Patent Abstract:
The present invention is related to patient interfaces, such as nasal masks ( 2 ), particularly though not solely for use in providing continuous positive airway pressure therapy or positive pressure ventilation to patients suffering from obstructive sleep apnoea. In a first form the invention is a patient interface that has securement means ( 601 ) releasably attaching the interface to headstraps wherein the securement means ( 601 ) is slidably engaged with the patient interface. In a second form of the invention the mask headgear is formed of a plurality of straps ( 701, 702 ) where at least one of the plurality of straps is slidably engaged with another of the plurality of straps. In a further form the patient interface may be provided with vertically adjustable engaging means ( 802 ) that engage the patient interface with the headgear straps.

Full Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to patient interfaces, particularly though not solely for use in providing Continuous Positive Airway Pressure (CPAP) therapy or positive pressure ventilation to patients suffering from obstructive sleep apnoea (OSA). 
   2. Summary of the Prior Art 
   In the art of respiration devices, there are well known a variety of respiratory masks which cover the nose and/or mouth of a human user in order to provide a continuous seal around the nasal and/or oral areas of the face such that gas may be provided at positive pressure within the mask for consumption by the user. The uses for such masks range from high altitude breathing (ie. aviation applications) to mining and fire fighting applications, to various medical diagnostic and therapeutic applications. 
   One requisite of such respiratory masks has been that they provide an effective seal against the user&#39;s face to prevent leakage of the gas being supplied. Commonly, in prior mask configurations, a good mask-to-face seal has been attained in many instances only with considerable discomfort for the user. This problem is most crucial in those applications, especially medical applications, which require the user to wear such a mask continuously for hours or perhaps even days. In such situations, the user will not tolerate the mask for long durations and optimum therapeutic or diagnostic objectives will not be achieved, or will be achieved with great difficulty and considerable user discomfort. 
   In common with prior art designs, is an inability to seal effectively when the user&#39;s face becomes distorted. For example, as shown in the prior art mask of  FIG. 1  when the user  100  is sleeping on his or her side, one side  101  of the headgear tends to be pulled tight while the other side  102  tends to be loose. This causes the axis of the mask  103  to be twisted with respect to the axis of the head  104 , due to the net torque from the headgear, resulting in leakage  105  on one side. The user  100  sleeping on his or her side may also distort the facial contours around the nasal area  106  and may lead to further leakage. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a nasal mask and headgear which goes some way to overcoming the abovementioned disadvantages in the prior art or which will at least provide the industry with a useful choice. 
   Accordingly in a first aspect the present invention may broadly be said to consist in a device for delivering a supply of gases to a user comprising or including: 
   a patient interface, which in use is in fluid communication with said supply of gases, 
   securement means attached to or around the head of said user, and 
   engaging means adapted to slidingly engage said securement means with said patient interface, 
   wherein said engaging means comprises or includes an attachment portion able to be engaged with said securement means and the engagement between said securement means and said engaging means is caused by the releasable engagement of a protrusion, located on one of said attachment portion and said securement means, into a complementary shaped aperture located on one of said member and said securement means. 
   In a second aspect the present invention consists in continuous positive airways pressure system for delivering gases to a user comprising or including a pressurised source of gases, transport means in fluid communication with said pressurised source adapted to convey said gases, and a nasal mask in fluid communication with said transport means, in use, delivering said gases to said user, said nasal mask comprising or including: 
   a body portion having an inlet, in use said inlet receiving a supply of gases, 
   sealing means engaged with said body portion, and adapted to seal against the facial contours of said user, and 
   engaging means adapted to in use provide a sliding engagement with a means of securement to a user, and a compressive force on said sealing means to ensure said supply of gases is delivered to a user without significant leakage, 
   wherein said engaging means comprises or includes an attachment portion able to be engaged with said securement means and the engagement between said securement means and said engaging means is caused by the releasable engagement of a protrusion, located on one of said attachment portion and said securement means, into a complementary shaped aperture located on one of said member and said securement means. 
   In a third aspect the present invention consists in a device for delivering a supply of gases to a user comprising or including: 
   a patient interface, which in use is in fluid communication with said supply of gases, 
   securement means attached to or around the head of said user, and 
   engaging means adapted to slidingly engage said securement means with said patient interface, 
   restraining means on said patient interface to restrain said engaging means at least in one dimension on said patient interface, but allowing said engaging means to slide within said restraining means in at least one other dimension, said restraining means being substantially vertically adjustable on said patient interface in either a freely moveable position or lockable in at least one vertical position. 
   In a fourth aspect the present invention consists in a continuous positive airways pressure system for delivering gases to a user comprising or including a pressurised source of gases, transport means in fluid communication with said pressurised source adapted to convey said gases, and a nasal mask in fluid communication with said transport means, in use, delivering said gases to said user, said nasal mask comprising or including: 
   a body portion having an inlet, in use said inlet receiving a supply of gases, 
   sealing means engaged with said body portion, and adapted to seal against the facial contours of said user, and 
   engaging means adapted to in use provides a sliding engagement with a means of securement to a user, and a compressive force on said sealing means to ensure said supply of gases is delivered to a user without significant leakage, 
   restraining means on said body portion to restrain said engaging means at least in one dimension on said body portion, but allowing said engaging means to slide within at least one other dimension, said restraining means being substantially vertically adjustable on said body portion in either a freely moveable position or lockable in at least one vertical position. 
   In a fifth aspect the present invention consists in a device for delivering a supply of gases to a user comprising or including: 
   a patient interface, which in use is in fluid communication with said supply of gases, 
   securement means attached to or around the head of said user, and 
   engaging means adapted to engage said securement means with said patient interface, 
   wherein said securement means comprises or includes a plurality of straps that are fastened around the head of said user in order to secure said patient interface to said users&#39; face, and at least one of said plurality of straps is slidably engaged with another of said plurality of straps. 
   In a sixth aspect the present invention consists in a continuous positive airways pressure system for delivering gases to a user comprising or including a pressurised source of gases, transport means in fluid communication with said pressurised source adapted to convey said gases, and a nasal mask in fluid communication with said transport means in use delivering said gases to said user, said nasal mask comprising or including: 
   a body portion having an inlet, in use said inlet receiving a supply of gases, 
   sealing means engaged with said body portion, and adapted to seal against the facial contours of said user, and 
   engaging means adapted to in use provide a sliding engagement with a means of securement to a user, and a compressive force on said sealing means to ensure said supply of gases is delivered to a user without significant leakage, 
   wherein said means of securement comprises or includes a plurality of straps, which are fastened around the head of said user in order to secure said patient interface to said users&#39; face, and at least one of said plurality of straps is slidably engaged with another of said plurality of straps. 
   To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One preferred form of the present invention will now be described with reference to the accompanying drawings in which; 
       FIG. 1  is a plan view of a prior art mask illustrating side leak, 
       FIG. 2  is a block diagram of a humidified positive pressure ventilation system as might be used in conjunction with the present invention, 
       FIG. 3  is an illustration of a prior art nasal mask that may be used with the headgear and glider straps of one of the preferred embodiment of the present invention, 
       FIG. 4  is a perspective view of a prior art nasal mask illustrating a sliding strap clipped in place on the mask, 
       FIG. 5  is a side view of the sliding strap of the prior art, 
       FIG. 6  is a front view of a sliding strap with clipping attachment means for use with a nasal mask of the present invention, 
       FIG. 7  is an illustration of the headgear attaching a nasal mask of the present invention to a user&#39;s head, showing a sliding strap in the back sections of the headgear, 
       FIG. 8  is a front view of an alternative form of the sliding strap of the present invention, and 
       FIG. 9  shows a side views of an alternative form of the sliding strap as may be used with the nasal mask of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention provides improvements in the field of nasal masks for use in positive pressure ventilation. In particular a nasal mask is described which is more comfortable for the user to wear and reduces the side leakage as compared with masks of the prior art. It will be appreciated that the nasal mask as described in the preferred embodiment of the present invention can be used in respiratory care generally or with a ventilator but will now be described below with reference to use in a humidified positive pressure ventilation system. 
   With reference to  FIG. 2  a humidified positive pressure ventilation system is shown in which a patient  1  is receiving humidified and pressurised gases through a nasal mask  2  connected to a humidified gases transportation pathway or inspiratory conduit  3 . It should be understood that delivery systems could also be VPAP (Variable Positive Airway Pressure) and BiPAP (Bi-level Positive Airway Pressure) or numerous other forms of respiratory therapy. Inspiratory conduit  3  is connected to the outlet  4  of a humidification chamber  5  which contains a volume of water  6 . Inspiratory conduit  3  may contain heating means or heater wires (not shown) which heat the walls of the conduit to reduce condensation of humidified gases within the conduit. Humidification chamber  6  is preferably formed from a plastics material and may have a highly heat conductive base (for example an aluminium base) which is in direct contact with a heater plate  7  of humidifier  8 . Humidifier  8  is provided with control means or electronic controller  9  which may comprise a microprocessor based controller executing computer software commands stored in associated memory. 
   Controller  9  receives input from sources such as user input means or dial  10  through which a user of the device may, for example, set a predetermined required value (preset value) of humidity or temperature of the gases supplied to patient  1 . The controller may also receive input from other sources, for example temperature and/or flow velocity sensors  11  and  12  through connector  13  and heater plate temperature sensor  14 . In response to the user set humidity or temperature value input via dial  10  and the other inputs, controller  9  determines when (or to what level) to energise heater plate  7  to heat the water  6  within humidification chamber  5 . As the volume of water  6  within humidification chamber  5  is heated, water vapour begins to fill the volume of the chamber above the water&#39;s surface and is passed out of the humidification chamber  5  outlet  4  with the flow of gases (for example air) provided from a gases supply means or blower  15  which enters the chamber through inlet  16 . Exhaled gases from the patient&#39;s mouth are passed directly to ambient surroundings in  FIG. 3 . 
   Blower  15  is provided with variable pressure regulating means or variable speed fan  21  which draws air or other gases through blower inlet  17 . The speed of variable speed fan  21  is controlled by electronic controller  18  (or alternatively the function of controller  18  could be carried out by controller  9 ) in response to inputs from controller  9  and a user set predetermined required value (preset value) of pressure or fan speed via dial  19 . 
   Nasal Mask 
   A nasal mask that may be used with the improvements to the securement means (headgear) and engagement means (glider straps) of the present invention is shown in  FIG. 3 . The patient interface or mask includes a hollow body  301  with an inlet  302  connected to the inspiratory conduit  3 . The mask  2  is positioned around the nose of the user  1  with the headgear  305  secured around the back of the head of the patient  1 . The restraining force from the headgear  305  on the hollow body  301  and the forehead rest  304  ensures enough compressive force on the mask cushion  303 , to provide an effective seal against the patient&#39;s face. 
   The hollow body  301  is constructed of a relatively inflexible material for example, polycarbonate plastic. Such a material would provide the requisite rigidity as well as being transparent and a relatively good insulator. The expiratory gases can be expelled through a valve (not shown) in the mask, a further expiratory conduit (not shown), or any other such method as is known in the art. 
   Mask Headgear 
   Referring now to  FIGS. 3 and 4 , the headgear  305  of a prior art device is shown that may be connected to the hollow body  301 . Rather than traditional fixed or adjustable attachments the present invention utilises a sliding engagement means (glider strap) between the headgear  305  and the hollow body  301 . This is achieved with a sliding member  306 , running through harnessing means (only one  307  is shown in  FIG. 3 ) located on either side of the headgear  305  and over the top of the hollow body  301 . The sliding member  306  is reciprocally engaged with guides  401 ,  402  mounted on the top surface of the hollow body  301 . The guides constrain the member  306  but allow it to slide sideways, meaning the headgear  305  can move laterally, independently of the hollow body  306 . Thus as a user&#39;s face is contorted during various sleeping positions the headgear is able to move with the changes in position while the mask is left in the correct position on the nose of the user and an effective seal is maintained. 
   To further ensure user comfort and effective pressure on the mask cushion  303 , the headgear  305  may be constructed either using two straps running around the back of the user&#39;s head as shown in  FIG. 3  or with a partial skull cap or any other configurations as are known in the art. In this case the straps or partial skull cap would be constructed using neoprene but may also be constructed using any material as is known in the art which will be comfortable for the user. 
   The sliding member  306  of the prior art, shown in  FIG. 5  in isolation, is constructed of polyacetal (Delrin 500P NC010) using injection moulding techniques to give a polished finish. This material, similar to other nylon based derivatives, with its polished finish has a particularly low friction coefficient, and therefore slides with respect to the hollow body  301  with very little resistance. 
   As shown in  FIG. 4 , the hollow body  301  has engaging guides  401 , 402 , wherein use the sliding member  306  snaps into place into the engaging guides ( 401 ,  402 ) and can only be removed therefrom using a substantial force. This means that with any normal use the sliding member  306  will stay retained within the engaging clips  401 ,  402 . 
   As shown in  FIG. 5  the sliding strap includes a mid-section  501  intended to reciprocate with the engaging guides, terminated at each end by loops  502 ,  503  which attach to the headgear. The first loop  502  is a full loop through which the headgear  305  is permanently attached with for example, a velcro strap. The loop  503  at the other end, is only a partial loop  504  designed so that a strap or loop from the headgear  305  can be easily slipped in or out of the open section  505  to allow easy removal and attachment of the mask. 
   Sliding Member Attachment Portion 
   The nasal mask of the present invention has a sliding member similar to that described above. As shown in  FIG. 6 , the ends  602 ,  603  of the sliding member  601  are attached to the headgear straps  604 ,  605  by way of engaging means  606 ,  607 . The engaging means  606 ,  607  comprise two parts. Firstly, attachment portions are integrally formed on the each end  602 ,  603  of the sliding member  601 . Secondly, complimentary portions (to the attachment portions) are either integrally formed or attached to the ends of the headgear straps  604 ,  605 . Each of the attachment and complementary portions are releasably attached to one another. Each attachment portion is a substantially square section  608 ,  610  each having an aperture  614 ,  615 . The ends of the headgear strap  609 ,  611  each having a complimentary portion having a protrusion  612 ,  613  fittable within the aperture  614 ,  615  of the attachment portion  608 ,  610 . Effectively, in use, when attaching the sliding member  601  to the headgear straps  604 ,  605 , the protrusion  612 ,  613  is fitted into the aperture  614 ,  615  on the attachment portion, thereby maintaining a connection between the sliding member and the headgear straps. 
   Alternatively, the protrusions  612 ,  613  as described above may be located on the attachment portions of the sliding member  601  and the apertures  614 ,  615  on the ends of the headgear straps. 
   In  FIG. 6  the protrusions  612 ,  613  is shown as being larger than the apertures  614 ,  615 . This is because the material making up the attachment portions and the end of the headgear straps is a deformable material, preferably of the plastics type, that allows for the large protrusion to be forced through the smaller aperture. The protrusion and aperture remain engaged until an opposing force causes the protrusion to disengage or be pulled from the aperture. 
   Sliding Headgear Strap 
   The nasal mask of the present invention in an alternative form may also be provided with headgear utilising a sliding strap.  FIG. 7  shows a sliding strap  701  that is located at the back of the user&#39;s head. When the user  703  turns their head, the circumferential distance from the nose to the back of the head changes. In prior art devices this movement produces unequal tension in the straps of the restraining headgear and therefore pulls the nasal mask in the direction of increased tension. By allowing the strap  701  to ‘slide’ within the rest of the headgear, in particular the skullcap portion  702 , an equal tension is produced and any translation of these forces to the mask is eliminated, hence side leakage as described earlier in relation to the prior art mask of  FIG. 1  is reduced. 
   Vertical Adjustment for Sliding Member 
   The nasal mask of the present invention in an alternative form may also be provided with adjustment means that allows for vertical adjustment of the sliding member. Due to variations in the size of user&#39;s head of the nasal mask, the location of the restraining means (engaging guides as referred to earlier with reference to  FIG. 4 , which hold the sliding member on the mask) that guide the “sliding member” is not always desirable. Allowing these guides to move vertically creates a more desirable mask for the user and may assist in reducing side leakages. The vertical movement of the guides also overcomes the problems with over tightening of the headgear straps that occurs when the user tilts their head vertically.  FIG. 8  shows restraining means that are vertically adjustable and which may be utilised with the sliding member of the present invention. The vertically adjustable restraining means  802  is a substantially rectangular section  804  having located thereon engaging guides  803 , that the sliding member  801  is pushed into, these guides retain the member  801  but allow it to slide within the guides  803 . The rectangular section  804  is located and moveable within vertical slides  805 ,  806 . These slides  805 ,  806  are attached by appropriate means to the mask body ( 301  on  FIG. 3 ). The rectangular section  804 , guides  803  and thus sliding member  801  can therefore be moved up and down as indicated by arrows A and B. The rectangular section  804  may be freely moveable within the slides  805 , 806  or may be moved and locked in various vertical positions. 
   Alternative Sliding Member 
   The nasal mask of the present invention in an alternative form may also be provided with an alternative sliding member. A user may find it difficult to insert the sliding member as described above into the engaging guides on the mask  301 .  FIG. 9  illustrates an alternative sliding member  901  having a section  902  with reduced diameter at one of its ends. The reduced diameter section  902  makes it easier to insert the sliding member  901  into the engaging guides on the mask base. When a user puts on the nasal mask and attaches the sliding member to the front of the mask within the engaging guides  903 , the user places the narrowed section  902  of the sliding member  901  within the engaging guides and moves the sliding member in a lateral direction into an “in use” position where the wider diameter of the sliding member resides within the guides. Thus tie larger diameter section of the sliding member  901  that remains in the engaging guides is more difficult to remove from the guides.

Technology Classification (CPC): 0