Utilizing the pressure-volume relationship to identify lung condition

Abstract

Systems, devices, and methods for determining a treatment decision for a subject during assisted ventilation are described herein. In an example method, a pressure and a volume of air in an airway of the subject is determined during one or more ventilation cycles. An airway parameter of the subject is determined based on generating and analyzing a pressure-volume relationship of the subject. A treatment decision is identified based on analyzing the airway parameter. In various implementations, a respiratory condition of the subject is determined based on analyzing the airway parameter of the subject. The example method can be implemented into a monitor-defibrillator or another portable medical device. Together, the methods can improve the treatment of subjects receiving CPR who have respiratory conditions.

Description

S397-6031 PCT I PHYS0276PCT & MEDI-2778UTILIZING THE PRESSURE-VOLUME RELATIONSHIP TO IDENTIFY LUNG CONDITIONCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 755,848 filed on February 7, 2025, which is incorporated herein by reference in its entirety as if fully set forth herein.BACKGROUND

[0002] In some emergency medical care circumstances, procedures and devices are utilized to establish or ensure safe and effective passage of air into and out of an individual's respiratory system. The application of such procedures and devices is commonly referred to as airway management. In one of several types of airway management, a patient is administered positive pressure ventilation (PPV). Ordinary breathing by the patient is a negative pressure phenomenon - the diaphragm and chest wall move to increase the volume of the pleural cavity, reducing the pressure in the lungs to below atmospheric pressure, which pulls air into the lungs. When patients are receiving PPV, a positive pressure is created in a device (e.g., a mechanical ventilator or a manual resuscitation bag) attached to the patient's airway, forcing air into the lungs. Changing the pressure differential between the device and the lungs can affect the volume of air travelling into and out of the patient’s lungs.

[0003] Several different forms of PPV may be utilized in an emergency medical care situation. In some cases, the patient receives PPV delivered via a bag-valve-mask (BVM) device. With a BVM device, a facemask is placed over the patient’s mouth and nose, and a medical care provider squeezes a self-inflating bag attached to the facemask to deliver PPV. BVM ventilation is a very common method of PPV that is performed in emergency medical care situations by different levels of medical care providers. In some cases, the patient receives PPV delivered through a device inserted into the airway. Examples of such devices include an endotracheal tube (ETT), and a supraglottic airway (SGA). Placement of such invasive airway devices is sometimes accompanied by administration of medications to better facilitate prompt and successful airway placement. Once the device is inserted, PPV is frequently delivered manually by squeezing a self-inflating bag attached to the airway.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] FIG. 1 illustrates an example environment in which a rescuer is managing respiratory care of a subject.

[0005] FIG. 2 illustrates example pressure-volume curves associated with various respiratory conditions.

[0006] FIG. 3 illustrates an example process of analyzing a pressure-volume relationship of a subject.

[0007] FIG. 4 illustrates a ventilation device configured to perform various functions described herein.

[0008] FIG. 5 illustrates an example of an external defibrillator configured to perform various functions described herein.S397-6031 PCT I PHYS0276PCT & MEDI-2778DETAILED DESCRIPTION

[0009] Implementations of the present disclosure are directed to specific improvements in the technical field of emergency medicine. In particular, implementations of the present disclosure relate to identifying a respiratory condition of a patient during administration of an emergency medical procedure, and determining whether the emergency medical procedure should be modified or discontinued. For instance, emergency medical personnel are trained to provide assisted ventilation with particular parameters (e.g., ventilation rate, ventilation volume, etc.) to individuals experiencing medical emergencies. In some cases, the assisted ventilation may provide insufficient ventilation to an individual or may negatively impact their health if, for instance, the individual has a respiratory condition that affects the compliance of their lungs (e.g., how their lungs expand in response to pressure).

[0010] Various implementations described herein relate to systems, devices, and methods for analyzing airway parameters of a subject while a treatment is administered to the subject. Various implementations described herein determine a lung compliance of the subject based on the airway parameters. Various implementations described herein determine a respiratory condition (e.g., a pathological condition affecting the respiratory system) of the subject based on the airway parameters. Accordingly, treatment parameters that are predicted to treat the respiratory condition and / or benefit the physiological condition of the subject can be determined more accurately. Determining the treatment parameters based on the lung compliance and / or the respiratory condition of the subject can improve the efficacy of medical treatment and avoid adverse effects on the subject’s condition such as, for instance, lung injury or pain.

[0011] Implementations of the present disclosure will now be described with reference to the accompanying figures.

[0012] FIG. 1 illustrates an example environment 100 in which a rescuer 102 is managing respiratory care of a subject 104. In various implementations, the subject 104 is in respiratory distress. For instance, the subject 104 is unable to spontaneously breathe, or is unable to spontaneously breathe in a manner sufficient to prevent hypoxic injury to one or more tissues (e.g., the brain or other vital organs) in the body of the subject 104. Various causes of respiratory distress include apnea, respiratory failure, brain injuries, receipt of medications that prevent spontaneous breathing, drug overdose, and the like. In some examples, the subject 104 has collapsed and ceased spontaneously breathing due to cardiac arrest. During cardiac arrest, the heart of the subject 104 stops effectively pumping blood to a body of the subject 104. For instance, the subject 104 may have a cardiac arrhythmia (e.g., ventricular fibrillation (VF), ventricular tachycardia (VT), or the like) that prevents the heart from effectively pumping blood through the body of the subject 104. That is, the subject 104 may have a condition that prevents the heart of the subject 104 from spontaneously circulating blood in the body of the subject 104 In some cases, the lack of spontaneous circulation causes the subject 104 to lose consciousness and stop breathing.

[0013] In various examples, the environment 100 is outside of a clinical environment. For example, the environment 100 may occur in a public setting (e.g., a mall, an airport, etc.), outdoors, in a home, in a workplace, in a patientS397-6031 PCT I PHYS0276PCT & MEDI-2778transport environment (e.g., an ambulance, helicopter, etc.), or the like. In some cases, the environment 100 is a prehospital environment, such that the subject 104 is actively being transported or transferred to a hospital environment.

[0014] In various cases, a ventilation device 106 provides assisted ventilation to the subject 104 at the environment 100. In various cases, the ventilation device 106 is a medical device. The ventilation device 106 may be portable. According to various implementations, the ventilation device 106 includes a ventilation source 108 (e.g., a gas source), an element configured to move the gas in and out of the airway of the subject 104, as well as an airway adaptor 110 that is configured to connect the ventilation device 106 to the airway of the subject 104. For instance, the ventilation source 108 may include an O2 tank or other container for an O2-containing gas that is administered to the subject 104. The ventilation source 108 configured to move the gas in and out of the airway of the subject 104, in some cases, includes a manual device such as a bag-valve device (e.g., a bag that is manually squeezed by the rescuer 102 in order to propel the gas into the airway of the subject 104 and that is manually released by the rescuer in order to facilitate expiration from the subject 104) or an automated device such as a mechanical ventilator. In some implementations, the airway adaptor 110 includes a mask that is disposed on the face of the subject 104 (e.g., over the mouth and nose of the subject 104), an endotracheal tube disposed in the trachea of the subject 104, or a supraglottic device disposed in a pharynx of the subject 104. The ventilation device 106, in various cases, includes at least one duct (e.g., a tube, pipe, or the like) that is fluidically coupled to the airway of the subject 104, and through which gas is moved into, through, and out of the airway of the subject 104. The term “airway” and its equivalents, as used herein, refers to the pathway that facilitates the flow of gas between an external environment and an individual’s lungs. Components of the airway, for instance, can include the nasal cavity, the oral cavity, the pharynx, the larynx, the trachea, and the bronchi. The term “fluidically coupled,” “fluidically connected,” and their equivalents, as used herein, refer to the ability for a fluid (e.g., a gas or a liquid) to flow between two components without leakage. In various examples, the gas traveling between the ventilation device 106 and the airway of the subject 104 is referred to herein as “air.”

[0015] In some implementations, the ventilation device 106 includes a bag-valve mask that includes a number of valves, including a valve configured to prevent exhaled gas from flowing back into the bag, thus avoiding rebreathing of expired CO2. A supraglottic device, in various examples, includes a bag attached to a duct that fits over or otherwise directs gas to the glottic opening of the subject 104, without being inserted through the vocal cords. In various examples, the ventilation device 106 includes a valve that selectively vents a fluid circuit connecting an interior of the ventilation device 106 and the airway of the subject 104 to an external environment.

[0016] The terms “inspiration," “inspiratory," “inhalation,” and their equivalents, as used herein, refer to the period of assisted ventilation during which gas travels from the ventilation device 106 to the airway of the subject 104. The terms “expiration,” “expiratory,” “exhalation,” and their equivalents, as used herein, refer to the period of assisted ventilation during which gas travels from the airway of the subject 104 to the ventilation device 106 or to the external environment.S397-6031 PCT I PHYS0276PCT & MEDI-2778

[0017] In various implementations, the subject 104 may have a respiratory condition. The rescuer 102, in some examples, is unaware of the respiratory condition. For instance, the rescuer 102 may have arrived to the environment 100 after the subject 104 has lost consciousness, and the subject 104 was unable to self-report the respiratory condition to the rescuer 102 prior to receiving assisted ventilation from the ventilation device 106. In some cases, the subject 104 is unaware that they have a respiratory condition. Examples of respiratory conditions include asthma, acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), pneumonia, infectious respiratory diseases, restrictive respiratory diseases, pulmonary vascular diseases, and the like.

[0018] According to some examples, the rescuer 102 may be unable to provide effective ventilation to the subject 104 without knowledge of the respiratory condition. For example, if the subject 104 has the respiratory condition, ordinary ventilation parameters (e.g., ventilation rate, volume, pressure, etc.) may cause the assisted ventilation provided to the subject 104 to be inadequate. In various cases, respiratory conditions can affect lung compliance (also referred to herein as “airway compliance’’). Providing normal assisted ventilation (e.g., assisted ventilation parameters suitable for an individual without a respiratory condition) may be harmful to an individual with a respiratory condition and / or abnormal lung compliance. For instance, individuals with ARDS are administered lower tidal volumes due to their relatively lower lung compliance compared to subjects without a respiratory condition. In various cases, providing normal assisted ventilation may cause lung injury or other complications to the subject 104.

[0019] These issues can be addressed, in various examples, by automatically detecting the respiratory condition of the subject 104 in the environment. For example, the ventilation device 106 is configured to predict and / or determine the respiratory condition based on a pressure-volume relationship of gas present in a fluid circuit including the airway of the subject 104, the airway adaptor 110, and the ventilation source 108. The pressure-volume relationship is indicative of the pressure of gas in the airway of the subject 104 and the corresponding volume of gas moving through the airway of the subject 104 (e.g., during the inspiratory and / or expiratory phases). Accordingly, the pressure-volume relationship reflects the pressure of gas in the airway and / or lungs of the subject 104 associated with the presence (or movement) of a particular volume of the gas in the airway and / or lungs of the subject 104. In some cases, the pressure-volume relationship is represented by a dataset, graph, or a line-of-best fit of the dataset. For instance, a pressure-volume relationship can be represented by a graph of the detected pressure in the fluid circuit with respect to the detected volume of gas in the airway and / or lungs of the subject 104.

[0020] In various implementations, the lung compliance of the subject 104 can be determined based on the pressure-volume relationship. In some examples, the respiratory condition of the subject 104 can be determined based on the pressure-volume relationship and / or the lung compliance. In various implementations of the present disclosure, identifying the respiratory condition and / or lung compliance of the subject 104 enables identification of appropriate ventilation parameters and administration of sufficient ventilation to the subject 104.

[0021] In various examples, one or more physiological parameters of the subject 104 are detected by one or more airway sensors 112. In some examples, the airway sensor(s) 112 are included in, or integrated with, the ventilationS397-6031 PCT I PHYS0276PCT & MEDI-2778device 106. For example, the airway sensor(s) 112 are integrated with and / or attached to a mechanical ventilator, a bag-valve mask, an endotracheal tube, a duct of the ventilation device 106, airway adaptors, or any other device fluidically coupled to the airway of the subject 104. In some examples, the airway sensor(s) 112 include at least one sensor configured to detect a flow parameter (e.g., volumetric flow rate, velocity, etc.) of a gas in the fluid circuit including the airway of the subject 104, such as a pressure-gradient flowmeter, an ultrasound-based flow sensor, a turbine-based flowmeter, a wire anemometer (including, e.g., a heated wire that changes temperature and resistance based on the magnitude of airflow it is exposed to), an analogic differential pressure flow sensor, a thermal mass flow sensor, or a combination thereof. According to some examples, a volume of the gas in the airway of the subject 104 is determined by analyzing (e.g., integrating with respect to time) the flow parameter of the gas in the fluid circuit. In various implementations, the airway sensor(s) 112 includes a pressure sensor configured to detect a pressure in the fluid circuit including an interior space of the ventilation device 106 and the airway of the subject 104. For example, the pressure sensor includes an electrical circuit that includes a pressure transducer or pressure-sensitive resistor connected to the airway of the subject 104. The circuit generates an analog signal that is based on the pressure of the airway of the subject 104

[0022] In some cases, the airway sensor(s) 112 are incorporated into a monitor. The monitor, for instance, is configured to be removably coupled with the airway adaptor 110, ventilation source 108, one or tubes connecting the airway adaptor 110 to the ventilation source 108, or any combination thereof. In some cases, the monitor is a reusable component of the ventilation device 106. In some implementations, within the monitor, the airway sensor(s) 112 are connected to memory and / or at least one processor that generates digital data indicative of the parameter(s) detected by the airway sensor(s) 112. Based on the flow parameter, for instance, the processor(s) may be configured to generate data indicative of inspiratory / expiratory volume, tidal volume, pressure, ventilation rate, inspiratory / expiratory time, or the like of the subject 104 during at least a portion of one or more ventilation cycles. For instance, the processor(s) may determine the inspiratory volume, the expiratory volume, or the tidal volume by integrating the flow rate with respect to time over one or more inspiratory phases and / or one or more expiratory phases. The processor(s) may identify a start time and an end time of an inspiratory phase and / or an expiratory phase by identifying when the flow rate decreases below a particular threshold. Accordingly, the processor(s) may determine the inspiratory time, the expiratory time, or the ventilation rate based on the start time and the end time of one or more inspiratory phases and / or one or more expiratory phases.

[0023] In some examples, the airway sensor(s) 112 are connected to an external device 114 that includes at least one processor configured to perform one or more operations associated with determining the lung compliance and / or the respiratory condition of the subject 104. For instance, the external device 114 may include one or more processors configured to generate the digital data indicative of the parameter(s) of the subject 104. In some cases, the external device 114 further includes memory configured to store instructions that are executed by theS397-6031 PCT I PHYS0276PCT & MEDI-2778processor(s). In various implementations, the external device 114 is configured to output one or more parameters of the subject 104 to the rescuer 102 (e.g., visually on a display).

[0024] In some instances, the ventilation device 106 is communicatively coupled to the external device 114 via one or more wired interfaces, one or more wireless interfaces, or a combination thereof. For example, the ventilation device 106 may include a processor configured to cause assisted ventilation to be administered to the subject 104 (e.g., via feedback to the rescuer 102 and / or by automatically controlling a mechanical ventilator within the ventilation source 108), and the external device 114 may transmit a signal to the ventilation device 106 that causes the processor to adjust a parameter of the assisted ventilation (e.g., a ventilation rate, a flow rate of gas administered to the subject 104, a volume of gas administered to the subject 104, a length of a ventilation pause, or any combination thereof) and / or activates the valve in order to vent the ventilation device 106.

[0025] In some cases, the external device 114 is a medical device. In some implementations, the external device 114 is further configured to monitor and / or treat the subject 104. For example, the external device 114 may include, or may be communicatively coupled with, one or more sensors configured to detect one or more physiological parameters of the subject 104. In some implementations, the external device 114 outputs an indication of the physiological parameter(s), such as visually on a display of the external device 114. In some implementations, the external device 114 is configured to determine a condition of the subject 104 by analyzing the physiological parameter(s) and / or one or more parameters detected and reported by the ventilation device 106. In some cases, the external device 114 is configured to administer a treatment to the subject 104. For instance, the external device 114 may be a monitor-defibrillator configured to output an electrotherapy (e.g., an electrical shock, pacing pulses, etc.) to the subject 104 via electrodes disposed on the skin of the subject 104.

[0026] According to some cases, the external device 114 is a computing device that includes a processor configured to perform various operations based on the physiological condition of the subject 104. In some examples, the external device 114 is a tablet computer, a personal computer, a mobile phone, or another type of user equipment. In various instances, the external device 114 is a wearable device, such as a smart watch or smart glasses. For example, the external device 114 is worn by the rescuer 102 or by the subject 104 at the environment 100.

[0027] The ventilation device 106 and / or medical device 114 is configured to output various information to the rescuer 102. For example, the ventilation device 106 and / or medical device 114 is configured to output an indication of one or more parameters (e.g., ventilation parameters, physiological parameters, or other parameters) to the rescuer 102. In some implementations, the indication is visually presented on a display, or audibly output by a speaker, of the ventilation device 106 and / or the medical device 114. In some cases, the ventilation device 106 and / or medical device 114 is configured to output coaching information to the rescuer 102 to facilitate the operation of the ventilation source 108. For instance, the ventilation device 106 and / or medical device 114 may output prompts or instructions to the rescuer 102 indicating the timing of an ideal ventilation cycle to be applied to the subject 104. InS397-6031 PCT I PHYS0276PCT & MEDI-2778some examples, the ventilation device 106 and / or medical device 114 outputs one or more alerts, such as in response to detecting that a parameter is outside of a predetermined threshold range.

[0028] According to various implementations, the ventilation device 106 and / or the external device 114 is configured to determine a pressure-volume relationship of the subject 104 based on the parameters detected by the airway sensor(s) 112. In various examples, the ventilation device 106 and / or external device 114 is configured to determine the pressure of the gas in the airway of the subject 104 and the volume of the gas in the fluid circuit including the airway of the subject 104 during inspiration and / or expiration.

[0029] In some instances, the ventilation device 106 and / or external device 114 is configured to determine the pressure of the gas in the airway of the subject 104 and the volume of the gas in the airway of the subject 104 during one or more ventilation cycles (e.g., one or more cycles of inspiration and expiration). For instance, the ventilation device 106 and / or external device 114 may determine the mean, median, or another statistical measure of the pressure-volume relationships of multiple ventilation cycles.

[0030] In some examples, the ventilation device 106 and / or external device 114 may identify noise or an artifact (e.g., an artifact due to movement, a chest compression, or an electrical shock administered to the subject 104) in the pressure data and / or the volume data collected by the airway sensor(s) 112. The ventilation device 106 and / or external device 114, in some examples, is configured to remove the noise or the artifact. In some examples, the external device 114 may exclude data that includes the noise or the artifact. For instance, the external device 114 may apply one or more filters to the data to remove the noise or the artifact. In various examples, a filter may be configured to eliminate or reduce particular frequencies present in the data. In some instances, the external device 114 applies a low-pass filter to remove high-frequency noise, such as vibrations or electrical interference. Examples of filters include low-pass filters, high-pass filters, band-pass filters, notch filters, Gaussian filters, Butterworth filters, Chebyshev Filter, and the like.

[0031] In some examples, the ventilation device 106 and / or external device 114 determines a pressure-volume curve to facilitate analysis of the pressure-volume relationship. According to various implementations, the pressurevolume curve may be indicative of the volume data with respect to the pressure data. In various cases, the ventilation device 106 and / or external device 114 is configured to analyze the pressure-volume relationship as a curve (e.g., a visual representation, a graph, etc.) and / or as a dataset (e.g., individual data points). While the analyses are described with reference to the pressure-volume curve in reference to FIG. 1, one or more of the analyses may be performed on the pressure-volume dataset.

[0032] In various implementations, the ventilation device 106 and / or external device 114 may determine one or more metrics associated with the pressure-volume curve (also referred to herein as “airway parameters”) to determine the lung compliance and / or the respiratory condition of the subject 104. In some cases, the ventilation device 106 and / or external device 114 may determine an upper inflection point of the pressure-volume curve to determine the lung compliance of the subject 104. The upper inflection point of the pressure-volume curve, in various examples,S397-6031 PCT I PHYS0276PCT & MEDI-2778corresponds to the pressure at a minimum value of the second derivative of the pressure-volume curve with respect to pressure As used herein, “minimum value,” and its equivalents refers to the lowest point of a curve or a dataset. In some cases, the upper inflection point of the pressure-volume curve can be determined by analyzing the derivative of the pressure-volume curve with respect to pressure. In various instances, the upper inflection point corresponds to the pressure at which the derivative of the pressure-volume curve is in a range of 0.4 L / cmHhO to 1 L / cmhbO. In various instances, the upper inflection point corresponds to the pressure at which the derivative of the pressurevolume curve is in a range of 0.6 L / cmFbO to 0.8 L / cmFhO.

[0033] According to various implementations, an upper inflection point corresponding to a pressure in a range of 15 CIT1H2O to 19 CIT1H2O and / or a volume in a range of 4 liters (L) to 4.75 L is indicative of lung compliance of a subject without a respiratory condition (also referred to herein as a “non-pathological lung compliance”). In some examples, an upper inflection point corresponding to a pressure in a range of 17 CIT1H2O to 23 CIT1H2O and / or a volume in a range of 3.0 L to 4.0 L is indicative of a relatively lower lung compliance compared to the non-pathological lung compliance (also referred to herein as “relatively lower lung compliance”). In various cases, an upper inflection point corresponding to a pressure in a range of 11 crnFfeO to 16 CIT1H2O and / or a volume in a range of 4.0 L to 5.0 L is indicative of relatively higher lung compliance compared to non-pathological lung compliance (also referred to herein as “relatively higher lung compliance”). In some cases, the upper inflection point corresponding to non-pathological lung compliance, relatively lower lung compliance, or relatively higher lung compliance is determined based on reference levels (e.g., clinical guidelines, scientific studies, or the like).

[0034] In some cases, the ventilation device 106 and / or external device 114 determines an area under the pressurevolume curve of the subject 104 to determine the lung compliance and / or the respiratory condition of the subject 104. The ventilation device 106 and / or external device 114 may integrate at least a portion of the pressure-volume curve of the subject 104. For instance, the ventilation device 106 and / or external device 114 may determine an integral of the pressure-volume curve from a pressure of 0 CIT1H2O to a pressure of 30 cmbkO. In various examples, an integral in a range of 7700 mL to 9700 mL is indicative of non-pathological lung compliance. In some examples, an integral in a range of 5200 mL to 7200 mL is indicative of relatively lower lung compliance. In some examples, an integral in a range of 9000 mL to 12,000 mL is indicative of relatively higher lung compliance. According to some implementations, the ventilation device 106 and / or external device 114 may be configured to extrapolate the pressure-volume curve if the limits of integration (e.g., the integration bounds) exceed the endpoints of the pressurevolume curve. In various examples, the ventilation device 106 and / or external device 114 integrates at least a portion of the pressure-volume curve with respect to pressure (e.g., across a range of pressures) or with respect to volume (e.g., across of a range of volumes).

[0035] I n various examples, the ventilation device 106 and / or external device 114 determines a derivative of the pressure-volume curve of the subject 104 to determine the lung compliance and / or the respiratory condition of the subject 104. In some cases, the ventilation device 106 and / or external device 114 determines the derivative of theS397-6031 PCT I PHYS0276PCT & MEDI-2778pressure-volume curve with respect to pressure. In some cases, the ventilation device 106 and / or external device 114 determines the derivative of the pressure-volume curve with respect to volume. The ventilation device 106 and / or external device 114 may identify the lung compliance of the subject 104 based on a maximum value of the derivative of the pressure-volume curve. As used herein, “maximum value,” and its equivalents refers to the highest point of a curve or a dataset. For instance, a maximum value of the derivative of the pressure-volume curve with respect to pressure that corresponds to a value in a range of 0.035 L / cmbbO to 0.065 L / cmF O and / or a pressure of 10 cmbbO to 15 cmFhO may be indicative of non-pathological lung compliance. A maximum value of the derivative of the pressure-volume curve with respect to pressure that corresponds to a value in a range of 0.002 L / cmFfeO to 0.005 L / cmF O and / or a pressure of 12 cmF O to 17 crnFfeO may be indicative of relatively lower lung compliance. A maximum value of the derivative of the pressure-volume curve with respect to pressure that corresponds to a value in a range of 0.005 L / cmF O to 0.008 L / cmF O and / or a pressure of 6 cmF O to 12 cmF O may be indicative of relatively higher lung compliance.

[0036] In various implementations, the ventilation device 106 and / or external device 114 determines a second derivative of the pressure-volume curve of the subject 104. In some examples, the second derivative of the pressurevolume curve may be with respect to pressure. In some examples, the second derivative of the pressure-volume curve may be with respect to volume. The ventilation device 106 and / or external device 114 may identify one or more parameters of the second derivative of the pressure-volume curve to identify the lung compliance and / or the respiratory condition of the subject 104. In various instances, the external device 114 may determine a maximum value of the second derivative. As used herein, “maximum value,” and its equivalents refers to the highest point of a curve or a dataset. A maximum value of the second derivative of the pressure-volume curve with respect to pressure that is in a range of 0.005 L / cmF O2to 0.01 L / cmFbO2, in various cases, is indicative of non-pathological lung compliance. A maximum value of the second derivative of the pressure-volume curve with respect to pressure that is in a range of 0.001 L / cmb O2to 0.007 L / cmF O2, in various cases, is indicative of relatively lower lung compliance. A maximum value of the second derivative of the pressure-volume curve with respect to pressure that is in a range of 0.011 L / cmFbO2to 0.017 L / cmFhO2, in various cases, is indicative of relatively higher lung compliance.

[0037] In various instances, the ventilation device 106 and / or external device 114 may determine a difference between a maximum value and a minimum value (e.g., a maximum-to-minimum range) of the second derivative of the pressure-volume curve. In some examples, the maximum-to-minimum range corresponds to the difference between the magnitude of the maximum value and the magnitude of the minimum value. In some examples, the maximum-to-minimum range corresponds to the difference between the pressure corresponding to the maximum value and the pressure corresponding to the minimum value. A maximum-to-minimum pressure range of the second derivative of the pressure-volume curve that is in a range of 7 crnFFO to 16 cmFbO is, in some cases, indicative of non-pathological lung compliance. A maximum-to-minimum pressure range of the second derivative of the pressurevolume curve that is in a range of 9 cmFbO to 18 cmFbO is, in some cases, indicative of relatively lower lungS397-6031 PCT I PHYS0276PCT & MEDI-2778compliance. A maximum-to-minimum pressure range of the second derivative of the pressure-volume curve that is in a range of 5 CIT1H2O to 12 CIT1H2O is, in some cases, indicative of relatively higher lung compliance.

[0038] In various instances, the ventilation device 106 and / or external device 114 may determine a zero-crossing of the second derivative of the pressure-volume curve. For instance, the ventilation device 106 and / or external device 114 may determine a pressure corresponding to a datapoint in which the second derivative of the pressure-volume curve is equal to zero. In some cases, the zero-crossing occurs between the maximum value and the minimum value of the second derivative of the pressure-volume curve. A zero-crossing of the second derivative of the pressurevolume curve that is in a range of 10 CIT1H2O to 15 crnFfeO is, in various examples, indicative of non-pathological lung compliance. A zero-crossing of the second derivative of the pressure-volume curve that is in a range of 11 cmFkO to 17 CIT1H2O is, in various examples, indicative of relatively lower lung compliance. A zero-crossing of the second derivative of the pressure-volume curve that is in a range of 5 cmfW to 11 CIT1H2O is, in various examples, indicative of relatively higher lung compliance.

[0039] As described above with reference to the upper inflection point, any of the values corresponding to non-pathological lung compliance, relatively lower lung compliance, or relatively higher lung compliance can be determined based on reference levels in some examples.

[0040] In some examples, the ventilation device 106 and / or external device 114 determines upper bounds and lower bounds of pressure-volume curves corresponding to non-pathological lung compliance, relatively lower lung compliance, and relatively higher lung compliance. For instance, the bounds may correspond to ±5%, ±10%, ±15%, ±20%, or the like of each point on a pressure-volume curve. In various cases, the ventilation device 106 and / or external device 114 determines the upper and lower bounds based on a standard deviation, a variance, a local average, a coefficient of variation, or the like of a pressure-volume curve. In some examples, the ventilation device 106 and / or external device 114 determines the upper and lower bounds based on pressure-volume curves collected from populations of subjects with non-pathological lung compliance, relatively lower lung compliance, and relatively higher lung compliance. The ventilation device 106 and / or external device 114 may compare the pressure-volume curve of the subject 104 to the interval between the upper bounds and the lower bounds. In various cases, the ventilation device 106 and / or external device 114 may identify that the subject 104 has relatively lower lung compliance by determining that the pressure-volume curve of the subject 104 falls within the upper bound and the lower bound of a reference pressure-volume curve corresponding to individuals with relatively lower lung compliance. According to various implementations, the ventilation device 106 and / or external device 114 may perform a similar analysis on the derivative, the second derivative, or the integral of the pressure-volume curve of the subject 104.

[0041] In various cases, the ventilation device 106 and / or external device 114 determines a particular value of the pressure-volume curve, the derivative of the pressure-volume curve, the second-derivative of the pressure-volume curve, or the integral of the pressure-volume curve. For instance, the ventilation device 106 and / or external device 114 may determine a value at a particular pressure of the derivative of the pressure-volume curve with respect toS397-6031 PCT I PHYS0276PCT & MEDI-2778pressure. The ventilation device 106 and / or external device 114 may compare the value to a reference value associated with non-pathological lung compliance, relatively lower lung compliance, relatively higher lung compliance, or a respiratory condition. In various instances, the ventilation device 106 and / or external device 114 determines a maximum value of the pressure-volume curve, a derivative of the pressure-volume curve, a second-derivative of the pressure-volume curve, or an integral of the pressure-volume curve. For example, the ventilation device 106 and / or external device 114 may determine that a maximum volume of the pressure-volume curve is lower than a reference value associated with non-pathological lung compliance. Accordingly, the ventilation device 106 and / or external device 114 may determine that the subject 104 has relatively lower lung compliance.

[0042] In some instances, the ventilation device 106 and / or external device 114 may determine an area under the derivative of the pressure-volume curve or under the second derivative of the pressure-volume curve. The ventilation device 106 and / or external device 114 may identify the lung compliance of the subject 104 based on comparing the area under the particular curve to a reference value associated with non-pathological lung compliance, relatively lower lung compliance, relatively higher lung compliance, or a respiratory condition. In various examples, the ventilation device 106 and / or external device 114 may determine another metric associated with the pressure-volume curve, including metrics associated with the derivative of the pressure-volume curve, the second derivative of the pressure-volume curve, the integral of the pressure-volume curve, and the like.

[0043] In some examples, the ventilation device 106 and / or external device 114 may determine a difference between a maximum value and a minimum value (e.g., a maximum-to-minimum range) of at least a portion of the pressure-volume curve or the derivative of the pressure-volume curve. For instance, the ventilation device 106 and / or external device 114 may determine that a maximum-to-minimum range across a pressure range of 0 cmF O to 5 cmF O of the derivative of the pressure-volume curve with respect to pressure is indicative of relatively higher lung compliance of the subject 104. In various examples, the maximum-to-minimum range of the derivative of the pressure-volume curve with respect to pressure associated with relatively higher lung compliance is greater than the corresponding reference value associated with non-pathological lung compliance.

[0044] The ventilation device 106 and / or external device 114 may perform one or more of the analyses described herein to determine the lung compliance of the subject 104. For instance, the ventilation device 106 and / or external device 114 may determine one or more metrics to identify the lung compliance of the subject 104 and one or more additional metrics to confirm the lung compliance. For instance, the external device 114 may determine, based on an upper inflection point of the pressure-volume curve corresponding to a volume of 4.5 L, that the subject 104 has relatively higher lung compliance. The external device 114 may determine that a maximum value of the first derivative of the pressure-volume curve with respect to pressure corresponds to 0.85 L / cmFbO, confirming that the subject 104 has relatively higher lung compliance. In some implementations, the ventilation device 106 and / or external device 114 outputs an indication of the lung compliance of the subject 104 to the rescuer 102. TheS397-6031 PCT I PHYS0276PCT & MEDI-2778ventilation device 106 and / or external device 114, in some cases, outputs an alert to the rescuer 102 in response to detecting that the determined lung compliance is outside of a threshold range.

[0045] In some implementations, the ventilation device 106 and / or external device 114 analyzes the pressurevolume curve captured from the subject 104 at distinct time intervals to identify a change in the lung compliance of the subject 104 over time. For instance, the ventilation device 106 and / or external device 114 may compare an airway parameter associated with a first pressure-volume curve corresponding to a first time interval to an airway parameter associated with a second pressure-volume curve corresponding to a second time interval. In various implementations of the present disclosure, analyzing the change in the lung compliance can identify when the subject 104 is not benefiting from assisted ventilation or another treatment (e.g., one or more medications). For instance, an abnormal decrease in lung compliance may indicate overdistension of the lungs of the subject 104 due to, in some cases, lung injury causing the stiffening of lung tissue. In some implementations, the ventilation device 106 and / or external device 114 outputs an alert to the rescuer 102 in response to detecting that a change in the lung compliance of the subject 104 is outside of a threshold range. Accordingly, the rescuer 102 can discontinue and / or modify the treatment to avoid causing harm to the subject 104

[0046] The ventilation device 106 and / or external device 114 may determine one or more of the airway parameters described herein during two or more distinct time intervals to identify the change in lung compliance. For instance, the ventilation device 106 and / or external device 114 may determine a first airway parameter corresponding to a first time interval before a treatment is administered to the subject 104. The ventilation device 106 and / or external device 114 may determine that the subject 104 is likely to have a restrictive respiratory disease, such as pulmonary fibrosis, based on identifying a relatively lower lung compliance during the first time interval. In some examples, the ventilation device 106 and / or external device 114 determines a second airway parameter corresponding to a second time interval after the treatment is initiated to the subject 104. Based on comparing the first airway parameter and the second airway parameter, the ventilation device 106 and / or external device 114 may determine that the lung compliance of the subject 104 has increased in response to treatment initiation. The ventilation device 106 and / or external device 114, in various cases, determines that the subject 104 is benefiting from the treatment based on, for instance, the increase in lung compliance. For example, the ventilation device 106 and / or external device 114 is configured to output an indication of an efficacy of the treatment based on the change in lung compliance observed after the treatment was initiated on the subject 104.

[0047] In some instances, the ventilation device 106 and / or external device 114 identifies the type of treatment and / or treatment parameters of the treatment being administered to the subject based on analyzing the first airway parameter and the second airway parameter. In various examples, the ventilation device 106 and / or external device 114 determines a third airway parameter corresponding to a third time interval during treatment initiation. The ventilation device 106 and / or external device 114 may identify that the lung compliance of the subject 104 has decreased, indicating injury to the lungs due to overtreatment. In some cases, the ventilation device 106 and / orS397-6031 PCT I PHYS0276PCT & MEDI-2778external device 114 determines a fourth airway parameter corresponding to a fourth time interval after treatment is discontinued. The ventilation device 106 and / or external device 114, for instance, may identify the type of treatment and / or a response of the subject 104 to the treatment based on analyzing the fourth airway parameter. For instance, the ventilation device 106 and / or external device 114 may identify that the lung compliance of the subject 104 is within, or closer to, a non-pathological lung compliance after treatment is discontinued, indicating that the subject 104 is regaining respiratory function. In some examples, the ventilation device 106 and / or external device 114 may determine, based on identifying an increase in the lung compliance of the subject 104, that the subject 104 was previously being administered chest compressions.

[0048] According to various implementations, the ventilation device 106 and / or external device 114 may determine the respiratory condition of the subject 104 based on determining one or more airway parameters. In some examples, the ventilation device 106 and / or external device 114 may determine a likelihood that the subject 104 has a particular respiratory condition based on one or more physiological parameters of the subject 104, parameters of the fluid circuit including the airway of the subject 104, derived parameters (e.g., the lung compliance, the change in lung compliance, etc ), or any combination thereof. For instance, based on determining that the subject 104 has relatively lower lung compliance, the ventilation device 106 and / or external device 114 may identify that the subject 104 is likely to have acute respiratory distress syndrome (ARDS), pulmonary fibrosis, pulmonary edema, pneumonia, asthma, sarcoidosis, obesity hypoventilation syndrome, kyphoscoliosis, a chest wall deformity, pleural effusion, pleuritis, a neuromuscular disorder, another restrictive respiratory condition, or the like. In various instances, based on determining that the subject 104 has relatively higher lung compliance, the external device 114 may identify that the subject 104 is likely to have chronic obstructive pulmonary disease (COPD), emphysema, Marfan syndrome, or the like. In some cases, the external device 114 may compare one or more airway parameters of the subject 104 to reference airway parameters associated with a particular respiratory condition to identify the respiratory condition of the subject 104. In various examples, the external device 114 may identify that the subject 104 has or is likely to have an infectious respiratory disease (e.g., an upper respiratory infection, a lower respiratory infection, influenza, a cold, pharyngitis, sinusitis, laryngitis, COVID-19, bronchitis, pneumonia, tuberculosis, respiratory syncytial virus (RSV), histoplasmosis, coccidioidomycosis, blastomycosis, aspergillosis, or the like), a pulmonary vascular disease (e.g , pulmonary hypertension, a pulmonary embolism, or the like), or another respiratory condition. The ventilation device 106 and / or medical device 114, for instance, is configured to output an indication of the respiratory condition of the subject 104 to the rescuer 102. With the knowledge of the respiratory condition, the rescuer 102 may protect themselves (e.g., in the case of a communicable illness of the subject 104), administer a medication to the subject 104 (e.g., albuterol in the case of the subject 104 having asthma), discontinue a medication or another treatment, initiate a treatment, modify the assisted ventilation to the subject 104, or any combination thereof.

[0049] In some cases, the ventilation device 106 and / or external device 114 may determine one or more treatment parameters based on identifying the lung compliance and / or the respiratory condition of the subject 104. In someS397-6031 PCT I PHYS0276PCT & MEDI-2778examples, the treatment parameter(s) include pausing a treatment of the subject 104, continuing a treatment of the subject 104, changing a parameter of a treatment of the subject 104, administering a second treatment to the subject 104, or the like. The treatment parameter(s) may include a ventilation rate, a ventilation pressure, or a ventilation volume of gas to be administered to the subject 104 via the ventilation device 106. In various instances, the treatment parameter(s) are predicted to provide sufficient ventilation to the subject 104 for the avoidance of hypoxic injury. In some cases, the ventilation device 106 and / or external device 114 is configured to modify, based on the predicted respiratory condition of the subject 104, coaching information indicating instructions for operation of the ventilation device 106. For instance, the ventilation device 106 and / or medical device 114 may automatically change a recommended ventilation rate for assisted ventilation applied to the subject 104 based, at least in part, on the respiratory condition.

[0050] In various cases, the treatment parameter(s) may include administration of chest compressions to the subject 104. In some examples, the external device 114 determines a frequency and / or a depth of the chest compressions. In various cases, the treatment parameter(s) may include administration of an electrical shock (e.g., a defibrillation shock) to the subject 104. In some examples, the external device 114 determines an energy level and / or a duration of the electrical shock. In various cases, the external device 114 determines a medication to be administered to the subject 104. For instance, the external device 114 may determine that the physiological condition of the subject 104 may benefit from administration of albuterol, epinephrine, budesonide, magnesium sulfate, dornase alpha, ipratropium bromide, etomidate, midazolam, propofol, thiopental, methylprednisolone, dexamethasone, epinephrine, or the like. In some examples, the external device 114 may determine that the physiological condition of the subject 104 may benefit from discontinuation of medication administration. In some cases, the ventilation device 106 and / or external device 114 is configured to output an indication of the treatment parameter(s) or related recommendations to the rescuer 102.

[0051] I n various implementations, the ventilation device 106 and / or external device 114 includes or is connected to an additional sensor 116 configured to detect an additional physiological parameter of the subject 104. The additional physiological parameter may include a blood oxygen saturation, a blood pressure, a pulse rate, a transthoracic impedance, an electrocardiogram (ECG), a level of carbon dioxide in the airway, a level of oxygen in the airway, a level of nitrogen in the airway, or another parameter of the subject 104. In various cases, the additional sensor 116 includes a pulse oximeter, a blood pressure monitor, electrodes, a capnometer, a gas analyzer, or the like. The additional sensor 116 may be a standalone device, such as a wireless sensor device, or may be integrated into another device, such as the external device 114.

[0052] The ventilation device 106 and / or external device 114, in some examples, is configured to determine a physiological condition of the subject 104 based, at least in part, on the physiological parameter. For instance, the ventilation device 106 and / or external device 114 may determine that the subject 104 has relatively higher lung compliance based on analyzing a derivative of the pressure-volume curve of the subject 104. In various cases, theS397-6031 PCT I PHYS0276PCT & MEDI-2778ventilation device 106 and / or external device 114 may analyze a blood oxygen saturation of the subject 104 to determine whether the subject 104 is receiving adequate ventilation from the ventilation device 106. The ventilation device 106 and / or external device 114 may analyze the additional physiological parameter by determining whether the additional physiological parameter is above or below a threshold. For instance, if the oxygen saturation is below a threshold, the ventilation device 106 and / or external device 114 may determine that the subject 104 is receiving inadequate ventilation from the ventilation device 106.

[0053] In some instances, the external device 114 may determine the treatment parameter(s) based on analyzing the airway parameter(s) and / or the additional physiological parameter. In various implementations, the ventilation device 106 and / or external device 114 analyzes the additional physiological parameter during treatment administration to the subject 104 to determine whether the physiological condition of the subject 104 is improving or deteriorating in response to the treatment. For instance, the ventilation device 106 and / or external device 114 may cause the ventilation device 106 to change a treatment parameter based on determining the lung compliance of the subject 104. The ventilation device 106 and / or external device 114 may analyze the additional physiological parameter before and after the treatment modification and determine that the physiological condition of the subject 104 is improving. In particular implementations, the ventilation device 106 and / or external device 114 may identify a return of spontaneous circulation based on analyzing the additional physiological parameter. The ventilation device 106 and / or external device 114 may output, to the rescuer 102, an indication that the subject 104 has spontaneous circulation of blood throughout the body of the subject 104. Accordingly, the rescuer 102 may pause administration of one or more treatments (e.g. , chest compressions and / or an electrotherapy) to the subject 104.

[0054] According to some examples, the ventilation device 106 and / or external device 114 is configured to output an indication of the condition of the subject 104 or of the treatment parameter(s) to the rescuer 102. For instance, the ventilation device 106 and / or external device 114 includes a screen that visually outputs a signal, a speaker that audibly outputs a signal, a haptic device that outputs a signal as vibration, or a combination thereof. In various cases, the ventilation device 106 and / or external device 114 outputs one or more signals indicative of the lung compliance of the subject 104, the respiratory condition of the subject 104, or the treatment parameter(s). In some cases, the ventilation device 106 and / or external device 114 stores data indicative of the lung compliance of the subject 104, the respiratory condition of the subject 104, or the treatment parameter(s), which can be accessed at a later time for the purposes of post-event review. In some implementations, the ventilation device 106 and / or external device 114 include at least one transceiver configured to transmit data to another device (e.g., a remote server) for storage, analysis, or playback for post-event review.

[0055] According to some cases, the ventilation device 106 and / or external device 114 alarms based on the airway parameter(s) or the additional physiological parameter. As used herein, the term "alarms,” “alerts,” and their equivalents, refers to a device selectively outputting a signal when a predetermined condition has been satisfied. For example, the ventilation device 106 and / or external device 114 may alarm when a particular airway parameterS397-6031 PCT I PHYS0276PCT & MEDI-2778exceeds a first threshold and / or is less than a second threshold, and may refrain from alarming when the airway parameter is between the first threshold and the second threshold. In some implementations, the ventilation device 106 and / or external device 114 alarms by outputting a particular visual signal (e.g., a flashing light, a particular color, such as red, etc.), a particular auditory signal (e.g., a particular beep, siren, etc.), or by vibrating. In some cases, the ventilation device 106 and / or external device 114 alarms by outputting a message to the rescuer 102, such as a warning about a suspected physiological condition of the subject 104, a warning about a suspected respiratory condition of the subject 104, or an instruction (e.g., to perform an action to prevent deterioration of the condition of the subject 104).

[0056] In some cases, the ventilation device 106 and / or external device 114 outputs a signal to the ventilation device 106 based on the airway parameter(s), which may cause the ventilation device 106 to perform an action associated with administering the assisted ventilation to the subject 104. For instance, the ventilation device 106 and / or external device 114 may output a signal indicative of one or more ventilation parameters (e.g., a target rate, a target pressure, or a target volume of air) to the ventilation device 106, causing the ventilation device 106 to modify one or more ventilation parameters of the assisted ventilation administered to the subject 104.

[0057] In various examples, one or more of the devices described herein (e.g., the ventilation device 106, the airway sensor(s) 112, the external device 114, or the additional sensor 116) are connected to a transceiver configured to transmit signals to another device (e.g., an external device). The transceiver is configured to transmit and receive communication signals using one or more communication network(s). In some implementations, the transceiver is configured to transmit signals to the external device in a wired fashion and / or wirelessly. For example, the communication network(s) includes one or more wireless networks that include a 3GPP network, such as an LTE radio access network (RAN) (e.g., over one or more LTE bands), an NR RAN (e.g., over one or more NR bands), or a combination thereof. In some instances, the communication signals are electromagnetic (EM) signals, radio waves, or the like. In some implementations, the transceiver is configured to communicate with external devices by transmitting and / or receiving signals wirelessly. The external devices, for example, includes at least one of a sensor (e.g., the airway sensor(s) 112, the additional sensor 116), a medical device (e.g., the ventilation device 106), a computing device (e.g., the external device 114), a mobile device, or a server. Examples of wireless networks include WI-FI®, cellular networks, wireless local area networks (WLANs), and BLUETOOTH®. In various examples, the transceiver includes a network interface card (NIC), a network adapter, a local area network (LAN) adapter, or a physical, virtual, or logical address to connect to the various external devices and / or systems. In various examples, the transceiver includes any sort of wireless transceivers capable of engaging in wireless communication (e.g., RF communication). In some examples, the transceiver transmits radio waves to the external device via a cell tower. In some cases, the transceiver is connected to a wireless modem, such as a modem for engaging in WI-FI®, WIGIG®, WIMAX®, BLUETOOTH®, or infrared communication. In some examples, the transceiver is configured to transmit signals in a wired fashion, such as by using a cable that connects the transceiver to the external device. TheS397-6031 PCT I PHYS0276PCT & MEDI-2778transceiver and the external device, in some implementations, include ports configured to receive connectors attached to the cable. In various examples, the transceiver includes a NIC to transmit data over the cable. Examples of wired connections include USB, USB-C, mini-USB, micro-USB, serial ports, and custom cables, among other examples.

[0058] FIG. 2 illustrates example pressure-volume curves associated with various respiratory conditions. In various examples, the pressure-volume curves may represent one or more breathing cycles (e.g. , cycles of inspiration and expiration of the subject). While FIG. 2 illustrates pressure-volume curves associated with the inspiratory phase, implementations of the present disclosure are not so limited. In various examples, pressure-volume curves may represent inspiratory and / or expiratory phases. The curves may be generated based on volume and pressure data collected over time (e.g., over one or more inspiratory phases and one or more expiratory phases). Example data points are indicated by circles. For instance, a flow rate may be measured (e.g., by a sensor) over time and integrated at different time points to determine the volume of gas flowing into or out of a subject’s airway. The pressure may be measured (e.g., by a sensor) at the different time points.

[0059] In various examples, the pressure-volume curve corresponds to a best-fit curve that is fitted to the data points. The best-fit curve may include one or more functions (e.g., a logistic function, a logarithmic function, a linear function, a polynomial function, an exponential function, or the like). For instance, the pressure-volume curve may include a logistic function that approximately corresponds to the data points. In some examples, the pressure-volume curve is generated by connecting the data points. For instance, the data points may be connected by a linear function or a curve (e.g., a polynomial, or the like).

[0060] The curves illustrated in FIG. 2 are indicative of an example subject without a respiratory condition (e.g., non-pathological), an example subject with acute respiratory distress syndrome (ARDS), and an example subject with chronic obstructive pulmonary disease (COPD). The curves corresponding to ARDS, in various examples, represent relatively lower lung compliance than the curves corresponding to a non-pathological subject. The curves corresponding to COPD, in various examples, represent relatively higher lung compliance than the curves corresponding to a non-pathological subject.

[0061] The top plot illustrates pressure-volume curves with volume shown with respect to pressure. The upper inflection point of each pressure-volume curve by indicated in the rectangle. The middle plot illustrates the first derivatives of the pressure-volume curves with respect to pressure. The maximum value of each of the curves is indicated by the rectangle. In some examples, the magnitude of the first derivative (e.g., the compliance) and / or the pressure corresponding to the maximum value may be utilized to determine the lung compliance of a subject. The bottom plot illustrates the second derivatives of the pressure-volume curves with respect to pressure. Various metrics are illustrated with respect to the curve corresponding to COPD. The maximum value of the curve corresponding to COPD is indicated by the single-bordered rectangle, and the minimum value of the curve corresponding to COPD is indicated by the double-bordered rectangle. Two metrics corresponding to the distance between the maximum valueS397-6031 PCT I PHYS0276PCT & MEDI-2778and the minimum value are illustrated by the lines with double arrows. The first metric, indicated by the vertical line with double arrows, represents a difference between the magnitude of the maximum value and the magnitude of the minimum value (e.g., a magnitude difference). The second metric, indicated by the horizontal line with double arrows, represents a difference between a pressure corresponding to the maximum value and a pressure corresponding to the minimum value (e.g., a pressure difference). The zero-crossing of the curve corresponding to COPD is indicated.

[0062] FIG. 3 illustrates an example process 300 of analyzing a pressure-volume relationship of a subject (e.g., the subject 104). According to some implementations, the process 300 is performed by an entity, such as a sensor (e.g., the airway sensor(s) 112 or the additional sensor 116), medical device (e.g , the ventilation device 106), computing device (e.g., the external device 114), at least one processor, or a combination thereof.

[0063] At 302, the entity identifies a pressure of gas and a volume of the gas in an airway of the subject. In various implementations, the subject is receiving assisted ventilation from a ventilation device (e.g., the ventilation device 106) operated by a rescuer (e.g., the rescuer 102). The entity may detect the pressure of the gas and the volume of the gas in the airway of the subject using one or more sensors (e.g., the airway sensor(s) 112). The sensor(s) may be included in, or connected to, the ventilation device.

[0064] At 304, the entity determines a pressure-volume curve of the subject by analyzing the pressure and the volume of the gas in the airway of the subject. In various cases, the pressure-volume curve is indicative of the pressure of the gas and the volume of gas during one or more ventilation cycles. In some examples, the pressurevolume curve is indicative of the pressure of the gas and the volume of the gas during inspiration and / or expiration.

[0065] At 306, the entity determines an airway parameter of the subject by analyzing the pressure-volume curve of the subject. According to various implementations, the airway parameter is indicative of one or more metrics associated with the pressure-volume curve. For instance, the entity may identify an upper inflection point of the pressure-volume curve of the subject. In some examples, the entity may identify an area under at least a portion of the pressure-volume curve. In various cases, the entity may identify a maximum value and / or a pressure corresponding to the maximum value of a derivative of the pressure-volume curve with respect to pressure. In some examples, the entity may identify a maximum value, a minimum value, a maximum-to-minimum range, or a zerocrossing of a second derivative of the pressure-volume curve. The airway parameter, according to various implementations, is indicative of a lung compliance of the subject. For example, the entity may compare the one or more metrics to one or more thresholds associated with non-pathological lung compliance, relatively lower lung compliance, or relatively higher lung compliance. In some cases, the entity compared the one or more metrics to one or more thresholds associated with a respiratory condition (e.g., ARDS, COPD, etc.) to determine a respiratory condition of the subject.

[0066] At 308, the entity determines a treatment parameter of a treatment administered to the subject. For instance, the entity may determine a ventilation parameter based on identifying the lung compliance of the subject. In various cases, the treatment parameter may include administration of chest compressions, administration of an electricalS397-6031 PCT I PHYS0276PCT & MEDI-2778shock, or administration of one or more medications to the subject. In some examples, the entity determines the treatment parameter based on a physiological parameter detected by a second sensor (e.g., the additional sensor 116). For instance, the entity may determine that the subject is receiving insufficient ventilation based on analyzing the physiological parameter.

[0067] In some examples, the entity outputs an indication of the lung compliance of the subject and / or the respiratory condition of the subject to the rescuer. In various cases, the entity outputs an indication of the treatment parameter to the rescuer. For example, the entity may output, based on the lung compliance of the subject, a ventilation parameter predicted to provide sufficient ventilation to the subject. In some instances, the entity causes the ventilation device or another treatment device to administer a treatment to the subject or to modify a treatment being administered to the subject. For instance, based on identifying that the subject has relatively higher lung compliance, the entity may output an indication that the subject is predicted to have COPD. The entity may output, to the rescuer, an instruction to reduce the ventilation rate of the assisted ventilation administered to the subject. In some cases, the entity may cause the ventilation device to reduce the ventilation rate.

[0068] FIG. 4 illustrates a ventilation device 400 configured to perform various functions described herein. For instance, the ventilation device 400 is the ventilation device 106 described above with reference to FIG. 1.

[0069] The ventilation device 400 is configured to provide assisted ventilation to a subject 402. The ventilation device 400 includes an airway adaptor 404 configured to be fluidically coupled with an airway of the subject 402. In some implementations, the airway adaptor 404 includes a mask configured to be disposed on a face of the subject 402. For example, the airway adaptor 404 may be pressed over the mouth onto the face of the subject 402. In some implementations, the airway adaptor 404 is inserted into the mouth of the subject 402. For example, the airway adaptor 404, in some cases, includes a supraglottic airway adaptor (also referred to as a “supraglottic airway”) configured to be disposed in a pharynx of the subject 402. In some cases, the airway adaptor 404 includes an extraglottic device, such as a laryngeal tube, a pharyngeal tube, a Combitube (also referred to as an “esophageal tracheal airway”), or any combination thereof. In some cases, the airway adaptor 404 includes an endotracheal tube. In various implementations, the airway adaptor 404 is configured to form a fluid-tight seal with a fluid circuit that includes the airway of the subject 402. In some examples, the airway adaptor 404 is disposable.

[0070] In various implementations, the ventilation device 400 further includes a gas source 406 configured to control a flow of a gas into the airway adaptor 404 and / or a flow of gas out of the airway adaptor 404. The gas source 406 is configured to be fluidically coupled with the airway adaptor 404. For instance, the gas source 406 is removably coupled with the airway adaptor 404. In cases in which the airway adaptor 404 is fluidically coupled with the airway of the subject 402, the gas source 406 is configured to control the flow of gas (e.g., air, oxygen, carbon dioxide, gaseous medications, or any combination thereof) into the airway and / or out of the airway. In some cases, the ventilation device 400 performs positive pressure ventilation (PPV) on the subject 402. For example, the gas source 406 is configured to induce a higher pressure within the gas source 406 than the airway of the subject 402, therebyS397-6031 PCT I PHYS0276PCT & MEDI-2778pushing a gas into the airway of the subject 402 through the airway adaptor 404. In some cases, the gas source 406 is configured to induce a lower pressure within the gas source 406 than the airway of the subject 402, thereby pulling a gas from the airway of the subject 402 into the gas source 406 through the airway adaptor 404. The gas source 406 may be at least partially reusable, at least partially disposable, or a combination thereof.

[0071] In some implementations, the gas source 406 operates automatically. For instance, the gas source 406 may include a mechanical ventilator configured to control the gas delivered to and from the airway of the subject 402 through the airway adaptor 404.

[0072] In some cases, the gas source 406 is manually operated. For instance, the gas source 406 may include a bag that is manually squeezed and released by a user 408. When the bag is squeezed (e.g., by the hands of the user 408), an interior pressure within the gas source 406 increases (e.g., producing a net flow of gas into the airway of the subject 402). When the bag is released, the interior pressure within the gas source 406 decreases (e.g., producing a net flow of gas out of the airway of the subject 402). Accordingly, the user 408 may be configured to control a rate of the assisted ventilation corresponding to the rate at which the user 408 squeezes and releases the bag. Moreover, the user 408 may be configured to control a volume of gas delivered into the airway and lungs of the subject 402 based on an amount of volume of gas that the user 408 squeezes out of the bag. In various cases, the user 408 may be configured to control a pressure of gas in the fluid circuit between the airway of the subject 402, the airway adaptor 404, and the gas source 406 based on a force at which the user 408 is squeezing the bag. The user 408 may additionally control a flow rate of gas through the fluid circuit by controlling a rapidity by which the user 408 squeezes the bag.

[0073] In some cases, the gas source 406 is selectively vented to an external environment containing air. In some examples, the gas source 406 includes a cannister, bag, or other receptacle containing a gas (e.g., oxygen) to be delivered to the airway of the subject 402. In some cases, the gas source 406 can be coupled with a source of a medication (e.g., albuterol) that can be delivered to the subject 402 by the delivery of the assisted ventilation. One or more valves can be disposed in the gas source 406 to control a type and / or amount of gas delivered to the subject 402.

[0074] In some examples, the ventilation device 400 includes one or more valves configured to control a direction of gas flow between the airway adaptor 404 and the gas source 406. For example, a valve may be coupled between the airway adaptor 404 and the gas source 406. In some cases, the valve is configured to open during an inspiratory phase (e.g., the pressure in the gas source 406 is greater than the pressure in the airway adaptor 404), thereby allowing the gas to flow from the gas source 406 to the airway adaptor 404. According to some cases, a valve (e.g., the same or a different valve) is coupled between the airway adaptor 404 and an expiratory port (e.g., exposed to an external environment). During an expiratory phase (e.g., the pressure in the airway adaptor 404 is greater than the pressure in the gas source 406), the valve may vent the fluid circuit to the expiratory port. Suitable valves include shutter valves, duckbill valves, and the like.S397-6031 PCT I PHYS0276PCT & MEDI-2778

[0075] In some implementations, the ventilation device 400 further includes a monitor 410 configured to monitor the subject 402 and to otherwise assist the user 408 with operating the ventilation device 400. In some cases, the monitor 410 is a reusable device that is configured to be clipped, inserted over, or otherwise disposed on a portion of the fluid circuit including the airway adaptor 404 and the gas source 406. For example, the monitor 410 is configured to be removably coupled with an intermediary tube connecting the airway adaptor 404 to the gas source 406.

[0076] The monitor 410 includes one or more input devices 412 and one or more output devices 414. Collectively, the input device(s) 412 and the output device(s) 414 function as an interface between the monitor 410 and the subject 402 and / or between the monitor 410 and the user 408 In some cases, the input device(s) 412 are configured to receive input signals from the user 408. For instance, the input device(s) 412 include at least one of a keypad, a cursor control, a touch-sensitive display, a voice input device (e.g., a microphone), a haptic feedback device (e.g., a gyroscope), or any combination thereof. The output device(s) 414 include at least one of a display (e.g., a screen, one or more light sources, etc.), a speaker, a haptic output device, a printer, or any combination thereof. In some implementations, the input device(s) 412 include one or more touch sensors, the output device(s) 414 include a display screen, and the touch sensor(s) are integrated with the display screen. Thus, in some cases, the monitor 410 includes a touchscreen configured to receive user input signal(s) and visually output information.

[0077] In various implementations, the input device(s) 412 further include, or are otherwise connected to, one or more sensors 416. The sensor(s) 416, for instance, are configured to detect one or more parameters. In some cases, the parameters are characteristics of the fluid circuit including the airway adaptor 404 and the gas source 406. In some implementations, the parameters include physiological parameters of the subject 402. According to some cases, the parameters include operation characteristics of the ventilation device 400 by the user 408. In various implementations, the sensor(s) 416 include at least one pressure sensor (e.g., configured to detect a pressure in the fluid circuit), at least one gas sensor (e.g., a nondispersive infrared sensor configured to detect a partial pressure of CO2 in the fluid circuit, an oxygen sensor configured to detect an amount of oxygen in the fluid circuit, or the like), at least one flow sensor (e.g., an ultrasound sensor or an interferometric sensor configured to detect a velocity or flow rate of gas in the fluid circuit), at least one humidity sensor (e.g., configured to detect a humidity in the fluid circuit), at least one temperature sensor (e.g., configured to detect a temperature in the fluid circuit), at least one accelerometer, at least one gyroscope, at least one microphone (e.g., configured to detect breath sounds of the subject 402), or any combination thereof.

[0078] The monitor 410 further includes at least one processor 418. In some implementations, the processor(s) 418 includes a central processing unit (CPU), a graphics processing unit (GPU), both CPU and GPU, or other processing unit or component known in the art.

[0079] The processor(s) 418 is operably connected to memory 420. In various implementations, the memory 420 is volatile (such as random access memory (RAM)), non-volatile (such as read only memory (ROM), flash memory, etc.) or some combination of the two. The memory 420 stores instructions that, when executed by the processor(s)S397-6031 PCT I PHYS0276PCT & MEDI-2778418, causes the processor(s) 418 to perform various operations. In various examples, the memory 420 stores methods, threads, processes, applications, objects, modules, any other sort of executable instruction, or a combination thereof. In some cases, the memory 420 stores files, databases, or a combination thereof. In some examples, the memory 420 includes, but is not limited to, RAM, ROM, electrically erasable programmable read-only memory (EEPROM), flash memory, or any other memory technology. In some examples, the memory 420 includes one or more of CD-ROMs, digital versatile discs (DVDs), content-addressable memory (CAM), or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by the processor(s) 418 and / or the monitor 410.

[0080] In various implementations, the processor(s) 418 are configured to assess a condition of the subject 402 by analyzing data derived from signals detected by the input device(s) 412. For example, the memory 420 stores a detector 422 that, when executed by the processor(s) 418, causes the processor(s) 418 to determine one or more physiological parameters of the subject 402 based on the signals detected by the sensor(s) 416. For instance, the processor(s) 418 may determine an airway pressure of the subject 402 by analyzing the pressure in the fluid circuit, a partial pressure of CO2 (e.g., capnograph) of the subject 402 by analyzing a partial pressure of CO2 in the fluid circuit, a lung volume of the subject 402 by analyzing the flow rate of gas in the fluid circuit, a respiratory rate of the subject 402 by analyzing one or more parameters of the fluid circuit, or any combination thereof. In some cases, the processor(s) 418 may determine whether the subject 402 is spontaneously breathing by one or more parameters of the fluid circuit. The processor(s) 418, in some cases, generates one or more alerts in response to detecting that one or more of the physiological parameters are outside of one or more threshold ranges.

[0081] According to some cases, the processor(s) 418 are further configured to identify a condition associated with operation of the ventilation device 400 by the user 408 based on one or more signals detected by the input device(s) 412. For example, upon executing the detector 422, the processor(s) 418 may be configured to detect a ventilation rate, a ventilation volume, a ventilation pressure, or the like, applied to the subject 402. In some cases, the processor(s) 418 are configured to detect one or more potential problems in operation of the ventilation device 400. For example, the processor(s) 418 may detect that the ventilation rate, volume, or pressure is outside of a threshold range, that there is a leak between the airway of the subject 402 and the airway adaptor 404, that the subject 402 is being hyperventilated, that the subject 402 is being hypoventilated, or any combination thereof.

[0082] In various implementations, the processor(s) 418 is configured to generate feedback based on the signals detected by the input devices 412, the condition of the subject 402, or the condition associated with operation of the ventilation device 400. In some cases, the processor(s) 418 cause the output device(s) 414 to output indications of the feedback to the user 408. Thus, the user 408 may be appraised of the condition of the subject 402 and / or of the quality of ventilation being applied to the subject 402. In some cases, the feedback is provided to the user 408 substantially in real-time.S397-6031 PCT I PHYS0276PCT & MEDI-2778

[0083] The monitor 410 further includes one or more transceivers 424 that transmit and / or receive data over one or more communication networks 426. For example, the transceiver(s) 424 includes a network interface card (NIC), a network adapter, a local area network (LAN) adapter, or a physical, virtual, or logical address to connect to the various external devices and / or systems. In various examples, the transceiver(s) 424 includes any sort of wireless transceivers capable of engaging in wireless communication (e.g., radio frequency (RF) communication). For example, the communication network(s) 426 includes one or more wireless networks that include a 3rdGeneration Partnership Project (3GPP) network, such as a Long Term Evolution (LTE) radio access network (RAN) (e.g., over one or more LTE bands), a New Radio (NR) RAN (e.g., over one or more NR bands), or a combination thereof. In some cases, the transceiver(s) 424 includes other wireless modems, such as a modem for engaging in WI-FI®, WIGIG®, WIMAX®, BLUETOOTH®, or infrared communication over the communication network(s) 426.

[0084] The monitor 410 is configured to transmit and / or receive data (e.g., one or more parameters of the fluid circuit, one or more physiological parameters of the subject 402, one or more parameters associated with operation of the ventilation device 400, feedback related to the condition of the subject 402, feedback related to operation of the ventilation device 400, etc.) with one or more external devices 428 via the communication network(s) 426. The external devices 428 include, for instance, mobile devices (e.g., mobile phones, smartwatches, etc.), Internet of Things (loT) devices, medical devices (e.g., monitor-defibrillators, AEDs, mechanical chest compression devices, etc.), transport equipment (e.g., hospital beds, stretchers, emergency medical services (EMS) cots, stretchers, etc.), computers (e.g., laptop devices, servers, etc.), or any other type of computing device configured to communicate over the communication network(s) 426. In some examples, the external device(s) 428 are located remotely from the ventilation device 400, such as at a remote clinical environment (e.g., a hospital). According to various implementations, the processor(s) 418 cause the transceiver(s) 424 to transmit data to the external device(s) 428. In some cases, the transceiver(s) 424 receives data from the external device(s) 428 and the transceiver(s) 424 provide the received data to the processor(s) 418 for further analysis.

[0085] In various implementations, the monitor 410 further includes a power source 430. The power source 430 is configured to store power that can be distributed to various components of the monitor 410. For instance, the power source 430 is configured to supply power to the input device(s) 412, the output device(s) 414, the sensor(s) 416, the processor(s) 418, the memory 420, the transceiver(s) 424, or any combination thereof. In some cases, the monitor 410, including the power source 430, is a portable electronic device. Examples of the power source 430 include at least one battery, at least one capacitor, at least one power generator (e.g., an antenna configured to induce a current in a circuit in response to receiving an electromagnetic signal from an external device), or any combination thereof. In some cases, the power source 430 is disposable. In some examples, the power source 430 is reusable and rechargeable. In some examples, the monitor 410 is configured to be powered by alternating current (AC) power For instance, the power source 430 may include a power supply unit configured to convert the AC power into direct current (DC) power.S397-6031 PCT I PHYS0276PCT & MEDI-2778

[0086] In implementations of the present disclosure, the memory 420 also stores instructions for executing one or more processes described with reference to the ventilation device 106, the external device 114, the airway sensor(s) 112, or the additional sensor 116 described with reference to FIG. 1. For example, the memory 420 may store instructions that, when executed by the processor(s) 418, cause the processor(s) 418 to determine a pressurevolume curve or one or more metrics associated with the pressure-volume curve. For instance, the processor(s) may be configured to determine a pressure-volume curve based on receiving data from one or more sensors collected during one or more breathing cycles of the subject 402. The processor(s), in some examples, determine a first derivative of the pressure-volume curve and / or a second derivative of the pressure-volume curve. The processor(s) may analyze at least one of the pressure-volume curve, the first derivative of the pressure-volume curve, and the second derivative of the pressure-volume curve to determine a lung compliance of the subject 402 and / or a respiratory condition of the subject 402. The processor(s), in various cases, are configured to determine a treatment parameter based on the lung compliance and / or the respiratory condition of the subject 402. In some examples, the processor(s) 418 are configured to control the flow of the gas into and out of the airway of the subject 402 by, for instance, controlling one or more valves of the ventilation device 400. In some examples, the processor(s) 418 are configured to output, via the output device(s) 414 or to the external devices 428, an indicative of the lung compliance of the subject 402.

[0087] FIG. 5 illustrates an example of an external defibrillator 500 configured to perform various functions described herein. For example, the external defibrillator 500 is the external device 114 described above with reference to FIG.1.

[0088] The external defibrillator 500 includes an electrocardiogram (ECG) port 502 connected to multiple ECG leads 504. In some cases, the ECG leads 504 are removeable from the ECG port 502. For instance, the ECG leads 504 are plugged into the ECG port 502. The ECG leads 504 are connected to ECG electrodes 506, respectively. In various implementations, the ECG electrodes 506 are disposed on different locations on an individual 508. A detection circuit 510 is configured to detect relative voltages between the ECG electrodes 506. These voltages are indicative of the electrical activity of the heart of the individual 508.

[0089] In various implementations, the ECG electrodes 506 are in contact with the different locations on the skin of the individual 508. In some examples, a first one of the ECG electrodes 506 is placed on the skin between the heart and right arm of the individual 508, a second one of the ECG electrodes 506 is placed on the skin between the heart and left arm of the individual 508, and a third one of the ECG electrodes 506 is placed on the skin between the heart and a leg (either the left leg or the right leg) of the individual 508. In these examples, the detection circuit 510 is configured to measure the relative voltages between the first, second, and third ECG electrodes 506. Respective pairings of the ECG electrodes 506 are referred to as "leads,” and the voltages between the pairs of ECG electrodes 506 are known as "lead voltages.” In some examples, more than three ECG electrodes 506 are included, such that 5-lead or 12-lead ECG signals are detected by the detection circuit 510.S397-6031 PCT I PHYS0276PCT & MEDI-2778

[0090] The detection circuit 510 includes at least one analog circuit, at least one digital circuit, or a combination thereof. The detection circuit 510 receives the analog electrical signals from the ECG electrodes 506, via the ECG port 502 and the ECG leads 504. In some cases, the detection circuit 510 includes one or more analog filters configured to filter noise and / or artifact from the electrical signals. The detection circuit 510 includes an analog-to-digital (ADC) in various examples. The detection circuit 510 generates a digital signal indicative of the analog electrical signals from the ECG electrodes 506. This digital signal can be referred to as an “ECG signal” or an “ECG."

[0091] In some cases, the detection circuit 510 further detects an electrical impedance between at least one pair of the ECG electrodes 506. For example, the detection circuit 510 includes, or otherwise controls, a power source that applies a known voltage (or current) across a pair of the ECG electrodes 506 and detects a resultant current (or voltage) between the pair of the ECG electrodes 506. The impedance is generated based on the applied signal (voltage or current) and the resultant signal (current or voltage). In various cases, the impedance corresponds to respiration of the individual 508, chest compressions performed on the individual 508, and other physiological states of the individual 508. In various examples, the detection circuit 510 includes one or more analog filters configured to filter noise and / or artifact from the resultant signal. The detection circuit 510 generates a digital signal indicative of the impedance using an ADC. This digital signal can be referred to as an “impedance signal” or an “impedance.” In various examples, the detection circuit 510 receives signals indicative of additional physiological parameters from one or more additional sensors (e.g., the airway sensor(s) 112 and / or the additional sensor 116 described with reference to FIG. 1).

[0092] The detection circuit 510 provides the ECG signal and / or the impedance signal one or more processors 512 in the external defibrillator 500. In some implementations, the processor(s) 512 includes a central processing unit (CPU), a graphics processing unit (GPU), both CPU and GPU, or other processing unit or component known in the art.

[0093] The processor(s) 512 is operably connected to memory 514. In various implementations, the memory 514 is volatile (such as random access memory (RAM)), non-volatile (such as read only memory (ROM), flash memory, etc.) or some combination of the two. The memory 514 stores instructions that, when executed by the processor(s) 512, causes the processor(s) 512 to perform various operations. In various examples, the memory 514 stores methods, threads, processes, applications, objects, modules, any other sort of executable instruction, or a combination thereof. In some cases, the memory 514 stores files, databases, or a combination thereof. In some examples, the memory 514 includes, but is not limited to, RAM, ROM, electrically erasable programmable read-only memory (EEPROM), flash memory, or any other memory technology. In some examples, the memory 514 includes one or more of CD-ROMs, digital versatile discs (DVDs), content-addressable memory (CAM), or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by the processor(s) 512S397-6031 PCT I PHYS0276PCT & MEDI-2778and / or the external defibrillator 500. In some cases, the memory 514 at least temporarily stores the ECG signal and / or the impedance signal.

[0094] In various examples, the memory 514 includes a detector 516, which causes the processor(s) 512 to determine, based on the ECG signal and / or the impedance signal, whether the individual 508 is exhibiting a particular heart rhythm. For instance, the processor(s) 512 determines whether the individual 508 is experiencing a shockable rhythm that is treatable by defibrillation. Examples of shockable rhythms include ventricular fibrillation (VF) and ventricular tachycardia (V-Tach). In some examples, the processor(s) 512 determines whether any of a variety of different rhythms (e.g., asystole, sinus rhythm, atrial fibrillation (AF), etc.) are present in the ECG signal.

[0095] The processor(s) 512 is operably connected to one or more input devices 518 and one or more output devices 520. Collectively, the input device(s) 518 and the output device(s) 520 function as an interface between a user and the defibrillator 500. The input device(s) 518 is configured to receive an input from a user and includes at least one of a keypad, a cursor control, a touch-sensitive display, a voice input device (e.g., a microphone), a haptic feedback device (e.g., a gyroscope), or any combination thereof. The output device(s) 520 includes at least one of a display, a speaker, a haptic output device, a printer, or any combination thereof. In various examples, the processor(s) 512 causes a display among the input device(s) 518 to visually output a waveform of the ECG signal and / or the impedance signal. In some implementations, the input device(s) 518 includes one or more touch sensors, the output device(s) 520 includes a display screen, and the touch sensor(s) are integrated with the display screen. Thus, in some cases, the external defibrillator 500 includes a touchscreen configured to receive user input signal(s) and visually output physiological parameters, such as the ECG signal and / or the impedance signal. In various examples, the output device(s) 520 include one or more medical devices configured to monitor and / or treat the individual 508. For instance, the external defibrillator 500 may be connected to a mechanical chest compression device, a device configured to provide assisted ventilation, or the like.

[0096] In some examples, the memory 514 includes an advisor 522, which, when executed by the processor(s) 512, causes the processor(s) 512 to generate advice and / or control the output device(s) 520 to output the advice to a user (e.g., a rescuer). In some examples, the processor(s) 512 provides, or causes the output device(s) 520 to provide, an instruction to perform CPR on the individual 508. In some cases, the processor(s) 512 evaluates, based on the ECG signal, the impedance signal, or other physiological parameters, CPR being performed on the individual 508 and causes the output device(s) 520 to provide feedback about the CPR in the instruction. According to some examples, the processor(s) 512, upon identifying that a shockable rhythm is present in the ECG signal, causes the output device(s) 520 to output an instruction and / or recommendation to administer a defibrillation shock to the individual 508.

[0097] The memory 514 also includes an initiator 524 which, when executed by the processor(s) 512, causes the processor(s) 512 to control other elements of the external defibrillator 500 in order to administer a defibrillation shock to the individual 508. In some examples, the processor(s) 512 executing the initiator 524 selectively causes theS397-6031 PCT I PHYS0276PCT & MEDI-2778administration of the defibrillation shock based on determining that the individual 508 is exhibiting the shockable rhythm and / or based on an input from a user (received, e.g., by the input device(s) 518. In some cases, the processor(s) 512 causes the defibrillation shock to be output at a particular time, which is determined by the processor(s) 512 based on the ECG signal and / or the impedance signal.

[0098] In various cases, the memory 514 includes an airway analyzer 525 which, when executed by the processor(s) 512, causes the processor(s) 512 to perform one or more functions described with reference to the external device 114 in FIG. 1. For instance, the processor(s) 512 executing the airway analyzer 525 selectively causes determination of a lung compliance and / or a respiratory condition of the individual 508. In some examples, the processor(s) 512 causes the administration of one or more treatments, such as a defibrillation shock, to the individual 508.

[0099] The processor(s) 512 is operably connected to a charging circuit 523 and a discharge circuit 526. In various implementations, the charging circuit 523 includes a power source 527, one or more charging switches 528, and one or more capacitors 530. The power source 527 includes, for instance, a battery. The processor(s) 512 initiates a defibrillation shock by causing the power source 527 to charge at least one capacitor among the capacitor(s) 530. For example, the processor(s) 512 activates at least one of the charging switch(es) 528 in the charging circuit 523 to complete a first circuit connecting the power source 527 and the capacitor to be charged. Then, the processor(s) 512 causes the discharge circuit 526 to discharge energy stored in the charged capacitor across a pair of defibrillation electrodes 534, which are in contact with the individual 508. For example, the processor(s) 512 deactivates the charging switch(es) 528 completing the first circuit between the capacitor(s) 530 and the power source 527, and activates one or more discharge switches 532 completing a second circuit connecting the charged capacitor 530 and at least a portion of the individual 508 disposed between defibrillation electrodes 534.

[0100] The energy is discharged from the defibrillation electrodes 534 in the form of a defibrillation shock. For example, the defibrillation electrodes 534 are connected to the skin of the individual 508 and located at positions on different sides of the heart of the individual 508, such that the defibrillation shock is applied across the heart of the individual 508. The defibrillation shock, in various examples, depolarizes a significant number of heart cells in a short amount of time. The defibrillation shock, for example, interrupts the propagation of the shockable rhythm (e.g., VF or V-Tach) through the heart. In some examples, the defibrillation shock is 200 J or greater with a duration of about 0.015 seconds. In some cases, the defibrillation shock has a multiphasic (e.g., biphasic) waveform. The discharge switch(es) 532 are controlled by the processor(s) 512, for example. In various implementations, the defibrillation electrodes 534 are connected to defibrillation leads 536. The defibrillation leads 536 are connected to a defibrillation port 538, in implementations. According to various examples, the defibrillation leads 536 are removable from the defibrillation port 538. For example, the defibrillation leads 536 are plugged into the defibrillation port 538.

[0101] In various implementations, the processor(s) 512 is operably connected to one or more transceivers 540 that transmit and / or receive data over one or more communication networks 542. For example, the transceiver(s) 540S397-6031 PCT I PHYS0276PCT & MEDI-2778includes a network interface card (NIC), a network adapter, a local area network (LAN) adapter, or a physical, virtual, or logical address to connect to the various external devices and / or systems. In various examples, the transceiver(s) 540 includes any sort of wireless transceivers capable of engaging in wireless communication (e.g., radio frequency (RF) communication). For example, the communication network(s) 542 includes one or more wireless networks that include a 3rdGeneration Partnership Project (3GPP) network, such as a Long Term Evolution (LTE) radio access network (RAN) (e.g., over one or more LTE bands), a New Radio (NR) RAN (e.g., over one or more NR bands), or a combination thereof. In some cases, the transceiver(s) 540 includes other wireless modems, such as a modem for engaging in WI-FI®, WIGIG®, WIMAX®, BLUETOOTH®, or infrared communication over the communication network(s) 542.

[0102] The defibrillator 500 is configured to transmit and / or receive data (e.g., ECG data, impedance data, data indicative of one or more detected heart rhythms of the individual 508, data indicative of one or more defibrillation shocks administered to the individual 508, etc.) with one or more external devices 544 via the communication network(s) 542. The external devices 544 include, for instance, mobile devices (e.g., mobile phones, smartwatches, etc.), Internet of Things (loT) devices, medical devices, computers (e.g., laptop devices, servers, etc.), or any other type of computing device configured to communicate over the communication network(s) 542. In some examples, the external device(s) 544 is located remotely from the defibrillator 500, such as at a remote clinical environment (e.g., a hospital). According to various implementations, the processor(s) 512 causes the transceiver(s) 540 to transmit data to the external device(s) 544. In some cases, the transceiver(s) 540 receives data from the external device(s) 544 and the transceiver(s) 540 provide the received data to the processor(s) 512 for further analysis.

[0103] In various implementations, the external defibrillator 500 also includes a housing 546 that at least partially encloses other elements of the external defibrillator 500. For example, the housing 546 encloses the detection circuit 510, the processor(s) 512, the memory 514, the charging circuit 523, the transceiver(s) 540, or any combination thereof. In some cases, the input device(s) 518 and output device(s) 520 extend from an interior space at least partially surrounded by the housing 546 through a wall of the housing 546. In various examples, the housing 546 acts as a barrier to moisture, electrical interference, and / or dust, thereby protecting various components in the external defibrillator 500 from damage.

[0104] In some implementations, the external defibrillator 500 is an automated external defibrillator (AED) operated by an untrained user (e.g., a bystander, layperson, etc.) and can be operated in an automatic mode. In automatic mode, the processor(s) 512 automatically identifies a rhythm in the ECG signal, makes a decision whether to administer a defibrillation shock, charges the capacitor(s) 530, discharges the capacitor(s) 530, or any combination thereof. In some cases, the processor(s) 512 controls the output device(s) 520 to output (e.g., display) a simplified user interface to the untrained user. For example, the processor(s) 512 refrains from causing the output device(s) 520 to display a waveform of the ECG signal and / or the impedance signal to the untrained user, in order to simplify operation of the external defibrillator 500.S397-6031 PCT I PHYS0276PCT & MEDI-2778

[0105] In some examples, the external defibrillator 500 is a monitor-defibrillator utilized by a trained user (e.g., a clinician, an emergency responder, etc.) and can be operated in a manual mode or the automatic mode. When the external defibrillator 500 operates in manual mode, the processor(s) 512 cause the output device(s) 520 to display a variety of information that may be relevant to the trained user, such as waveforms indicating the ECG data and / or impedance data, notifications about detected heart rhythms, and the like.EXAMPLE CLAUSES1. A medical device including: a ventilation mask configured to be disposed on a face of a subject; a ventilation bag coupled with the ventilation mask and configured to output inspired air to the ventilation mask when squeezed and to receive expired air from the ventilation mask when released; a sensor disposed between the ventilation mask and the ventilation bag, the sensor being configured to: detect a volume of the inspired air; and detect a pressure of the inspired air; an output device configured to output an indication of a respiratory condition of the subject; and a processor configured to: generate a pressure-volume curve by analyzing the volume of the inspired air and the pressure of the inspired air; determine an airway compliance of the subject by analyzing the pressure-volume curve; and determine that the respiratory condition of the subject includes chronic obstructive pulmonary disease (COPD) by analyzing the airway compliance.2. The medical device of clause 1 , wherein the processor is configured to determine that the respiratory condition of the subject includes COPD by: determining that an upper inflection point of the pressure-volume curve corresponds to a pressure in a range of about 12 cmH20 to about 15 CIT1H2O; determining that an area under the pressure-volume curve is in a range of about 9,000 mL to about 12,000 mL; determining that a maximum value of a derivative of the pressure-volume curve is in a range of about 0.005 L / cmHhO to about 0.008 L / cmhkO; or determining that a value at a zero-crossing of a second derivative of the pressure-volume curve is in a range of about 7 cmPhO to about 9 CIT1H2O.3. The medical device of clause 1 or 2, wherein the processor is further configured to: in response to determining that the respiratory condition of subject includes COPD, cause the output device to output an instruction to reduce a ventilation rate of the subject.4. A medical device, including: an airway adaptor configured to be fluidically coupled with an airway of a subject; a ventilation source configured to be fluidically coupled with the airway adaptor and to output air into the airway of the subject through the airway adaptor; a sensor configured to detect a volume of the air and to detect a pressure of the air; and a processor configured to: generate a pressure-volume curve by analyzing the volume of the air and the pressure of the air; determine an airway parameter of the subject by analyzing the pressure-volume curve; and predict a respiratory condition of the subject by analyzing the airway parameter.5. The medical device of clause 4, wherein the sensor is configured to detect the volume and the pressure of inspired air, of expired air, or of inspired and expired air.S397-6031 PCT I PHYS0276PCT & MEDI-27786. The medical device of clause 4 or 5, wherein the airway parameter includes an airway compliance of the subject.7. The medical device of any one of clauses 4-6, wherein the processor is configured to determine the airway parameter by: determining a derivative of the pressure-volume curve with respect to pressure or with respect to volume; determining a second derivative of the pressure-volume curve with respect to pressure or with respect to volume; or determining an integral of the pressure-volume curve with respect to pressure or with respect to volume.8. The medical device of clause 7, wherein the airway parameter includes: an upper inflection point of the pressure-volume curve, a maximum value of the derivative of the pressure-volume curve, or a maximum value of the second derivative of the pressure-volume curve.9. The medical device of clause 8, wherein the airway parameter includes: a pressure corresponding to the upper inflection point of the pressure-volume curve, the maximum value of the derivative of the pressure-volume curve, or the maximum value of the second derivative of the pressure-volume curve.10. The medical device of any one of clauses 7-9, wherein the airway parameter includes: a value at a zerocrossing of the second derivative of the pressure-volume curve.11. The medical device of any one of clauses 7-10, wherein the airway parameter includes: a value of the pressure-volume curve at a particular pressure, a value of the pressure-volume curve at a particular volume, a value of the derivative of the pressure-volume curve at the particular pressure, a value of the second derivative of the pressure-volume curve at the particular pressure, a value of the integral of the pressure-volume curve over a particular range of pressures, or a value of the integral of the pressure-volume curve over a particular range of volumes.12. The medical device of any one of clauses 7-11, wherein the airway parameter includes: a maximum-to-minimum range of the pressure-volume curve, a maximum-to-minimum range of the derivative of the pressurevolume curve, or a maximum-to-minimum range of the second derivative of the pressure-volume curve.13. The medical device of any one of clauses 7-12, wherein the airway parameter includes: an area underneath a portion of the pressure-volume curve, an area underneath a portion of the derivative of the pressure-volume curve, or an area underneath a portion of the second derivative of the pressure-volume curve.14. The medical device of any one of clauses 4-13, wherein the predicted respiratory condition of the subject includes asthma, acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), pneumonia, an infectious respiratory disease, a restrictive respiratory disease, or a pulmonary vascular disease.15. The medical device of any one of clauses 4-14, wherein the processor is further configured to determine a treatment configured to treat the predicted respiratory condition of the subject, the treatment including administration of: chest compressions to the subject; or albuterol, epinephrine, budesonide, magnesium sulfate, dornase alpha, ipratropium bromide, etomidate, midazolam, propofol, thiopental, methylprednisolone, dexamethasone, or epinephrine to the subject.S397-6031 PCT I PHYS0276PCT & MEDI-277816. The medical device of any one of clauses 4-15, wherein the processor is further configured to determine, by analyzing the airway parameter and the predicted respiratory condition of the subject, a target rate, a target pressure, or a target volume of air of assisted ventilation to be administered to the subject.17. The medical device of any one of clauses 4-16, further including a second sensor configured to detect a physiological parameter of the subject, wherein the processor is configured to: determine that the subject is receiving insufficient ventilation by determining that the physiological parameter is above a first threshold or is lower than a second threshold; and in response to determining that the subject is receiving insufficient ventilation, determine a rate, a pressure, or a volume of air predicted to provide sufficient ventilation to the subject.18. The medical device of clause 17, wherein the physiological parameter includes a blood oxygen saturation, a blood pressure, a pulse rate, a carbon dioxide level in the airway, an oxygen level in the airway, or a nitrogen level in the airway of the subject.19. The medical device of clause 17 or 18, wherein the physiological parameter includes a transthoracic impedance, and wherein the processor is configured to determine that the subject is receiving insufficient ventilation by: determining a change in lung volume between ventilation cycles by analyzing the transthoracic impedance; and determining that the change in the lung volume is lower than a threshold.20. The medical device of any one of clauses 4-19, further including a second sensor configured to detect a physiological parameter of the subject, the physiological parameter including a blood oxygen saturation, a blood pressure, or a pulse rate of the subject, wherein the processor is configured to: identify a return of spontaneous circulation in the subject by determining that the physiological parameter is greater than a threshold.21. A method, including: identifying a pressure of air and a volume of air outputted by a ventilation source into an airway of a subject; generating a pressure-volume curve by analyzing the pressure of the air and the volume of the air; identifying an airway parameter of the subject by analyzing the pressure-volume curve; and predicting a respiratory condition of the subject by analyzing the airway parameter.22. The method of clause 21 , wherein identifying the airway parameter includes: determining a derivative of the pressure-volume curve with respect to pressure or with respect to volume; determining a second derivative of the pressure-volume curve with respect to pressure or with respect to volume; or determining an integral of the pressurevolume curve with respect to pressure or with respect to volume.23. The method of clause 22, wherein the airway parameter includes: an upper inflection point of the pressurevolume curve, a maximum value of the derivative of the pressure-volume curve, or a maximum value of the second derivative of the pressure-volume curve.24. The method of clause 23, wherein the airway parameter includes: a pressure corresponding to the upper inflection point of the pressure-volume curve, the maximum value of the derivative of the pressure-volume curve, or the maximum value of the second derivative of the pressure-volume curve.S397-6031 PCT I PHYS0276PCT & MEDI-277825. The method of any one of clauses 22-24, wherein the airway parameter includes: a value at a zero-crossing of the second derivative of the pressure-volume curve.26. The method of any one of clauses 22-25, wherein the airway parameter includes: a value of the pressurevolume curve at a particular pressure, a value of the pressure-volume curve at a particular volume, a value of the derivative of the pressure-volume curve at the particular pressure, a value of the second derivative of the pressurevolume curve at the particular pressure, a value of the integral of the pressure-volume curve over a particular range of pressures, or a value of the integral of the pressure-volume curve over a particular range of volumes.27. The method of any one of clauses 22-26, wherein the airway parameter includes: a maximum-to-minimum range of the pressure-volume curve, a maximum-to-minimum range of the derivative of the pressure-volume curve, or a maximum-to-minimum range of the second derivative of the pressure-volume curve.28. The method of any one of clauses 22-27, wherein the airway parameter includes: an area underneath a portion of the pressure-volume curve, an area underneath a portion of a portion of the derivative of the pressurevolume curve, or an area underneath a portion of a portion of the second derivative of the pressure-volume curve.29. The method of any one of clauses 21-28, wherein the predicted respiratory condition of the subject includes asthma, acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), pneumonia, an infectious respiratory disease, a restrictive respiratory disease, or a pulmonary vascular disease.30. The method of any one of clauses 21-29, further including: determining a treatment configured to treat the predicted respiratory condition of the subject, the treatment including administration of: chest compressions to the subject; or albuterol, epinephrine, budesonide, magnesium sulfate, dornase alpha, ipratropium bromide, etomidate, midazolam, propofol, thiopental, methylprednisolone, dexamethasone, or epinephrine.31. The method of any one of clauses 21-30, further including: identifying a physiological parameter of the subject; determining that the subject is receiving insufficient ventilation by determining that the physiological parameter is above a first threshold or below a second threshold; and in response to determining that the subject is receiving insufficient ventilation, determining a target rate, a target pressure, or a target volume of air predicted to provide sufficient ventilation to the subject.32. The method of clause 31, wherein the physiological parameter includes a blood oxygen saturation, a blood pressure, a pulse rate, a carbon dioxide level in the airway, an oxygen level in the airway, or a nitrogen level in the airway of the subject.33. The method of clause 31 or 32, wherein the physiological parameter includes a transthoracic impedance, and wherein determining that the subject is receiving insufficient ventilation includes: determining a change in lung volume by analyzing the transthoracic impedance; and determining that the change in lung volume is lower than a threshold.S397-6031 PCT I PHYS0276PCT & MEDI-277834. The method of any one of clauses 21-33, further including: identifying a blood oxygen saturation, a blood pressure, or a pulse rate of the subject; and determining a return of spontaneous circulation in the subject by determining that the blood oxygen saturation, the blood pressure, or the pulse rate is greater than a threshold.35. A medical device, including: a ventilation mask configured to be disposed on a face of a subject; a ventilation bag coupled with the ventilation mask and configured to output inspired air to the ventilation mask when compressed and to receive expired air from the ventilation mask when released; a sensor disposed between the ventilation mask and the ventilation bag, the sensor being configured to: detect a volume of the inspired air; and detect a pressure of the inspired air; an output device; and a processor configured to: generate a first pressurevolume curve by analyzing the volume of the inspired air and the pressure of the inspired air corresponding to a first time interval; determine a first airway compliance by analyzing the first pressure-volume curve; generate a second pressure-volume curve by analyzing the volume of the inspired air and the pressure of the inspired air corresponding a second time interval; determine a second airway compliance by analyzing the second pressure-volume curve; determine that the second airway compliance is lower than the first airway compliance; and in response to determining that the second airway compliance is lower than the first airway compliance, cause the output device to output an indication that a respiratory condition of the subject is deteriorating.36. The medical device of clause 35, wherein the first time interval occurs before administration of chest compressions to the subject, and wherein the second time interval occurs after administration of chest compressions have been initiated.37. The medical device of clause 35 or 36, wherein the processor is further configured to determine that the respiratory condition of the subject includes acute respiratory distress syndrome (ARDS) or a restrictive respiratory disease.38. The medical device of any one of clauses 35-37, wherein the processor is configured to determine that the second airway compliance is lower than the first airway compliance by: determining that a pressure corresponding to an upper inflection point of the second pressure-volume curve is higher than a pressure corresponding to an upper inflection point of the first pressure-volume curve; determining that a maximum value of a derivative of the second pressure-volume curve is lower than a maximum value of a derivative of the first pressure-volume curve; or determining that a pressure corresponding to a zero-crossing of a second derivative of the second pressure-volume curve is greater than a pressure corresponding to a zero-crossing of a second derivative of the first pressure-volume curve.39. A medical device, including: an airway adaptor configured to be fluidically coupled with an airway of a subject; a ventilation source configured to be fluidically coupled with the airway adaptor and to output air into the airway of the subject through the airway adaptor; a sensor configured to detect a volume and to detect a pressure of the air; and a processor configured to: generate a first pressure-volume curve by analyzing the volume of the air and the pressure of the air corresponding to a first time interval; determine a first airway parameter by analyzing the firstS397-6031 PCT I PHYS0276PCT & MEDI-2778pressure-volume curve; generate a second pressure-volume curve by analyzing the volume of the air and the pressure of the air corresponding a second time interval; determine a second airway parameter by analyzing the second pressure-volume curve; compare the first airway parameter and the second airway parameter; and in response to comparing the first airway parameter and the second airway parameter, determine a respiratory condition of the subject.40. The medical device of clause 39, wherein the first pressure-volume curve is indicative of the volume and the pressure of inspired air, of expired air, or of inspired and expired air corresponding to the first time interval, and wherein the second pressure-volume curve is indicative of the volume and the pressure of inspired air, of expires air, or of inspired and expired air corresponding to the second time interval.41. The medical device of clause 39 or 40, wherein the first airway parameter and the second airway parameter include an airway compliance of the subject.42. The medical device of any one of clauses 39-41 , wherein the first time interval occurs before treatment administration to the subject, and wherein the second time interval occurs after initiation of the treatment administration to the subject.43. The medical device of clause 42, wherein the treatment administration includes administration of: assisted ventilation to the subject; chest compressions to the subject; or albuterol, epinephrine, budesonide, magnesium sulfate, dornase alpha, ipratropium bromide, etomidate, midazolam, propofol, thiopental, methylprednisolone, dexamethasone, or epinephrine to the subject.44. The medical device of any one of clauses 39-43, wherein the processor is configured to: determine the first airway parameter by: determining a derivative of the first pressure-volume curve with respect to pressure or with respect to volume; determining a second derivative of the first pressure-volume curve with respect to pressure or with respect to volume; or determining an integral of the first pressure-volume curve with respect to pressure or with respect to volume.45. The medical device of clause 44, wherein the first airway parameter includes: an upper inflection point of the first pressure-volume curve, a maximum value of the derivative of the first pressure-volume curve, or a maximum value of the second derivative of the first pressure-volume curve.46. The medical device of clause 45, wherein the first airway parameter includes: a pressure corresponding to the upper inflection point of the first pressure-volume curve, the maximum value of the derivative of the first pressurevolume curve, or the maximum value of the second derivative of the first pressure-volume curve.47. The medical device of any one of clauses 44-46, wherein the first airway parameter includes: a value at a zero-crossing of the second derivative of the first pressure-volume curve.48. The medical device of any one of clauses 44-47, wherein the first airway parameter includes: a value of the first pressure-volume curve at a particular pressure, a value of the first pressure-volume curve at a particular volume, a value of the derivative of the first pressure-volume curve at a particular pressure, a value of the second derivativeS397-6031 PCT I PHYS0276PCT & MEDI-2778of the first pressure-volume curve at a particular pressure, a value of the integral of the first pressure-volume curve over a particular range of pressures, or a value of the integral of the first pressure-volume curve over a particular range of volumes.49. The medical device of any one of clauses 44-48, wherein the first airway parameter includes: a maximum-to-minimum range of the first pressure-volume curve, a maximum-to-minimum range of the derivative of the first pressure-volume curve, or a maximum-to-minimum range of the second derivative of the first pressure-volume curve.50. The medical device of any one of clauses 44-49, wherein the first airway parameter includes: an area underneath a portion of the first pressure-volume curve, an area underneath a portion of a portion of the derivative of the first pressure-volume curve, or an area underneath a portion of a portion of the second derivative of the first pressure-volume curve.51. The medical device of any one of clauses 39-50, wherein the respiratory condition of the subject includes asthma, acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), pneumonia, an infectious respiratory disease, a restrictive respiratory disease, or a pulmonary vascular disease.52. The medical device of any one of clauses 39-51 , wherein the respiratory condition of the subject includes a deterioration or an improvement of a physiological condition of the subject.53. The medical device of any one of clauses 39-52, wherein the processor is further configured to: determine that the subject is receiving insufficient ventilation by analyzing the first airway parameter and the second airway parameter of the subject; and determine a rate, a pressure, or a volume of air predicted to provide sufficient ventilation to the subject.54. The medical device of any one of clauses 39-53, further including: a second sensor configured to detect a physiological parameter of the subject, wherein the processor is configured to: determine that the subject is receiving insufficient ventilation by analyzing the physiological parameter; and in response to determining that the subject is receiving insufficient ventilation, determine a rate, a pressure, or a volume of air predicted to provide sufficient ventilation to the subject.55. The medical device of clause 54, wherein the physiological parameter includes a blood oxygen saturation, a blood pressure, a pulse rate, a transthoracic impedance, a carbon dioxide level in the airway, an oxygen level in the airway, or a nitrogen level in the airway.56. A method, including: identifying a pressure of air and a volume of air outputted by a ventilation source into an airway of a subject; generating a first pressure-volume curve by analyzing the pressure of the air and the volume of the air corresponding to a first time interval; determining a first airway parameter by analyzing the first pressurevolume curve; generating a second pressure-volume curve by analyzing the pressure of the air and the volume of the air corresponding to a second time interval; determining a second airway parameter by analyzing the second pressure-volume curve; comparing the first airway parameter and the second airway parameter; and in response toS397-6031 PCT I PHYS0276PCT & MEDI-2778comparing the first airway parameter and the second airway parameter, determining a respiratory condition of the subject.57. The method of clause 56, wherein determining the first airway parameter includes: determining a derivative of the first pressure-volume curve with respect to pressure or with respect to volume; determining a second derivative of the first pressure-volume curve with respect to pressure or with respect to volume; or determining an integral of the first pressure-volume curve with respect to pressure or with respect to volume.58. The method of clause 57, wherein the first airway parameter includes: an upper inflection point of the first pressure-volume curve, a maximum value of the derivative of the first pressure-volume curve, or a maximum value of the second derivative of the first pressure-volume curve.59. The method of clause 58, wherein the first airway parameter includes: a pressure corresponding to the upper inflection point of the first pressure-volume curve, the maximum value of the derivative of the first pressurevolume curve, or the maximum value of the second derivative of the first pressure-volume curve.60. The method of any one of clauses 57-59, wherein the first airway parameter includes: a value at a zerocrossing of the second derivative of the first pressure-volume curve.61. The method of any one of clauses 57-60, wherein the first airway parameter includes: a value of the first pressure-volume curve at a particular pressure, a value of the first pressure-volume curve at a particular volume, a value of the derivative of the first pressure-volume curve at a particular pressure, a value of the second derivative of the first pressure-volume curve at a particular pressure, a value of the integral of the first pressure-volume curve over a particular range of pressures, or a value of the integral of the first pressure-volume curve over a particular range of volumes.62. The method of any one of clauses 57-61, wherein the first airway parameter includes: a maximum-to-minimum range of the first pressure-volume curve, a maximum-to-minimum range of the derivative of the first pressure-volume curve, or a maximum-to-minimum range of the second derivative of the first pressure-volume curve.63. The method of any one of clauses 57-62, wherein the first airway parameter includes: an area underneath a portion of the first pressure-volume curve, an area underneath a portion of the derivative of the first pressure-volume curve, or an area underneath a portion of the second derivative of the first pressure-volume curve.64. The method of any one of clauses 56-63, wherein the respiratory condition of the subject includes asthma, acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), pneumonia, an infectious respiratory disease, a restrictive respiratory disease, or a pulmonary vascular disease.65. The method of any one of clauses 56-64, wherein the respiratory condition of the subject includes a deterioration or an improvement of a physiological condition of the subject.66. The method of any one of clauses 56-65, further including: determining that the subject is receiving insufficient ventilation by analyzing the first airway parameter and the second airway parameter; and determining a rate, a pressure, or a volume of air predicted to provide sufficient ventilation to the subject.S397-6031 PCT I PHYS0276PCT & MEDI-277867. The method of any one of clauses 56-66, further including: in response to comparing the first airway parameter and the second airway parameter, identifying a treatment previously administered to the subject or a treatment being administered to the subject.68. The method of clause 67, wherein the treatment includes administration of: chest compressions to the subject; or albuterol, epinephrine, budesonide, magnesium sulfate, dornase alpha, ipratropium bromide, etomidate, midazolam, propofol, thiopental, methylprednisolone, dexamethasone, or epinephrine to the subject.

[0106] The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be used for realizing implementations of the disclosure in diverse forms thereof.

[0107] As will be understood by one of ordinary skill in the art, each implementation disclosed herein can comprise, consist essentially of or consist of its particular stated element, step, or component. Thus, the terms “include” or “including” should be interpreted to recite: “comprise, consist of, or consist essentially of.” The transition term “comprise” or “comprises” means has, but is not limited to, and allows for the inclusion of unspecified elements, steps, ingredients, or components, even in major amounts. The transitional phrase “consisting of' excludes any element, step, ingredient or component not specified. The transition phrase “consisting essentially of” limits the scope of the implementation to the specified elements, steps, ingredients or components and to those that do not materially affect the implementation. As used herein, the term “based on” is equivalent to “based at least partly on,” unless otherwise specified.

[0108] Unless otherwise indicated, all numbers expressing quantities, properties, conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. When further clarity is required, the term “about” has the meaning reasonably ascribed to it by a person skilled in the art when used in conjunction with a stated numerical value or range, i.e. denoting somewhat more or somewhat less than the stated value or range, to within a range of ±20% of the stated value; ±19% of the stated value; ±18% of the stated value; ±17% of the stated value; ±16% of the stated value; ±15% of the stated value; ±14% of the stated value; ±13% of the stated value; ±12% of the stated value; ±11 % of the stated value; ±10% of the stated value; ±9% of the stated value; ±8% of the stated value; ±7% of the stated value; ±6% of the stated value; ±5% of the stated value; ±4% of the stated value; ±3% of the stated value; ±2% of the stated value; or ±1 % of the stated value.S397-6031 PCT I PHYS0276PCT & MEDI-2778

[0109] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0110] The terms “a,” ''an," “the" and similar referents used in the context of describing implementations (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate implementations of the disclosure and does not pose a limitation on the scope of the disclosure. No language in the specification should be construed as indicating any non-claimed element essential to the practice of implementations of the disclosure.

[0111] Groupings of alternative elements or implementations disclosed herein are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

[0112] Certain implementations are described herein, including the best mode known to the inventors for carrying out implementations of the disclosure. Of course, variations on these described implementations will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for implementations to be practiced otherwise than specifically described herein. Accordingly, the scope of this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by implementations of the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

S397-6031 PCT I PHYS0276PCT & MEDI-2778CLAIMSWhat is claimed is:

1. A medical device, comprising:an airway adaptor configured to be fluidically coupled with an airway of a subject;a ventilation source configured to be fluidically coupled with the airway adaptor and to output air into the airway of the subject through the airway adaptor;a sensor configured to detect a volume of the air and to detect a pressure of the air; anda processor configured to:generate a pressure-volume curve by analyzing the volume of the air and the pressure of the air; determine an airway parameter of the subject by analyzing the pressure-volume curve; and predict a respiratory condition of the subject by analyzing the airway parameter.

2. The medical device of claim 1 , wherein the sensor is configured to detect the volume and the pressure of inspired air, of expired air, or of inspired and expired air.

3. The medical device of claim 1 or 2, wherein the airway parameter comprises an airway compliance of the subject.

4. The medical device of any one of claims 1-3, wherein the processor is configured to determine the airway parameter by:determining a derivative of the pressure-volume curve with respect to pressure or with respect to volume; determining a second derivative of the pressure-volume curve with respect to pressure or with respect to volume; ordetermining an integral of the pressure-volume curve with respect to pressure or with respect to volume.

5. The medical device of claim 4, wherein the airway parameter comprises:an upper inflection point of the pressure-volume curve, a maximum value of the derivative of the pressurevolume curve, or a maximum value of the second derivative of the pressure-volume curve.

6. The medical device of claim 5, wherein the airway parameter comprises:a pressure corresponding to the upper inflection point of the pressure-volume curve, the maximum value of the derivative of the pressure-volume curve, or the maximum value of the second derivative of the pressure-volume curve.

7. The medical device of any one of claims 4-6, wherein the airway parameter comprises:a value at a zero-crossing of the second derivative of the pressure-volume curve.

8. The medical device of any one of claims 4-7, wherein the airway parameter comprises:a value of the pressure-volume curve at a particular pressure, a value of the pressure-volume curve at a particular volume, a value of the derivative of the pressure-volume curve at the particular pressure, a value of the second derivative of the pressure-volume curve at the particular pressure, a value of the integral of the pressure-S397-6031 PCT I PHYS0276PCT & MEDI-2778volume curve over a particular range of pressures, or a value of the integral of the pressure-volume curve over a particular range of volumes.

9. The medical device of any one of claims 4-8, wherein the airway parameter comprises:a maximum-to-minimum range of the pressure-volume curve, a maximum-to-minimum range of the derivative of the pressure-volume curve, or a maximum-to-minimum range of the second derivative of the pressurevolume curve.

10. The medical device of any one of claims 4-9, wherein the airway parameter comprises:an area underneath a portion of the pressure-volume curve, an area underneath a portion of the derivative of the pressure-volume curve, or an area underneath a portion of the second derivative of the pressure-volume curve.

11. The medical device of any one of claims 1-10, wherein the predicted respiratory condition of the subject comprises asthma, acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), pneumonia, an infectious respiratory disease, a restrictive respiratory disease, or a pulmonary vascular disease.

12. The medical device of any one of claims 1-11, wherein the processor is further configured to determine a treatment configured to treat the predicted respiratory condition of the subject, the treatment comprising administration of:chest compressions to the subject; oralbuterol, epinephrine, budesonide, magnesium sulfate, dornase alpha, ipratropium bromide, etomidate, midazolam, propofol, thiopental, methylprednisolone, dexamethasone, or epinephrine to the subject.

13. The medical device of any one of claims 1-12, wherein the processor is further configured to determine, by analyzing the airway parameter and the predicted respiratory condition of the subject, a target rate, a target pressure, or a target volume of air of assisted ventilation to be administered to the subject.

14. The medical device of any one of claims 1-13, further comprising a second sensor configured to detect a physiological parameter of the subject,wherein the processor is configured to:determine that the subject is receiving insufficient ventilation by determining that the physiological parameter is above a first threshold or is lower than a second threshold; andin response to determining that the subject is receiving insufficient ventilation, determine a rate, a pressure, or a volume of air predicted to provide sufficient ventilation to the subject.

15. The medical device of claim 14, wherein the physiological parameter comprises a blood oxygen saturation, a blood pressure, a pulse rate, a carbon dioxide level in the airway, an oxygen level in the airway, or a nitrogen level in the airway of the subject.S397-6031 PCT I PHYS0276PCT & MEDI-277816. The medical device of claim 14 or 15, wherein the physiological parameter comprises a transthoracic impedance, and wherein the processor is configured to determine that the subject is receiving insufficient ventilation by:determining a change in lung volume between ventilation cycles by analyzing the transthoracic impedance; anddetermining that the change in the lung volume is lower than a threshold.

17. The medical device of any one of claims 1-16, further comprising a second sensor configured to detect a physiological parameter of the subject, the physiological parameter comprising a blood oxygen saturation, a blood pressure, or a pulse rate of the subject,wherein the processor is configured to:identify a return of spontaneous circulation in the subject by determining that the physiological parameter is greater than a threshold.

18. A medical device comprising:a ventilation mask configured to be disposed on a face of a subject;a ventilation bag coupled with the ventilation mask and configured to output inspired air to the ventilation mask when squeezed and to receive expired air from the ventilation mask when released;a sensor disposed between the ventilation mask and the ventilation bag, the sensor being configured to:detect a volume of the inspired air; anddetect a pressure of the inspired air;an output device configured to output an indication of a respiratory condition of the subject; and a processor configured to:generate a pressure-volume curve by analyzing the volume of the inspired air and the pressure of the inspired air;determine an airway compliance of the subject by analyzing the pressure-volume curve; and determine that the respiratory condition of the subject comprises chronic obstructive pulmonary disease (COPD) by analyzing the airway compliance19. The medical device of claim 18, wherein the processor is configured to determine that the respiratory condition of the subject comprises COPD by:determining that an upper inflection point of the pressure-volume curve corresponds to a pressure in a range of about 12 cmbfeO to about 15 cmbfeO;determining that an area under the pressure-volume curve is in a range of about 9,000 mL to about 12,000 ml_;determining that a maximum value of a derivative of the pressure-volume curve is in a range of about 0.005 L / CIT1H2O to about 0.008 L / cmH2O; orS397-6031 PCT I PHYS0276PCT & MEDI-2778determining that a value at a zero-crossing of a second derivative of the pressure-volume curve is in a range of about 7 CIT1H2O to about 9 cmF O.

20. The medical device of claim 18 or 19, wherein the processor is further configured to:in response to determining that the respiratory condition of subject comprises COPD, cause the output device to output an instruction to reduce a ventilation rate of the subject.

21. A method, comprising:identifying a pressure of air and a volume of air outputted by a ventilation source into an airway of a subject; generating a pressure-volume curve by analyzing the pressure of the air and the volume of the air; identifying an airway parameter of the subject by analyzing the pressure-volume curve; andpredicting a respiratory condition of the subject by analyzing the airway parameter.

22. The method of claim 21 , wherein identifying the airway parameter comprises:determining a derivative of the pressure-volume curve with respect to pressure or with respect to volume; determining a second derivative of the pressure-volume curve with respect to pressure or with respect to volume; ordetermining an integral of the pressure-volume curve with respect to pressure or with respect to volume.

23. The method of claim 22, wherein the airway parameter comprises:an upper inflection point of the pressure-volume curve, a maximum value of the derivative of the pressurevolume curve, or a maximum value of the second derivative of the pressure-volume curve.

24. The method of claim 23, wherein the airway parameter comprises:a pressure corresponding to the upper inflection point of the pressure-volume curve, the maximum value of the derivative of the pressure-volume curve, or the maximum value of the second derivative of the pressure-volume curve.

25. The method of any one of claims 22-24, wherein the airway parameter comprises:a value at a zero-crossing of the second derivative of the pressure-volume curve.

26. The method of any one of claims 22-25, wherein the airway parameter comprises:a value of the pressure-volume curve at a particular pressure, a value of the pressure-volume curve at a particular volume, a value of the derivative of the pressure-volume curve at the particular pressure, a value of the second derivative of the pressure-volume curve at the particular pressure, a value of the integral of the pressurevolume curve over a particular range of pressures, or a value of the integral of the pressure-volume curve over a particular range of volumes.

27. The method of any one of claims 22-26, wherein the airway parameter comprises:a maximum-to-minimum range of the pressure-volume curve, a maximum-to-minimum range of the derivative of the pressure-volume curve, or a maximum-to-minimum range of the second derivative of the pressurevolume curve.S397-6031 PCT I PHYS0276PCT & MEDI-277828. The method of any one of claims 22-27, wherein the airway parameter comprises:an area underneath a portion of the pressure-volume curve, an area underneath a portion of a portion of the derivative of the pressure-volume curve, or an area underneath a portion of a portion of the second derivative of the pressure-volume curve.

29. The method of any one of claims 21-28, wherein the predicted respiratory condition of the subject comprises asthma, acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), pneumonia, an infectious respiratory disease, a restrictive respiratory disease, or a pulmonary vascular disease.

30. The method of any one of claims 21-29, further comprising: determining a treatment configured to treat the predicted respiratory condition of the subject, the treatment comprising administration of:chest compressions to the subject; oralbuterol, epinephrine, budesonide, magnesium sulfate, dornase alpha, ipratropium bromide, etomidate, midazolam, propofol, thiopental, methylprednisolone, dexamethasone, or epinephrine.

31. The method of any one of claims 21-30, further comprising:identifying a physiological parameter of the subject;determining that the subject is receiving insufficient ventilation by determining that the physiological parameter is above a first threshold or below a second threshold; andin response to determining that the subject is receiving insufficient ventilation, determining a target rate, a target pressure, or a target volume of air predicted to provide sufficient ventilation to the subject.

32. The method of claim 31 , wherein the physiological parameter comprises a blood oxygen saturation, a blood pressure, a pulse rate, a carbon dioxide level in the airway, an oxygen level in the airway, or a nitrogen level in the airway of the subject.

33. The method of claim 31 or 32, wherein the physiological parameter comprises a transthoracic impedance, andwherein determining that the subject is receiving insufficient ventilation comprises:determining a change in lung volume by analyzing the transthoracic impedance; and determining that the change in lung volume is lower than a threshold.

34. The method of any one of claims 21-33, further comprising:identifying a blood oxygen saturation, a blood pressure, or a pulse rate of the subject; anddetermining a return of spontaneous circulation in the subject by determining that the blood oxygen saturation, the blood pressure, or the pulse rate is greater than a threshold.

35. A medical device, comprising:a ventilation mask configured to be disposed on a face of a subject;a ventilation bag coupled with the ventilation mask and configured to output inspired air to the ventilation mask when compressed and to receive expired air from the ventilation mask when released;S397-6031 PCT I PHYS0276PCT & MEDI-2778a sensor disposed between the ventilation mask and the ventilation bag, the sensor being configured to: detect a volume of the inspired air; anddetect a pressure of the inspired air;an output device; anda processor configured to:generate a first pressure-volume curve by analyzing the volume of the inspired air and the pressure of the inspired air corresponding to a first time interval;determine a first airway compliance by analyzing the first pressure-volume curve; generate a second pressure-volume curve by analyzing the volume of the inspired air and the pressure of the inspired air corresponding a second time interval;determine a second airway compliance by analyzing the second pressure-volume curve; determine that the second airway compliance is lower than the first airway compliance; and in response to determining that the second airway compliance is lower than the first airway compliance, cause the output device to output an indication that a respiratory condition of the subject is deteriorating.

36. The medical device of claim 35, wherein the first time interval occurs before administration of chest compressions to the subject, and wherein the second time interval occurs after administration of chest compressions have been initiated.

37. The medical device of claim 35 or 36, wherein the processor is further configured to determine that the respiratory condition of the subject comprises acute respiratory distress syndrome (ARDS) or a restrictive respiratory disease.

38. The medical device of any one of claims 35-37, wherein the processor is configured to determine that the second airway compliance is lower than the first airway compliance by:determining that a pressure corresponding to an upper inflection point of the second pressure-volume curve is higher than a pressure corresponding to an upper inflection point of the first pressure-volume curve;determining that a maximum value of a derivative of the second pressure-volume curve is lower than a maximum value of a derivative of the first pressure-volume curve; ordetermining that a pressure corresponding to a zero-crossing of a second derivative of the second pressurevolume curve is greater than a pressure corresponding to a zero-crossing of a second derivative of the first pressurevolume curve.

39. A medical device, comprising:an airway adaptor configured to be fluidically coupled with an airway of a subject;a ventilation source configured to be fluidically coupled with the airway adaptor and to output air into the airway of the subject through the airway adaptor;S397-6031 PCT I PHYS0276PCT & MEDI-2778a sensor configured to detect a volume and to detect a pressure of the air; anda processor configured to:generate a first pressure-volume curve by analyzing the volume of the air and the pressure of the air corresponding to a first time interval;determine a first airway parameter by analyzing the first pressure-volume curve; generate a second pressure-volume curve by analyzing the volume of the air and the pressure of the air corresponding a second time interval;determine a second airway parameter by analyzing the second pressure-volume curve; compare the first airway parameter and the second airway parameter; andin response to comparing the first airway parameter and the second airway parameter, determine a respiratory condition of the subject.

40. The medical device of claim 39, wherein the first pressure-volume curve is indicative of the volume and the pressure of inspired air, of expired air, or of inspired and expired air corresponding to the first time interval, andwherein the second pressure-volume curve is indicative of the volume and the pressure of inspired air, of expires air, or of inspired and expired air corresponding to the second time interval.

41. The medical device of claim 39 or 40, wherein the first airway parameter and the second airway parameter comprise an airway compliance of the subject.

42. The medical device of any one of claims 39-41 , wherein the first time interval occurs before treatment administration to the subject, and wherein the second time interval occurs after initiation of the treatment administration to the subject.

43. The medical device of claim 42, wherein the treatment administration comprises administration of: assisted ventilation to the subject;chest compressions to the subject; oralbuterol, epinephrine, budesonide, magnesium sulfate, dornase alpha, ipratropium bromide, etomidate, midazolam, propofol, thiopental, methylprednisolone, dexamethasone, or epinephrine to the subject.

44. The medical device of any one of claim 39-43, wherein the processor is configured to: determine the first airway parameter by:determining a derivative of the first pressure-volume curve with respect to pressure or with respect to volume;determining a second derivative of the first pressure-volume curve with respect to pressure or with respect to volume; ordetermining an integral of the first pressure-volume curve with respect to pressure or with respect to volume.S397-6031 PCT I PHYS0276PCT & MEDI-277845. The medical device of claim 44, wherein the first airway parameter comprises:an upper inflection point of the first pressure-volume curve, a maximum value of the derivative of the first pressure-volume curve, or a maximum value of the second derivative of the first pressure-volume curve.

46. The medical device of claim 45, wherein the first airway parameter comprises:a pressure corresponding to the upper inflection point of the first pressure-volume curve, the maximum value of the derivative of the first pressure-volume curve, or the maximum value of the second derivative of the first pressure-volume curve.

47. The medical device of any one of claims 44-46, wherein the first airway parameter comprises: a value at a zero-crossing of the second derivative of the first pressure-volume curve.

48. The medical device of any one of claims 44-47, wherein the first airway parameter comprises: a value of the first pressure-volume curve at a particular pressure, a value of the first pressure-volume curve at a particular volume, a value of the derivative of the first pressure-volume curve at a particular pressure, a value of the second derivative of the first pressure-volume curve at a particular pressure, a value of the integral of the first pressure-volume curve over a particular range of pressures, or a value of the integral of the first pressure-volume curve over a particular range of volumes.

49. The medical device of any one of claims 44-48, wherein the first airway parameter comprises: a maximum-to-minimum range of the first pressure-volume curve, a maximum-to-minimum range of the derivative of the first pressure-volume curve, or a maximum-to-minimum range of the second derivative of the first pressure-volume curve.

50. The medical device of any one of claims 44-49, wherein the first airway parameter comprises: an area underneath a portion of the first pressure-volume curve, an area underneath a portion of a portion of the derivative of the first pressure-volume curve, or an area underneath a portion of a portion of the second derivative of the first pressure-volume curve.

51. The medical device of any one of claims 39-50, wherein the respiratory condition of the subject comprises asthma, acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), pneumonia, an infectious respiratory disease, a restrictive respiratory disease, or a pulmonary vascular disease.

52. The medical device of any one of claims 39-51 , wherein the respiratory condition of the subject comprises a deterioration or an improvement of a physiological condition of the subject.

53. The medical device of any one of claims 39-52, wherein the processor is further configured to: determine that the subject is receiving insufficient ventilation by analyzing the first airway parameter and the second airway parameter of the subject; anddetermine a rate, a pressure, or a volume of air predicted to provide sufficient ventilation to the subject.

54. The medical device of any one of claims 39-53, further comprising:a second sensor configured to detect a physiological parameter of the subject,S397-6031 PCT I PHYS0276PCT & MEDI-2778wherein the processor is configured to:determine that the subject is receiving insufficient ventilation by analyzing the physiological parameter; andin response to determining that the subject is receiving insufficient ventilation, determine a rate, a pressure, or a volume of air predicted to provide sufficient ventilation to the subject.

55. The medical device of claim 54, wherein the physiological parameter comprises a blood oxygen saturation, a blood pressure, a pulse rate, a transthoracic impedance, a carbon dioxide level in the airway, an oxygen level in the airway, or a nitrogen level in the airway.

56. A method, comprising:identifying a pressure of air and a volume of air outputted by a ventilation source into an airway of a subject;generating a first pressure-volume curve by analyzing the pressure of the air and the volume of the air corresponding to a first time interval;determining a first airway parameter by analyzing the first pressure-volume curve; generating a second pressure-volume curve by analyzing the pressure of the air and the volume of the air corresponding to a second time interval;determining a second airway parameter by analyzing the second pressure-volume curve; comparing the first airway parameter and the second airway parameter; andin response to comparing the first airway parameter and the second airway parameter, determining a respiratory condition of the subject.

57. The method of claim 56, wherein determining the first airway parameter comprises: determining a derivative of the first pressure-volume curve with respect to pressure or with respect to volume;determining a second derivative of the first pressure-volume curve with respect to pressure or with respect to volume; ordetermining an integral of the first pressure-volume curve with respect to pressure or with respect to volume 58. The method of claim 57, wherein the first airway parameter comprises:an upper inflection point of the first pressure-volume curve, a maximum value of the derivative of the first pressure-volume curve, or a maximum value of the second derivative of the first pressure-volume curve.

59. The method of claim 58, wherein the first airway parameter comprises:a pressure corresponding to the upper inflection point of the first pressure-volume curve, the maximum value of the derivative of the first pressure-volume curve, or the maximum value of the second derivative of the first pressure-volume curve.

60. The method of any one of claims 57-59, wherein the first airway parameter comprises:S397-6031 PCT I PHYS0276PCT & MEDI-2778a value at a zero-crossing of the second derivative of the first pressure-volume curve.

61. The method of any one of claims 57-60, wherein the first airway parameter comprises:a value of the first pressure-volume curve at a particular pressure, a value of the first pressure-volume curve at a particular volume, a value of the derivative of the first pressure-volume curve at a particular pressure, a value of the second derivative of the first pressure-volume curve at a particular pressure, a value of the integral of the first pressure-volume curve over a particular range of pressures, or a value of the integral of the first pressure-volume curve over a particular range of volumes.

62. The method of any one of claims 57-61 , wherein the first airway parameter comprises:a maximum-to-minimum range of the first pressure-volume curve, a maximum-to-minimum range of the derivative of the first pressure-volume curve, or a maximum-to-minimum range of the second derivative of the first pressure-volume curve.

63. The method of any one of claims 57-62, wherein the first airway parameter comprises:an area underneath a portion of the first pressure-volume curve, an area underneath a portion of the derivative of the first pressure-volume curve, or an area underneath a portion of the second derivative of the first pressure-volume curve.

64. The method of any one of claims 56-63, wherein the respiratory condition of the subject comprises asthma, acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), pneumonia, an infectious respiratory disease, a restrictive respiratory disease, or a pulmonary vascular disease.

65. The method of any one of claims 56-64, wherein the respiratory condition of the subject comprises a deterioration or an improvement of a physiological condition of the subject.

66. The method of any one of claims 56-65, further comprising:determining that the subject is receiving insufficient ventilation by analyzing the first airway parameter and the second airway parameter; anddetermining a rate, a pressure, or a volume of air predicted to provide sufficient ventilation to the subject.

67. The method of any one of claims 56-66, further comprising:in response to comparing the first airway parameter and the second airway parameter, identifying a treatment previously administered to the subject or a treatment being administered to the subject.

68. The method of claim 67, wherein the treatment comprises administration of:chest compressions to the subject; oralbuterol, epinephrine, budesonide, magnesium sulfate, dornase alpha, ipratropium bromide, etomidate, midazolam, propofol, thiopental, methylprednisolone, dexamethasone, or epinephrine to the subject.

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