when the outlet connector is connected to the outlet assembly, and the outlet connector may be shaped to cover the opening of the electrical connector receiver when the outlet connector is connected to the outlet assembly, (l) the outlet connector may include a recess proximal to the electrical connector shaped to correspond to a protruding portion of the electrical connector receiver, (m) the outlet housing may include a retainer, said retainer may be configured to retain the slack portion within the void of the outlet housing as the swivelling disc is rotated from the second position to the first position, (n) the outlet connector may include at least one retention feature to releasably connect the outlet connector to the swivelling disc via at least one corresponding notch located on the swivelling disc, (o) the outlet connector may include at least one tab, each said at least one retention feature may be located on a corresponding tab having a corresponding actuator, and each said actuator may be adapted to release each said retention feature from a corresponding notch of the swivelling disc, (p) the gas delivery tube may include a heating element disposed along at least a portion of the gas delivery tube, said heating element may be connected to the electrical connector, (q) the outlet connector may include a grommet to connect the gas delivery tube to a tube connection region of the outlet connector, (r) the grommet may include threads to receive corresponding coils of the gas delivery tube, (s) the grommet may be comprised of a thermoplastic elastomer, (t) the grommet may include at least one keyway for restraining the grommet during forming, (u) the grommet may include at least one radial flange to engage a mold tool during forming, (v) the grommet may include a grip section, (w) the grip section may include a plurality of ridges and recesses disposed radially about the grommet, (x) the outlet connector may comprise an elbow, (y) the elbow may be bent at about 90°, (z) when the outlet connector is connected to the outlet assembly a rotatable, electrical, and pneumatic connection may be formed, (aa) the outlet assembly may comprise an airflow tube having a tapered end to connect to the outlet connector and form a pneumatic seal therewith, (bb) the swivelling disc may include at least one tang to rotatably connect the swivelling disc to the outlet housing, (cc) the slack portion may comprise a fixed length that is less than a circumference of the swivelling disc, (dd) when the swivelling disc is in the first position the slack portion may gather in the void, (ee) a larger portion of the cable may be contained in the void when the swivelling disc is in the first position than when the swivelling disc is in the second position, (ff) an electrical connection formed by the connection assembly may comprise at least one wire to perform powering and/or signalling functions, (gg) the outlet connector may include at least one rib at an outlet connection region to support the outlet connector on the airflow tube when connected to the outlet assembly, (hh) the connection assembly may comprise an outlet connector located at an end of a gas delivery tube to connect the gas delivery tube to the outlet assembly, said outlet connector including an electrical connector, wherein said outlet connector and said swivelling disc are connectable such that said outlet connector and said swivelling disc are rotatable in unison, (ii) the annular section may be defined, at least in part, by the inner wall and an outer wall of the outlet housing, (jj) the void and annular section may be on opposing sides of the inner wall, (kk) the outlet housing may be comprised of thermoplastic elastomer, (ll) the elbow may be bent at an angle between about 0° and about 120°, (mm) the airflow tube may be removable, (nn) the outlet connector may include a receiver at a tube connection region, said receiver comprising receiver threads, a receiver flange, and at least one protrusion, (oo) the outlet connector may comprise a clip to secure the gas delivery tube within the receiver, the clip comprising clip threads, a clip flange, and at least one tab and each at least one tab may be structured to engage with a respective one of the at least one protrusion to secure the clip to the receiver, (pp) the clip threads and the receiver threads may be structured to receive corresponding coils of the gas delivery tube, and/or (qq) the clip flange and the receiver flange may be structured to engage a mold tool during forming. 
     Another aspect of the present technology is directed to a method of manufacturing an air circuit for use with a respiratory therapy device. The method may comprise: molding an outlet connector substructure including a tube connection region, wherein an interior of said tube connection region is formed around a mandrel such that an orifice is formed in the outlet connector substructure opposite the tube connection region; threading a grommet onto a first end of a gas delivery tube having a helical heating element disposed thereon such that a connection portion of the gas delivery tube extends through the grommet; connecting the connection portion of the gas delivery tube to the tube connection region of the outlet connector substructure; attaching an electrical connector to the helical heating element at the tube connection region of the outlet connector substructure; molding an outlet connector housing over the outlet connector substructure, at least in part by sealing the mold tool around the grommet; and attaching an end cap over the orifice. 
     Another aspect of the present technology is directed to a respiratory therapy system for the treatment of sleep disordered breathing in a patient. The respiratory therapy system may comprise: a pressure generator to provide a flow of air to the patient at positive pressure, the pressure generator comprising a housing; an outlet assembly located on the housing, said outlet assembly comprising: an outlet housing and a swivelling disc located on said outlet housing, said outlet housing comprising a void; and a cable having a first end to connect to an electrical connector and a second end to connect to at least one electrical component of the respiratory therapy system, said cable having a slack portion; and an air circuit configured to connect to the outlet assembly at a first end and to a patient interface at a second end, said air circuit comprising: an outlet connector located at the second end of a gas delivery tube to connect the gas delivery tube to the outlet assembly, said outlet connector including the electrical connector, wherein said outlet connector and said swivelling disc are connectable such that said outlet connector and said swivelling disc are rotatable in unison relative to said outlet housing between a first position and a second position, and wherein a larger portion of the cable is contained in the void when the swivelling disc is in the first position than when the swivelling disc is in the second position. 
     In examples, (a) said swivelling disc may include a first pair of stop surfaces and said outlet housing may include a second pair of stop surfaces to limit the rotation of the swivelling disc relative to the outlet housing, (b) each pair of stop surfaces may be arranged to limit the rotation of the swivelling disc relative to the outlet housing to less than 360°, (c) each pair of stop surfaces may be arranged to limit the rotation of the swivelling disc relative to the outlet housing to greater than 180°, (d) the first pair of stop surfaces may be located on either side of and adjacent to a receiver opening in the swivelling disc that receives the cable, (e) the outlet housing may include an inner wall, said second pair of stop surfaces may be located on the inner wall and said inner wall may be configured to rotatably receive said swivelling disc, (f) the void may be defined, at least in part, by the inner wall and an outer wall of the outlet housing, (g) a distance between the inner wall and the outer wall of the outlet housing and across the void may be in the range of about 2 mm to about 5 mm, (h) the cable may comprise a flexible circuit board or a ribbon cable, (i) the cable may have a substantially rectangular cross-section, and a major side of the substantially rectangular cross-section may be oriented in parallel to an axis of rotation of the swivelling disc, (j) the swivelling disc may include an electrical connector receiver to receive the electrical connector, and the electrical connector may be electrically connectable to the cable within the electrical connector receiver, (k) the electrical connector receiver may include an opening to receive the electrical connector when the outlet connector is connected to the outlet assembly, and the outlet connector may be shaped to cover the opening of the electrical connector receiver when the outlet connector is connected to the outlet assembly, (l) the outlet connector may include a recess proximal to the electrical connector shaped to correspond to a protruding portion of the electrical connector receiver, (m) the outlet housing may include a retainer, said retainer may be configured to retain the slack portion within the outlet housing as the swivelling disc is rotated from the second position to the first position, (n) the outlet connector may include at least one retention feature to releasably connect the outlet connector to the swivelling disc via at least one corresponding notch located on the swivelling disc, (o) the outlet connector may include at least one tab, each said at least one retention feature may be located on a corresponding tab having a corresponding actuator, and each said actuator may be adapted to release each said retention feature from a corresponding notch of the swivelling disc, (p) the gas delivery tube may include a heating element disposed along at least a portion of the gas delivery tube, said heating element may be connected to the electrical connector, (q) the outlet connector may include a grommet to connect the gas delivery tube to a tube connection region of the outlet connector, (r) the grommet may include threads to receive corresponding coils of the gas delivery tube, (s) the grommet may be comprised of a thermoplastic elastomer, (t) the grommet may include at least one keyway for restraining the grommet during forming, (u) the grommet may include at least one radial flange to engage a mold tool during forming, (v) the grommet may include a grip section, (w) the grip section may include a plurality of ridges and recesses disposed radially about the grommet, (x) the outlet connector may comprise an elbow, (y) the elbow may be bent at about 90°, (z) the outlet housing may be comprised of thermoplastic elastomer, (aa) when the outlet connector is connected to the outlet assembly a rotatable, electrical, and pneumatic connection may be formed, (bb) the outlet assembly may comprise a airflow tube having a tapered end to connect to the outlet connector and form a pneumatic seal therewith, (cc) the swivelling disc may include at least one tang to rotatably connect the swivelling disc to the outlet housing, (dd) the slack portion may comprise a fixed length that is less than a circumference of the swivelling disc, (ee) when the swivelling disc is in the first position the slack portion may gather in the void, (ff) the slack portion of the cable may extend from the void and wrap around the annular section as the swivelling disc is rotated from the first position to the second position, (gg) an electrical connection formed by the connection assembly may comprise at least one wire to perform powering and/or signalling functions, (hh) the outlet connector may include at least one rib at an outlet connection region to support the outlet connector on the airflow tube when connected to the outlet assembly, (ii) the respiratory therapy system may comprise a humidifier to humidify the flow of air, (jj) the outlet housing may comprise an annular section configured to receive the cable when the swivelling disc is in the second position, (kk) the elbow may be bent at an angle between about 0° and about 120°, (ll) the airflow tube may be removable, (mm) the outlet connector may include a receiver at a tube connection region, said receiver comprising receiver threads, a receiver flange, and at least one protrusion, (nn) the outlet connector may comprise a clip to secure the gas delivery tube within the receiver, the clip comprising clip threads, a clip flange, and at least one tab and each at least one tab may be structured to engage with a respective one of the at least one protrusion to secure the clip to the receiver, (oo) the clip threads and the receiver threads may be structured to receive corresponding coils of the gas delivery tube, and/or (pp) the clip flange and the receiver flange may be structured to engage a mold tool during forming. 
     Another aspect of the present technology is directed to a connection assembly for a respiratory therapy system. The connection assembly may comprise: a housing; an outlet assembly located on the housing and including an outlet tube; an outlet connector having a first end adapted to pneumatically connect to a gas delivery tube and a second end adapted to removably connect to the outlet assembly and form a pneumatic connection with the outlet tube; a plurality of first electrical connectors; and a second electrical connector adapted to electrically connect to one of the plurality of first electrical connectors, wherein the outlet assembly and the outlet connector are removably connectable in a plurality of predetermined and discrete positions to form both pneumatic and electrical connections. 
     In examples, (a) the quantity of the plurality of first electrical connectors may equal the quantity of the plurality of predetermined and discrete positions, (b) the outlet assembly may comprise the plurality of first electrical connectors and the outlet connector may comprise the second electrical connector, (c) the outlet assembly may include at least one cable to electrically connect the plurality of first electrical connectors to at least one electronic component of the respiratory therapy system, (d) the outlet assembly may comprise the second electrical connector and the outlet connector may comprise the plurality of first electrical connectors, (e) the connection assembly may comprise at least one dummy connector configured to cover at least one of the plurality of first electrical connectors that is not connected to the second electrical connector, (f) a quantity of the at least one dummy connectors may be one less than a quantity of the plurality of first electrical connectors, (g) the outlet connector may comprise an elbow, (h) the elbow may be bent at about 90°, (i) the outlet assembly may include a recess to receive the second end of the outlet connector, and the recess and the second end of the outlet connector may be shaped substantially correspondingly, (j) the elbow may be bent between about 0° and about 120°, and/or (k) an electrical connection formed by the connection assembly may comprise at least one wire to perform powering and/or signalling functions. 
     Another aspect of the present technology is directed to a method of manufacturing an air circuit for use with a respiratory therapy device. The method may comprise: molding an outlet connector substructure, the outlet connector substructure including a receiver and receiver threads at a tube connection region, wherein an interior of said outlet connector substructure is formed around a mandrel such that an orifice is formed in the outlet connector substructure opposite the tube connection region; threading a first end of a gas delivery tube having a helical heating element disposed thereon into the receiver threads such that a connection portion of the gas delivery tube extends through the receiver; connecting the connection portion of the gas delivery tube to the tube connection region of the outlet connector substructure by securing a clip around the connection portion of the gas delivery tube such that the connection portion of the gas delivery tube is substantially surrounded by the receiver and the clip; attaching an electrical connector to the helical heating element at the tube connection region of the outlet connector substructure; molding an outlet connector housing over the outlet connector substructure, at least in part by sealing the mold tool around the tube connection region; and attaching an end cap over the orifice. 
     In examples, (a) the clip may be a separate component from the receiver, the clip comprising a pair of tabs and the receiver comprising a pair of protrusions, and securing the clip may comprise snapping each of the pair of tabs onto respective ones of the pair of protrusions, and/or (b) the clip and the receiver may comprise one piece and the clip is joined to the receiver by a hinge, the clip comprising a tab and the receiver comprising a protrusion, and securing the clip may comprise snapping the tab onto the protrusion. 
     Another aspect of the present technology is directed to an outlet connector assembly for a device to deliver continuous positive airway pressure to a patient for treatment of sleep disordered breathing. The outlet connector assembly may comprise: a body having a tube connection region and an outlet connection region; a cap structured to attach to the body such that the cap and the body at least partially define an airflow path between the tube connection region and the outlet connection region; and an electrical contact assembly molded to the body and configured to form an electrical connection between the tube connection region and the outlet connection region. 
     In examples, (a) the airflow path defined at least partially by the cap and the body may have a curved shape and the airflow path may have a substantially uniform cross-section, (b) a radius of the curved shape of the airflow path may be 1 to 3 times the diameter of the airflow path, (c) an inner radius and an outer radius of the curved shape of the airflow may share a common arc center, (d) the tube connection region may comprise a shoulder and contact recesses, (e) the electrical contact assembly may comprise contacts positioned in the contact recesses, the contacts being extended completely around the outlet connection region, (f) the cap may comprise tabs and prongs and the body may comprise notches and detents, and the tabs may engage the notches and the prongs may engage the detents to attach the cap to the body, (g) the tube connection region may comprise a thread shaped to receive a helical coil of a gas delivery tube, and/or (h) the outlet connector assembly may comprise a housing overmolded to the body and the cap to pneumatically seal the airflow path. 
     Of course, portions of the examples/aspects may form sub-examples/sub-aspects of the present technology. Also, various ones of the sub-examples/sub-aspects and/or examples/aspects may be combined in various manners and also constitute additional examples/aspects or sub-examples/sub-aspects of the present technology. 
     Other features of the technology will be apparent from consideration of the information contained in the following detailed description, abstract, drawings and claims. 
    
    
     
       5 (D) BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The present technology is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference numerals refer to similar elements including: 
       5.1 Therapy Systems 
         FIG.  1   a    shows a system in accordance with the present technology. A patient  1000  wearing a patient interface  3000 , in the form of a nasal pillows, receives a supply of air at positive pressure from a RPT device  4000 . Air from the RPT device is humidified in a humidifier  5000 , and passes along an air circuit  4100  to the patient  1000 . 
         FIG.  1   b    shows a system including a patient  1000  wearing a patient interface  3000 , in the form of a nasal mask, receiving a supply of air at positive pressure from a RPT device  4000 . Air from the RPT device is humidified in a humidifier  5000 , and passes along an air circuit  4100  to the patient  1000 . 
         FIG.  1   c    shows a system including a patient  1000  wearing a patient interface  3000 , in the form of a full-face mask, receiving a supply of air at positive pressure from a RPT device  4000 . Air from the RPT device is humidified in a humidifier  5000 , and passes along an air circuit  4100  to the patient  1000 . 
       5.2 Therapy 
       5.2.1 Respiratory System 
         FIG.  2   a    shows an overview of a human respiratory system including the nasal and oral cavities, the larynx, vocal folds, oesophagus, trachea, bronchus, lung, alveolar sacs, heart and diaphragm. 
         FIG.  2   b    shows a view of a human upper airway including the nasal cavity, nasal bone, lateral nasal cartilage, greater alar cartilage, nostril, lip superior, lip inferior, larynx, hard palate, soft palate, oropharynx, tongue, epiglottis, vocal folds, oesophagus and trachea. 
       5.2.2 Patient Interface 
         FIG.  2   c    shows a patient interface in the form of a nasal mask in accordance with one form of the present technology. 
       5.3 RPT Device and Humidifier 
         FIG.  3   a    shows a RPT device in an exploded view in accordance with one form of the present technology. 
         FIG.  3   b    shows another RPT device  4000  with an integrated humidifier  5000  in an exploded view in accordance with one aspect of the present technology. 
         FIG.  3   c    shows a front perspective view of an RPT device  4000  with an integrated humidifier  5000  in accordance with one aspect of the present technology. 
         FIG.  3   d    shows a rear perspective view of an RPT device  4000  with an integrated humidifier  5000  in accordance with one aspect of the present technology. 
         FIG.  3   e    shows a schematic diagram of the pneumatic circuit of a RPT device in accordance with one form of the present technology. The directions of upstream and downstream are indicated. 
         FIG.  3   f    shows a schematic diagram of electrical components of an RPT device in accordance with one form of the present technology. 
         FIG.  3   g    shows a perspective view of a humidifier  5000  in accordance with one form of the present technology. 
         FIG.  3   h    shows a perspective view of a humidifier  5000  in accordance with one form of the present technology, showing the humidifier reservoir  5180  in an exploded state. 
         FIG.  4   a    shows a perspective view of an air circuit comprising an outlet connector according to an example of the present technology. 
         FIG.  4   b    shows another perspective view of an air circuit comprising an outlet connector according to an example of the present technology. 
         FIG.  4   c    shows a detailed view of an electrical connector of an outlet connector according to an example of the present technology. 
         FIG.  4   d    shows another perspective view of a portion of an outlet connector according to an example of the present technology. 
         FIG.  4   e    shows a detailed bottom view of an outlet connector and a portion of an airflow tube according to an example of the present technology. 
         FIG.  4   f    shows another detailed bottom view of an outlet connector according to an example of the present technology. 
         FIG.  4   g    shows another perspective view of an air circuit comprising an outlet connector according to an example of the present technology. 
         FIG.  4   h    shows another perspective view of an air circuit comprising an outlet connector according to an example of the present technology. 
         FIG.  5   a    shows a perspective view of an air circuit comprising an outlet connector and a tube according to an example of the present technology. 
         FIG.  5   b    shows a bottom view of an air circuit comprising an outlet connector and a tube according to an example of the present technology. 
         FIG.  5   c    shows a side view of an air circuit comprising an outlet connector and a tube according to an example of the present technology. 
         FIG.  5   d    shows an end view of an air circuit comprising an outlet connector and a tube according to an example of the present technology. 
         FIG.  5   e    shows a bottom perspective view of an air circuit comprising an outlet connector and a tube according to an example of the present technology. 
         FIG.  5   f    shows an exploded perspective view of an air circuit comprising an outlet connector and a tube according to an example of the present technology. 
         FIG.  5   g    shows a partially exploded perspective view of an air circuit comprising an outlet connector and a tube according to an example of the present technology. 
         FIG.  5   h    shows a detailed side cross-section view of an air circuit comprising an outlet connector and a tube according to an example of the present technology. 
         FIG.  5   i    shows a side cross-section view of an air circuit comprising an outlet connector and a tube according to an example of the present technology. 
         FIG.  6   a    shows a perspective view of a substructure of an outlet connector and an electrical connector according to an example of the present technology. 
         FIG.  6   b    shows a perspective view of an electrical connector of an outlet connector according to an example of the present technology. 
         FIG.  6   c    shows a detailed perspective view of a substructure of an outlet connector according to an example of the present technology. 
         FIG.  6   d    shows a top perspective view of a substructure of an outlet connector according to an example of the present technology. 
         FIG.  6   e    shows another detailed perspective view of a substructure of an outlet connector according to an example of the present technology. 
         FIG.  6   f    shows a perspective view of a substructure of an outlet connector, a tube and an electrical connector according to an example of the present technology. 
         FIG.  6   g    shows a cross-sectional perspective view of a substructure of an outlet connector, a tube and an electrical connector according to an example of the present technology. 
         FIG.  6   h    shows a perspective view of a substructure of an outlet connector according to an example of the present technology. 
         FIG.  6   i    shows a bottom perspective view of a substructure of an outlet connector according to an example of the present technology. 
         FIG.  7   a    shows a perspective view of a grommet according to an example of the present technology. 
         FIG.  7   b    shows a cross-sectional perspective view of a grommet according to an example of the present technology. 
         FIG.  7   c    shows a perspective view of a grommet according to an example of the present technology. 
         FIG.  7   d    shows another perspective view of a grommet according to an example of the present technology. 
         FIG.  7   e    shows a side view of a grommet according to an example of the present technology. 
         FIG.  7   f    shows an end view of a grommet according to an example of the present technology. 
         FIG.  8   a    shows a bottom perspective view of a swivelling disc and a cable according to an example of the present technology. 
         FIG.  8   b    shows a bottom perspective view of a cable housing, a swivelling disc, and a cable according to an example of the present technology. 
         FIG.  8   c    shows a perspective view of a cable housing according to an example of the present technology. 
         FIG.  8   d    shows a perspective view of a cable housing with a swivelling disc and a cable in a first position relative to the cable housing according to an example of the present technology. 
         FIG.  8   e    shows a perspective view of a cable housing with a swivelling disc and a cable in a second position relative to the cable housing according to an example of the present technology. 
         FIG.  8   f    shows a perspective view of a cable housing with a swivelling disc and a cable in a third position relative to the cable housing according to an example of the present technology. 
         FIG.  8   g    shows a perspective view of a cable housing with a swivelling disc, a cable, and a substructure of an outlet connector in a first position relative to the cable housing according to an example of the present technology. 
         FIG.  8   h    shows a perspective view of a cable housing with a swivelling disc, a cable, and a substructure of an outlet connector in a second position relative to the cable housing according to an example of the present technology. 
         FIG.  8   i    shows a top view of a cable housing according to an example of the present technology. 
         FIG.  9   a    shows a perspective view of a swivelling disc according to an example of the present technology. 
         FIG.  9   b    shows a side view of a swivelling disc according to an example of the present technology. 
         FIG.  9   c    shows another side view of a swivelling disc according to an example of the present technology. 
         FIG.  9   d    shows a bottom perspective view of a swivelling disc according to an example of the present technology. 
         FIG.  9   e    shows a bottom view of a swivelling disc according to an example of the present technology. 
         FIG.  10   a    shows a side view of an airflow tube according to an example of the present technology. 
         FIG.  10   b    shows another side view of an airflow tube according to an example of the present technology. 
         FIG.  10   c    shows another side view of an airflow tube according to an example of the present technology. 
         FIG.  10   d    shows an exploded perspective view of an airflow tube according to an example of the present technology. 
         FIG.  11   a    shows a side view of a cable housing according to an example of the present technology. 
         FIG.  11   b    shows a perspective view of a cable housing according to an example of the present technology. 
         FIG.  11   c    shows a top view of a cable housing according to an example of the present technology. 
         FIG.  11   d    shows another side view of a cable housing according to an example of the present technology. 
         FIG.  12   a    shows a bottom perspective view of an air circuit comprising an outlet connector and a tube connected to a cable housing and an airflow tube according to an example of the present technology. 
         FIG.  12   b    shows a bottom view of an air circuit comprising an outlet connector and a tube connected to a cable housing and an airflow tube according to an example of the present technology. 
         FIG.  12   c    shows an end view of an air circuit comprising an outlet connector and a tube connected to a cable housing and an airflow tube according to an example of the present technology. 
         FIG.  12   d    shows a side view of an air circuit comprising an outlet connector and a tube connected to a cable housing and an airflow tube according to an example of the present technology. 
         FIG.  12   e    shows a partially exploded perspective view of an air circuit comprising an outlet connector and a tube connected to a cable housing and an airflow tube according to an example of the present technology. 
         FIG.  12   f    shows a perspective view of an air circuit comprising an outlet connector and a tube connected to a cable housing and an airflow tube according to an example of the present technology. 
         FIG.  13   a    shows a top view of an outlet connector connected to a humidifier housing according to an example of the present technology. 
         FIG.  13   b    shows a side view of an outlet connector connected to a humidifier housing according to an example of the present technology. 
         FIG.  13   c    shows another side view of an outlet connector connected to a humidifier housing according to an example of the present technology. 
         FIG.  13   d    shows a perspective view of an outlet connector connected to a humidifier housing according to an example of the present technology. 
         FIG.  13   e    shows a perspective view of an outlet connector detached from a humidifier housing according to an example of the present technology. 
         FIG.  13   f    shows a perspective view of an outlet of a humidifier housing according to an example of the present technology. 
         FIG.  13   g    shows a front view of an outlet of a humidifier housing according to an example of the present technology. 
         FIG.  13   h    shows another perspective view of an outlet connector detached from a humidifier housing according to an example of the present technology. 
         FIG.  13   j    shows a perspective view of an outlet connector connected to a humidifier housing according to an example of the present technology. 
         FIG.  13   k    shows a side view of an outlet connector according to an example of the present technology. 
         FIG.  13   l    shows a top view of an outlet connector according to an example of the present technology. 
         FIG.  13   m    shows another side view of an outlet connector according to an example of the present technology. 
         FIG.  13   n    shows a perspective view of an outlet assembly according to an example of the present technology. 
         FIG.  14   a    shows a partially exploded perspective view of an air circuit comprising an outlet connector and a tube, a swivelling disc, a cable and a cable housing according to an example of the present technology. 
         FIG.  14   b    shows another partially exploded perspective view of an air circuit comprising an outlet connector and a tube, a swivelling disc, and a cable housing according to an example of the present technology. 
         FIG.  14   c    shows another partially exploded perspective view of an air circuit comprising an outlet connector and a tube, a swivelling disc, a cable and a cable housing according to an example of the present technology. 
         FIG.  14   d    shows a perspective view of an air circuit comprising an outlet connector and a tube connected to a swivelling disc, a cable and a cable housing according to an example of the present technology. 
         FIG.  14   e    shows a perspective view of a swivelling disc according to an example of the present technology. 
         FIG.  14   f    shows a perspective view of a cable housing and a cable according to an example of the present technology. 
         FIG.  14   g    shows a perspective view of an electrical connector detached from an elbow according to an example of the present technology. 
         FIG.  14   h    shows a perspective view of an electrical connector connected to an elbow according to an example of the present technology. 
         FIG.  14   i    shows a top perspective view of a tube and tube cuff according to an example of the present technology. 
         FIG.  14   j    shows a bottom perspective view of a tube and tube cuff according to an example of the present technology. 
         FIG.  15   a    shows a perspective view of a swivelling disc, a swivel electrical connector, and a cable housing assembled together according to an example of the present technology. 
         FIG.  15   b    shows a side view of an air circuit comprising an outlet connector and a tube detached from a swivelling disc, a swivel electrical connector, and a cable housing according to an example of the present technology. 
         FIG.  16   a    shows a side view of an air circuit comprising an outlet connector and a tube detached from a swivelling disc, and a cable housing according to an example of the present technology. 
         FIG.  16   b    shows a top perspective view of a cable housing and a swivelling disc according to an example of the present technology. 
         FIG.  17    shows a cross-sectional view of an air circuit comprising an outlet connector and a tube with mold tools according to an example of the present technology. 
         FIG.  18   a    shows a perspective view of a female electrical connector according to an example of the present technology. 
         FIG.  18   b    shows a side view of a female electrical connector according to an example of the present technology. 
         FIG.  18   c    shows a rear view of a female electrical connector according to an example of the present technology. 
         FIG.  18   d    shows a perspective view of a female electrical connector according to an example of the present technology. 
         FIG.  18   e    shows a front-on view of a female electrical connector according to an example of the present technology, indicating the cross section taken for  FIG.  18     f.    
         FIG.  18   f    shows a side cross-sectional view of a female electrical connector according to an example of the present technology. 
         FIG.  18   g    shows a rear perspective view of an electrical connector receiver contact element according to an example of the present technology. 
         FIG.  18   h    shows a front perspective view of an electrical connector receiver contact element according to an example of the present technology. 
         FIG.  19   a    shows an exploded bottom perspective view of a portion of a RPT device/humidifier and an airflow tube according to an example of the present technology. 
         FIG.  19   b    shows a bottom perspective view of a portion of a RPT device/humidifier and an airflow tube according to an example of the present technology. 
         FIG.  19   c    shows an exploded rear perspective view of a portion of a RPT device/humidifier and an airflow tube according to an example of the present technology. 
         FIG.  19   d    shows a rear perspective view of a portion of a RPT device/humidifier and an airflow tube according to an example of the present technology. 
         FIG.  19   e    shows a rear perspective view of a portion of a RPT device/humidifier, an airflow tube and a cable housing according to an example of the present technology. 
         FIG.  20   a    shows an exploded rear perspective view of a RPT device/humidifier and an airflow tube according to an example of the present technology. 
         FIG.  20   b    shows a rear perspective view of a RPT device/humidifier and an airflow tube according to an example of the present technology. 
         FIG.  21   a    shows a top view of an outlet assembly according to an example of the present technology. 
         FIG.  21   b    shows a cross-sectional view of the outlet assembly of  FIG.  21   a    taken through line  21   b - 21   b  according to an example of the present technology. 
         FIG.  21   c    shows a cross-sectional view of the outlet assembly of  FIG.  21   a    taken through line  21   c - 21   c  according to an example of the present technology. 
         FIG.  22   a    shows a front perspective view of a substructure assembly of an outlet connector according to an example of the present technology. 
         FIG.  22   b    shows a rear perspective view of a substructure assembly of an outlet connector according to an example of the present technology. 
         FIG.  22   c    shows another front perspective view of a substructure assembly of an outlet connector according to another example of the present technology. 
         FIG.  22   d    shows a side view of a substructure assembly of an outlet connector according to an example of the present technology. 
         FIG.  22   e    shows another side view of a substructure assembly of an outlet connector according to an example of the present technology. 
         FIG.  22   f    shows a top view of a substructure assembly of an outlet connector according to an example of the present technology. 
         FIG.  22   g    shows an exploded front perspective view of a substructure assembly of an outlet connector according to an example of the present technology. 
         FIG.  22   h    shows a partially exploded rear perspective view of a substructure assembly of an outlet connector according to an example of the present technology. 
         FIG.  23   a    shows a front perspective view of a substructure assembly of an outlet connector without electrical connectors according to an example of the present technology. 
         FIG.  23   b    shows another front perspective view of a substructure assembly of an outlet connector without electrical connectors according to an example of the present technology. 
         FIG.  23   c    shows a rear perspective view of a substructure assembly of an outlet connector without electrical connectors according to an example of the present technology. 
         FIG.  23   d    shows a side view of a substructure assembly of an outlet connector without electrical connectors according to an example of the present technology. 
         FIG.  23   e    shows a top view of a substructure assembly of an outlet connector without electrical connectors according to an example of the present technology. 
         FIG.  23   f    shows another side view of a substructure assembly of an outlet connector without electrical connectors according to an example of the present technology. 
         FIG.  24    shows a cap for a substructure assembly of an outlet connector according to an example of the present technology. 
         FIG.  25   a    shows unformed electrical connectors for an outlet connector according to an example of the present technology. 
         FIG.  25   b    shows formed electrical connectors for an outlet connector according to an example of the present technology. 
         FIG.  26   a    shows a cross-sectional view an outlet end of an outlet connector joined to a respiratory apparatus according to an example of the present technology. 
         FIG.  26   b    shows a detailed cross-sectional view an outlet end of an outlet connector joined to a respiratory apparatus according to an example of the present technology. 
         FIG.  27   a    shows a cross-sectional view an outlet end of an outlet connector joined to a respiratory apparatus according to an example of the present technology. 
         FIG.  27   b    shows a cross-sectional view an outlet end of an outlet connector joined to a respiratory apparatus according to an example of the present technology. 
         FIG.  27   c    shows a detailed cross-sectional view an outlet end of an outlet connector joined to a respiratory apparatus according to an example of the present technology. 
         FIG.  28   a    shows a cross-sectional view an outlet end of an outlet connector joined to a respiratory apparatus according to an example of the present technology. 
         FIG.  28   b    shows a cross-sectional view an outlet end of an outlet connector joined to a respiratory apparatus according to an example of the present technology. 
         FIG.  28   c    shows a detailed cross-sectional view an outlet end of an outlet connector joined to a respiratory apparatus according to an example of the present technology. 
         FIG.  29   a    shows a cross-sectional view an outlet end of an outlet connector being joined to a respiratory apparatus according to an example of the present technology. 
         FIG.  29   h    shows a cross-sectional view an outlet end of an outlet connector after being joined to a respiratory apparatus according to an example of the present technology. 
         FIG.  30   a    shows a front perspective view of a substructure assembly of an outlet connector according to an example of the present technology. 
         FIG.  30   b    shows an exploded front perspective view of a substructure assembly of an outlet connector according to an example of the present technology. 
         FIG.  30   c    shows a perspective view of a substructure assembly of an outlet connector joined to a tube portion according to an example of the present technology. 
         FIG.  30   d    shows a partially exploded perspective view of a substructure assembly of an outlet connector joined to a tube portion according to an example of the present technology. 
         FIG.  30   e    shows a perspective view of an outlet connector joined to a tube portion according to an example of the present technology. 
         FIG.  30   f    shows a cross-sectional view of a substructure assembly of an outlet connector joined to a tube portion according to an example of the present technology. 
         FIG.  30   g    shows a partially exploded bottom perspective view of a substructure assembly of an outlet connector joined to a tube portion according to an example of the present technology. 
         FIG.  30   h    shows a partially exploded bottom perspective view of a substructure assembly of an outlet connector joined to a tube portion according to an example of the present technology. 
         FIG.  30   i    shows another partially exploded bottom perspective view of a substructure assembly of an outlet connector joined to a tube portion according to an example of the present technology. 
     
    
    
     6 (E) DETAILED DESCRIPTION OF EXAMPLES OF THE TECHNOLOGY 
     Before the present technology is described in further detail, it is to be understood that the technology is not limited to the particular examples described herein, which may vary. It is also to be understood that the terminology used in this disclosure is for the purpose of describing only the particular examples discussed herein, and is not intended to be limiting. 
     The following description is provided in relation to various examples which may share one or more common characteristics and/or features. It is to be understood that one or more features of any one example may be combinable with one or more features of another example or other examples. In addition, any single feature or combination of features in any of the examples may constitute a further example. 
     6.1 Therapy Systems 
     In one form, the present technology comprises a respiratory therapy system for treating a respiratory disorder. The respiratory therapy system may comprise a RPT device  4000  for supplying a flow of breathable gas, such as air, to the patient  1000  via an air circuit  4100  leading to a patient interface  3000 . In some forms, the respiratory therapy system may further comprise a humidifier  5000  configured to humidify the flow of air relative to the ambient. 
     6.2 Therapy 
     In one form, the present technology comprises a method for treating a respiratory disorder comprising the step of applying positive pressure to the entrance of the airways of a patient  1000 . 
     In one form, the present technology comprises a method of treating Obstructive Sleep Apnea in a patient by applying nasal continuous positive airway pressure to the patient. 
     In certain examples of the present technology, a supply of air at positive pressure is provided to the nasal passages of the patient via one or both nares. 
     In certain examples of the present technology, mouth breathing is limited, restricted or prevented. 
     6.3 Patient Interface  3000   
     A non-invasive patient interface  3000  in accordance with one aspect of the present technology comprises the following functional aspects: a seal-forming structure  3100 , a plenum chamber  3200 , a positioning and stabilising structure  3300  and a connection port  3600  for connection to air circuit  4100 . For example, see  FIG.  2   c   . In some forms a functional aspect may be provided by one or more physical components. In some forms, one physical component may provide one or more functional aspects. In use the seal-forming structure is arranged to surround an entrance to the airways of the patient so as to facilitate the supply of air at positive pressure to the airways. 
     6.3.1 Seal-Forming Structure 
     In one form of the present technology, a seal-forming structure  3100  provides a sealing-forming surface, and may additionally provide a cushioning function. 
     A seal-forming structure in accordance with the present technology may be constructed from a soft, flexible, resilient material such as silicone. 
     In one form, the seal-forming structure comprises a sealing flange and a support flange. The sealing flange may comprise a relatively thin member with a thickness of less than about 1 mm, for example about 0.25 mm to about 0.45 mm, that extends around the perimeter of the plenum chamber. A support flange may be relatively thicker than the sealing flange. The support flange is disposed between the sealing flange and the marginal edge of the plenum chamber, and extends at least part of the way around the perimeter. The support flange is or includes a spring-like element and functions to support the sealing flange from buckling in use. In use the sealing flange can readily respond to system pressure in the plenum chamber acting on its underside to urge it into tight sealing engagement with the face. 
     In another form, the seal-forming portion of the non-invasive patient interface  3000  comprises a pair of nasal puffs, or nasal pillows, each nasal puff or nasal pillow being constructed and arranged to form a seal with a respective naris of the nose of a patient. 
     Nasal pillows in accordance with an aspect of the present technology include: a frusto-cone, at least a portion of which forms a seal on an underside of the patient&#39;s nose; a stalk, a flexible region on the underside of the cone and connecting the cone to the stalk. In addition, the structure to which the nasal pillow of the present technology is connected includes a flexible region adjacent the base of the stalk. The flexible regions can act in concert to facilitate a universal joint structure that is accommodating of relative movement—both displacement and angular—of the frusto-cone and the structure to which the nasal pillow is connected. For example, the frusto-cone may be axially displaced towards the structure to which the stalk is connected. 
     In one form the non-invasive patient interface  3000  comprises a seal-forming portion that forms a seal in use on an upper lip region (that is, the lip superior) of the patient&#39;s face. 
     In one form the non-invasive patient interface  3000  comprises a seal-forming portion that forms a seal in use on a chin-region of the patient&#39;s face. 
     6.3.2 Plenum Chamber 
     The plenum chamber  3200  may have a perimeter that is shaped to be complementary to the surface contour of the face of an average person in the region where a seal will form in use. In use, a marginal edge of the plenum chamber is positioned in close proximity to an adjacent surface of the face. Actual contact with the face is provided by the seal-forming structure. The seal-forming structure may extend in use about the entire perimeter of the plenum chamber. 
     6.3.3 Positioning and Stabilising Structure 
     The seal-forming portion of the patient interface  3000  of the present technology may be held in sealing position in use by the positioning and stabilising structure  3300 , for example a headgear system or strap. 
     6.3.4 Vent 
     In one form, the patient interface  3000  may include a vent  3400  constructed and arranged to allow for the washout of exhaled carbon dioxide. 
     One form of the vent  3400  in accordance with the present technology comprises a plurality of holes, for example, about 20 to about 80 holes, or about 40 to about 60 holes, or about 45 to about 55 holes. 
     The vent  3400  may be located in the plenum chamber  3200 . Alternatively, the vent may be located in a decoupling structure, e.g. a swivel or ball and socket. 
     6.3.5 Other Patient Interface Components 
     The patient interface  3000  may include one or more of the following additional components:
         (i) a forehead support  3700  that assists with supporting the patient interface on the face;   (ii) an anti-asphyxia valve to allow a patient  1000  to receive fresh air into the patient interface  3000  if required; and   (iii) one or more ports (e.g. connection port  3600 ) to allow access to the volume within the plenum chamber. In one form this allows a clinician to supply supplemental oxygen. In one form, this allows for the direct measurement of a property of gases within the plenum chamber, such as the pressure.       

     6.4 RPT Device  4000   
     A RPT device  4000  in accordance with one aspect of the present technology (see  FIG.  3   a   ) comprises mechanical and pneumatic components  4300 , electrical components  4200  and is programmed to execute one or more algorithms. An exemplary RPT device has an external housing  4010 , formed in two parts, an upper portion  4012  and a lower portion  4014 . Furthermore, the external housing  4010  may include one or more panel(s)  4015 . The RPT device  4000  may comprise a chassis  4016  that supports one or more internal components of the RPT device  4000 . In one form a pneumatic block  4020  is supported by, or formed as part of the chassis  4016 . The RPT device  4000  may include a handle  4018 . Another example of an RPT device  4000  including an integrated humidifier  5000  is shown in  FIGS.  3   b   - 3   d.    
     The pneumatic path of the RPT device  4000  (e.g. shown in  FIG.  3   e   ) may comprise an inlet air filter  4312 , an inlet muffler  4322 , a controllable pressure device  4340  capable of supplying air at positive pressure (e.g., a blower  4342 ), and an outlet muffler  4324 . One or more pressure transducers and flow transducers may be included in the pneumatic path. 
     A pneumatic block  4020  houses at least the controllable pressure device  4340  (e.g. blower  4342 ). The pneumatic block may comprise a portion of the pneumatic path that is located within the external housing  4010 . In one form, the chassis  4016  may form a part of the pneumatic block  4020  as shown in  FIG.  3   a   . In another form, the chassis  4016  may support the pneumatic block  4020  without forming a part thereof as shown in  FIG.  3     b.    
     The RPT device  4000  may have an electrical power supply  4210 , one or more input devices  4220 , a central controller  4230 , a therapy device controller  4240 , a pressure device, one or more protection circuits, memory, transducers  4270 , data communication interface and one or more output devices. Electrical components  4200  may be mounted on a single Printed Circuit Board Assembly (PCBA)  4202 . In an alternative form, the RPT device  4000  may include more than one PCBA  4202 . 
     The central controller of the RPT device  4000  may be programmed to execute one or more algorithm modules, including a pre-processing module, a therapy engine module, a pressure control module, and further a fault condition module. 
     6.4.1 RPT Device Mechanical &amp; Pneumatic Components  4300   
     6.4.1.1 Air Filter(s)  4310   
     A RPT device in accordance with one form of the present technology may include an air filter  4310 , or a plurality of air filters  4310 . 
     In one form, an inlet air filter  4312  is located at the beginning of the pneumatic path upstream of a blower  4342 . See  FIG.  3     e.    
     In one form, an outlet air filter  4314 , for example an antibacterial filter, is located between an outlet of the pneumatic block  4020  and a patient interface  3000 . See  FIG.  3     e.    
     6.4.1.2 Muffler(s)  4320   
     In one form of the present technology, an inlet muffler  4322  is located in the pneumatic path upstream of a blower  4342 . See  FIG.  3     e.    
     In one form of the present technology, an outlet muffler  4324  is located in the pneumatic path between the blower  4342  and a patient interface  3000 . See  FIG.  3     e.    
     6.4.13 Pressure Device  4340   
     In a form of the present technology, a pressure device  4340  (also referred to as a pressure generator) for producing a flow of air at positive pressure is a controllable blower  4342 . For example, the blower may include a brushless DC motor  4344  with one or more impellers housed in a volute. The blower may be capable of delivering a supply of air, for example about 120 litres/minute, at a positive pressure in a range from about 4 cmH 2 O to about 20 cmH 2 O, or in other forms up to about 30 cmH 2 O. 
     The pressure device  4340  is under the control of the therapy device controller  4240 . 
     6.4.1.4 Transducer(s)  4270   
     One or more transducers  4270  may be constructed and arranged to measure properties of the air at one or more predetermined points in the pneumatic path, or of the ambient air. 
     In one form of the present technology, one or more transducers  4270  are located downstream of the pressure device  4340 , and upstream of the air circuit  4100 . In one form of the present technology, one or more transducers  4270  are located upstream of the pressure device  4340 . 
     In one form of the present technology, one or more transducers  4270  are located proximate to the patient interface  3000 . 
     6.4.1.5 Anti-Spill Back Valve  4360   
     In one form of the present technology, an anti-spill back valve is located between the humidifier  5000  and the pneumatic block  4020 . The anti-spill back valve is constructed and arranged to reduce the risk that water will flow upstream from the humidifier  5000 , for example to the motor  4344 . 
     6.4.1.6 Air Circuit  4100   
     An air circuit  4100  in accordance with an aspect of the present technology is constructed and arranged to allow a flow of air or breathable gasses between the pneumatic block  4020  and the patient interface  3000 . 
     6.4.1.7 Oxygen Delivery  4380   
     In one form of the present technology, supplemental oxygen  4380  is delivered to a point in the pneumatic path. 
     In one form of the present technology, supplemental oxygen  4380  is delivered upstream of the pneumatic block  4020 . 
     In one form of the present technology, supplemental oxygen  4380  is delivered to the air circuit  4100 . 
     In one form of the present technology, supplemental oxygen  4380  is delivered to the patient interface  3000 . 
     6.4.2 RPT Device Electrical Components  4200   
     6.4.2.1 Power Supply  4210   
     Power supply  4210  supplies power to the other components of the basic RPT device  4000 : the input device  4220 , the central controller  4230 , the pressure device  4340 , and the output device  4290  (see  FIG.  3   f   ). 
     In one form of the present technology, power supply  4210  is internal of the external housing  4010  of the RPT device  4000 . In another form of the present technology, power supply  4210  is external of the external housing  4010  of the RPT device  4000 . 
     6.4.2.2 Input Device(s)  4220   
     Input device  4220  comprises buttons, switches or dials to allow a person to interact with the RPT device  4000 . The buttons, switches or dials may be physical devices, or software devices accessible via a touch screen. The buttons, switches or dials may, in one form, be physically connected to the external housing  4010 , or may, in another form, be in wireless communication with a receiver that is in electrical connection to the central controller. 
     In one form, the input device  4220  may be constructed and arranged to allow a person to select a value and/or a menu option. 
     6.4.2.3 Central Controller  4230   
     In one form of the present technology, the central controller  4230  is one or a plurality of processors suitable to control an RPT device  4000 . The central controller  4230  may be configured to receive input signal(s) from the input device  4220 , and to provide output signal(s) to the output device  4290  and/or the therapy device controller  4240   
     Suitable processors may include an x86 INTEL processor, a processor based on ARM Cortex-M processor from ARM Holdings such as an STM32 series microcontroller from ST MICROELECTRONIC. In certain alternative forms of the present technology, a 32-bit RISC CPU, such as an STR9 series microcontroller from ST MICROELECTRONICS or a 16-bit RISC CPU such as a processor from the MSP430 family of microcontrollers, manufactured by TEXAS INSTRUMENTS may also be suitable. 
     In one form of the present technology, the central controller  4230  is a dedicated electronic circuit. 
     In one form, the central controller  4230  is an application-specific integrated circuit. In another form, the central controller  4230  comprises discrete electronic components. 
     6.4.2.4 Output Device  4290   
     An output device  4290  in accordance with the present technology may take the form of one or more of a visual, audio, and haptic output. A visual output may be a Liquid Crystal Display (LCD) or Light Emitting Diode (LED) display. An audio output may be a speaker or audio tone emitter. 
     6.5 Humidifier  5000   
     6.5.1 Humidifier Overview 
     In one form of the present technology there is provided a humidifier  5000  to change the absolute humidity of air for delivery to a patient relative to ambient air. Typically, the humidifier  5000  is used to increase the absolute humidity and increase the temperature of the flow of air relative to ambient air before delivery to the patient&#39;s airways. The humidifier  5000  typically comprises an inlet to receive a flow of air, and an outlet to deliver the flow of air with added humidity. 
     In one form, a humidifier  5000  may comprise a humidifier reservoir  5180 , a heating element  5240  and one or more transducers. The humidifier  5000  may be configured to receive a flow of air from a RPT device and deliver a flow of humidified air to a patient interface  3000  for example via an air circuit  4100 . The air circuit  4100  may be coupled to the humidifier  5000  through an outlet, such as the humidifier reservoir outlet  5182  as shown in  FIG.  3   g    and  FIG.  3     h.    
     As described above, the humidifier  5000  may deliver a pressurised flow of air to the patient  1000  with sufficient humidity to prevent drying of the mucosa and increase patient airway comfort. At the same time, the humidifier  5000  and the air circuit  4100  is configured to prevent occurrence of any condensation, especially in the air circuit  4100 . To this end, the air circuit  4100  may be provided with a heating element as will be described in greater detail below. The humidifier  5000  and the air circuit  4100  may be further configured to allow the patient  1000  to arrange the air circuit  4100  to improve their sleeping comfort. Further, the humidifier  5000  and the air circuit  4100  are configured to allow cleaning of the air circuit  4100  and/or the humidifier  5000 , and to prevent ingress of water into any electronic components, such as in the humidifier  5000 , the air circuit  4100  or the RPT device  4000 . 
     An example of a humidifier  5000  which is integrated with an RPT device  4000  is shown in  FIGS.  3   b - 3   d   . Another example of a humidifier  5000  is shown in  FIGS.  3   g   - 3   h.    
     6.6 Air Circuit-Outlet Connection 
     6.6.1 Connection Overview 
     As described in some detail above, a respiratory therapy system may include certain components such as a RPT device  4000 , a humidifier  5000 , and a patient interface  3000 . The RPT device  4000  and humidifier  5000  may be combined into a single, integrated unit as shown in  FIG.  3   b - 3   d   . Alternatively, the RPT device  4000  and the humidifier  5000  may be separable such that the patient can use the RPT device without the humidifier. In either scenario a connection must be made to the patient interface  3000  so that the patient can receive the flow of gas from the RPT device  4000  and/or the humidifier  5000 . An air circuit  4100 , as described above, may be provided to pneumatically connect the patient interface  3000  to the RPT device  4000  and/or the humidifier  5000 . As shown in  FIG.  4   a   , the air circuit  4100  may include a tube portion  4102  and an outlet connector  4106  to connect the air circuit to the RPT device  4000  and/or the humidifier  5000 . The tube portion  4102  may also include a helical coil  4103  to provide support for the tube portion. The air circuit  4100  may also incorporate a heating element, which may be provided within the helical coil  4103 . The heating element in the air circuit  4100  may heat the air circuit  4100  and the flow of gas travelling therethrough in order to prevent rainout (condensation of water vapor, for example, within the tube portion  4102  or the patient interface  3000 ). When a heating element is provided in the helical coil  4103  electrical power and/or signalling may be necessary if, for example, the heating element is an electrical resistance heater. In some instances, an electrical connection may be required between the patient interface  3000  and the RPT device  4000  and/or the humidifier  5000  for electrical power and/or communication therebetween. 
       FIG.  20   a    and  FIG.  20   b    show an example of the RPT device  4000  and a humidifier  5000  that has been combined into a single, integrated unit, wherein a water reservoir is not shown.  FIG.  20   a    shows an air circuit  4100  separated from the RPT device  4000  in an exploded view, and  FIG.  20   b    shows the air circuit  4100  assembled with the RPT device  4000 . 
     6.6.1.1 Pneumatic and Electrical Connections with a Single Connector 
     The air circuit  4100  may require both pneumatic and electrical connections to be formed to the humidifier  5000  (or the RPT device  4000 ), as well as a mechanical connection. These connections may be formed through the outlet connector  4106  to allow the pressurized gas to flow to the patient interface  3000 , to provide electrical power and signalling to the heating element in the helical coil  4103  and to locate and secure the air circuit  4100  relative to the humidifier  5000  (or the RPT device  4000 ). These connections may be formed simultaneously or in series such that one of the mechanical, pneumatic or electrical connections is completed before others. The air circuit  4100  may comprise on another end a patient interface connector  4107  to couple to a patient interface  3000 . In some forms, the patient interface connector  4107  may be different to the outlet connector  4106  as shown in  FIGS.  4   g   - 4   h.    
       FIGS.  4   a - h  and  5   a - i    depict air circuits or portions thereof according to examples of the present technology.  FIGS.  12   a - f    also depict exemplary air circuits that are connected to an outlet assembly  5107 . As can be seen in  FIG.  4   a   , for example, a tube portion  4102  having a helical coil  4103  may be connected to an outlet connector  4106 . As shown in  FIG.  5   a    the connection of the helical coil  4103  to the outlet connector  4106  may be facilitated by the use of a grommet  4104 . The helical coil  4103 , as discussed above, may include a heating element and it may also function as a support structure for the tube portion  4102 . An electrical connection may be formed by inserting the outlet connector  4106  on the outlet assembly  5107  (to be discussed in greater detail below) so that an electrical connector  4112  comes into electrical contact with electrical components of the outlet assembly. As can be seen in  FIGS.  4   c - d   , the electrical connector  4112  may be oriented parallel a centre axis of the outlet connection region  4114  and extend downward from an underside of the outlet connector  4106  and out from an opening  4118 . 
     6.6.1.1.1 Formation of Pneumatic and Electrical Connections 
     A recess  4116  may also be formed on the outlet connector  4106 , the recess  4116  being configured to couple to an electrical connector receiver  5114  of a swivelling disc  5104  (see  FIG.  8   d    and further discussion below) to aid in releasably securing the outlet connector  4106  to the humidifier  5000 , for example at the outlet assembly  5107 . The recess  4116  may also provide a visual aid to the patient to locate the outlet connector  4106  in relation to the outlet assembly  5107  by being shaped to correspond to the electrical connector receiver  5114  (see  FIG.  12   e   ). The electrical connector receiver  5114  may house a female electrical connector  5158  such as that shown in  FIGS.  18   a - 18   h   . The outlet connector  4106  may also include an actuator  4108  that controls a retention feature  4110 . When the outlet connector is inserted onto the outlet assembly  5107 , the retention feature  4110  may engage with a corresponding notch  5126  of the swivelling disc  5104  (see  FIG.  21   b    and further discussion below). The actuator  4108  in conjunction with the notch  5126  may produce an audible sound and/or provide tactile feedback at the actuator  4108  upon engagement. The actuator  4108  and/or the retention feature  4110  may be produced with higher wear characteristics than the swivelling disc  5104  to allow wear to occur on the air circuit  4100 , which is typically a consumable component. This may be achieved by use of a material with lower hardness to form the retention feature  4110  compared to the material from which the swivelling disc  5104  is formed. The retention feature  4110  and notch  5126  may engage by a snap-fit and the actuator  4108  may be depressible to bring in the retention feature to release it from the notch  5126 . In some cases, the retention feature  4110  and the notch  5126  may be configured so that when they are not completely engaged, they may be forced into place at commencement of therapy by the therapy pressure, for example by being configured so that the therapy pressure acting on the tab  4148  urges the retention feature  4110  towards the notch  5126 . As shown in  FIG.  6   a   , the actuator  4108  and the retention feature  4110  may both be located on a tab  4148  such that pushing the actuator inward also causes the retention feature to be moved inward, thereby freeing it from the notch  5126 . In one form, the actuator  4108  may be located further from a pivot of the tab  4148  than the retention feature  4110 , which would impart a mechanical advantage to the user and increase the travel required to depress the actuator  4108  to improve the resolution of movement of the retention feature  4110  to the user. This arrangement may further improve the feedback provided to the user during engagement/disengagement of the outlet connector  4106 . An outlet connection region  4114  may be shaped to correspond with the shape of the swivelling disc  5104 , as shown in  FIG.  9   a   , for example. 
     As shown in  FIGS.  6   h  and  6   g   , a travel stop  4178  located at the inner ends of the ribs  4120  may be used in some examples of this technology in order to limit the travel, or level of squeezing, of the actuator  4108  during insertion and removal to prevent plastic deformation of the surrounding portions and/or to prevent tear of the housing  4134 . The travel stops  4178  extend from the inner ends of the ribs  4120  and are aligned with the inner surface of the outlet connector  4106  in the location of the actuator  4108 . When the actuator is squeezed or pushed inwards the inner surface of the outlet connector  4106  is correspondingly squeezed or pushed inwards until it contacts the travel stop  4178 . The travel stop prevents further squeezing or pushing of the actuator. 
     In a further example of the technology, the notch may be replaced with a radial slot that is capable of retaining the outlet connector via the retention feature(s) but allowing rotation thereof. In such an example the swivelling disc may be fixed relative to the outlet housing or it may be eliminated completely such that the radial slot is located on the housing. Furthermore, it should be understood that such examples would retain the need for a movable electrical connector within the outlet assembly such that the electrical connection may be maintained while the outlet connector rotates. 
       FIGS.  4   e  and  4   f    show detailed bottom views of examples of the outlet connector  4106  and specifically the outlet connection region  4114 .  FIG.  4   e    shows the outlet connector  4106  connected at the outlet connection region  4114  to an outlet end  5134  of an airflow tube  5130  (shown in  FIGS.  10   a - d    and discussed further below). The airflow tube  5130  may be formed as a multiple patient/multiple user (MPMU) tube that is removable, replaceable and/or cleanable. It should be noted that for the sake of clarity the outlet end  5134  is shown in this view and reference should be made to  FIGS.  10   a - d    for further depiction. The airflow tube  5130  may function as a removable intermediate pneumatic coupling between the outlet connector  4106  of the air circuit  4100  and the air outlet of RPT device  4000  and/or the humidifier  5000 . 
     6.6.1.1.2 Internal Ribs of the Outlet Connector  4106   
       FIG.  4   e    shows a plurality of ribs  4120  disposed around the inner periphery of the outlet connection region  4114  of the outlet connector  4106 . In the illustrated example four ribs  4120  are shown but a different number of ribs such as two, three, five or more ribs may be utilised. The ribs  4120  may function to support and position the outlet connector  4106  relative to the outlet end  5134  of the airflow tube  5130 . The ribs  4120  may function to guide the outlet connector  4106  during insertion to couple to the outlet end  5134  of the airflow tube  5130  in the outlet assembly  5107  to form the pneumatic connection. This guidance may also assist in aligning the outlet connection region  4114  to facilitate the electrical connection between the electrical connector  4112  and the electrical connector receiver  5114  on the swivelling disc  5104  of the outlet assembly  5107 . In this arrangement, although a single action is required for insertion or connection of the air circuit outlet connector  4106  to the RPT device outlet assembly  5107 , the pneumatic connection is formed first and the electrical connection is formed second. The outlet connector  4106 , the outlet assembly  5107  and the airflow tube  5130  may be configured such that airflow tube  5130  engages the seal  4170  of the outlet connector  4106  prior to the electrical connector receiver  5114  forming an electrical connection with the electrical connector  4112 . Accordingly, during removal or disconnection, the electrical connection is the first to be disconnected and the pneumatic connection is disconnected second. This may be advantageous to ensure that a pneumatic seal is maintained from the RPT device  4000  and/or the humidifier  5000  to the air circuit  4100  and, more specifically, between the outlet connector  4106  and the airflow tube  5130 . Furthermore, this may provide improved safety, for examples if supplemental oxygen is added to the flow of air delivered by the humidifier  5000 , as this arrangement may prevent oxygen from being exposed to connection and/or disconnection of the electrical connections.  FIG.  4   f    shows a similar view to  FIG.  4   e   , however, the outlet end  5134  of the airflow tube  5130  is not shown to provide a clearer depiction of an example of the ribs  4120 . Both of these views also show the profile of the recess  4116 . 
     In some cases, a non-heated air circuit  4100  may be used that does not incorporate a heating element. Accordingly, the diameter of the central opening in the swivelling disc  5104  may be arranged (e.g., sufficiently sized and/or shaped) to accept such a non-heated air circuit  4100 . Accordingly, in one example of the current technology, the external diameter of the airflow tube may be approximately 22 mm to allow connection to a standard 22 mm external diameter non-heated air circuit, and the external diameter of the outlet connector  4106  may be approximately 36 mm. However, it is recognised that other external diameter sizes may be utilised. 
     Internal ribs  4120  may be used to reduce any radial gaps between the interior of the outlet connection region  4114  and the airflow tube  5130 . Still further, the ribs  4120  and the airflow tube  5130  may be configured so that the gaps therebetween are relatively smaller than the gap between the exterior of the outlet connection region  4114  and the swivelling disc  5104 . This may allow more of the wear from rotation to occur on the airflow tube  5130  in comparison to the swivelling disc  5104 , which may be advantageous as the airflow tube  5130  may be more readily replaced than the swivelling disc  5104 . 
     Another advantage of the ribs  4120  may be to allow a greater portion of any mechanical load that may result from tilting and/or non-axial movement to be transferred from the outlet connector  4106  to the airflow tube  5130 . This may be advantageous in that this may help wear occur on the consumable components such as the air circuit  4100  and/or the airflow tube  5130  than the non-consumable components of the humidifier  5000 , such as the swivelling disc  5104 . Yet another advantage of the ribs  4120  may be to maintain or restrict the deformation of the base seal  4170  (as shown in  FIG.  5   e   ) during engagement of the outlet connector  4106  with the outlet assembly  5107  by limiting the maximum axial deformation that the base seal  4170  can undergo towards the interior of the outlet connector  4106 . 
     6.6.1.1.3 Electrical Connection 
     The electrical connector  4112  may include one or more lead-in features, such as chamfers, or curved radii on its edges on the leading surface in the direction of insertion such as shown in  FIG.  5   c   . This may assist insertion of the electrical connector  4112  into the electrical connector receiver  5114  to provide a surface wipe connection and prevents damage to the conductors on the electrical connector  4112 . The thickness of the electrical leads  4128  on the electrical connector  4112  may be approximately between 0.2 mm to 1.2 mm, for example 0.4 mm, 0.6 mm, 0.8 mm or 1 mm. The thickness may vary according to a number of parameters such as, the design life of the electrical connector  4112 , material chosen for the electrical leads  4128  and the material chosen for the receiver contact elements  5146 . One suitable example of material for the electrical leads  4128  may be high temper phosphor bronze, that is nickel plated and then gold plated. In some circumstances, an increased amount of conductive material and/or high conductivity plating (such as gold and/or platinum) may be used on the electrical leads  4128 . This may have the advantage of improving wear characteristics and/or dissipating heat from the connector  4112 . The electrical leads  4128  may have exposed conductive surfaces on the lower end of the electrical connector  4112  to ensure full insertion is required to make the electrical connection. 
     Another feature provided by the connection of the electrical connector  4112  to the electrical connector receiver  5114  on the swivelling disc  5104  may be that when assembled together, the electrical connector receiver  5114  is covered by the outlet connector  4106  as shown in  FIG.  12   e    and  FIG.  12   f   .  FIG.  12   e    shows an exploded view wherein the outlet connector  4106  is shown above the swivelling disc  5104 , and  FIG.  12   f    shows the outlet connector  4106  in engagement with the swivelling disc  5104 . Discussed above was the shape of the recess  4116 , as shown in  FIG.  4   c   , such that it may conform to the inward portion of the electrical connector receiver  5114  depicted in  FIG.  9   a   , for example.  FIGS.  4   c  and  4   d    also depict the region of the outlet connector  4106  that surrounds the opening  4118  of the outlet connector where the electrical connector  4112  (not shown in  FIG.  4   d   ) is received. When the outlet connector  4106  is inserted onto the swivelling disc  5104 , as shown in  FIGS.  12   c  and  12   d   , the region of the outlet connector that surrounds the electrical connector  4112  may cover over the opening in the electrical connector receiver  5114  to prevent debris and contaminants (such as liquids) from entering into the electrical connector receiver. As mentioned above, the connector  4112  and the receiver  5114  are configured so that the electrical connection between them is to be made after the outlet connector  4106  is mechanically engaged with the swivelling disc  5104 . This reduces the proportion of any deformation or load from misalignment between the outlet connector  4106  and the swivelling disc  5104  that is supported by the electrical connector  4112  and the receiver  5114 . This may be achieved by configuring the outlet connector  4106  and the swivelling disc  5104  so that during insertion of the outlet connector  4106  with the swivelling disc  5104 , the airflow tube  5130  and the ribs  4120  engage prior to engagement of the electrical connector  4112  and the receiver  5114 . This configuration may also be advantageous in cases where the gas provided via the air circuit  4100  includes supplementary oxygen, as it may prevent occurrence of electrical arcing while the pneumatic circuit is not isolated. 
     A yet another feature of the current technology may be found in the arrangement of the receiver contact elements  5146  on the female electrical connector  5158  in the electrical connector receiver  5114  as shown in  FIG.  18   a - 18   b   . The electrical leads  4128  may engage the receiver contact elements  5146  as the electrical connector  4112  is inserted into the receiver  5114  from the top of the connector TS. This engagement may occur via a sliding action in the direction of the arrow ENG shown in  FIG.  18   a - 18   b   . The receiver contact elements  5146  may be configured in a sloped, triangular profile as shown in  FIG.  18   b    and/or to be compliant in a perpendicular direction PER to the sliding plane to assist in their engagement with the electrical leads  4128 . 
     The aforementioned triangular profile and/or compliance may allow improved engagement between the electrical leads  4128  on the connector  4112  and the receiver contact elements  5146  as the connector  4112  is progressively inserted into the electrical connector receiver  5114 . During engagement with the connector  4112 , as the connector  4112  slides along the length of the female electrical connector  5158  the contact elements  5146  may be depressed inwards and maintain contact to the electrical leads  4128 . This may allow improved accommodation of mechanical tolerances from such sources as manufacturing variance or in-use deformation. 
     Still further, the receiver contact elements  5146  may be biased, so that when deformed from its original configuration (as shown in  FIG.  18   b   ) and depressed inwards, the receiver contact elements  5146  may be biased towards returning to the undeformed position, thereby improving the fidelity of its connection with the electrical leads  4128 . Another advantage of such an arrangement of the female electrical connector  5158  may be that it is self-cleaning. As the female electrical connector  5158  and the connector  4112  may engage each other in a slide-on, slide-off action, it may prevent build-up of contaminants which, if left uncleaned, may affect the fidelity of the electrical connection formed between the two parts. Any contaminants that have been removed by the wiping action may be prevented from entering the air path, for example by swivel disc seal  5113 . In addition when the female electrical connector  5158  is arranged in a vertical position and the connection is made in a vertical direction any contaminants that are wiped off the electrical contacts will fall down below the connector. A cavity may be formed below the female electrical connector  5158  within the receiver  5114  into which the contaminants may collect. This cavity is not in communication with the airpath. 
       FIG.  18   c    shows the surface of the female electrical connector  5158  that may be connected to the cable  5102 . The connector comprises a plurality of weld points  5150 ,  5152 ,  5154 , for example there may be two weld points for each of the conductive tracks, which allows for improved mechanical strength against load. The connector may also incorporate one or more pegs, rivets or pins  5156  for alignment during assembly and/or mechanical bonding. Optionally the one or more pegs, rivets or pins  5156  may be heat staked to provide a mechanical restraint. In certain arrangements a washer or plate may be provided between the one or more pegs, rivets or pins  5156  and the cable to spread the mechanical restraint force over a larger surface of the connector. 
       FIGS.  18   d - 18   f    show another example of the female electrical connector  5158 , including another example of receiver contact elements  5146 , shown in further detail in  FIGS.  18   g - 18   h   . A feature of this example of the receiver contact element  5146  is that a bifurcated retention feature  5162  is formed from the base portion  5166  rather than the contact portion  5164  and/or the curved portion  5168 . The receiver contact elements  5146  may be made from a material of high electrical and thermal conductivity with high strength and hardness, such as beryllium copper. 
     Having the exposed electrical connections on the outlet connector  4106  of the air circuit  4100  provides additional electrical safety as the air circuit does not include a power supply but requires connection to swivelling disc  5104  on the RPT device  4000  and/or humidifier  5000  to receive power. Also, the exposed electrical connections that may be exposed to cleaning processes are also on the replaceable air circuit  4100  component. 
     6.6.1.2 Elbow Outlet Connector 
     By forming the outlet connector  4106  with an elbow, as can be seen in  FIGS.  4   a - b ,  5   a - f , and  12   a - d   , the chance that the air circuit  4100  is accidentally or unintentionally pulled off of the RPT device  4000  and/or the humidifier  5000  (e.g., by the patient tugging at the air circuit  4100  during sleep by accident) may be reduced, because the direction of the tension force vector of the air circuit will be located at an angle (e.g., perpendicular) to the direction of engagement of the air circuit  4100  with RPT device  4000  and/or the humidifier  5000 . Also, as shown in  FIGS.  1   a - c   , the RPT device  4000  and/or the humidifier  5000  may be located on a nightstand, for example, during treatment such that the patient lying in bed is at substantially the same height as the RPT device and/or the humidifier. In such a situation, the inclusion of an elbow as part of the outlet connector  4106  may allow the air circuit  4100  to be pointed more directly at the patient such that bend angles of the air circuit may be reduced, particularly at or near the elbow, which in turn may reduce stress on the air circuit. In one example of the present technology, the outlet connector  4106  may include an elbow having an angle of about 90°. It should be understood, however, that any number of angles may be possible, such as for example between 0° and 120°, including 20°, 40°, 60°, 80° or 100°. The choice of this angle may be affected by any number of design requirements such as flow impedance, convenience, location of the outlet connector  4106  or noise implications. 
     6.6.1.3 Rotatable Outlet Connector 
     As the patient may move during treatment, thus pulling the air circuit  4100 , it may be advantageous to further reduce the bend angles of the air circuit and reduce stress on the assembly, in particular the air circuit, as well as the connection thereto from the outlet connector  4106 . This may be accomplished by allowing the outlet connector  4106  to rotate relative to the RPT device  4000  and/or the humidifier  5000  while the mechanical, pneumatic and electrical connections are maintained. 
     As described above, the air circuit  4100  may be connected to the RPT device  4000  and/or the humidifier  5000  by inserting the outlet connector  4106  onto the outlet assembly  5107 , as shown in  FIGS.  12   a - d   . Rotatability may be provided by features shown in  FIGS.  8   a - h ,  9   a - c ,  11   a - d ,  12   a - d , and  21   a   - c.    
       FIGS.  8   a ,  8   b ,  8   d - h ,  9   a - c ,  21   a - c    show various views of the swivelling disc  5104  according to various examples of the technology. It has been described above that the swivelling disc  5104  may be the component that receives the outlet connector  4106  when connecting the air circuit  4100  to the RPT device  4000  and/or the humidifier  5000 . The swivelling disc  5104  may also provide rotatability (e.g., for the outlet connector  4106 ) relative to the RPT device and/or the humidifier while maintaining the pneumatic and the electrical connections. 
       FIGS.  8   a  and  9   a - c    show views of swivelling disc  5104  according to examples of the present technology.  FIG.  8   a    shows a perspective view of the bottom of the exemplary swivelling disc  5104 . In other words, this view depicts features of the swivelling disc  5104  that are located opposite the side to which the outlet connector  4106  may connect. A cable  5102 , to be discussed in greater detail below, can be seen extending from an underside of the electrical connector receiver  5114 . An end of the cable  5102  that is inside of the electrical connector receiver  5114  may be in electrical communication with the electrical connector  4112  when the outlet connector  4106  is inserted onto the swivelling disc  5104 . The free end of the cable  5102  shown may be in electrical communication with at least one electrical component  4200  of the RPT device  4000  and/or the humidifier  5000  (e.g., a controller, printed circuit board (PCB) and/or a power supply), for example at another end of the cable  5102  (not shown). It should also be understood that the cable  5102  may be of any sufficient length to perform its connective function, as will be discussed in greater detail below. 
     A pair of disc stop surfaces  5108 ,  5110  on either side of and adjacent to the cable  5102  are shown in  FIG.  8   a   . These disc stop surfaces  5108 ,  5110  may limit rotation of the swivelling disc  5104  relative to a cable housing  5100 , as will be described in greater detail below. The exit flange  5109  around the cable  5102  also supports the cable  5102  as it extends through the outlet assembly  5107  from where it is connected to the female electrical connector  5158  in the electrical connector receiver  5114 . A flange  5112  may be disposed radially about the swivelling disc  5104  to perform sealing and/or cable  5102  containment functions, as will be discussed in greater detail below as well. The notch  5126 , of which there may be more than one, may also be seen. 
       FIGS.  9   b - e    show similar features to those described in relation to  FIG.  8   a   , but also show tangs  5128  that may allow the swivelling disc  5104  to be snap-fit onto the cable housing  5100 . The tangs  5128  may also retain the swivelling disc  5104  on the cable housing  5100  while allowing it to rotate relative thereto. 
     The swivelling disc  5104  may also incorporate a swivel disc seal  5113  as shown in  FIG.  9   a - 9   e    that may comprise a compliant material such as TPE. The swivel disc seal  5113  may function to maintain a seal between the swivelling disc  5104  and the airflow tube  5130  to prevent any contaminants from entering the air path. 
     As described above, the outlet connector  4106  may be releasably coupled to the swivelling disc  5104  by engagement of the retention features  4110  in corresponding notches  5126  and by engagement of the recess  4116  onto the electrical connector receiver  5114 . When connected to the swivelling disc  5104 , the outlet connector  4106  may be able to rotate in unison with the swivelling disc and relative to the cable housing  5100 . 
       FIGS.  21   a - c    show views of the swivelling disc  5104  joined to the cable housing  5100 .  FIG.  21   a    shows a top view of an outlet assembly according to an example of the present technology. In  FIGS.  21   a - c    the swivelling disc  5104  may be in an intermediate rotational position relative to the cable housing  5100 . 
       FIG.  21   b    shows a cross-section of the outlet assembly  5107  across the symmetrical plane of the female electrical connector  5158  taken through line  21   b - 21   b  of  FIG.  21   a   . This example of the current technology shows an internal shoulder  5160  that recesses the female electrical connector  5158  from the opening of the electrical connector receiver  5114 , which may improve the electrical safety of the electrical connector receiver  5114  when engaging with and/or disengaging from the connector  4112 . Recessed placement of the female electrical connector  5158  from the opening of the electrical connector receiver  5114  may also prevent occurrence of any electrical arcing at or near an exposed area. The current arrangement of the female electrical connector  5158  and the electrical connector receiver  5114  may also prevent any powered components from being touched by a user. 
       FIG.  21   c    shows another cross-sectional view of the outlet assembly  5107  taken through line  21   c - 21   c  of  FIG.  21   a   . Inner wall  5101  of the swivelling disc  5104  can be seen within the outer wall of the cable housing  5100 . The tabs  5106  of the cable housing  5100  can also be seen. The flange  5112  of the swivelling disc  5104  can also be seen above the outer wall  5103  of the cable housing  5100 . 
     6.6.1.3.1 Limited Rotation 
     Another feature of the present technology can be seen in  FIGS.  8   a  and  8   c   . The disc stop surfaces  5108 ,  5110  (shown in  FIG.  8   a   ), discussed above, have a pair of complementary housing stop surfaces  5120 ,  5122  (shown in  FIG.  8   c   ) that may be located on an inner wall  5101  of the cable housing  5100 . By connecting the swivelling disc  5104  to and within the inner wall  5101  of the cable housing  5100 , for example as shown in  FIGS.  8   d - 8   f   , the rotation of the swivelling disc  5104  relative to the cable housing  5100  may be limited by engagement of corresponding stop surfaces at or near its extreme positions. Rotation of the swivelling disc  5104 , in one example of the technology, may be limited to less than about 360°. Rotation may also be limited to an amount that is greater than about 180°. In a further example, rotation may be limited to about 270°. The desired range of rotation of the swivelling disc  5104  may be determined by a number of factors, such as the location of the swivelling disc  5104  with respect to the RPT device  4000  and/or humidifier  5000 , the elbow angle of the outlet connector  4106 , and material properties of the components. 
     The depicted examples show two pairs of complementary stop surfaces, as discussed above, that may represent opposite ends or surfaces of one structure. It may be possible to have multiple stop structures formed on respective components. For example, the stop surfaces on the inner wall of the housing may be provided with two separate protrusions thereon and likewise for the swivelling disc. It is also envisioned that multiple configurations of stop surfaces may be provided on a single combination of housing and swivelling disc such that one combination may include a number of available rotational limits. 
       FIG.  8   d    shows the swivelling disc  5104  rotated into one extreme position in the counter-clockwise direction relative to the cable housing  5100 .  FIG.  8   f    shows the swivelling disc  5104  rotated into another extreme position towards the other limit of travel in the clockwise direction relative to the cable housing  5100 .  FIG.  8   e    shows the swivelling disc  5104  in a position relative to the cable housing  5100  that is between the extreme positions shown in  FIGS.  8   d  and  8   f   . Although the swivelling disc  5104  does not allow the stop surfaces  5108 ,  5110 ,  5120 ,  5122  to be seen in  FIGS.  8   d - f   , it should be understood that when the swivelling disc  5104  is in either extreme position shown in  FIGS.  8   d  and  8   f    that one of the disc stop surfaces  5108 ,  5110  is engaged and/or abutted against a corresponding housing stop surface  5120 ,  5122 . 
       FIGS.  8   g  and  8   h    also show examples of the swivelling disc  5104  rotated into clockwise and counter-clockwise extreme positions relative to the cable housing  5100 .  FIGS.  8   g  and  8   h    also show a substructure  4132  (shown in greater detail in  FIGS.  6   a - g    and described further below) of the outlet connector  4106  connected to the swivelling disc  5104 . The position of the swivelling disc  5104  and the substructure  4132  in  FIG.  8   g    corresponds to the position shown in  FIG.  8   f    and, likewise,  FIG.  8   h    corresponds to  FIG.  8   d   . While not visible in  FIGS.  8   g  and  8   h   , it should be understood that each tab  4148  includes a retention feature  4110  that is engaged with a corresponding notch  5126  of the swivelling disc  5104  to releasably connect the substructure to the swivelling disc so that they may rotate in unison relative to the cable housing  5100 . It should also be understood that  FIGS.  8   g  and  8   h    depict possible extreme positions of the rotation of the substructure  4132  in this example by virtue of the connection of the substructure to the swivelling disc  5104 . 
     6.6.1.4 Electrical Cable Connection 
     As discussed above, the cable  5102  may be provided to electrically connect the electrical connector  4112  to at least one electrical component of the RPT device  4000  and/or the humidifier  5000 . The cable  5102  shown in  FIGS.  8   a - h    may be a flexible circuit board (FCB) or a ribbon cable. The cable  5102  may also include multiple wires to provide multiple electrical connections for powering and signalling functions. The cable  5102  may be oriented such that the major or longer side is oriented in parallel to the axis of rotation of the swivelling disc. If an FCB is used as the cable  5102 , it may be oriented so that the surface of the FCB where the conductive tracks are located is protected from frictional contact with the cable housing  5100  as it rotates with the swivelling disc  5104 , in order to help prolong the life of the cable  5102 . Still further, the contacting surface (away from the conductive tracks) may comprise a low-friction surface so that when it slides relative to the cable housing  5100  the friction force created is minimised. This may have the effect of reducing the amount of wear occurring on the cable  5102 , as well as reducing the load imposed on the solder/mounting joints between the cable  5102  and any electrical connectors connected thereto, such as the female electrical connector  5158 . An example of such a low-friction surface may be a polyamide substrate. 
     6.6.1.4.1 Cable Management 
     In accordance with an example of the present technology, the cable  5102  may be fixed at one end to the electrical connector receiver  5114  of the swivelling disc  5104 . Although not shown, it should be understood that the opposite end of the cable  5102  may be fixedly connected to at least one electrical component  4200  of the RPT device  4000  and/or the humidifier  5000  such as a PCB to provide power to the cable. Thus, the cable  5102  may have a fixed length between the connection to the swivelling disc  5104  and the connection to at least one electrical component  4200  of the RPT device  4000  and/or the humidifier  5000 . 
     The cable  5102 , in an example of the present technology shown in  FIGS.  8   d - h   , may also include a slack portion that may be contained within either an annular section  5174  between the inner wall  5101  and the outer wall  5103 , or a recess or void  5124  defined, at least in part, by the cable housing  5100  depending upon the position of the swivelling disc  5104 . The flange  5112  of the swivelling disc  5104  may also contribute to defining the upper cover of the annular section  5174 , however, the flange  5112  does not contact the cable  5102  within the annular section  5174 . The cable housing  5100  (see  FIG.  8   c   ) may also include the inner wall  5101  and an outer wall  5103 , both of which may further define the void  5124 . The cable housing  5100  may also include a retainer  5118 , which may help to maintain the cable  5102  in the proper orientation by reducing the chance of entanglement or pinching and to prevent the slack portion from being pushed out of the cable housing  5100 . The outer diameter of the retainer  5118  may be designed to provide a minimum diameter for bend of the cable  5102  without damaging the electrical elements of the cable  5102 , for example an outer diameter of approximately 4 mm, 4.5 mm, 5 mm or some other outer diameter. It is to be understood that the outer diameter size of the retainer  5118  may be varied depending upon the size and type of cable used. As can be seen in  FIG.  8   c   , the exemplary cable housing  5100  depicted may include an opening  5116  that may be formed in the shape of a slot and through which the cable  5102  may pass, while maintaining a substantially fixed length of the cable  5102  within the cable housing  5100 . 
     The cable  5102  is at least partially wrapped around the inner wall  5101  within the annular section  5174  when the swivelling disc is rotated towards the extreme position shown in  FIG.  8   f   . The cable  5102  does not wrap around the swivelling disc  5104  but moves with the swivelling disc within the annular section  5174  as the swivelling disc  5104  is rotated. 
       FIGS.  8   d - i    depict another feature of the depicted examples of the technology. As the swivelling disc  5104  is rotated between extreme positions the cable  5102  may be pushed and pulled between the void  5124  and annular section  5174  of the cable housing  5100  due to its connection to the swivelling disc. For example, when the swivelling disc  5104  is rotated from the position shown in  FIG.  8   d    to the position shown in  FIG.  8   e    it can be seen that a portion of the cable  5102  is pulled out of the void  5124  and into the annular section  5174 . It should be understood that the portion of the cable  5102  shown doubled back in the void  5124  in  FIG.  8   d   , for example, may be considered the slack portion. In other words, the slack portion may be the excess cable that represents a length of the cable beyond what is necessary for direct connection to the swivelling disc  5104 . Thus, as the swivelling disc  5104  is rotated from the position shown in  FIG.  8   d    to the position shown in  FIG.  8   e    the slack portion may be progressively removed from the void  5124  so that the slack portion of the cable  5102  may be progressively pulled into the annular section  5174  and begin to wrap around the inner wall  5101  as the cable is pulled. As the swivelling disc  5104  is rotated further, from the position shown in  FIG.  5   e    to the position shown in  FIG.  5   f   , the portion of the cable  5102  that is pulled into the annular section  5174  increases and the slack portion may be pulled completely or nearly completely from the void  5124 . The recess or void  5124  and the annular section  5174  may be form on opposing sides of the inner wall  5101 . 
     Rotation of the swivelling disc  5104  in the opposite direction, from the position in  FIG.  8   f    to the position in  FIG.  8   e    to the position in  FIG.  8   d   , may cause the cable  5102  to be progressively pushed from the annular section  5174  and unwrapped from around the inner wall  5101  such that the slack portion in the void  5124  may increase and begin to double hack. In an example of the present technology, the maximum slack portion of the cable  5102  may be of a fixed length. In another example, that fixed length may be less than about the circumference of the swivelling disc  5104  and/or about equal to the distance of an arc swept out by the electrical connector receiver  5114  as the swivelling disc rotates between extreme positions. It should also be understood that in an example of the present technology when the swivelling disc  5104  is in the position shown in  FIG.  8   d    the largest amount of the slack portion of the cable  5102  is gathered or contained in the void  5124 . Also, it should be understood that the examples of the technology depicted in  FIGS.  8   g  and  8   h    illustrate similar features to those depicted in  FIGS.  8   d  and  8   f    and as described above. 
     6.6.1.4.2 Cable Housing 
       FIGS.  8   b - i  and  11   a - d    depict features of the cable housing  5100  according to examples of the present technology. As described above, the cable housing  5100  may include the inner wall  5101  and the outer wall  5103  that together may define the void  5124  and the annular section  5174 . The inner wall  5101  may define an opening through which the airflow tube  5130  may extend when the outlet assembly  5107  is assembled onto the RPT device  4000  and/or the humidifier  5000 . Further facilitating this assembly, tabs  5106  may be located on the cable housing  5100  to attach the cable housing to the RPT device  4000  and/or the humidifier  5000 , or a further housing thereof. This may improve the manufacturability and serviceability of the cable housing  5100 . The tabs  5106  may be configured so that they are, by themselves and/or as a set, able to support the weight of the humidifier  5000  and/or the RPT device  4000 . This may prevent damage from occurring to the humidifier  5000 , the RPT device  4000  and/or the cable housing  5100  when the assembly is accidentally lifted by the air circuit  4100  and/or the outlet connector  4106 . In some instances, the air circuit  4100  and/or the outlet connector  4106  may be configured to mechanically fail if the humidifier  5000  and/or the RPT device  4000  is held in place and a force is imposed onto the air circuit  4100  and/or the outlet connector  4106  in the upwards direction (in relation to  FIG.  5   c   ). 
     Returning to the inner wall  5101  and the outer wall  5103 , in an example of the present technology, the slack portion of the cable  5102  can be seen (for example, in  FIG.  8   e   ) to form a radius in the void  5124 . This radius may affect the stress imposed on the cable  5102  (and therefore potentially its operating life) and is defined in part by the distance (VO_H in  FIG.  8   i   ) between the inner wall  5101  and the outer wall  5103  in the void  5124 . Therefore, these walls may be separated by a distance in the range of 2 mm to 5 mm across the void  5124  based on a desired minimum radius of the cable  5102 . In one example, the distance is in the range of 4 mm to 5 mm. It should be understood that the desired minimum radius of the cable may change as a function of the properties of the cable  5102  and its design parameters such as design life, or usage cases. Similarly, the length (VO_L in  FIG.  8   i   ) of the void  5124  may be lengthened or shortened according to the maximum slack length of the cable  5102 , which may be driven by the maximum rotation of the swivelling disc  5104 . 
     The width (AN_W in  FIG.  8   i   ) of the annular section  5174  between the inner wall  5101  and the outer wall  5103  may be minimised as the cable  5102  travels therein as the swivelling disc  5104  rotates from one extreme position to the other. This may have the benefit of reducing noise produced by the cable and preventing buckling of the cable in the annular section. The width of the annular section may be between approximately 1 mm and 4 mm, such as 2 mm or 3 mm, and it should be understood that the width may depend on various characteristics and/or properties of the assembly, such as the characteristics of the cable chosen or the radius of the inner wall  5101 . In some arrangements the inner wall  5101  of the annular section  5174  and/or the outer wall  5103  of the annular section  5174  may include dampening material to help improve sound performance when the swivelling disc is rotated. A dampening material may also ensure the cable moves around the inner wall  5101  rather than the outer wall  5103  or vice versa. 
     In an example of the present technology, the cable housing  5100  may be formed from polypropylene, or polycarbonate/acrylonitrile butadiene styrene (PC/ABS). The swivelling disc  5104  may be formed from a combination of polycarbonate/acrylonitrile butadiene styrene (PC/ABS) and a thermoplastic elastomer (TPE). 
     6.6.1.5 Airflow Tube 
       FIGS.  10   a - d    show various views of the airflow tube  5130 . As noted above, the airflow tube may be a multiple patient/multiple user (MPMU) tube formed as a removable component that may be replaced or cleaned. The airflow tube  5130  may include an inlet end  5132  that connects to the humidifier  5000  or the RPT device  4000  as shown in  FIG.  19   a - 19   d   . The inlet end  5132  may comprise a pressure activated face seal or bellows seal to provide sealed pneumatic connection from an outlet of the RPT device  4000  and/or the humidifier  5000 . A seal may be used such as that described in U.S. Patent Application Publication No. 2011/0271956, which is incorporated herein by reference in its entirety. In another example of the present technology, the airflow tube  5130  may be connected at the inlet end  5132  to at least one conduit that is in turn connected to the RPT device  4000  and/or the humidifier  5000 . In any of these scenarios one function of the airflow tube  5130 , and specifically the inlet end  5132 , may be to receive the flow of gas from the RPT device  4000  and/or the humidifier  5000  and direct it outside of the device to the air circuit  4100  via the outlet connector  4106 . The airflow tube  5130  also facilitates rotation of the outlet connector  4106  of the air circuit  4100  by allowing the outlet connector  4106  to rotate around the outlet end  5134 . 
     A portion of the humidifier  5000  is shown in  FIGS.  19   a - 19   e    with the airflow tube  5130  and/or the cable housing  5100 . The airflow tube  5130  may also incorporate a latch portion  5172  to connect with a receiving portion  5176  of the RPT device  4000  and/or the humidifier  5000  to locate and/or retain the airflow tube in a correct position within the RPT device  4000  and/or the humidifier  5000 . The latch portion  5172  may assist in locating the inlet end  5132  of the airflow tube in the correction position. The engagement of the latch portion  5172  with the receiving portion may provide a sensory feedback, such as a click, to indicate correct connection. The latch portion  5172  may be further configured so that the airflow tube  5130  would be dislodged from receiving portion as it disengages therefrom. The latch portion  5172  may be a different colour to the complementary receiving portion or RPT device  4000  and/or the humidifier  5000  component for improved visibility. In certain circumstances, the airflow tube  5130  and/or the receiving portion  5176  may be configured so that a button such as at the end of the latch portion  5172  may be used to release the airflow tube  5130  from the receiving portion  5176 . A tool may be used to release the airflow tube  5130  from the receiving portion  5176 . 
     The airflow tube  5130  may be configured so that engagement of the latch portion  5172  with the receiving portion  5176  also completes a pneumatic connection between the air circuit  4100  and the RPT device  4000  and/or the humidifier  5000  when the air circuit  4100  is attached to the RPT device  4000  and/or humidifier  5000 . Accordingly, it may be possible to detect the absence or incorrect connection of the airflow tube  5130  or a disengagement thereof by detection of air leak. 
     In a further optional arrangement, when the outlet connector  4106  of the air circuit  4100  is connected to the RPT device  4000  and/or the humidifier  5000  the connection action may be configured to ensure the correct connection of the airflow tube  5130  with the receiving portion  5176 . Incorrect connection of the airflow tube  5130  to the receiving portion  5176  may prevent the outlet connector  4106  from being able to connect correctly to the airflow tube  5130 , which may be indicated by the RPT device  4000  through detection of a high leak flow, for example. In a further alternative the outlet connector  4106  of the air circuit  4100  may be used to facilitate insertion and/or removal of the airflow tube  5130  from the RPT device  4000  and/or the humidifier  5000 . 
     As discussed above, when the air circuit  4100  is attached to the RPT device  4000  and/or humidifier  5000 , the outlet end  5134  of the airflow tube  5130  may be coupled to the outlet connection region  4114  of the outlet connector  4106 . The outlet end  5134  may also be formed with an ISO taper, such as a 22 mm outer diameter ISO taper, to allow connection of standard non-heated air circuit. 
     As seen in  FIG.  10   a    the airflow tube  5130  may comprise a flow bend, having an internal circular or curved cross-section configured to reduce the impedance of the air flow through the airflow tube  5130 . The airflow tube  5130  may be constructed as a two-part process as shown in  FIG.  10   d   , wherein the first portion  5130   a  is moulded from rigid material such as Bisphenol A (BPA) free polycarbonate/acrylonitrile butadiene styrene (PC/ABS), and the second portion  5130   b  comprising at least a part of the flow bend is overmoulded from a compliant material such as silicone. Use of a compliant material to form the second portion  5130   b  that comprises a portion of the bend may allow withdrawal of a moulding tool that comprises the internal bend from the internal cavity at the end of the moulding process by deforming the second portion  5130   b.    
     The airflow tube  5130  may also include a retaining flange  5136  to assist in locating and/or securing the airflow tube  5130  to the RPT device  4000  and/or the humidifier  5000 , or a housing or chassis thereof. The retaining flange  5136  may assist in correctly locating or positioning the outlet end  5134  of the airflow tube  5130  within the outlet of the RPT device  4000  and/or humidifier  5000  as shown in  FIG.  19   c - 19   d    by abutting a locating flange in the RPT device  4000  and/or humidifier  5000 . It should be understood that the retaining flange  5136  may allow for fixed attachment of the airflow tube  5130 . The retaining flange  5136  may, alternatively, allow for removable attachment of the airflow tube  5130  so that it may be cleaned or replaced, for example. 
     6.6.2 Producing the Air Circuit 
     Certain features of the air circuit  4100  and their relationship to its production, according to examples of the present technology, will now be described.  FIG.  5   f    shows an exploded view of the components of the air circuit  4100  according to an example of the present technology. The substructure  4132  of the outlet connector  4106  may be a molded part that includes the tube connection region  4136  with structure to attach the tube portion  4102 . The orifice  4144  opposite the tube connection region  4136  may receive an end cap  4124  to partially provide a pneumatic seal to the outlet connector  4106 . A housing  4134  may be provided over the top of the substructure  4132  to further seal the outlet connector  4106  pneumatically and to provide additional structural support. The housing  4134  may be introduced to the substructure  4132  by way of an overmoulding process. The electrical connector  4112  may include a support structure  4126  to support at least one electrical lead  4128 . The electrical connector  4112  may be produced by insert moulding, whereby the electrical lead  4128  is moulded into the electrical connector  4112  by moulding the support structure  4126  around the electrical lead  4128 . The electrical connector  4112  may be located and/or connected onto the outlet connector  4106  by the protruding tabs  4180  near the tube connection region  4136  of the substructure  4132 . The grommet  4104  is also shown with threads  4130  to allow the grommet to be threaded onto the tube portion  4102 , as will be discussed in greater detail below. 
       FIGS.  6   a  and  6   c - e    show various views of the substructure  4132  including the electrical connector  4112 . The substructure  4132  and the support structure  4126  of the electrical connector  4112  may be molded from polycarbonate/acrylonitrile butadiene styrene (PC/ABS). Also visible in  FIG.  6   a    are the tube connection region  4136  and the tab  4148  having the actuator  4108  and the retention feature  4110  disposed thereon. The orifice  4144  can also be seen opposite the tube connection region. The orifice  4144  may be formed on the substructure  4132  during molding of the substructure. A mandrel may be used to form the tube connection region  4136  and the interior of the substructure  4132  during molding and the orifice  4144  may be formed around the mandrel leaving this region open when the mandrel is pulled out after the substructure is molded. The end cap  4124 , as shown in  FIG.  5   f   , may be welded ultrasonically onto the substructure  4132  to sealingly cover the orifice  4144 . The end cap  4124  may comprise an internal profile configured to reduce flow impedance through the outlet connector  4106 . For instance, the end cap  4124  may incorporate a flow radius  4176  as shown in  FIG.  5   g - 5   i    configured to increase the radius of the internal corners of the outlet connector  4106 . The flow radius  4176  may also be constructed from materials suited for improved thermal and/or acoustic performance, and/or comprise an air gap between the flow radius  4176  and the housing  4134  for improved thermal and/or acoustic performance. 
       FIG.  6   b    shows the support structure  4126  of the electrical connector  4112  together with the at least one electrical lead  4128 . A connection end  4138  and a tube end  4140  of the support structure  4126  are also shown. It is noted that in  FIG.  6   b   , the electrical lead  4128  shows a snap-off plate  4174  protruding towards the tube end  4140 , which is not shown in the assembly figure ( FIG.  60   . The snap-off plate  4174  is used during assembly only, and does not form a part of the completed outlet connector  4106 . In one form, the snap-off plate  4174  is removed after individual wires (e.g., of the helical coil  4103 ) are connected to their corresponding electrical lead  4128 . 
       FIG.  6   f    shows a perspective view of the assembled outlet connector  4106  with the housing  4134  removed to show the internal structures.  FIG.  6   g    shows a similar view in cross-section.  FIG.  6   g    shows engagement of the threads  4130  of the grommet  4104  onto the helical coil  4103  of the tube portion  4102 . Also, a portion of the tube portion  4102  can be seen extending through the grommet  4104  for attachment to the tube connection region  4136  of the substructure  4132  at connector threads  4142 . These connector threads  4142  can also be seen in  FIG.  6   c   . In some forms, the portion of tube portion  4102  which engages with the tube connection region  4136  may be torn to enable a portion of the helical coil  4103  to be unwound. This may allow the unwound portion of the helical coil  4103  to be routed around the tube connection region  4136  to form the electrical connections with the electrical connector  4112 . 
       FIG.  17    shows a hatched cross-sectional view, in accordance with the present technology, of how the housing  4134  may be formed around the assembly of the tube portion  4102 , the grommet  4104 , and the substructure  4132 .  FIG.  17    shows the outlet connector  4106  assembled as shown in  FIGS.  6   f  and  6   g    with upper and lower mold tools  6000 ,  6002  above and below the assembly. The mold tools  6000 ,  6002  can be seen to define the exterior of the housing  4134 , and the interior of the housing  4134  may be defined by the grommet  4104 , and the substructure  4132 . A function of the grommet  4104  may also be understood from this view and may be explained as follows. When molding the housing  4134  to complete the outlet connector  4106  the mold tools  6000 ,  6002  may need to complete a seal around the internal structures which may require some pressure to affect a sufficient seal. The requisite amount of pressure from the mold tools  6000 ,  6002  to achieve this seal may damage the tube portion  4102  if the mold tools are pressed against it. Typically, a mandrel (not shown) would be inserted in the tube portion  4102  to maintain its shape while molding, which may then effectively ‘clamp’ any exposed portions of the tube portion  4102  against the mold tools  6000 ,  6002 . Thus, the grommet  4104  may be included to allow the mold tools  6000 ,  6002  to form a sealed chamber to mold the housing  4134  while the grommet protects the tube portion  4102 . Another feature that can also be seen in  FIGS.  6   f ,  6   g   , and  17  is that the gas delivery tube portion  4102  may be threaded through the grommet  4104  such that the grommet will abut against the tube connection region  4136  of the substructure  4132 . This may provide a further sealing function. 
     6.6.2.1 the Grommet 
       FIGS.  7   a - f    show views of the grommet  4104  according to examples of the present technology. As shown in  FIGS.  7   b - d   , the grommet  4104 , according to examples of the present technology, may include threads  4130  internally to allow the grommet to be threaded onto the tube portion  4102 . Threads  4130  may be configured to accept the helical coil  4103  of the tube portion  4102  and may be shaped and dimensioned to cover one complete turn of the helical coil. As shown in  FIGS.  7   c - f   , the grommet  4104  may also include a grip section or grips  4154  around a radial portion. The grips  4154  may allow for easier gripping of the grommet  4104  as it is threaded onto the tube portion  4102 . 
     6.6.2.1.1 Producing the Grommet 
     The grommet  4104 , according to an example of the present technology, may be pre-molded or molded separately from the other components of the air circuit  4100 . In such a situation it may be advantageous to include at least one keyway  4150  on the grommet  4104 , as shown in  FIG.  7   a   . The inclusion of a keyway in this exemplary grommet  4104  may allow the grommet to be restrained by the keyway  4150  while an internal mold tool is rotated and extracted from the molded grommet. The grips  4154  may also be used for securement of the grommet  4104  during removal of an internal tool. 
     The grommet  4104 , in accordance with an example of the present technology, may be formed of a material of sufficient strength and hardness to protect the tube portion  4102  during molding of the housing  4134 , as shown in  FIG.  17   . At the same time, the material should not be so hard such that the grommet  4104  itself damages the tube portion  4102 . 
     The grommet  4104  may also include at least one flange  4152  disposed about a radial portion thereof. The flange  4152  may allow the upper and lower mold tools  6000 ,  6002  to better seal around the grommet  4104  during molding, as shown in  FIG.  17   . The flange  4152  may also help to distribute the pressure of the mold tools  6000 ,  6002  around the grommet  4104  to prevent pinching, as lower pressures may be required for the mold tools  6000 ,  6002  to achieve sealing in comparison to if the flange  4152  was absent. 
     Another feature of the grommet  4104  may be to lengthen the life of the tube portion  4102  by reducing the peak stress created at the joint of the tube portion  4102  and the tube connection region  4136 . Typically, the tube connection region  4136  is of much higher stiffness than in the tube portion  4102  in the bending direction, and a sudden change in stiffness as such may lead to a localised high stress area. The grommet  4104  may achieve the stress reduction by decreasing the change in stiffness along the length of the assembled outlet connector  4106  between the tube connection region  4136  and the tube portion  4102 . This may decrease the stress concentration created on the tube portion  4102 . 
     Thus, according to an example of the present technology, a thermoplastic elastomer may be used to form the grommet  4104 . It should be understood, however, that other materials having similar properties may be equally suitable. 
     6.6.2.2 Clip-Receiver Tube Attachment 
       FIGS.  30   a  to  30   i    depict further examples of the present technology for connecting the tube portion  4102  to the substructure  4132 . According to these examples of the present technology, a clip-receiver arrangement is provided to locate and/or secure the tube portion  4102  to the substructure  4132  prior to overmolding to form the outlet connector  4106 . The clip-receiver arrangement may also protect the tube portion  4102  from damage while the substructure  4132  is overmoulded, for example with the housing  4134 . 
     The tube connection region  4136  of these examples is formed with a receiver  4135 . The receiver  4135  may be integrally molded with the substructure  4132  in one piece. Receiver threads  4135 . 1  are provided internally to the receiver  4135  so that the helical coil  4103  may be threaded onto the receiver threads to locate the tube portion  4102  in the substructure  4132 . In one form, the receiver  4135  may not completely surround the periphery (or circumference) of the tube portion  4102 , yet allow the tube portion  4102  to be inserted into the receiver such that the receiver threads  4135 . 1  fit onto the helical coil  4103 . In this form, a clip  4137  may be provided to fit around the remainder of the periphery of the tube portion  4102 , and may engage with the receiver  4135 . Clip threads  4137 . 1  may be formed internally on the clip  4137  such that when the clip is attached to the receiver  4135  the outer periphery of the tube portion  4102  is surrounded by the clip and the receiver. Also, the clip threads  4137 . 1  and the receiver threads  4135 . 1  may be formed so that when assembled these threads have complementary shapes that substantially match the helical coil  4103 . 
     To attach the clip  4137  onto the receiver  4135  to secure the tube portion  4102 , a protrusion  4139 . 1  may be provided on each side of the receiver  4135  and corresponding tabs  4139  may be formed on the clip. The tabs  4139  may snap onto the respective protrusions  4139 . 1  to hold the clip  4137  onto the receiver  4135  with a snap-fit.  FIG.  30   a    shows the clip  4137  attached to the receiver  4135  and  FIG.  30   b    shows how the clip may be attached.  FIGS.  30   d  and  30   g    show the tube portion  4102  inserted into the receiver  4135  prior to attachment of the clip  4137  and  FIG.  30   c    shows the clip attached to secure the tube in the tube connection region  4136 . 
       FIGS.  30   e  and  30   f    show views of the substructure  4132  attached to the tube portion  4102  and then overmolded with the housing  4134  to complete the outlet connector  4106  of the air circuit  4100 . Once the tube portion  4102  is attached to the substructure  4132  and secured at the tube connection region  4136  between the receiver  4135  and the clip  4137 , as shown in  FIG.  30   c   , this assembly may be overmolded in a manner similar to what is shown in  FIG.  17   . However, since the grommet  4104  described above is not used in the present example, the receiver  4135  may be provided with a receiver flange  4135 . 2  and the clip  4137  may be provided with a clip flange  4137 . 2  in place of the flange  4152  on the grommet to form a seal with the mold tools  6000 ,  6002  during overmolding of the housing  4134 .  FIG.  30   f    shows a cross-sectional view of the outlet connector  4106  after overmolding the housing  4134  onto the substructure  4132 . The helical coil  4103  can be seen to be engaged to the receiver threads  4135 . 1  and the clip threads  4137 . 1 . In order to connect the helical coil  4103  electrically to the electrical connector  4112 , an end of the tube portion  4102  may be torn to allow the helical coil  4103  to be moved into position (e.g., by unwinding). Also, the housing  4134  can be seen molded around the receiver  4135  and the clip  4137  up to the receiver flange  4135 . 2  and the clip flange  4137 . 2 . 
       FIGS.  30   h  and  30   i    show another example of the present technology where the clip  4137  is attached to the receiver  4135  by a pivoting structure such as a hinge  4141 . According to this example, the hinge  4141  and the clip  4137  may be integrally molded with the substructure  4132  such that these components are one piece. To secure the tube portion  4102  to the substructure  4132 , the tube may be inserted into the receiver  4135 , as described above, then the clip  4137  may be positioned over the exposed periphery of the tube portion  4102  and secured by snapping the tab  4139  onto the protrusion  4139 . 1 . Accordingly, this example may have only one protrusion  4139 . 1  and one tab  4139  for attachment of the clip  4137 . 
     6.6.2.3 Separable Gas Delivery Tube and Elbow Connector 
       FIGS.  14   a - j    depict another example of the present technology where the tube portion  4102  may be separable from an elbow connector  4158 . In this example the tube portion  4102  may be connected to a tube cuff  4156  that includes at least one cuff retention feature  4160  and a cuff electrical connector  4164  (see  FIGS.  141  and  14     j ). The tube cuff  4156  may be attachable to the elbow connector  4158  which may be a component of the outlet connector  4106 . The elbow connector  4158  may include at least one cuff receiver  4162  to receive a corresponding cuff retention feature  4160 , thereby releasably attaching the tube cuff  4156  to the elbow connector  4158 . 
     The tube cuff  4156  may also include a cuff electrical connector  4164  to form an electrical connection with the electrical connector  4112  of the outlet connector  4106 . The electrical connector  4112  may, in turn, connect electrically to the cable  5102  via a swivel electrical connector  5105 . 
     This arrangement may, in similar fashion to other examples described herein, provide for the formation of both pneumatic and electrical connections with the outlet connector  4106 . In this example one electrical and pneumatic connection may be formed by the connection of the cuff  4156  to the elbow connector  4158  and another may be formed by the connection of the outlet connector  4106  to the outlet assembly  5107 . Also, this example may provide a rotatable arrangement. 
     6.6.2.3.1 Electrical Connector Fixed to the Outlet Assembly 
       FIGS.  15   a  and  15   b    show an alternative example to the arrangement depicted in  FIGS.  14   a - j   . In this example the swivel electrical connector  5105  is shaped to form an electrical connection with the cuff electrical connector  4164  (shown in  FIG.  14   j   ) such that the electrical connector  4112  is not required. It should be understood that the swivel electrical connector  5105  may be fixedly attached to the outlet assembly  5107  and electrical and pneumatic connections are both made by the attachment of the outlet connector  4106  to the outlet assembly  5107 . In other words, this arrangement may be the inverse of that which is disclosed in other examples such that the exposed electrical connector in this example is located on the outlet assembly  5107  and the outlet connector  4106  has a feature to receive and form an electrical connection. 
     6.6.2.4 Connection Assembly with Extended Tube 
       FIGS.  16   a  and  16   b    depict another example of the present technology. Similar to other examples, this example may provide for both electrical and pneumatic connections to be made between an outlet assembly  5107  and an outlet connector  4106 . The connection may also be rotatable in similar fashion to the other examples. This example also includes an outlet tube  5142  that may extend from the outlet assembly  5107  to form the pneumatic connection and define the axis of rotation of the connection. The outlet tube  5142  may be part of an airflow tube  5130  as described above. 
     6.6.3 Air Circuit-Outlet Connection Having Multiple Discrete Positions 
     According to another example of the present technology, as shown in  FIGS.  13   a - n   , provides for a connection assembly wherein the air circuit  4100 , specifically the outlet connector  4106 , may be connected to an outlet  5140  in one of a plurality of discrete positions. The outlet  5140  of this example of the present technology may be located on a housing  5138  of the RPT device  4000  and/or the humidifier  5000 . The outlet  5140  may also include an outlet tube  5142  and at least one outlet electrical connector  5144 . The outlet tube  5142  may be part of an airflow tube  5130  as described above. Although not shown in these views, it should be understood that the outlet connector  4106  will be connectable to a gas delivery tube that is connectable to a patient interface at the opposite end and may include a heating element as described above. The gas delivery tube may be formed integrally with the outlet connector  4106  or it may be removable, in which case a further electrical connection would need to be provided for the tube. The examples depicted in these views may also provide for an electrical and pneumatic connection as disclosed above. The outlet connector  4106  depicted in these examples may be shaped as an elbow and may be bent about 90°, although it should be understood that a number angles may be possible, such as straight (180°), 150°, 120° or 60°. 
     One feature of the exemplary arrangement shown in  FIGS.  13   a - 13   n    is the provision of multiple discrete positions for removable attachment of the outlet connector  4106  on the outlet  5140 . This may be accomplished by providing multiple outlet electrical connectors  5144  on the outlet  5140  as shown in  FIGS.  13   f - h   . The outlet connector  4106  may then include an electrical connector  4112  as shown in  FIG.  13   k   . Thus, when the outlet connector  4106  is connected to the outlet  5140 , the electrical connector  4112  electrically communicates with a corresponding one of the outlet electrical connectors  5144 .  FIGS.  13   b  and  13   d    show the outlet connector  4106  connected to the outlet  5140  in a first position and  FIG.  13   j    shows the outlet connector in a second position. The examples depicted in these Figures show two possible positions for the outlet connector  4106  relative to the outlet  5140 , however it should be understood that any number of positions may be provided by additional outlet electrical connectors  5144 . 
     It should also be understood that an alternative to the examples heretofore described may provide for a plurality of electrical connectors  4112  on the outlet connector  4106  while the outlet  5140  includes a single outlet electrical connector  5144 . Such an arrangement would provide for a similar arrangement described above with multiple discrete positions for the outlet connector. In other words, this arrangement is merely the inverse of the arrangement described above such that in the instant arrangement the outlet connector is provided with multiple electrical connectors. 
     As can be seen in  FIGS.  13   b ,  13   d , and  13   j   , the outlet  5140  and the outlet connector  4106  may be shaped complementary to one another. While complementary rectangular shapes are shown in these views it should be understood that the outlet  5140  and the outlet connector  4106  may take on any other complementarily shaped arrangement. 
       FIG.  13   n    depicts a view of the connection assembly that is similar to that shown in  FIG.  13   j   , for example, with the external components removed to show the internal components. An outlet connector tube  4168  is shown as an elbow with a bend of about 90° and is connected to the outlet  5140 . The electrical connector  4112  can also be seen connected to a corresponding outlet electrical connector  5144  and another outlet electrical connector is not occupied. The cable  5102  is also shown passing across and in communication with the outlet electrical connectors  5144 . This view shows how the components of the outlet connector  4106 , the outlet connector tube  4168  and the electrical connector  4112 , may provide both pneumatic and electrical connections. It also may be envisioned that the electrical connector  4112  may be connected to the other outlet electrical connector  5144  and, accordingly, the outlet connector tube  4168  may be pointed in the opposite direction. Alternative examples may include the outlet electrical connectors  5144  positioned in various vertical and horizontal orientations. 
     The cable  5102  may be a flexible circuit board (FCB), as shown in  FIG.  13   n   , to connect to at least one electrical component  4200  of the RPT device  4000  and/or the humidifier  5000 . In such an arrangement a multi-layer FCB may facilitate multiple signalling paths for each outlet electrical connector  5144 . Alternatively, a number of separate wiring looms may be provided. Each wiring loom would, in such an arrangement, be connected to individual outlet electrical connectors  5144 . 
     The outlet electrical connectors  5144 , the electrical connector  4112 , and the cable  5102  may also include multiple connections for the provision of powering and/or signalling functions. 
     6.6.3.1.1 Protection of Electrical Connectors 
     The outlet connector  4106  may also include at least one dummy connector  4113 . The dummy connector  4113  may function to cover and protect the unused outlet electrical connector  5144  when the outlet connector  4106  is attached to the outlet  5140 , as shown in  FIGS.  13   e  and  13   h   . By covering the unused outlet electrical connector  5144  it may be protected from damage due to debris and contaminants. In arrangements where more than one unused electrical connector is provided a corresponding number of dummy connectors may also be provided. Also, in the situation where there are multiple electrical connectors  4112  on the outlet connector  4106  and one outlet electrical connector  5144 , the outlet  5140  may include a number of dummy connectors sufficient to protect the unused electrical connectors. 
     6.6.4 Rotatable Outlet Connector 
       FIGS.  22   a  to  29   b    show examples of the present technology where an outlet connector may provide pneumatic, electrical, and mechanical connections simultaneously while allowing a full rotational degree of freedom, or freedom of rotation over 360° when connected. The outlet connector may be used, for example, to join an air circuit comprising electrical circuitry (such as a heated air circuit, or an air circuit capable of communicating electrical signals) to a respiratory apparatus such as a RPT device, a humidifier, or an integrated PAP-humidifier device. 
       FIGS.  22   a  to  22   h    show an exemplary substructure assembly  4500  of an outlet connector.  FIG.  22   g    shows an exploded view of the substructure assembly  4500  to depict individual components of the substructure assembly. A body  4502  may provide structure to the substructure assembly  4500 . The body  4502  may facilitate the mechanical connection with the respiratory apparatus at the outlet connection region  4530  and with the tube portion  4102  at a tube connection region  4526 . A shoulder  4532  may be formed on the body  4502  near the outlet connection region  4530  to resist detachment from the respiratory apparatus, as will be described in greater detail below. The tube connection region  4526  may have threads  4528  to join with the helical coil of a tube portion  4102 . 
     The body  4502  alone may not form a completely pneumatically sealed path for the flow of gas generated by the respiratory apparatus from the outlet connection region  4530  to the tube connection region  4526 , as can be seen in  FIG.  22   g   . Thus, a cap  4504 , shown separately in  FIG.  24   , may be joined to the body  4502  to provide an airflow path from the outlet connection region  4530  to the tube connection region  4526 . The cap  4504  may be provided with a retaining feature, such as tabs  4520  to engage with notches  4524  on the body  4502 . The cap  4504  may also be provided with prongs  4518  to engage with detents  4522  on the body  4502 . The engagement between the tabs  4520  and the notches  4524  and between the prongs  4518  and the detents  4522  may locate and/or securely connect the cap  4504  to the body  4502 .  FIG.  22   h    shows an example of the attachment of the cap  4504  to the body  4502 . While this engagement may provide a mechanical connection between the body  4502  and the cap  4504 , it should be understood that a complete pneumatic seal for the airflow path between the outlet connection region  4530  and the tube connection region  4526  may not be formed between the cap and the body. The complete pneumatic seal may be formed by an overmoulding process similar to that described above in section 5.6.2. Thus, the substructure assembly  4500  may be joined to a tube portion at the tube connection region  4526  and then this assembly may be overmoulded to form a seal around the substructure assembly and the tube portion by molding a housing around the substructure assembly  4500 . 
     As the air circuit  4100  may be heated according to this example of the technology, connector contacts  4510 ,  4512 ,  4514  are provided to the substructure assembly  4500  at the outlet connection region  4530 . The connector contacts  4510 ,  4512 ,  4514  may form electrical connections with the respiratory apparatus to provide electrical power and/or signal to the air circuit. The connector contacts  4510 ,  4512 ,  4514  may surround the outer periphery of the outlet connection region  4530 . The connector contacts  4510 ,  4512 ,  4514  may be joined to wires  4508  of an electrical contact assembly  4506 . A snap-off plate  4536  may be provided to the electrical contact assembly  4506  and the snap-off plate may be removed when joining electrical wires of the tube portion to the electrical contact assembly  4506  during production. The electrical contact assembly  4506  may be joined to the body  4502  by moulding the body over the electrical contact assembly such that only the connector contacts  4510 ,  4512 ,  4514  and the snap-off plate  4536  are exposed. The connector contacts  4510 ,  4512  and  4514  are protected from being covered by the injected polymer during the moulding process. For example, the connector contacts  4510 ,  4512  and  4514  are held tightly within a mould tool so they are not displaced during the moulding process and are not covered by the injected polymer. Moulding the body  4502  over the electrical contact assembly  4506  may protect the wires  4508  and/or preserve the electrical power and/or signal carried by the wires  4508 . For instance, by moulding the body  4502  over electrical contact assembly  4506 , the wires  4508  may be protected from moisture in the airflow path during operation of the respiratory apparatus, and any risk of short-circuiting within the wires  4508  may be also reduced. It should be understood that the components of the electrical contact assembly  4506  may be comprised of a material that conducts electricity, e.g., a metal or a metallic alloy. Although the electrical contact assembly  4506  is shown with three connector contacts  4510 ,  4512  and  4514 , it will be understood that any number of connector contacts may be utilised. 
       FIGS.  25   a  and  25   b    show a portion of wires  4508  and the connector contacts  4510 ,  4512 ,  4514  with snap-off plate  4536 .  FIG.  25   a    shows the wires  4508 , the connector contacts  4510 ,  4512 ,  4514 , and the snap-off plate  4536  in a flat shape and these parts may be stamped and formed from a flat sheet of material.  FIG.  25   b    shows the wires  4508  wrapped in a circular shape to form the connector contacts  4510 ,  4512 ,  4514  that will be exposed at the outlet connection region  4530  when the body  4502  is moulded over the electrical contact assembly  4506 . It will be appreciated that the portion of wires  4508  shown in  FIGS.  25   a  and  25   b    may be joined with one or more portions of wires to produce the electrical contact assembly  4506  as shown in  FIG.  22   g   , or in some forms, the electrical contact assembly  4506  may be produced from one sheet (e.g., by stamping and/or bending from a sheet of electrically conductive material). 
     As noted above, it may be desirable to shield the electrical contact assembly  4506  from exposure to moisture in the airflow path and this may be accomplished by moulding the body  4502  onto the electrical contact assembly, for example by insert moulding. Moulding the body  4502  onto the electrical contact assembly  4506  in this manner may result in the formation of a wire overmould  4534 . The wire overmould  4534  may be formed as a portion of the body  4502  to enclose the wires  4508  and protect the wires from moisture in the airflow path up to the point in the body where the wires emerge to be joined with the tube portion at the tube connection region. 
       FIG.  22   d    shows a side view of an exemplary substructure assembly  4500  to depict a sweep bend of the substructure assembly. The sweep bend may be understood in a two-dimensional (planar) sense as bend shape of the substructure assembly  4500  where an inner radius Ri and an outer radius Ro of the substructure assembly may have a common arc center. In a three-dimensional sense, a sweep bend may be understood as a bend wherein the entire outline of a cross section has a common arc center, thereby provides a constant cross-sectional shape through the length of the bend in the substructure assembly  4500  along the airflow path. In some forms, Ro may be between about 1 and about 3 times that of a diameter of the cross-section. In further examples, Ro may be between 1.5 and 2 times that of a diameter of the cross-section. 
     A sweep bend (in a two- or three-dimensional sense) may be advantageous in that a smaller pressure drop may result from a sweep bend as compared to a sharper and/or more abrupt bend, for example a right-angle bend, or a right-angle bend which comprise internal radii of substantially similar diameters. Additionally, an exemplary sweep bend may have a relatively large radius of curvature in that the center radius of the sweep bend (average of the inner radius and the outer radius) may be 0.5-3 times the internal diameter of the airflow path defined by the interior of the substructure assembly  4500 . 
       FIGS.  23   a  to  23   f    show examples of the substructure assembly  4500  without the electrical contact assembly  4506 . While the substructure assembly  4500  has been described above as having the electrical contact assembly  4506  moulded with the body  4502 , it should be understood that these views depict some structural features of the substructure assembly  4500  that may not be visible because of the presence of the electrical contact assembly. For example, contact recesses  4511 ,  4513 ,  4515  may be formed in the body  4502  at the outlet connection region  4530 . The contact recesses  4511 ,  4513 ,  4515  may be formed around the connector contacts  4510 ,  4512 ,  4514  when moulding the body  4502  onto the electrical contact assembly  4506 .  FIGS.  23   d  and  23   f   , for example, show the absence of the connector contacts  4510 ,  4512 ,  4514  at the outlet connection region  4530 . Also, the outlet connection region  4530  can be seen to taper down to decrease in external diameter towards a housing end of the outlet connection region  4530 . As will be described in further detail below, this arrangement may comprise one detent  4522 , and thus provide one point of force feedback to the user upon engagement. It is also envisaged that multiple detents may be used, however in some cases this may not be desirable, as the user may potentially perceive engagement of one detent (whilst others may not be engaged) as the engagement of the connection. 
     6.6.4.1 Manufacture of the Outlet Connector 
     In one form, the substructure assembly  4500  may be manufactured according to the following steps. The electrical contact assembly  4506  may be formed by stamping a flat sheet of material, and forming the bends and curvatures as required to a final shape as shown in  FIG.  22   g   . The body  4502  may be moulded including the electrical contact assembly  4506 , for example by insert moulding over the electrical contact assembly  4506 . 
     Then, the cap  4504  may then be located on the body  4502 , for example joined by the detents  4522  and tabs  4520 , and the electrical contact assembly  4506  may be joined to wires to form electrical connections with the tube portion  4102 . The plate  4536  may then be removed, and the substructure assembly  4500  may be overmoulded with the housing (not shown) similarly to above. During this process, one or more internal jigs (not shown) may be inserted into the substructure assembly  4500  to prevent the cap  4504  from collapsing to the interior of the air path of the body  4502 . 
     6.6.4.2 Connecting the Outlet Connector 
       FIG.  26   a    shows a cross-sectional view of a connection arrangement between the outlet connection region  4530  and a housing  5200  of a respiratory apparatus according to an example of the present technology. The connector contacts  4510 ,  4512 ,  4514  at the outlet connection region  4530  are shown in contact with outlet contacts  5202 ,  5204 ,  5206 . The outlet contacts  5202 ,  5204 ,  5206  may be positioned in grooves  5208 ,  5210 ,  5212  in the periphery of an opening  5201  of the housing  5200 . 
       FIG.  26   b    shows a detailed view of this connection arrangement. In  FIG.  26   b    it can also be seen how the shoulder  4532  may be shaped to engage with the outlet contact  5202  to facilitate retention of the outlet connection region  4530  within the housing  5200 . Although the outlet contact  5202  may primarily perform the retention function in the depicted example, it should be understood that in further examples more than one of the outlet contacts may perform the retention function. Accordingly, additional corresponding shoulders may be formed on the outlet connection region  4530 . 
     According to an example of the present technology, each of the outlet contacts  5202 ,  5204 ,  5206  may comprise a canted spring in a corresponding groove  5208 ,  5210 ,  5212 . Exemplary canted springs are BalContact™ springs from Bal Seal Engineering Co. Inc. In the example where the outlet contacts  5202 ,  5204 ,  5206  are canted springs, the canted springs may be comprised of an elastic material that conducts electricity, e.g., a metal or a metallic alloy. It may be advantageous for the material and/or a configuration of the outlet contacts  5202 ,  5204 ,  5206  to be elastic so that the outlet contacts will elastically deform during engagement and/or disengagement with the outlet connection region  4530 . This may ensure that the outlet contacts  5202 ,  5204 ,  5206  maintain electrical contact with the connector contacts  4510 ,  4512 ,  4514  when the outlet connection region  4530  is engaged with the housing  5200 . It may also be advantageous to use canted springs as the outlet contacts  5202 ,  5204 ,  5206  because their elasticity may provide mechanical and/or audible feedback to indicate to the user that a connection has been made, while also providing secure retention of the outlet connection region  4530 . Moreover, canted springs may also allow for some play within the connection necessary for rotation, while maintaining secure engagement. Also, each of the grooves  5208 ,  5210 ,  5212  may be formed from a material that conducts electricity, e.g., a metal or a metallic alloy. Although not shown in these views, it should be understood that the grooves  5208 ,  5210 ,  5212  are in electrical communication with a source of electrical power, for example with a source of electrical power in the respiratory apparatus. Thus, the respiratory apparatus may deliver electrical power to heat the tube, which is provided from the grooves  5208 ,  5210 ,  5212  through the outlet contacts  5202 ,  5204 ,  5206  to the connector contacts  4510 ,  4512 ,  4514 . The electrical connections formed may also provide communication functions such as electrical signalling. 
     According to these depicted examples, electrical, pneumatic, and mechanical connections may be formed and maintained when the outlet connection region  4530  is inserted into the housing  5200 . The outlet connector may be rotated once this connection is formed while maintaining these electrical, pneumatic, and mechanical connections. The electrical connection may be maintained because the connector contacts  4510 ,  4512 ,  4514  extend peripherally around the outlet connection region  4530  such that at least a portion of each connector contact is always in contact with a respective one of the outlet contacts  5202 ,  5204 ,  5206  during within the housing  5200 . Engagement of the shoulder  4532  with the outlet contact  5202  may serve to maintain the mechanical connection during rotation. It should be understood that additional shoulders may be provided to engage with the other outlet contacts should additional retention be desired. The pneumatic connection may be maintained during rotation because the outlet connection region  4530  may be sized and shaped to form close fit with the opening  5201  of the housing  5200 . Additionally, peripheral seal(s) may be provided to ensure a secure pneumatic connection between the outlet connector and the respiratory apparatus. 
       FIGS.  27   a  to  27   c    show cross-sectional views of further examples of connection arrangements according to the present technology.  FIG.  27   a    shows an example where the outlet connection region  4530  includes the connector contact  4510  with the shoulder  4532  on one side and an additional shoulder  4532 . 1  on the other side such that the connector contact  4510  is recessed. The outlet contact  5202  may extend from the groove  5208  into the recessed connector contact  4510  between the shoulder  4532  and the additional shoulder  4532 . 1 .  FIG.  27   c    depicts a detailed view of this arrangement.  FIG.  27   b    shows a further alternative where the connector contact  4510  may be further recessed between the shoulder  4532  and the additional shoulder  4532 . 1 . Also, in this example the outlet contact  5202  is carried on the outlet connection region  4530  between the shoulder  4532  and the additional shoulder  4532 . 1 , rather than in the groove  5208  of the housing  5200 . The peripheral surfaces of the connector contact  4510  and of the groove  5208  in these examples may be flat where they engage with the outlet contact  5202 . 
       FIGS.  28   a  to  28   c    show cross-sectional views of further examples of connection arrangements according to examples of the present technology. The example shown in  FIGS.  28   a  and  28   c    varies from the example shown in  FIGS.  27   a  and  27   c    in that the surface of the groove  5208  is V-shaped. The example shown in  FIG.  28   b    varies from the example shown in  FIG.  27   b    in that the connector contact  4510  is V-shaped. 
       FIGS.  29   a  and  29   b    show examples of the present technology where the outlet connection region  4530  may be attached and retained in the housing  5200 .  FIG.  29   a    shows the outlet connection region  4530  being inserted into the housing  5200 . The outlet connection region  4530  may be tapered to progressively compress the outlet contact  5202  into the groove  5208  as the outlet connection region is inserted into the housing. Once inserted, as shown in  FIG.  29   b   , the outlet contact  5202  may abut against the shoulder  4532  and/or the additional shoulder  4532 . 1  to limit axial movement of the outlet connection region  4530  relative to the housing  5200 . 
     While  FIGS.  27   a - c ,  28   a - c , and  29   a - b    each show one set of a connector contact  4510 , an outlet contact  5202 , and a groove  5208 , it should be understood that a plurality of sets of these components may be provided. 
     While the examples discussed above have referred to connecting the depicted outlet connector to a respiratory apparatus, it should be understood that these connection arrangements may be suitable for forming electrical, mechanical and pneumatic connections between other components, such as two air circuits, a RPT device to a humidifier, a RPT device to a patient interface and/or a humidifier to a patient interface. For example, the ability to maintain electrical, mechanical, and pneumatic connections while allowing a full rotational degree of freedom may be beneficial because it may help to reduce tube stress resulting from patient movement while wearing a patient interface at the opposite end of the tube. Another advantage of the present technology may be that rotational alignment may not be required to engage and/or disengage the connection arrangement, such as between the outlet connector and the respiratory apparatus. 
     6.7 Glossary 
     For the purposes of the present technology disclosure, in certain forms of the present technology, one or more of the following definitions may apply. In other forms of the present technology, alternative definitions may apply. 
     6.7.1 General 
     Air: In certain forms of the present technology, air supplied to a patient may be atmospheric air, and in other forms of the present technology atmospheric air may be supplemented with oxygen. 
     Continuous Positive Airway Pressure (CPAP): CPAP treatment will be taken to mean the application of a supply of air or breathable gas to the entrance to the airways at a pressure that is continuously positive with respect to atmosphere, and preferably approximately constant through a respiratory cycle of a patient. In some forms, the pressure at the entrance to the airways will vary by a few centimeters of water within a single respiratory cycle, for example being higher during inhalation and lower during exhalation. In some forms, the pressure at the entrance to the airways will be slightly higher during exhalation, and slightly lower during inhalation. In some forms, the pressure will vary between different respiratory cycles of the patient, for example being increased in response to detection of indications of partial upper airway obstruction, and decreased in the absence of indications of partial upper airway obstruction. 
     6.7.2 Aspects of RPT Devices 
     Air circuit: A conduit or tube constructed and arranged in use to deliver a supply of air or breathable gas between two components such as a RPT device and a patient interface, a RPT device and humidifier, or a humidifier and a patient interface. The air circuit may be referred to as air delivery tube. In some cases there may be separate limbs of the circuit for inhalation and exhalation. In other cases a single limb is used. 
     Controller: A device, or portion of a device that adjusts an output based on an input. For example one form of controller has a variable that is under control—the control variable—that constitutes the input to the device. The output of the device is a function of the current value of the control variable, and a set point for the variable. A servo-ventilator may include a controller that has ventilation as an input, a target ventilation as the set point, and level of pressure support as an output. Other forms of input may be one or more of oxygen saturation (SaO2), partial pressure of carbon dioxide (PCO2), movement, a signal from a photoplethysmogram, and peak flow. The set point of the controller may be one or more of fixed, variable or learned. For example, the set point in a ventilator may be a long term average of the measured ventilation of a patient. Another ventilator may have a ventilation set point that changes with time. A pressure controller may be configured to control a blower or pump to deliver air at a particular pressure. 
     Transducers: A device for converting one form of energy or signal into another. A transducer may be a sensor or detector for converting mechanical energy (such as movement) into an electrical signal. Examples of transducers include pressure transducers, flow transducers, carbon dioxide (CO 2 ) transducers, oxygen (O 2 ) transducers, effort transducers, movement transducers, noise transducers, a plethysmograph, and cameras. 
     6.73 Humidifiers 
     Dew Point: The atmospheric temperature (varying according to pressure and humidity) below which water droplets begin to condense and dew can form. 
     Humidity, absolute: The amount of water vapor present in a unit volume of air, usually expressed in mass per volume (e.g. g/m 3 ). 
     Humidity, relative: The amount of water vapor present in air expressed as a percentage of the amount needed for saturation at the same temperature. 
     6.7.4 Materials 
     Silicone or Silicone Elastomer: A synthetic rubber. In this specification, a reference to silicone is a reference to liquid silicone rubber (LSR) or a compression moulded silicone rubber (CMSR). One form of commercially available LSR is SILASTIC (included in the range of products sold under this trademark), manufactured by Dow Corning. Another manufacturer of LSR is Wacker. Unless otherwise specified to the contrary, a preferred form of LSR has a Shore A (or Type A) indentation hardness in the range of about 35 to about 45 as measured using ASTM D2240. 
     Polycarbonate: a typically transparent thermoplastic polymer of Bisphenol-A Carbonate. 
     6.7.5 Aspects of a Patient Interface 
     Anti-asphyxia valve (ΛΛV): The component or sub-assembly of a mask system that, by opening to atmosphere in a failsafe manner, reduces the risk of excessive CO 2  rebreathing by a patient. 
     6.7.6 Terms Used in Relation to Patient Interface 
     Curvature (of a surface): A region of a surface having a saddle shape, which curves up in one direction and curves down in a different direction, will be said to have a negative curvature. A region of a surface having a dome shape, which curves the same way in two principle directions, will be said to have a positive curvature. A flat surface will be taken to have zero curvature. 
     Floppy: A quality of a material, structure or composite that is the combination of features of: 
     Readily conforming to finger pressure. 
     Unable to retain its shape when caused to support its own weight. 
     Not rigid. 
     Able to be stretched or bent elastically with little effort. 
     The quality of being floppy may have an associated direction, hence a particular material, structure or composite may be floppy in a first direction, but stiff or rigid in a second direction, for example a second direction that is orthogonal to the first direction. 
     Resilient: Able to deform substantially elastically, and to release substantially all of the energy upon unloading, within a relatively short period of time such as 1 second. 
     Rigid: Not readily deforming to finger pressure, and/or the tensions or loads typically encountered when setting up and maintaining a patient interface in sealing relationship with an entrance to a patient&#39;s airways. 
     Semi-rigid: means being sufficiently rigid to not substantially distort under the effects of mechanical forces typically applied during positive airway pressure therapy. 
     6.8 Other Remarks 
     Unless the context clearly dictates otherwise and where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit, between the upper and lower limit of that range, and any other stated or intervening value in that stated range is encompassed within the technology. The upper and lower limits of these intervening ranges, which may be independently included in the intervening ranges, are also encompassed within the technology, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the technology. 
     Furthermore, where a value or values are stated herein as being implemented as part of the technology, it is understood that such values may be approximated, unless otherwise stated, and such values may be utilized to any suitable significant digit to the extent that a practical technical implementation may permit or require it. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this technology belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present technology, a limited number of the exemplary methods and materials are described herein. 
     When a particular material is identified as being used to construct a component, obvious alternative materials with similar properties may be used as a substitute. Furthermore, unless specified to the contrary, any and all components herein described are understood to be capable of being manufactured and, as such, may be manufactured together or separately. 
     It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include their plural equivalents, unless the context clearly dictates otherwise. 
     All publications mentioned herein are incorporated by reference to disclose and describe the methods and/or materials which are the subject of those publications. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present technology is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates, which may need to be independently confirmed. 
     The subject headings used in the detailed description are included only for the ease of reference of the reader and should not be used to limit the subject matter found throughout the disclosure or the claims. The subject headings should not be used in construing the scope of the claims or the claim limitations. 
     Although the technology herein has been described with reference to particular examples, it is to be understood that these examples are merely illustrative of the principles and applications of the technology. In some instances, the terminology and symbols may imply specific details that are not required to practice the technology. For example, although the terms “first” and “second” may be used, unless otherwise specified, they are not intended to indicate any order but may be utilised to distinguish between distinct elements. Furthermore, although process steps in the methodologies may be described or illustrated in an order, such an ordering is not required. Those skilled in the art will recognize that such ordering may be modified and/or aspects thereof may be conducted concurrently or even synchronously. 
     It is therefore to be understood that numerous modifications may be made to the illustrative examples and that other arrangements may be devised without departing from the spirit and scope of the technology. 
     7 REFERENCE NUMERAL LIST 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 patient 
                 1000 
               
               
                   
                 bed partner 
                 1100 
               
               
                   
                 patient interface 
                 3000 
               
               
                   
                 structure 
                 3100 
               
               
                   
                 plenum chamber 
                 3200 
               
               
                   
                 structure 
                 3300 
               
               
                   
                 vent 
                 3400 
               
               
                   
                 connection port 
                 3600 
               
               
                   
                 forehead support 
                 3700 
               
               
                   
                 rpt device 
                 4000 
               
               
                   
                 external housing 
                 4010 
               
               
                   
                 upper portion 
                 4012 
               
               
                   
                 portion 
                 4014 
               
               
                   
                 panel 
                 4015 
               
               
                   
                 chassis 
                 4016 
               
               
                   
                 handle 
                 4018 
               
               
                   
                 pneumatic block 
                 4020 
               
               
                   
                 air circuit 
                 4100 
               
               
                   
                 tube portion 
                 4102 
               
               
                   
                 helical coil 
                 4103 
               
               
                   
                 grommet 
                 4104 
               
               
                   
                 outlet connector 
                 4106 
               
               
                   
                 patient interface connector 
                 4107 
               
               
                   
                 actuator 
                 4108 
               
               
                   
                 retention feature 
                 4110 
               
               
                   
                 electrical connector 
                 4112 
               
               
                   
                 dummy connector 
                 4113 
               
               
                   
                 outlet connection region 
                 4114 
               
               
                   
                 recess 
                 4116 
               
               
                   
                 opening 
                 4118 
               
               
                   
                 rib 
                 4120 
               
               
                   
                 end cap 
                 4124 
               
               
                   
                 support structure 
                 4126 
               
               
                   
                 electrical lead 
                 4128 
               
               
                   
                 thread 
                 4130 
               
               
                   
                 substructure 
                 4132 
               
               
                   
                 housing 
                 4134 
               
               
                   
                 receiver 
                 4135 
               
               
                   
                 receiver thread 
                   4135.1 
               
               
                   
                 receiver flange 
                   4135.2 
               
               
                   
                 tube connection region 
                 4136 
               
               
                   
                 clip 
                 4137 
               
               
                   
                 clip thread 
                   4137.1 
               
               
                   
                 clip flange 
                   4137.2 
               
               
                   
                 connection end 
                 4138 
               
               
                   
                 tab 
                 4139 
               
               
                   
                 protrusion 
                   4139.1 
               
               
                   
                 tube end 
                 4140 
               
               
                   
                 hinge 
                 4141 
               
               
                   
                 connector thread 
                 4142 
               
               
                   
                 orifice 
                 4144 
               
               
                   
                 tab 
                 4148 
               
               
                   
                 keyway 
                 4150 
               
               
                   
                 flange 
                 4152 
               
               
                   
                 grip 
                 4154 
               
               
                   
                 cuff 
                 4156 
               
               
                   
                 elbow connector 
                 4158 
               
               
                   
                 cuff retention feature 
                 4160 
               
               
                   
                 least one cuff receiver 
                 4162 
               
               
                   
                 cuff electrical connector 
                 4164 
               
               
                   
                 outlet connector tube 
                 4168 
               
               
                   
                 base seal 
                 4170 
               
               
                   
                 plate 
                 4174 
               
               
                   
                 flow radius 
                 4176 
               
               
                   
                 travel stop 
                 4178 
               
               
                   
                 tab 
                 4180 
               
               
                   
                 electrical component 
                 4200 
               
               
                   
                 PCBA 
                 4202 
               
               
                   
                 power supply 
                 4210 
               
               
                   
                 input device 
                 4220 
               
               
                   
                 central controller 
                 4230 
               
               
                   
                 therapy device controller 
                 4240 
               
               
                   
                 transducer 
                 4270 
               
               
                   
                 output device 
                 4290 
               
               
                   
                 pneumatic component 
                 4300 
               
               
                   
                 air filter 
                 4310 
               
               
                   
                 inlet air filter 
                 4312 
               
               
                   
                 outlet air filter 
                 4314 
               
               
                   
                 muffler 
                 4320 
               
               
                   
                 inlet muffler 
                 4322 
               
               
                   
                 outlet muffler 
                 4324 
               
               
                   
                 pressure device 
                 4340 
               
               
                   
                 blower 
                 4342 
               
               
                   
                 motor 
                 4344 
               
               
                   
                 back valve 
                 4360 
               
               
                   
                 supplemental oxygen 
                 4380 
               
               
                   
                 substructure assembly 
                 4500 
               
               
                   
                 body 
                 4502 
               
               
                   
                 cap 
                 4504 
               
               
                   
                 electrical contact assembly 
                 4506 
               
               
                   
                 wire 
                 4508 
               
               
                   
                 connector contact 
                 4510 
               
               
                   
                 contact recess 
                 4511 
               
               
                   
                 connector contact 
                 4512 
               
               
                   
                 contact recess 
                 4513 
               
               
                   
                 connector contact 
                 4514 
               
               
                   
                 contact recess 
                 4515 
               
               
                   
                 prong 
                 4518 
               
               
                   
                 tab 
                 4520 
               
               
                   
                 detent 
                 4522 
               
               
                   
                 notches 
                 4524 
               
               
                   
                 tube connection region 
                 4526 
               
               
                   
                 thread 
                 4528 
               
               
                   
                 outlet connection region 
                 4530 
               
               
                   
                 shoulder 
                 4532 
               
               
                   
                 additional shoulder 
                   4532.1 
               
               
                   
                 wire overmould 
                 4534 
               
               
                   
                 plate 
                 4536 
               
               
                   
                 humidifier 
                 5000 
               
               
                   
                 cable housing 
                 5100 
               
               
                   
                 inner wall 
                 5101 
               
               
                   
                 cable 
                 5102 
               
               
                   
                 outer wall 
                 5103 
               
               
                   
                 swivelling disc 
                 5104 
               
               
                   
                 swivel electrical connector 
                 5105 
               
               
                   
                 tab 
                 5106 
               
               
                   
                 outlet assembly 
                 5107 
               
               
                   
                 stop surface 
                 5108 
               
               
                   
                 exit flange 
                 5109 
               
               
                   
                 stop surface 
                 5110 
               
               
                   
                 flange 
                 5112 
               
               
                   
                 swivel disc seal 
                 5113 
               
               
                   
                 electrical connector receiver 
                 5114 
               
               
                   
                 opening 
                 5116 
               
               
                   
                 retainer 
                 5118 
               
               
                   
                 stop surface 
                 5120 
               
               
                   
                 stop surface 
                 5122 
               
               
                   
                 void 
                 5124 
               
               
                   
                 notch 
                 5126 
               
               
                   
                 tang 
                 5128 
               
               
                   
                 airflow tube 
                 5130 
               
               
                   
                 first portion 
                  5130a 
               
               
                   
                 second portion 
                  5130b 
               
               
                   
                 inlet end 
                 5132 
               
               
                   
                 outlet end 
                 5134 
               
               
                   
                 flange 
                 5136 
               
               
                   
                 housing 
                 5138 
               
               
                   
                 outlet 
                 5140 
               
               
                   
                 outlet tube 
                 5142 
               
               
                   
                 outlet electrical connector 
                 5144 
               
               
                   
                 contact element 
                 5146 
               
               
                   
                 point 
                 5150 
               
               
                   
                 point 
                 5152 
               
               
                   
                 point 
                 5154 
               
               
                   
                 pin 
                 5156 
               
               
                   
                 female electrical connector 
                 5158 
               
               
                   
                 internal shoulder 
                 5160 
               
               
                   
                 retention feature 
                 5162 
               
               
                   
                 contact portion 
                 5164 
               
               
                   
                 base portion 
                 5166 
               
               
                   
                 curved portion 
                 5168 
               
               
                   
                 latch portion 
                 5172 
               
               
                   
                 annular section 
                 5174 
               
               
                   
                 portion 
                 5176 
               
               
                   
                 humidifier reservoir 
                 5180 
               
               
                   
                 humidifier reservoir outlet 
                 5182 
               
               
                   
                 housing 
                 5200 
               
               
                   
                 opening 
                 5201 
               
               
                   
                 outlet contact 
                 5202 
               
               
                   
                 outlet contact 
                 5204 
               
               
                   
                 outlet contact 
                 5206 
               
               
                   
                 groove 
                 5208 
               
               
                   
                 groove 
                 5210 
               
               
                   
                 groove 
                 5212 
               
               
                   
                 heating element 
                 5240 
               
               
                   
                 mold tool 
                 6000 
               
               
                   
                 mold tool 
                 6002