Patent Publication Number: US-2022233857-A1

Title: Implantable stimulator with external device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of, and priority to, U.S. Provisional Patent Application No. 62/855,487, filed May 31, 2019, which is hereby incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to treatment of respiratory-related disorders and more specifically to systems and methods with implantable stimulators and corresponding external devices for addressing one or more types of apnea events. 
     BACKGROUND 
     Various systems exist for aiding users experiencing sleep apnea and related respiratory disorders. Some such systems rely on the user to wear a mask that aids in suppling pressurized air to the airway of the user. Some users find such systems to be uncomfortable, difficult to use, expensive, aesthetically unappealing, etc. 
     Thus, a need exists for alternative systems and methods for addressing sleep apnea and related respiratory disorders. The present disclosure is directed to solving these problems and addressing other needs. 
     SUMMARY 
     According to some implementations of the present disclosure, a method for aiding a user includes receiving, from one or more sensors, data associated with an airway of the user. The method also includes analyzing the data to determine if the user is experiencing an apnea event, if the user is about to experience and apnea event, if the user is no longer experiencing an apnea event, or any combination thereof. The method further includes in response to a determination that the user is experiencing an apnea event or the user is about to experience an apnea event, causing a stimulator to provide electrical stimulation to a portion of the user to aid in stopping or preventing the apnea event. 
     According to some implementations of the present disclosure, a system for aiding a user includes a housing, a stimulator, a receiver, a collar, a transmitter, a sensor, a memory, and a control system. The housing is configured to be positioned in the user adjacent to an airway of the user. The stimulator is coupled to the housing. The receiver is coupled to the housing. The collar is configured to be worn around a neck of the user. The transmitter is coupled to the collar and is configured to communicate with the receiver to cause the stimulator to selectively provide electrical stimulation to (i) one or more muscles of the user that are adjacent to the airway (ii) one or more nerves associated with the one or more muscles, or (iii) both (i) and (ii). The sensor is configured to generate data associated with the airway of the user. The memory stores machine-readable instructions. The control system includes one or more processors configured to execute the machine-readable instructions to analyze the generated data. The analysis of the data is for determining (i) if the user is experiencing an apnea event, (ii) if the user is about to experience an apnea event, (iii) if the user is no longer experiencing an apnea event, (iv) or any combination thereof. In response to a determination that (i) the user is experiencing an apnea event or (ii) the user is about to experience an apnea event, the control system causes the transmitter to communicate with the receiver such that the stimulator provides the electrical stimulation to aid in stopping or preventing the apnea event. 
     According to some implementations of the present disclosure, a method includes receiving, from one or more sensors, data associated with an airway of the user. The method also includes determining that the user is currently experienced an apnea event based at least in part on the received data. The method further includes in response to determining that the user is currently experiencing an apnea event, causing a stimulator to provide electrical stimulation, at a first intensity level, to one or more muscles of the user that are adjacent to the airway to aid in stopping the apnea event. 
     According to some implementations of the present disclosure, a system for aiding a user includes a stimulator, a sensor, a memory, and a control system. The stimulator is configured to be positioned in the user adjacent to an airway of the user. The sensor is configured to generate data associated with the airway of the user. The memory stores machine-readable instructions. The control system includes one or more processors configured to execute the machine-readable instructions to determine, based at least on an analysis of the generated data, that the user is currently experiencing an apnea event. In response to the determination that the user is currently experiencing an apnea event, the control system causes the stimulator to provide electrical stimulation, at a first intensity level, to one or more muscles of the user that are adjacent to the airway to aid in stopping the apnea event. 
     According to some implementations of the present disclosure, a method includes receiving, from one or more sensors, data associated with the user. The method also includes analyzing the data to determine if the user is currently experiencing a first type of apnea event and analyzing the data to determine if the user is currently experiencing a second type of apnea event that is different from the first type of apnea event. The method further includes responsive to determining that the user is currently experiencing the first type of apnea event, causing a first stimulator to provide electrical stimulation to one or more muscles of the user that are adjacent to a throat of the user to aid in stopping the first type of apnea event. The method additionally includes responsive to determining that the user is currently experiencing the second type of apnea event, causing a second stimulator to provide electrical stimulation to a diaphragm of the user to aid in stopping the second type of apnea event. 
     According to some implementations of the present disclosure, a system for aiding a user in breathing during sleep includes a first stimulator, a second stimulator, one or more sensors, a memory, and a control system. The first stimulator is configured to be positioned in the user adjacent to a throat of the user. The second stimulator is configured to be positioned in the user adjacent to a diaphragm of the user. The one or more sensors is configured to generate data. The memory stores machine-readable instructions. The control system includes one or more processors configured to execute the machine-readable instructions to analyze the generated data to determine if the user is currently experiencing a first type of apnea event. The control system further analyzes the generated data to determine if the user is currently experiencing a second type of apnea event that is different than the first type of apnea event. In response to a determination that the user is currently experiencing the first type of apnea event, the control system causes the first stimulator to provide electrical stimulation to one or more muscles of the user that are adjacent to the throat of the user to aid in stopping the first type of apnea event. In response to a determination that the user is currently experiencing the second type of apnea event, the control system causes the second stimulator to provide electrical stimulation to the diaphragm of the user to aid in stopping the second type of apnea event. 
     The foregoing and additional aspects and implementations of the present disclosure will be apparent to those of ordinary skill in the art in view of the detailed description of various embodiments and/or implementations, which is made with reference to the drawings, a brief description of which is provided next. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other advantages of the present disclosure will become apparent upon reading the following detailed description and upon reference to the drawings. 
         FIG. 1A  is a diagram that illustrates an overview of a respiratory system of a user; 
         FIG. 1B  is a diagram that illustrates an upper airway of the user of  FIG. 1A ; 
         FIG. 2  is a block diagram of a system for aiding a user (e.g., in breathing during sleep), according to some implementations of the present disclosure; 
         FIG. 3A  is a perspective view of a system with a stimulator (positioned in the user) and an external device (unrolled) in the form of a collar for aiding a user (e.g., in breathing during sleep), according to some implementations of the present disclosure; 
         FIG. 3B  is a perspective view of the system of  FIG. 3A  where the external device is worn/donned by the user; 
         FIG. 4A  is a perspective view of a user wearing a system with two stimulators (positioned in the user) and two external devices, one external device in the form of a collar and the other external device in the form of a band/belt, for aiding the user (e.g., in breathing during sleep), according to some implementations of the present disclosure; and 
         FIG. 4B  illustrates the system of  FIG. 4A  relative to a cross-sectional diagram view of the user to better illustrate the positioning of the two stimulators in the user, according to some implementations of the present disclosure. 
     
    
    
     While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the present disclosure is not intended to be limited to the particular forms disclosed. Rather, the present disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims. 
     DETAILED DESCRIPTION 
     Referring to  FIG. 1A , an overview of a respiratory system  12  of a user  10  (e.g., patient) is shown, which generally includes a nasal cavity, an oral cavity, a larynx, vocal folds, an oesophagus, a trachea, a bronchus, lungs, alveolar sacs, a heart, and a diaphragm. More generally, the user  10  has a throat  20 , which includes a region(s) of the respiratory system  12  of the user  10  generally in the neck area of the user  10 . The diaphragm of the user  10  is a sheet of muscle that extends across the bottom of the rib cage of the user  10 . The diaphragm generally separates the thoracic cavity  30  of the user  10 , which contains the heart, lungs, and ribs, from the abdominal cavity  40  of the user  10 . As the diaphragm contracts, the volume of the thoracic cavity  30  increases and air is drawn into the lungs. 
     As is described below in greater detail, one or more stimulators of the present disclosure can be placed (e.g., implanted via surgery, injected via syringe, etc.) inside the user  10  to aid the user  10 , for example, in breathing while sleeping. For example, one or more stimulators can be placed in the throat  20  of the user  10  (e.g., adjacent to one or more nerves innervating the muscles of the neck/throat and/or the diaphragm, and/or contacting one or more muscles in the neck/throat  20  of the user  10 ), in the thoracic cavity  30  and/or the abdominal cavity  40  (e.g., adjacent to and/or contacting the diaphragm of the user  10 ), or a combination thereof. 
     Referring to  FIG. 1B , a view of an upper airway  14  of the user  10  is shown, which includes the nasal cavity, nasal bone, lateral nasal cartilage, greater alar cartilage, nostrils (one shown), a lip superior, a lip inferior, the larynx, a hard palate, a soft palate, an oropharynx, a tongue, an epiglottis, the vocal folds, the oesophagus, and the trachea. 
     The respiratory system  12  of the user  10  facilitates gas exchange. The nose  50  and mouth  60  of the user  10  form the entrance to the airways of the user  10 . As best shown in  FIG. 1A , the airways include a series of branching tubes, which become narrower, shorter, and more numerous as they penetrate deeper into the lungs of the user  10 . The prime function of the lungs is gas exchange, allowing oxygen to move from the inhaled air into the venous blood and carbon dioxide to move in the opposite direction. 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 lungs is where the gas exchange takes place, and is referred to as the respiratory zone. 
     A range of respiratory disorders exist that can impact the user  10 . Certain disorders are characterized by particular events (e.g., apneas, hypopneas, hyperpneas, or any combination thereof). Examples of respiratory disorders include Obstructive Sleep Apnea (OSA), Cheyne-Stokes Respiration (CSR), respiratory insufficiency, Obesity Hyperventilation Syndrome (OHS), Chronic Obstructive Pulmonary Disease (COPD), Neuromuscular Disease (NMD), and Chest wall disorders. 
     Obstructive Sleep Apnea (OSA) is a form of Sleep Disordered Breathing (SDB) and is characterized by events including occlusion and/or obstruction of the upper air passage during sleep. OSA 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 in duration, sometimes 200 to 300 times per night. OSA 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. 
     Cheyne-Stokes Respiration (CSR) is another form of sleep disordered breathing. CSR is a disorder of a user&#39;s respiratory controller in which there are rhythmic alternating periods of waxing and waning ventilation known as CSR cycles. CSR is characterized by repetitive de-oxygenation and re-oxygenation of the arterial blood. It is possible that CSR is harmful because of the repetitive hypoxia. In some users, CSR is associated with repetitive arousal from sleep, which causes severe sleep disruption, increased sympathetic activity, and increased afterload. 
     Respiratory failure is an umbrella term for respiratory disorders in which the lungs are unable to inspire sufficient oxygen or exhale sufficient CO 2  to meet the user&#39;s needs. Respiratory failure may encompass some or all of the following disorders. 
     A user with respiratory insufficiency (a form of respiratory failure) may experience abnormal shortness of breath on exercise. 
     Obesity Hyperventilation Syndrome (OHS) is 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 users suffering from NMD are characterized 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: characterized 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: characterized 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 generalized 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 characterized 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. 
     According to some implementations of the present disclosure, a system (e.g., system  100 ,  200 ,  300 ) is provided to aid users (e.g., patients) experiencing respiratory events (e.g., apnea events) during sleep. An apnea typically occurs when air flow for a user falls below a predetermined threshold for a duration (e.g. 10 seconds). A first type of apnea event is called an obstructive apnea. Obstructive apneas typically occur when, despite user effort to breathe, some obstruction of the airway does not allow air to flow. A second type of apnea event is called a central apnea. Central apneas typically occur when an apnea is detected that is due to a reduction in breathing effort, or the absence of breathing effort, despite the airway being patent (e.g., open). A third type of apnea event is called a mixed apnea. Mixed apneas typically occur when a reduction or absence of breathing effort coincides with an obstructed airway. 
     Referring to  FIG. 2 , a block diagram of a system  100  for aiding a user (e.g., user  10  in  FIGS. 1A and 1B ) is shown. The system  100  can aid the user  10  ( i ) in breathing while sleeping, (ii) in breathing while awake, (iii) in opening an airway of the user, (iv) in starting or increasing a breathing function (e.g., contracting a diaphragm), (v) or any combination thereof. In some implementations, the system  100  aids the user  10  by causing one or more muscles of the user  10  to contract to (i) open an airway of the user  10 , (ii) to cause the user  10  to inhale air (e.g., breathing effort), or (iii) both. 
     The system  100  includes one or more of: a housing  102 , a stimulator  104 , a receiver  108 , a transmitter  110 , a motion sensor  112 , a magnetic field generator  114 , a microphone  116 , a conductance sensor  118 , a heart rate sensor  120 , an air flow sensor  122 , a photoplethysmography (PPG) sensor  124 , one or more other sensors  126  (e.g., EKG sensor, EEG sensor, EMG sensor, blood flow sensor, respiration sensor, pulse sensor, etc.), a memory  128 , a control system  130 , a battery  132 , an external device  150 , or any combination(s) thereof. That is the system  100  can include any portion of and any combination of these elements and the elements can be combined in various different arrangements (e.g., physical and/or wireless) and/or housings. 
     Some of the elements of the system  100  are positioned in the user  10  (e.g., implanted in the user  10 ) and others of the elements of the system  100  are positioned outside the user  10  (e.g., worn/donned by the user  10 ). One or more of the elements of the system  100  that are positioned in the user  10  can be so positioned by being injected into the user  10  using, for example, a syringe with a hypodermic needle attached thereto. Alternatively or additionally, one or more of the elements of the system  100  that are positioned in the user  10  can be so positioned by being surgically placed therein (e.g., cutting open the skin and positioning the element(s) therein and suturing the skin closed). 
     The stimulator  104  is positioned in the user  10  such that one or more electrical leads  105  of the stimulator  104  are positioned adjacent to one or more muscles of the user  10  and/or one or more nerves of the user  10  that are connected to the one or more muscles of the user  10 . In some implementations, the one or more electrical leads  105  includes a first electrical lead  105  that is positioned to stimulate a first one of the one or more muscles and/or a first one of the one or more nerves. Similarly, a second electrical lead  105  is positioned to stimulate a second one of the one or more muscles and/or a second one of the one or more nerves. In some implementations, the first electrical lead  105  provides the electrical stimulation at a first frequency and the second electrical lead  105  provides the electrical stimulation at a second frequency that is different from the first frequency. In some implementations, the first electrical lead  105  provides the electrical stimulation at a first intensity and the second electrical lead  105  provides the electrical stimulation at a second intensity that is different from the first intensity. Alternatively, the stimulator  104  may be leadless, with the stimulator body being conductive and the ends of the body acting as electrodes. 
     Once the stimulator  104  is positioned in the user  10 , the stimulator  104  is capable of delivering electrical and/or magnetic stimulation to the user  10  to aid in causing the one or more muscles of the user  10  to contract. The contraction of the one or more muscles of the user  10  can aid in opening an airway of the user  10 . The contraction can alternatively or additionally aid in causing the user  10  to have breathing effort (e.g., causing the diaphragm to draw/suck in air). 
     The electrical stimulation can be applied directly to the one or more muscles of the user  10  (e.g., muscles in the throat  20  of the user  10 , muscles surrounding and/or adjacent to an airway of the user  10 , the diaphragm of the user  10 , etc. or any combination thereof) and/or directly to the one or more nerves that are connected to the one or more muscles. Directing the electrical stimulation to the one or more nerves (as opposed to the one or more muscles directly) allows for a relatively lower intensity (e.g., voltage, amperage, etc. or any combination thereof) of the electrical stimulation to be applied to cause the one or more muscles (connected to the one or more nerves) to contract. 
     The stimulator  104  includes or is an electrical conductor (e.g., one or more electrically conductive wires with or without a portion being electrically insulated). The stimulator  104  includes the one or more electrical leads  105 , which are capable of carrying and/or flowing and delivering electrical current to the one or more muscles and/or one or more nerves of the user  10 . The electrical current can be supplied by the battery  132  or other power source that is directly and physically connected to the stimulator  104 . The battery  132  can be rechargeable. In some implementations, the battery  132  can be recharged by the magnetic field generator  114  and/or the external device  150 . Alternatively to the stimulator  104  including the battery  132 , in some implementations, the electrical current is supplied wirelessly by the magnetic field generator  114  (which can be included in the external device  150 ) directly to the electrical conductor(s). 
     In some implementations, the stimulator  104  only includes one or more electrically conductive wires, with or without a portion being electrically insulated. In some such implementations, the stimulator  104 /wire has a length between about 1 millimeter and about 100 centimeters; between about 1 millimeter and about 100 millimeters; between about 1 millimeter and about 10 millimeters; or any length therebetween. Further, in some such implementations, the stimulator  104 /wire has a diameter between about 0.01 millimeters and about 5 millimeters; between about 0.1 millimeter and about 2 millimeters; between about 0.1 millimeter and about 1 millimeter; or any diameter therebetween. The size and shape of the stimulator  104  can be selected to permit the injection of the stimulator  104  into the user  10  via a syringe with an attached hypodermic needle. 
     In some implementations, the stimulator  104  is directly positioned in the user  10 . In such implementations, the housing  102  is not required. Alternatively, the stimulator  104  or a portion thereof is coupled to the housing  102  (e.g., positioned at least partially therein) and the housing  102  (with the stimulator  104  coupled thereto) is positioned in the user  10 . The housing  102  can have the shape of an elongated pill (or any other shape) that is conducive to being injected into the user  10  using, for example, a syringe with a hypodermic needle attached thereto. In some implementations, the housing  102  electrically insulates at least a portion of the stimulator  104  (e.g., the entire stimulator  104  except for the one or more electrical leads  105  or conductive ends) from surrounding tissue of the user  10 . 
     In addition to the stimulator  104  being coupled to the housing  102 , a number of other elements of the system  100  can be coupled to the housing  102  and placed into the user  10 . For example, in some implementations, the receiver  108 , the motion sensor  112 , the microphone  116 , the conductance sensor  118 , the heart rate sensor  120 , the air flow sensor  122 , the photoplethysmography (PPG) sensor  124 , the other sensor(s)  126 , the memory  128 , the control system  130 , the battery  132 , or any combination thereof can be coupled to the housing  102  and positioned in the user  10  along with the stimulator  104 . By coupled to the housing  102  it is meant that the element coupled to the housing  102  is completely incased within the housing  102 , attached to an exterior surface of the housing  102 , partially protruding from one or more openings in the housing  102 , directly or indirectly attached to the housing  102 , or any combination thereof. 
     For example, the stimulator  104  and the receiver  108  are coupled to the housing  102  and positioned in the user  10 . For another example, the stimulator  104 , the receiver  108 , and the PPG sensor  124  are coupled to the housing  102  and positioned in the user  10 . For yet another example, the stimulator  104 , the receiver  108 , the PPG sensor  124 , the memory  128 , and the control system  130  are coupled to the housing  102  and positioned in the user  10 . Various other combinations of elements being coupled to the housing  102  and positioned in the user  10  are contemplated. 
     In some implementations, the receiver  108  is coupled to the housing  102  and/or the stimulator  104 . The receiver  108  is able to receive communications (e.g., signals) from the transmitter  110 . The transmitter  110  can be coupled to and/or positioned within the external device  150 . The communications received by the receiver  108  can cause the stimulator  104  to provide the electrical stimulation to the one or more muscles of the user  10  and/or the one or more nerves of the user  10 . In some implementations, the receiver  108  and the transmitter  110  enable wireless communication between the stimulator  104  and the external device  150 . In some implementations, the communications are indicative of instructions to cause the stimulator  104  to deliver electrical stimulation. In some implementations, the receiver  108  and/or the transmitter  110  are referred to as wireless control elements (e.g., wireless control elements  235 ). 
     Various sensors can be included in the system  100  for generating data that can be analyzed by the control system  130  and/or by one or more other systems (e.g., mobile phones, computers, servers, cloud based devices, etc.) to determine information and/or to make decisions regarding the application and/or cessation of electrical stimulation to be applied to the user  10  via the stimulator  104 . 
     In some such implementations, the system  100  includes the motion sensor  112 . The motion sensor  112  can include one or more accelerometers, one or more gyroscopes, or any combination thereof. The motion sensor  112  can be used to generate motion data that is indicative of breathing or a lack thereof by the user  10 . 
     In some implementations, the motion sensor  112  can be coupled to the housing  102  and positioned in the user  10 . Alternatively, the motion sensor  112  can be separate from the housing  102  and/or the stimulator  104  and positioned in the user  10 . In such implementations where the motion sensor  112  is positioned in the user  10 , the motion sensor  112  can be positioned adjacent to the airway of the user  10  to generate data associated with movements or lack of movements of the airway that indicate breathing or a lack thereof. The positioning of the motion sensor  112  can be in the throat  20  ( FIGS. 1A and 1B ) of the user  10 , the thoracic cavity  30 , the abdominal cavity  40 , or a combination thereof. 
     In some other implementations, the motion sensor  112  can be coupled to the external device  150  (e.g., a collar, a band/belt, etc., or any combination thereof) and worn by the user  10 . In the implementations where the external device  150  is a collar that is configured to be worn/donned about a neck and/or throat  20  of the user  10 , the motion sensor  112  can be coupled to the external device  150  such that the motion sensor  112  is positioned adjacent to a portion of the airway of the user  10  when the external device  150  is worn/donned around the neck/throat  20  of the user  10 . As such, the motion sensor  112  is positioned to generate motion data indicative of breathing or a lack thereof by the user  10  (e.g., moving, expanding, retracting, etc. of the neck/throat  20  adjacent to an airway indicates breathing). 
     Similarly, in the implementations where the external device  150  is a band and/or belt that is configured to be worn/donned about a chest and/or abdomen of the user  10 , the motion sensor  112  can be coupled to the external device  150  such that the motion sensor  112  is positioned adjacent to the chest and/or abdomen of the user  10  when the external device  150  is worn/donned by the user  10 . As such, the motion sensor  112  is positioned to generate motion data indicative of breathing or a lack thereof by the user  10  (e.g., moving, expanding, retracting, etc. of the chest and/or abdomen indicates breathing). 
     In addition to, or in lieu of, the motion sensor  112 , the system  100  can include the microphone  116 , the conductance sensor  118 , the heart rate sensor  120 , the air flow sensor  122 , the PPG sensor  124 , the other sensor(s)  126 , or any combination thereof, where such sensors or portion thereof is in the user  10  and/or coupled to the external device  150  in the same, or similar, fashion as described above for the motion sensor  112 . 
     For example, in some implementations, the system  100  includes the PPG sensor  124  coupled to the external device  150  such that the PPG sensor  124  is positioned adjacent to the throat  20 , or on the neck of the user  10 , when the external device  150  is worn/donned by the user  10  as a collar. In such implementations, the PPG sensor  124  is able to generate data that is indicative of blood flow of the user adjacent to the airway, blood oxygen levels of the user adjacent to the airway, heart rate of the user, an apnea event the user is currently experiencing, an apnea event the user is likely to experience in the future, or any combination thereof. 
     For another example, in some implementations, the system  100  includes the microphone  116  coupled to the external device  150  such that the microphone  116  is positioned adjacent to the throat  20  and/or neck of the user  10  when the external device  150  is worn by the user  10  as a collar. In such implementations, the microphone  116  is able to generate data (e.g., sound data) that is indicative of snoring, choking, an apnea event the user is currently experiencing, an apnea event the user is likely to experience in the future, or any combination thereof. 
     For another example, in some implementations, the system  100  includes the speaker  117  coupled to the external device  150 . In such implementations, the microphone  116  and the speaker  117  can be combined into an acoustic sensor, as described in, for example, WO 2018/050913, which is hereby incorporated by reference herein in its entirety. In such implementations, the speaker  117  generates or emits sound waves at a predetermined interval and the microphone  116  detects the reflections of the emitted sound waves from the speaker  117 . The sound waves generated or emitted by the speaker  117  have a frequency that is not audible to the human ear (e.g., below 20 Hz or above around 18 kHz) so as not to disturb the sleep of the user  10  or a bed partner. Based at least in part on the data from the microphone  116  and/or the speaker  117 , the control system  130  can determine movement of the user  10  and/or determine whether the user is or is going to experience an apnea, as described herein. 
     For another example, in some implementations, the system  100  includes the heart rate sensor  120  coupled to the external device  150  such that the heart rate sensor  120  is positioned adjacent to the chest of the user  10  when the external device  150  is worn by the user  10  as a band/belt. In such implementations, the heart rate sensor  120  is able to generate data that is indicative a heart rate and/or pulse of the user  10 . 
     For another example, in some implementations, the system  100  includes the air flow sensor  122  coupled to the housing  102  such that the air flow sensor  122  is positioned adjacent to and/or at least partially within the airway of the user  10  when the housing  102  is positioned in the user  10 . In such implementations, the air flow sensor  122  is able to generate data that is indicative of air flow in the airway of the user  10 . 
     The other sensor(s)  126  that can be included in the system  100  and positioned in the user  10  and/or be coupled to the external device  150  include, for example, a blood oxygen sensor, a blood flow sensor, a pulse sensor, a respiration sensor, an EKG sensor, an EMG sensor, an EEG sensor, a strain gauge, an accelerometer, a capacitive sensor, a strain gauge sensor, an analyte sensor, a moisture sensor, a camera, an infrared (IR) sensor, an ultrasonic oxygen sensor, an electrical oxygen sensor, a chemical oxygen sensor, an optical oxygen sensor, a sphygmomanometer sensor, an oximetry sensor, a galvanic skin response (GSR) sensor or any combination thereof. Each of such other sensor(s)  126  can generate data that can be analyzed by the control system  130  and/or by one or more other systems to determine information and/or to make decisions regarding the application and/or cessation of electrical stimulation to be applied to the user  10  via the stimulator  104 . 
     The memory  128  can include one or more physically separate memory devices, such that one or more memory devices can be coupled to the housing  102  and/or the external device  150 . The memory  128  acts as a non-transitory computer readable storage medium on which is stored machine-readable instructions that can be executed by the control system  130  and/or one or more other systems. The memory  128  is also able to store (temporarily and/or permanently) the data generated by the sensors of the system  100 . In some implementations, the memory  128  includes non-volatile memory, battery powered static RAM, volatile RAM, EEPROM memory, NAND flash memory, or any combination thereof. In some implementations, the memory  128  is a removable form of memory  128  (e.g., a memory card). 
     Like the memory  128 , the control system  130  can be coupled to the housing  102  and/or the external device  150 . The control system  130  is coupled to the memory  128  such that the control system  130  is configured to execute the machine-readable instructions stored in the memory  128 . The control system  130  includes one or more processors  131  and/or one or more controllers. In some implementations, the one or more processors  131  includes one or more x86 INTEL processors, one or more processors based on ARM® Cortex®-M processor from ARM Holdings such as an STM32 series microcontroller from ST MICROELECTRONIC, or any combination thereof. In some implementations, the one or more processors  131  include 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. 
     In some implementations, the control system  130  is a dedicated electronic circuit. In some implementations, the control system  130  is an application-specific integrated circuit. In some implementations, the control system  130  includes discrete electronic components. 
     The control system  130  is able to receive input(s) (e.g., signals, generated data, instructions, etc.) from any of the other elements of the system  100  (e.g., the sensors, etc.). The control system  130  is able to provide output signal(s) (e.g., via the transmitter  110 , via the magnetic field generator  114 , via the external device  150 , etc.) to cause one or more actions to occur in the system  100  (e.g., to cause the stimulator  104  to provide electrical stimulation to the user  10 , etc.). 
     The control system  130  is able to analyze the data generated by any of the sensors of the system  100  to determine (i) if the user  10  is experiencing an apnea event, (ii) if the user is about to experience an apnea event, (iii) if the user is no longer experiencing an apnea event, (iv) a current sleep state of the user  10 , (v) a tension of the one or more muscles of the user  10 , (vi) or any combination thereof. 
     Based on one or more of such determinations, the control system  130  is able to cause the stimulator  104  to provide electrical and/or magnetic stimulation to the user  10  to (i) aid in stopping an apnea event currently being experienced by the user  10  and/or (ii) aid in preventing an apnea event about to be experienced by the user  10 . In some such implementations, the control system  130  causes the transmitter  110  to transmit a signal to the receiver  108  to cause the electrical stimulation of the one or more muscles of the user  10 . In some other implementations, the control system  130  causes the external device  150  and/or the magnetic field generator  114  to wireless power the stimulator  104  to provide the electrical stimulation to the one or more muscles and/or the one or more nerves of the user  10 . 
     In addition to causing the stimulator  104  to provide the electrical and/or magnetic stimulation, the control system  130  is able to vary one or more parameters of the electrical stimulation provided by the stimulator  104 . The one or more parameters of the stimulation include frequency, intensity, duration, dwell time, rise time in a pulse, a ratio of on-time to an off-time, or any combination thereof. 
     In some implementations, the one or more parameters of the stimulation are varied based on a measured response (e.g., using one or more of the sensors of the system  100 ) of the one or more muscles to the stimulation. In some implementations, the modification to the parameters can be based on a continuous feedback loop by the control system  130  continuing to analyze the data generated by one or more of the sensors of the system  100  (e.g., the motion sensor  112 , the air flow sensor  122 , the PPG sensor  124 , etc. or any combination thereof). As such, the control system  130  is able to modify (e.g., in real-time, while the user is experiencing the same apnea event, after the user experiences an apnea event but before the user experiences another apnea event, etc.) one or more of the parameters based on the continued analysis. 
     For example, if the continued analysis of the generated data from one or more of the sensors of the system  100  indicates that the user  10  is still experiencing an apena event in the presence of the stimulation, the control system  130  can cause the stimulator  104  to increase the intensity of the stimulation applied to the user  10 . For another example, if the continued analysis indicates that the user  10  is no longer experiencing an apena event after stimulation, the control system  130  can cause the stimulator  104  to stop providing the simulation to the user  10 . As such, the user  10  is less likely to be desensitized over time to the stimulation as compared to systems that continually apply stimulation (even when the user is not experiencing an apnea event). 
     In some implementations, the control system  130  causes the stimulator  104  to automatically increase an intensity of the stimulation applied to the user  10 . As such, the intensity is likely to reach a level that causes the one or more muscles of the user  10  to contract without the intensity having to be set artificially high from the beginning of the stimulation. 
     As discussed above, the control system  130  can continually monitor the generated data to determine if a current level of the automatically increased intensity of the stimulation has caused the one or more muscles of the user  10  to contract. When the control system  130  determines that the current level has not caused the one or more muscles of the user  10  to contract, the control system  130  causes and/or permits the stimulator  104  to continue automatically increasing the intensity of the stimulation beyond the current level. Similarly, when the control system  130  determines that the current level has caused the one or more muscles of the user  10  to contract, the control system  130  causes the stimulator  104  to stop automatically increasing the intensity of the stimulation at the current level. As such, a proper intensity (e.g., not an artificially high intensity, which can be painful) for the stimulation for the user  10  is reached. 
     As described above, the external device  150  can be in the form of a collar, a band, a belt, etc., or any combination thereof and worn/donned by the user  10 . In some such implementations, the external device  150  includes a housing made entirely or at least partially from a stretchable material such that the external device  150  can be at least partially held close to the skin of the user  10  when worn. For example, the collar (e.g., external device  150 ) can include stretchable material so the collar is snug around the neck of the user  10  (without choking the user  10 ). As such, when a PPG sensor  124  is included in the collar (e.g., external device  150 ), the PPG sensor  124  can be held in close relationship to the neck of the user  10 , which can aid in providing more accurate data from the PPG sensor  124 . 
     Additionally or alternatively to the collar, band, and belt form factors for the external device  150 , the external device  150  can also include and/or be in the form of a patch that is able to be stuck to the skin of the user  10 . The external device  150  can also include and/or be a headgear that is configured to be worn about a head of the user  10 . Other form factors for the external device  150  are contemplated. For example, the external device  150  include and/or be in the form of a scarf, a shirt, pants, a mobile phone, a tablet, a computer, or any combination thereof. 
     The external device  150  can include any number of the elements of the system  100 . For example, in some implementations, the transmitter  110 , the motion sensor  112 , the magnetic field generator  114 , the microphone  116 , the conductance sensor  118 , the heart rate sensor  120 , the photoplethysmography (PPG) sensor  124 , the other sensor(s)  126 , the memory  128 , the control system  130 , the battery  132 , or any combination thereof is coupled to and/or positioned within the external device  150 . In some implementations, the external device  150  at least includes one or more of the sensors of the system  100 , the magnetic field generator  114 , the memory  128 , the control system  130 , and the battery  132 . In some implementations, the external device  150  at least includes the transmitter  110 , the memory  128 , the control system  130 , and the battery  132 . In some implementations, the external device  150  is plugged directly into a power source (e.g., a wall outlet) such that there is no need for the battery  132  in the external device  150 . 
     As discussed above, the control system  130  is able to determine if a user is experiencing or about to experience one or more types of apneas and to take one or more actions in response thereto. Additionally, the control system  130  is able to determine if a user is experiencing or about to experience one or more other respiratory events and/or respiration related diseases and to take one or more actions in response thereof. Such other respiratory events and/or respiration related diseases as discussed herein include, for example, hypopneas, hyperpneas, sleep disordered breathing, cheyne-stokes respiration, respiratory failure, obesity hyperventilation syndrome, chronic obstructive pulmonary disease, neuromuscular disease, chest wall disorders, or any combination thereof. 
     The control system  130  executes a respiration event determination algorithm for the determination of the presence of respiration events (e.g., apneas, hypopneas, hyperpneas, etc.). In some implementations, the respiration event determination algorithm receives as an input at least a portion of the data generated from one or more of the sensors of the system  100  and provides as an output a flag that indicates that a respiration event (e.g., an apnea, a hypopnea etc.) has been detected. In some implementations, the respiration event determination algorithm receives as an input at least a portion of the data generated from one or more of the sensors of the system  100  and provides as an output an instruction to activate the stimulator  104  to provide electrical stimulation to the user  10 . In some such implementations, the instruction includes instructions for setting at least a portion of the one or more parameters of the electrical stimulation to be provided by the stimulator  104 . 
     In some implementations of the system  100 , a respiration event of an apnea is detected when a function of respiratory flow rate (e.g., determined at least partially using the air flow sensor  122 ) falls below a flow rate threshold for a predetermined period of time. The function may determine a peak flow rate, a relatively short-term mean flow rate, or a flow rate intermediate of relatively short-term mean and peak flow rate, for example an RMS flow rate. The flow rate threshold may be a relatively long-term measure of flow rate. 
     In some implementations of the system  100 , a respiration event of a hypopnea is detected when a function of respiratory flow rate (e.g., determined at least partially using the air flow sensor  122 ) falls below a second flow rate threshold for a predetermined period of time. The function may determine a peak flow rate, a relatively short-term mean flow rate, or a flow rate intermediate of relatively short-term mean and peak flow rate, for example an RMS flow rate. The second flow rate threshold is greater than the flow rate threshold used to detect apneas. 
     In some implementations of the system  100 , a respiration event of an apnea is detected when a function of blood flow rate (e.g., determined at least partially using the PPG sensor  124 ) falls below a flow rate threshold for a predetermined period of time. The function may determine a peak flow rate, a relatively short-term mean flow rate, or a flow rate intermediate of relatively short-term mean and peak flow rate. The flow rate threshold may be a relatively long-term measure of flow rate. 
     The control system  130  executes a snore event determination algorithm for the determination of the presence of snoring related events (e.g., snoring, choking, etc.). In some implementations, the snoring event determination algorithm receives as an input at least a portion of the data generated from one or more of the sensors (e.g., the microphone  116 , the motion sensor  112 , etc.) of the system  100  and provides as an output (i) a flag that indicates that a snoring event (e.g., an apnea, a hypopnea etc.) has been detected, (ii) a metric of the extent to which snoring is present, or (iii) both (i) and (ii). 
     In some implementations of the system  100 , the snore event determination algorithm may determine an intensity of a flow rate signal in the range of 30-300 Hz. Further, the snore event determination algorithm may filter the respiratory flow rate signal to reduce background noise. 
     The control system  130  executes an airway patency algorithm for the determination of the patency (e.g., openness) of a user&#39;s airway. In some implementations, the airway patency algorithm receives as an input a respiratory flow rate signal (e.g., determined at least partially using the air flow sensor  122 ) and determines the power of the signal in the frequency range of about 0.75 Hz and about 3 Hz. The presence of a peak in this frequency range is indicative of an open airway. The absence of a peak in this frequency range is indicative of a closed airway. In some implementations, the airway patency algorithm receives as an input a respiratory flow rate signal and determines the presence or absence of a cardiogenic signal. The absence of a cardiogenic signal is indicative of a closed airway. 
     The control system  130  executes a therapy parameter algorithm for the determination of one or more of the parameters (e.g., intensity, frequency, duration, etc.) of the stimulator  104 . In some such implementations, the therapy parameter algorithm receives as an input the output(s) of one or more other algorithms described herein and outputs one or more values for the one or more parameters (e.g., intensity, frequency, duration, etc.) of the electrical stimulation provided by the stimulator  104 . 
     While the system  100  is shown as including one stimulator  104 , one external device  150 , and one battery  132 , it is contemplated that the system  100  can include any number of stimulators  104  (e.g., one, two, three, five, ten, fifty, etc.), the system  100  can include any number of external devices (e.g., one, two, three, five, ten, fifty, etc.), and the system  100  can include any number of batteries  132  (e.g., one, two, three, five, ten, etc.). The ratio of stimulators to external devices can be one-to-one or a different ratio. For example, in some implementations, two or more stimulators  104  can be controlled by and/or communicate with one external device  150 . 
     A method of using the system  100  to aid the user  10  when experiencing an apnea event is now described. The control system  130  (in the external device  150  or in the housing  102 ) executes a respiration event determination algorithm for the determination of the presence of respiration events in the user  10 . In some such implementations, the respiration event determination algorithm is stored as instructions in the memory  128 . 
     The control system  130  analyzes data generated by one or more of the sensors (e.g., the motion sensor  112 , the PPG sensor  124 , etc.) of the system  100  included in the external device  150  to determine if the user  10  is currently experiencing an apnea event (e.g., an obstructive apnea event). If the control system  130  determines that the user  10  is currently experiencing an apnea event, the control system  130  causes the stimulator  104  to provide stimulation. The stimulation can be provided to one or more muscles and/or one or more nerves of the user  10  that are adjacent to the throat  20  of the user  10 . The stimulation can aid in stopping the apnea event (e.g., by causing the one or more muscles in the throat  20  to contract and open the airway of the user  10 ). 
     Referring to  FIGS. 3A and 3B , a system  200  is shown relative to a user  10 B, where an external device  250  (in the form of a collar) is worn by the user  10 B in  FIG. 3B  and removed from the user  10 B in  FIG. 3A  for better illustration of the components of the external device  250 . The system  200  is the same as, or similar to, the system  100 . The system  200  includes (i) a stimulator  204  positioned in a throat  20 B of the user  10 B and (ii) the external device  250 . 
     The stimulator  204  is the same as, or similar to, the stimulator  104  described herein in connection with  FIG. 2 . The stimulator  204  is shown with two electrical leads  205  adjacent to one or more muscles of the user  10 B, although any number of electrical leads  205  are contemplated (e.g., one electrical lead, three electrical leads, five electrical leads, ten electrical leads, etc.). Likewise, the stimulator may be leadless with the ends of the stimulator capsule acting as electrodes to deliver stimulation. 
     The stimulator  204  is shown without a housing for ease of illustration, but just like stimulator  104 , the stimulator  204  can be coupled to a housing and/or any other elements described herein (e.g., a receiver, a sensor, a battery, a wireless control element  235 ). The stimulator  204  is positioned generally in the throat  20 B of the user  10 B such that the stimulator  204  is positioned to provide electrical stimulation to one or more muscles in the throat  20 B and/or the neck of the user  10 B. As such, the stimulator  204  can aid in opening an airway of the user  10 B. 
     The external device  250  is in the form of a collar that is wearable by the user  10 B around the throat  20 A/neck of the user  10 B. The external device  250  can be made of any type of material(s) (e.g., one or more types of plastic, one or more types of metal, nylon, one or more types of fabric, stretchable fabric, etc., or any combination thereof) suitable for being worn on a human body (e.g., neck). 
     The external device  250  can include any type of coupling mechanism  260  ( FIG. 3A ) to aid in attaching the external device  250  about the neck and/or throat  20 B of the user  10 B. For example, the coupling mechanism  260  can include a hook and loop fastener, a magnetic clasp, a snap connection, a ball clasp, a bead clasp, a barrel clasp, a fishhook clasp, a push button clasp, a springing clasp, a lobster claw clasp, a hook and loop clasp, etc. or any combination thereof. 
     In some implementations, the coupling mechanism  260  includes a loop at one end of the external device  250  into which the opposite end of the external device  250  fits through and doubles back to secure to an outside surface of the external device  250  using, for example, hook and loop fasteners. Various other ways of securing the external device  250  about the user  10 B are contemplated. In some implementations, the coupling mechanism  260  aids in securing the external device  250  to the user  10 B in a snug fashion. Alternatively, the coupling mechanism  260  aids in securing the external device  250  to the user  10 B in a loose fashion. 
     As best shown in  FIG. 3A , the external device  250  includes a sensor  275 , a memory  228 , a control system  230 , and a battery  232 . The sensor  275  is the same as, or similar to, the motion sensor  112 , the microphone  116 , the conductance sensor  118 , the heart rate sensor  120 , the PPG sensor  124 , the other sensor(s)  126 , or any combination thereof. The memory  228  is the same as, or similar to, the memory  128  described herein in connection with  FIG. 2 . The control system  230  is the same as, or similar to, the control system  130  described herein in connection with  FIG. 2 . The battery  232  is the same as, or similar to, the battery  132  described herein in connection with  FIG. 2 . 
     The external device  250  (and/or the stimulator  204 ) can also include one or more wireless control elements  235  such that the external device  250  and the stimulator  204  can wirelessly communicate with and/or wirelessly power the stimulator  204 . The one or more wireless control elements  235  can be imbedded/included in the control system  230  and/or be separate therefrom. For example, the external system  250  can include a transmitter that is the same as, or similar to, the transmitter  110  (and the stimulator  204  can include a receiver that is the same as, or similar to, the receiver  108 ), the magnetic field generator  114 , a wireless control module, or any combination thereof. In some implementations, the stimulator  204  itself (e.g., the electrically conductive wire forming at least a portion of the stimulator  204 ) serves as a wireless receiver without needing any other components. In some implementations, the wireless control element  235  of the stimulator  204  is or includes a receiver (e.g., receiver  108 ) and the wireless control element  235  of the external device  250  is or includes a transmitter (e.g., transmitter  110 ). 
     As shown in  FIG. 3B , when the user  10 B wears the external device  250  around the throat  20 B/neck of the user  10 B, the external device  250 , or a portion thereof, is directly adjacent to the stimulator  204 . As such, in some implementations, wireless communication and/or wireless charging/powering between the external device  250  and the stimulator  204  is enabled. Additionally, such positioning of the external device  250  positions the sensor  275  adjacent to the airway of the user  10 B. 
     In some implementations, indicia can be included on the external device  250  to aid the user  10 B in aligning the external device  250  with one or more portions of the anatomy of the user  10 B. As such, the sensor  275  can be appropriately placed relative to the user  10 B. For example, a vertical line indicium  280  can be included (e.g., printed) on an external surface of the external device  250 . The vertical line indicium  280  can indicate to the user  10 B a location of the sensor  275  (which can be imbedded and/or otherwise hidden in the external device  250 ) to be aligned with the user&#39;s anatomy (e.g., midline of the throat  20 B). 
     For another example, the external device  250  can include other features to aid the user  10 B in aligning the external device  250  when donning the external device  250 . For example, a cutout  285  (e.g., having a circular shape, a square shape, a triangular shape, a polygonal shape, etc. or any combination thereof) in the external device  250  can indicate a location of the external device  250  that should be aligned with a specific part of the user&#39;s anatomy (e.g., midline of the throat  20 B) such that, for example, the sensor  275  is appropriately placed relative to the user  10 B. 
     By appropriately placed, it is meant that the sensor  275  is positioned in a location relative to the user  10 B such that the sensor  275  is able to generate reliable and/or usable data. In some such implementations, the location of the sensor  275  depends on the type of sensor(s) included in the sensor  275 . For example, if the sensor  275  is a motion sensor, the appropriate location for the sensor  275  maybe be in a first location and if the sensor  275  is a PPG sensor, the appropriate location for the sensor  275  maybe be in a second location that is the same or different from the first location. 
     Referring to  FIG. 4A , a system  300  is shown relative to a user  10 C. The system  300  is the same as, or similar to, the systems  100 ,  200 . The system  300  includes a first external device  350 A worn about a throat  20 C of the user  10 C and a second external device  350 B worn about a chest  30 C of the user  10 C. The first external device  350 A can be referred to as a collar and the second external device can be referred to as a chest band. The system  300  also includes a first stimulator  304 A positioned in the throat  20 C or neck of the user  10 C and a second stimulator  304 B positioned in an abdominal cavity or a thoracic cavity of the user  10 C. 
     The stimulators  304 A and  304 B are both the same as, or similar to, the stimulators  104 ,  204  described herein in connection with  FIGS. 2, 3A, and 3B . The external devices  350 A and  350 B are the same as, or similar to, the external devices  150 ,  250  described herein in connection with  FIGS. 2, 3A, and 3B . The system  300  mainly differs in that the system  300  includes two stimulators and two external devices that work together to aid the user  10 C. 
     Referring to  FIG. 4B , the system  300  is shown relative to a cross-sectional diagram view of the user  10 C to better illustrate the positioning of the stimulators  304 A,  304 B in the user  10 C. Also shown are more details on the external devices  350   a ,  350 B. As noted above, the first and second external devices  350 A,  350 B are the same as, or similar to, the external devices  150 ,  250 . Specifically, each of the external devices  350 A,  350 B includes a sensor  375 , a memory  328 , a control system  330 , a battery  332 , a coupling mechanism  360 , and a wireless control element  335 , which are the same as, or similar to, the sensor  275 , the memory  228 , the control system  230 , the battery  232 , the coupling mechanism  260 , and the wireless control element  235  of the system  200  described in connection with  FIGS. 3A and 3B . The second external device  350 B mainly differs in its size relative to the first external device  350 A and the external device  250 . Namely, the second external device  350 B is larger to be wearable about a chest of the user  10 C. 
     In some implementations, the first external device  350 A and the first stimulator  304 A operate independently from the second external device  350 B and the second stimulator  304 B. In such implementations, the first external device  350 A and the first stimulator  304 A form a first sub-system of the system  300  that aid the user  10 C in addressing a first type of apnea events (e.g., obstructive apneas) by, for example, causing muscles in the throat  20 C to contract to open an airway. Similarly, in such implementations, the second external device  350 B and the second stimulator  304 B form a second sub-system of the system  300  that aid the user  10 C in addressing a second type of apnea events (e.g., central apneas) by, for example, causing the diaphragm of the user  10 C to contract to aid breathing effort of the user  10 C. In such implementations, both the first external device  350 A (collar) and the second external device  350 B (chest band) include respective memories  328  and respective control systems  330 . 
     In some other implementations, the first and second external devices  350 A,  350 B operate together and are coupled together (e.g., wirelessly and/or wired). In some such implementations, only one of the first and second external devices  350 A,  350 B includes the memory  328  and the control system  330 . That is, for example, the second external device  350 B (chest band) includes the memory  328 , the control system  330 , the sensor  375 , and the battery  332 , and the first external device  350 A (collar) includes the sensor  375  and the battery  332 . For another example, the first external device  350 A (collar) includes the memory  328 , the control system  330 , the sensor  375 , and the battery  332 , and the second external device  350 B (chest band) includes the sensor  375  and the battery  332 . 
     It should be understood that the sensor  375  in the first external device  350 A and the sensor  375  in the second external device  350 B can be the same type of sensor(s) or different sensor(s). For example, in some implementations, the sensor  375  in the first external device  350 A (collar) is a PPG sensor (e.g., like the PPG sensor  124 ) and the sensor  375  in the second external device  350 B (chest band) is a motion sensor (e.g., like the motion sensor  112 ). 
     While the first and second stimulators  304 A,  304 B are shown as being two separate and distinct stimulators, it is contemplated that the first and second stimulators  304 A,  304 B can be physically and/or electrically linked. For example, a common housing (not shown) can be implanted in the user  10 C (e.g., in the thoracic cavity of the user  10 C). From the common housing, one or more electrical leads of the first stimulator  304 A can extend into the neck of the user  10 C to be adjacent to one or more muscles and/or one or more nerves in the neck of the user  10 C. Further, from the common housing, one or more electrical leads of the second stimulator  304 B can extend into the abdominal cavity and/or thoracic cavity of the user  10 C to be adjacent to the diaphragm of the user  10 C. In some such implementations, one or more batteries can be coupled to the common housing for suppling electrical current to the first and second stimulators  304 A,  304 B. 
     A method of using the system  300  to aid the user  10 C when experiencing one or more types of apnea events is now described. The control system  330  (in the first external device  350 A, in the second external device  350 B, or a combination thereof) executes a respiration event determination algorithm for the determination of the presence of respiration events in the user  10 C. In some such implementations, the respiration event determination algorithm is stored as instructions in the memory  328 . 
     The control system  330  analyzes data generated by the sensor  375  in the first external device  350 A to determine if the user  10 C is currently experiencing a first type of apnea event (e.g., an obstructive apnea event). The control system  330  also analyzes data generated by the sensor  375  in the second external device  350 B to determine if the user  10 C is currently experiencing a second type of apnea event (e.g., a central apnea event). 
     If the control system  330  determines that the user  10 C is currently experiencing the first type of apnea event, the control system  330  causes the first stimulator  304 A to provide electrical stimulation. The electrical stimulation can be provided to one or more muscles and/or one or more nerves of the user  10 C that are adjacent to the throat  20 C of the user  10 C. The electrical stimulation can aid in stopping the first type of apnea event (e.g., by causing the one or more muscles in the throat  20 C to contract and open the airway of the user  10 C). 
     If the control system  330  determines that the user  10 C is currently experiencing the second type of apnea event, the control system  330  causes the second stimulator  304 B to provide electrical stimulation. The electrical stimulation can be provided to the diaphragm and/or one or more nerves connected to the diaphragm of the user  10 C. The electrical stimulation can aid in stopping the second type of apnea event (e.g., by causing the diaphragm to contract and cause the user  10 C to breathe/suck air into the respiration system). 
     Further, if the control system  330  determines that the user  10 C is currently experiencing the first type of apnea event and the second type of apnea event at the same time, the control system  330  (i) causes the first stimulator  304 A to provide electrical stimulation to the one or more muscles and/or one or more nerves of the user  10 C that are adjacent to the throat  20 C of the user  10 C and (ii) causes the second stimulator  304 B to provide electrical stimulation to the diaphragm and/or one or more nerves connected to the diaphragm of the user  10 C. 
     One or more elements or aspects or steps, or any portion(s) thereof, from one or more of any of claims  1 - 75  below can be combined with one or more elements or aspects or steps, or any portion(s) thereof, from one or more of any of the other claims  1 - 75  or combinations thereof, to form one or more additional implementations and/or claims of the present disclosure. 
     While the present disclosure has been described with reference to one or more particular embodiments and implementations, those skilled in the art will recognize that many changes may be made thereto without departing from the spirit and scope of the present disclosure. Each of these embodiments and implementations and obvious variations thereof is contemplated as falling within the spirit and scope of the present disclosure, which is set forth in the claims that follow.