Patent Description:
Ventilator systems, such as High Flow Nasal Therapy (HFNT) ventilator systems can be used to improve oxygenation of a user by introducing flows of oxygen rich air through a loose-fitting nasal cannula. A secondary effect of HFNT is that an increased level of expiratory pressure, such as a Positive End-Expiratory Pressure (PEEP) is created, which helps to increase removal of carbon dioxide from the user's airways and/or blood. Utilising the PEEP effect of HFNT could enable such ventilator systems to be used as an alternative to pressure support devices, such as Continuous Positive Airway Pressure (CPAP) and Biphasic Positive Airway Pressure (BiPAP) systems and other non-invasive ventilator systems. However, the lack of control over the level of expiratory pressure achieved by HFNT systems is currently limiting this use. In particular, when the user opens their mouth, the positive pressure is effectively lost. This complicates the task of accurately setting and controlling the PEEP, especially at night whilst the user is asleep.

<CIT> discloses a respiratory muscle training device, which applies a variable load the user so that varying respiratory muscle capabilities are taken into account. <CIT> discloses a ventilator which aims to deliver an air supply at a pressure equivalent to the average Intrinsic PEEP of the subject. <CIT> discloses a ventilator with a expiratory hole which is opened and closed by a valve. The valve is controlled based on a sensed pressure.

According to an aspect of the present disclosure, there is provided ventilator system, such as a High Flow Nasal Therapy, HFNT, system, comprising:
a mouthpiece, to be received within a user's mouth, wherein the mouthpiece comprises:.

The controller may be configured to determine a Positive End-Expiratory Pressure, PEEP, based on one or more pressure measurements from the pressure sensor. The controller may be configured to control: the flow rate and/or concentration of oxygen supplied through the nasal cannula; the total flow rate of air and oxygen supplied through the nasal cannula; and/or the flow area of the passage, based on the determined PEEP.

The ventilator system further comprises the nasal cannula for supplying a flow of air and/or oxygen to one or both nares of the user. Additionally the ventilator system further comprises:
an air and/or oxygen supplying apparatus configured to supply flows of air and/or oxygen to the nasal cannula. Flow rates and/or concentrations of the air and oxygen supplied by air and/or oxygen supplying apparatus are controllable.

The ventilator system may further comprise an oxygen saturation sensor configured to determine oxygen saturation of the user. For example, the oxygen saturation sensor may comprise one or more light-emitting diodes arranged to face a photodiode through a translucent part of the user's body. Additionally or alternatively, the controller may be configured to receive an oxygen saturation measurement. The controller may be configured to control: the flow rate and/or concentration of oxygen supplied through the nasal cannula; the total flow rate of air and oxygen supplied through the nasal cannula; and/or the flow area of the passage, based on the oxygen saturation. The oxygen saturation sensor may be mounted on the mouthpiece or on the nasal cannula.

The sensors may comprise a temperature sensor configured to measure a temperature of gases passing through the passage. The temperature sensor may be configured to measure the temperature of the gases repeatedly with a predetermined frequency. In this way, the temperature sensor may be configured to measure a temperature of gasses when the user is exhaling and when the user is not exhaling. The controller may be configured to control: a flow rate and/or concentration of oxygen supplied through the nasal cannula; a total flow rate of air and oxygen supplied through the nasal cannula; and/or the flow area of the passage, based on the measured temperature.

The sensors may comprise a capnogram configured to measure a partial pressure of carbon dioxide in gases passing through the passage. For example, the capnogram may comprise a source of infrared, such as an infrared light-emitting diode, arranged to pass infrared light through the gases passing through the passage, and an infrared sensor for measuring infrared light and determining a power of infrared light absorbed by the gases. The controller is configured to determine an end tidal carbon dioxide measurement based on measurements from the capnogram. Alternatively, the controller may be configured to receive an end tidal carbon dioxide measurement. The controller may be configured to control: a flow rate and/or concentration of oxygen supplied through the nasal cannula; a total flow rate of air and oxygen supplied through the nasal cannula; and/or the flow area of the passage, based on the measurement from the capnogram, such as the partial pressure of carbon dioxide and/or the end tidal carbon dioxide measurement, and/or based on the received end tidal carbon dioxide measurement.

The controller may be configured to determine a partial pressure of carbon dioxide within arterial blood of the user based on measurements from the capnogram. Alternatively, the controller may be configured to receive a determined partial pressure of carbon dioxide within arterial blood. The controller may be configured to control: a flow rate and/or concentration of oxygen supplied through the nasal cannula; a total flow rate of air and oxygen supplied through the nasal cannula; and/or the flow area of the passage, based on the determined partial pressure of carbon dioxide within the arterial blood.

The ventilator system may comprise a user input device. The controller may be configured to receive one or more input control parameters from the user or another user via the user input device. The controller may be configured to control: a flow rate and/or concentration of oxygen supplied through the nasal cannula; a total flow rate of air and oxygen supplied through the nasal cannula; and/or the flow area of the passage, based on the one or more input control parameters. The input control parameters may comprise: a target pressure, e.g. PEEP value, a target oxygen saturation value and/or a target value of partial pressure of carbon dioxide, e.g. partial pressure of carbon dioxide within the arterial blood of the user.

The controller may be configured to monitor measurements from the one or more sensors mounted on the mouthpiece. The controller may be further configured to control: a flow rate and/or concentration of oxygen supplied through the nasal cannula; a total flow rate of air and oxygen supplied through the nasal cannula; and/or the flow area of the passage, in order to maintain determined values of pressure, oxygen saturation and/or partial pressure of carbon dioxide within respective desirable ranges, e.g. within ranges greater than or equal to, less than or equal to, and/or within ranges defined by predetermined threshold differences from the respective target values. The desirable ranges may be determined based on respective target values defined by the input control parameters.

According to another aspect of the present disclosure, there is provided a mouthpiece for the above-mentioned ventilator system, wherein the mouthpiece is to be received within the user's mouth, wherein the mouthpiece comprises: a passage for permitting a flow of gases through the mouthpiece between a first side of the passage to be inside the user's mouth and a second side of the passage to be outside the user's mouth; a passage adjustment component for selectively adjusting a flow area of the passage; and one or more sensors mounted on the mouthpiece, wherein the sensors comprise a pressure sensor configured to measure a pressure at the first side of the passage.

According to another aspect of the present disclosure but not part of the claimed invention, there is provided a method of operating a ventilator system, wherein the ventilator system comprises: a nasal cannula for supplying a flow of air and/or oxygen to one or both nares of a user; a mouthpiece, to be received within the user's mouth, wherein the mouthpiece comprises: a passage for permitting a flow of gases through the mouthpiece between a first side of the passage to be inside the user's mouth and a second side of the passage to be outside the user's mouth; a passage adjustment component for selectively adjusting a flow area of the passage; and one or more sensors mounted on the mouthpiece, wherein the sensors comprise a pressure sensor configured to measure a pressure at the first side of the passage; and a controller configured to control the operation of the ventilator system, wherein the method comprises: determining a pressure measurement from the pressure sensor; and, based on the determined pressure measurement: controlling a flow rate and/or concentration of oxygen supplied through the nasal cannula; controlling a total flow rate of air and oxygen supplied through the nasal cannula; and/or controlling the flow area of the passage.

With reference to <FIG>, a ventilator system <NUM>, such as a High Flow Nasal Therapy (HFNT) system, according to arrangements of the present disclosure comprises a nasal cannula <NUM>, for supplying a flow of air and/or oxygen to one or both nares of a user, a mouthpiece <NUM>, to be received within the user's mouth, and a controller <NUM> for controlling the operation of the ventilator system <NUM>.

The ventilator system <NUM> further comprises an air and/or oxygen supplying apparatus <NUM> configured to supply flows of air and/or oxygen to the nasal cannula <NUM>. The air and/or oxygen supplying apparatus <NUM> may have a first inlet <NUM> configured to be coupled to a supply of air, e.g. high pressure air, such as a high pressure airline, e.g. provided at a hospital or other facility in which the ventilator system <NUM> is to be used, a cylinder containing pressurised air, or a mechanical flow generator.

The air and/or oxygen supplying apparatus <NUM> further comprises a second inlet <NUM> to be coupled to a supply of oxygen, e.g. high pressure oxygen, such as a high pressure oxygen-line, e.g. provided at a hospital or other facility in which the ventilator system <NUM> is to be used, a cylinder containing pressurised oxygen, or an oxygen concentrator.

The air and/or oxygen supplying apparatus <NUM> further comprises an outlet <NUM> to be coupled to the nasal cannula <NUM>. The air and/or oxygen supplying apparatus is configured to blend the air and oxygen received at the first and second inlets <NUM>, <NUM>, e.g. by adjusting the relative flow rate of air and oxygen output via the outlet <NUM>, and supply the blended air and/or oxygen to the nasal cannula <NUM> via the outlet <NUM>. The flow rates and/or concentrations of the air and oxygen supplied by the air and/or oxygen supplying apparatus may be controllable, e.g. by the controller <NUM>.

The air and/or oxygen supplying apparatus <NUM> may be configured to adjust a temperature and/or humidity of the air and/or oxygen supplied to the nasal cannula <NUM>, in order to improve the comfort of the user.

As depicted, the nasal cannula <NUM> may comprise a tube <NUM> coupled to the air and/or oxygen supplying apparatus <NUM> at a first end 112a of the tube. At a second end 112b, the tube <NUM> may be divided into two prongs 114a, 114b to be received within the nares of the user, so that the supply of air and/or oxygen can flow into the user's nose. The prongs 114a, 114b may be configured to engage the inside of the user's nares in order to create a seal between the prongs and the user's nares to prevent or reduce leakage of the supplied air and/or oxygen out of the user's nose.

As described in more detail below, the mouthpiece <NUM> comprises a passage <NUM> for permitting a flow of gases, such as air and/or oxygen from the nasal cannula that is not inhaled and exhaled gases, to pass through the mouthpiece <NUM> between a first side 202a of the passage the inside of the user's mouth and a second side 202b of the passage outside of the user's mouth when the mouthpiece is received within the user's mouth during use of the ventilator system <NUM>. The mouthpiece <NUM> further comprises a passage adjustment component <NUM> for selectively adjusting a flow area through the passage <NUM>.

The mouthpiece <NUM> further comprises one or more sensors <NUM> mounted on the mouthpiece. The sensors may comprise a pressure sensor <NUM> configured to measure a pressure at the first side of the passage or within the passage <NUM>. The pressure sensors <NUM> may thereby be configured to measure a pressure of air and other gases within the user's airway, e.g. within the user's mouth. The controller <NUM> may be configured to determine a Positive End-Expiratory Pressure (PEEP) of the user based on one or more pressure measurement made by the pressure sensor <NUM>.

As described in more detail below, the controller <NUM> is further configured to control the operation of the ventilator system <NUM> based on measurements from the one or more sensors <NUM>, such as based on pressure, e.g. the determined PEEP. The controller <NUM> may control a flow rate and/or concentration of oxygen supplied through the nasal cannula <NUM> based on measurements from the one or more sensors <NUM>. For example, the controller <NUM> may control the operation of the air and/or oxygen supplying apparatus <NUM> in order to control the flow rate and/or concentration of oxygen supplied to the nasal cannula <NUM>. Additionally or alternatively, the controller <NUM> may control the total flow rate of air and oxygen suppled though the nasal cannula <NUM> based on the measurements from the one or more sensors <NUM>. For example, the controller <NUM> may control the operation of the air and/or oxygen supplying apparatus <NUM> in order to control the total flow rate of air and oxygen suppled to the nasal cannula <NUM>. The controller <NUM> may be further configured to control the passage adjustment component <NUM> to selectively adjust the flow area of the passage <NUM> based on the measurements from the one or more sensors <NUM>, e.g. based on the pressured pressure or determined PEEP.

<FIG> illustrates the relationship between diameter of the passage and mean airway pressure of a user. As can be seen in <FIG>, mean airway pressure of the user increases as diameter of the passage decreased. For example, mean air pressure may be inversely proportion to the diameter of the passage.

In the arrangement shown in <FIG>, the controller <NUM> is separate from the mouthpiece <NUM>, nasal cannula <NUM> and the air and/or oxygen supplying apparatus <NUM>. However, in other arrangements, the controller <NUM>, or modules of the controller <NUM>, may be integrated into the mouthpiece <NUM>, nasal cannula <NUM> and/or the air and/or oxygen supplying apparatus <NUM>. For example, a plurality of circuits for performing the functions of the controller <NUM> described herein may be integrated into the mouthpiece <NUM>, nasal cannula <NUM> and/or the air and/or oxygen supplying apparatus <NUM>.

With reference to <FIG> and <FIG>, collectively referred to as <FIG>, the mouthpiece <NUM> may comprises a body part <NUM> to be received between the upper and lower teeth of the user. The mouthpiece <NUM> may further comprise an outer wall <NUM> extending at least partially around an outer periphery of the body part <NUM>. The outer wall <NUM> may projected upwardly relative to the body part <NUM> and may be shaped so that at least a portion of the outer wall <NUM> is positioned between the user's teeth and upper lip when the mouthpiece <NUM> is received within the user's mouth. The mouthpiece <NUM> may further comprise in inner wall <NUM> extending at least partially around an inner periphery of the body part <NUM>. The inner wall <NUM> may similarly project upwardly relative to the body part <NUM>, so that the inner and outer walls <NUM>, <NUM> together form an upper channel <NUM> between them, in which the user's upper teeth are received when the mouthpiece <NUM> is installed within the user's mouth. A bottom of the upper channel <NUM> may be formed by the body part <NUM>. In some arrangements, the outer wall <NUM> may additionally or alternatively project downwards relative to the body part <NUM>, and may be shaped so that at least a portion of the outer wall is positioned between the user's lower teeth and lower lip when the mouthpiece <NUM> is received within the user's mouth. In such arrangements, the inner wall <NUM> may similarly project downwards relative to the body portion in order to create a lower channel <NUM> for receiving the user's bottom teeth when the mouthpiece <NUM> is installed within the user's mouth.

As depicted in <FIG>, the passage <NUM> may be formed in the body part <NUM> and optionally the inner and/or outer walls <NUM>, <NUM>. The mouthpiece <NUM>, e.g. the body part <NUM>, may be sized and shaped so that when the mouthpiece is installed within the user's mouth and the user's mouth is closed, the passage <NUM> is substantially uncovered by the user's lips. In this way, the mouthpiece <NUM> may ensure that the user's is able to exhale, and optionally inhale, through the passage <NUM> whilst their mouth is closed when the mouthpiece <NUM> is installed.

In other arrangements, the mouthpiece <NUM> may be shaped in any other way such that the passage <NUM> is arranged to permit a flow of gases through the mouthpiece between the inside of the user's mouth and outside the user's mouth, and so that the user's mouth is otherwise substantially sealed when the mouthpiece is installed and, optionally, the user's mouth is closed.

As depicted in <FIG>, the passage adjustment component <NUM> may comprise a moveable element mounted on the mouthpiece <NUM>, which is configured to be selectively moved relative to the passage <NUM> in order to at least partially occlude the passage and thereby adjust a flow area through the passage. In the arrangement shown in <FIG>, the moveable element <NUM> has been moved such that the movable element is at least partially disposed within the passage <NUM>, or over an opening into the passage <NUM>, in order to reduce the flow area though the passage.

In other arrangements, the movable element <NUM> may be coupled to or configured to engage a wall of the passage <NUM> such that movement of the movable element can displace the wall of the passage and thereby adjust the flow area through the passage, e.g. by collapsing or opening the passage. The mouthpiece, e.g. the body part <NUM>, may comprise a resilient material and may be configured such that the passage <NUM> is biased into an open configuration when the wall is not being displaced by the movable element <NUM>. In other arrangements, the passage adjustment component <NUM> may be configured in any other way in order to permit the flow area of the passage to be selectively adjusted.

The ventilator system <NUM> may further comprise an oxygen saturation sensor <NUM>. The oxygen saturation sensor may be configured to measure an oxygen saturation (SpO<NUM>) of a user of the ventilator system <NUM>. As depicted in <FIG>, the oxygen saturation sensor <NUM> may be mounted on the mouthpiece <NUM>. In other words, the oxygen saturation sensor <NUM> may be one of the sensors <NUM> mentioned above. In the arrangement shown, the oxygen saturation sensor <NUM> comprises two or more light-emitting diodes 214a configured to emit light of two or more difference wavelengths. The two or more light-emitting diodes are arranged to face a photodiode 214b through a translucent part of the user's body, such as part of the user's upper or lower lip, when the ventilator system <NUM> is in use. The oxygen saturation sensor <NUM> may be configured to determine the oxygen saturation based on differences in the absorption of the different wavelengths of light.

In other arrangements, the oxygen saturation sensor <NUM> may be integrated into the nasal cannula <NUM>. For example, the light emitting diodes 214a of the oxygen saturation sensor may be arranged to pass light through user's skin around the user's nose, such as through one of the user's alae, to reach the photodiode 214b.

In still further arrangements, the oxygen saturation sensor <NUM> may be separate from the mouthpiece and the nasal cannula. For example, the oxygen saturation sensor <NUM> may comprise an oximeter to be attached to the user's finger or ear. In such arrangements, the oxygen saturation sensor <NUM> may be part of, or may be separate from, the ventilator system <NUM>.

The controller <NUM> may be configured to receive a measurement of an oxygen saturation, e.g. from the oxygen saturation sensor <NUM>, and control the operation of the ventilator system <NUM> based on the oxygen saturation. In particular, the controller <NUM> may be configured to control the flow rate and/or concentration of oxygen supplied through the nasal cannula <NUM>, the total flow rate of air and oxygen supplied through the nasal cannula and/or the flow area of the passage <NUM>, based on the received measurement of oxygen saturation.

The ventilator system <NUM> may further comprise one or more temperature sensors <NUM> configured to measure a temperature of gases passing through the passage <NUM>. As depicted in <FIG>, one or more of the temperature sensors <NUM> may be mounted on the mouthpiece <NUM>. In other words, one or more of the temperature sensor <NUM> may be ones of the sensors <NUM>.

The one or more temperature sensors <NUM> may be configured to measure the temperature of the gases passing through the passage <NUM> repeatedly with a predetermined frequency. For example, the temperature sensors <NUM> may be configured to measure the temperature of the gases once per second or twice per second. In this way, the temperature sensor may be configured to measure the temperature of gases when the user is exhaling and when the user is not exhaling, e.g. when the user is inhaling.

When the user is not exhaling, the gases passing through the passage <NUM> may be gases that have been delivered through the nasal cannula <NUM>. When the user is exhaling, the gases passing through the passage <NUM> may include exhaled gases from the user's lungs and airways. The exhaled gases may have a different, e.g. higher, temperature from the gases introduced though the nasal cannula <NUM>.

The controller <NUM> may be configured to determine when the user is inhaling and when the user is exhaling based on the temperature measurements from the one or more temperature sensors <NUM>. The controller <NUM> may be configured to control the operation of the ventilator system <NUM> based on the temperature measured by the temperature sensor <NUM>, or the determination when the user is inhaling and exhaling. In particular, the controller <NUM> may be configured to control the flow rate and/or concentration of oxygen supplied through the nasal cannula, the total flow rate of air and oxygen supplied through the nasal cannula and/or the passage adjustment component to selectively adjust the area of the passage, based on the temperature of gases passing through the passage. For example, when the user is inhaling and/or the temperature is at or below a threshold value, the flow rate and concentration of oxygen supplied through the nasal cannula and, optionally, the total flow rate of air and oxygen supplied through the nasal cannula may be greater than when the user is exhaling, or the temperature is below the threshold value, or another threshold value.

The ventilator system <NUM> may further comprise a capnogram <NUM> configured to measure a partial pressure of carbon dioxide in gases passing through the passage <NUM>. The capnogram <NUM> may be mounted on the mouthpiece <NUM>. In other words, the capnogram <NUM> may be one of the sensors <NUM> mentioned above. As depicted in <FIG>, the capnogram <NUM> may comprise a source of infrared light, such as an infrared light-emitting diode 218a, arranged to pass infrared light through the gases passing through the passage <NUM>, and an infrared sensor 218d, such as a photodiode, for measuring infrared light and determining a power of infrared light absorbed by the gases. The capnogram <NUM> may be configured to determine the partial pressure of carbon dioxide within the gases based on the power of infrared light absorbed by the gases.

The controller <NUM> may be configured to determine an end tidal carbon dioxide measurement based on measurements from the capnogram <NUM>, e.g. based on the partial pressure of carbon dioxide within the gases.

The controller <NUM> may be configured to control the operation of the ventilator system <NUM> based on the measured partial pressure of carbon dioxide in gases passing through the passage <NUM> and/or the end tidal carbon dioxide measurement. In particular, the controller may be configured to control the flow rate and/or concentration of oxygen supplied through the nasal cannula <NUM>, the total flow rate of air and oxygen supplied through the nasal cannula and/or the passage adjustment component <NUM> to selectively adjust the flow area of the passage <NUM>, based on the measured partial pressure of carbon dioxide in gases passing through the passage <NUM> and/or the end tidal carbon dioxide measurement.

Additionally or alternatively, the controller <NUM> may be configured to determine, e.g. estimate, a partial pressure of carbon dioxide within arterial blood of the user based on one or more measurements from the capnogram, or receive a determination of a partial pressure of carbon dioxide within arterial blood. In such arrangements, the controller <NUM> may be configured to control the operation of the ventilator system <NUM> based on the partial pressure of carbon dioxide within arterial blood. In particular, the controller may be configured to control the flow rate and/or concentration of oxygen supplied through the nasal cannula <NUM>, the total flow rate of air and oxygen supplied through the nasal cannula and/or the passage adjustment component to selectively adjust the area of the passage, based on the partial pressure of carbon dioxide within arterial blood.

In other arrangements, the controller <NUM> may be configured to receive a measurement of partial pressure of carbon dioxide, e.g. within arterial blood. For example, the controller may receive the measurement of partial pressure of carbon dioxide from a transcutaneous sensor, which may be included in or separate from the ventilator system <NUM>. The controller <NUM> may be configured to control the operation of the ventilator system <NUM> based on the received partial pressure measurement. In particular, the controller may be configured to control the flow rate and/or concentration of oxygen supplied through the nasal cannula <NUM>, the total flow rate of air and oxygen supplied through the nasal cannula and/or the passage adjustment component to selectively adjust the area of the passage, based on the received partial pressure measurement.

The ventilator system <NUM> may further comprise a user input device <NUM>, such as one or more switches, buttons, a touch screen, or any other device for receiving an input from the user or another user. As depicted in <FIG>, the user input device <NUM> may be provided on the controller <NUM>. In other arrangements, the user input device <NUM> may be provided on any other component of the ventilator system <NUM>. In some arrangements, the user input device <NUM> may be provided on a separate computing device, e.g. a portable computing device, such as a tablet computer or smartphone.

The controller <NUM> may be configured to receive one or more input control parameters from the user or another user via the user input device <NUM>. For example, the input control parameters may comprise a target pressure, e.g. PEEP, value, a target oxygen saturation value and/or a target value of partial pressure of carbon dioxide within arterial blood. The controller <NUM> may be configured to control the operation of the ventilator system <NUM> based on one or more of the target values input via the user input device. In particular, the controller may be configured to control the flow rate and/or concentration of oxygen supplied through the nasal cannula <NUM>, the total flow rate of air and oxygen supplied through the nasal cannula and/or the passage adjustment component to selectively adjust the area of the passage, based on the target values.

In one or more arrangements, the controller <NUM> may be configured to monitor measurements from the one or more sensors <NUM> and control the operation of the ventilator system <NUM> in order to maintain received and/or determined values of pressure, e.g. PEEP, oxygen saturation and/or partial pressure of carbon dioxide within arterial blood of the user at or close to the respective target values. The controller <NUM> may be configured to determine desirable ranges of the pressure, e.g. PEEP, oxygen saturation and/or partial pressure of carbon dioxide within arterial blood based on the target values. For example, the desirable ranges may be ranges greater than and optionally equal to, less than and optionally equal to, or within a threshold difference of the target value. The controller <NUM> may be configured to monitor measurements from the one or more sensors <NUM> and control the operation of the ventilator system <NUM> in order to maintain received and/or determined values of pressure, e.g. PEEP, oxygen saturation and/or partial pressure of carbon dioxide within arterial blood within the respective desirable ranges. The controller <NUM> may be configured to control the flow rate and/or concentration of oxygen supplied through the nasal cannula, the total flow rate of air or oxygen supplied through the nasal cannula and/or the passage adjustment component to selectively adjust the area of the passage in order to maintain received and/or determined values of pressure, e.g. PEEP, oxygen saturation and/or partial pressure of carbon dioxide within arterial blood within the respective desirable ranges.

With reference to <FIG>, a method <NUM> of operating a ventilator system, such as the ventilator system <NUM> comprises a first step <NUM>, in which a sensor measurement value is determined, e.g. from a sensor of the ventilator system, such as one of the sensors <NUM> mounted on the mouthpiece. For example, in the first step a pressure at the first side 202a of the passage <NUM>, e.g. a PEEP of the user, may be determined based on a pressure measurement from the pressure sensor <NUM> mounted on the mouthpiece <NUM>. Additionally or alternatively, in the first step <NUM>, an oxygen saturation of the user, an end tidal carbon dioxide measurement of the user and/or a partial pressure of carbon dioxide within arterial blood of the user may be determined or received by a controller performing the method <NUM>.

The method <NUM> further comprises a second step <NUM>, in which a flow rate and/or concentration of oxygen supplied through the nasal cannula of the ventilator system is controlled based on the sensor measurement value, such as the pressure, e.g. PEEP, oxygen saturation, end tidal carbon dioxide measurement and/or partial pressure of carbon dioxide within arterial blood.

Additionally or alternatively, the method may comprise a third step <NUM>, in which a total flow rate of air and oxygen supplied through the nasal cannula is controlled based on the sensor measurement value.

Additionally or alternatively again, the method <NUM> may comprise a fourth step <NUM>, in which the flow area of the passage is adjusted based on the sensor measurement value, e.g. by controlling the operation of the passage adjustment component.

<FIG> is a flow chart illustrating the operation of one arrangement of the ventilator system <NUM> described above. <FIG> illustrates the input of target values <NUM>, such as target values of pressure, e.g. PEEP <NUM>, oxygen saturation (SpO<NUM>) <NUM> and partial pressure of carbon dioxide (PaCO<NUM>) <NUM>, e.g. with the user's blood. The input target values <NUM> may be received from a user input device, such as the user input device <NUM>. <FIG> illustrates a control block <NUM> illustrating processing of the input target values and sensor measurements <NUM>, e.g. by the controller <NUM> of the ventilator system. <FIG> further illustrates output control parameters <NUM> of the controller <NUM> for controlling the operation of the ventilator system. In the arrangement shown in <FIG>, the output control parameters <NUM> comprise total flow rate of air and oxygen <NUM> supplied to the nasal cannula, flow rate of oxygen <NUM> supplied to the nasal cannula and flow area <NUM> of the passage <NUM> in the mouthpiece. At a sensors block <NUM>, sensors, e.g. the sensors <NUM> described above, are configured to measure pressure, e.g. PEEP, oxygen saturation of the user and the partial pressure of arterial blood. As illustrated in <FIG>, these sensor measurements <NUM> are provided to the controller <NUM> at control block <NUM>, and the controller <NUM> controls the operation of ventilator system <NUM> as described above, e.g. by generating the output control parameters <NUM>. As illustrated in <FIG>, the control block <NUM> and sensors block <NUM> and the connections between the two are configured to form a feedback loop which enables the operation of the ventilator system <NUM> to be monitored and controlled in order to maintain the sensor measurements <NUM> at desired values and/or within desired ranges, based on the target values <NUM>. In particular, the controller <NUM> may be configured, in the control block <NUM>, to generate the output control values so that the ventilators system is operated to maintain a difference between a determined PEEP and the target PEEP value <NUM> is less than a predetermined threshold, such that a determined oxygen saturation is greater than or equal to a target oxygen saturation value <NUM> and/or such that a determined partial pressure of carbon dioxide within arterial blood of the user is less than or equal to a target partial pressure value <NUM>.

<FIG>, collectively referred to as <FIG>, illustrate example variations of values of PEEP, oxygen saturation, partial pressure of carbon dioxide, total flow rate of air and oxygen supplied via the nasal cannula and orifice area, e.g. flow area of the passage <NUM>, respectively during operation of the ventilator system <NUM>, e.g. according to the method illustrated in <FIG>.

As illustrated in <FIG>, at time T<NUM> a measured value of pressure e.g. PEEP, may be outside of, e.g. below, a desirable pressure range, a measured value of oxygen saturation may be less than the target oxygen saturation value <NUM> and a measured value of partial pressure of carbon dioxide may be greater than the target partial pressure value <NUM>.

At time T<NUM>, the controller <NUM> controls the operation of the ventilator system <NUM> to reduce a flow area of the passage <NUM> in the mouthpiece and accordingly, between T<NUM> and T<NUM>, the pressure measurement increases to within the desirable pressure range and the measured oxygen saturation increased to a value greater than the target oxygen saturation value <NUM>. However, the partial pressure of carbon dioxide does remains greater than the target partial pressure value <NUM>.

In response measurement from the sensors, at time T<NUM>, the controller <NUM> controls the operation of the ventilator system <NUM> to increase the flow area of the passage <NUM> in the mouthpiece and accordingly, between T<NUM> and T<NUM>, the pressure measurement, the measured oxygen saturation value and the partial pressure of carbon dioxide reduce. As depicted, the value of pressure may be within the desirable range. However, the value of oxygen saturation and partial pressure of carbon dioxide may be below and above the corresponding target values respectively.

In response to measurement from the sensors, at time T<NUM>, the controller <NUM> controls the operation of the ventilator system <NUM> to increase a flow rate of oxygen supplied through the nasal cannula and a total flow rate of air and oxygen supplied though the nasal cannula. Accordingly, between T<NUM> and T<NUM>, the pressure measurement increases, remaining within the desirable pressure range, and the partial pressure of carbon dioxide reduces to below the target partial pressure value <NUM>. However, the measured oxygen saturation reduced further to a value less than the target oxygen saturation value <NUM>.

In response to the measurements from the sensors, at time T<NUM>, the controller <NUM> controls the operation of the ventilator system <NUM> to further increase the flow rate of oxygen supplied through the nasal cannula without changing the total flow rate of air and oxygen supplied through the nasal cannula, thereby increasing a concentration of oxygen supplied through the nasal cannula. Accordingly, between times T<NUM> and T<NUM>, the pressure measurement and partial pressure of carbon dioxide remain constant and the oxygen saturation value increases to above the target oxygen saturation value <NUM>. At time T<NUM> the values of pressure, e.g. PEEP, oxygen saturation and partial pressure of carbon dioxide are within the respective desirable ranges. Hence, the controller may continue operating the ventilator system <NUM> in this way and monitoring the values determined by the sensors until the measured values change.

In the example described above, the controller <NUM> is configured to control the flow area of the passage <NUM> in the mouthpiece, e.g. in order increase the pressure value and/or the oxygen saturation value, before controlling the flow rate of oxygen supplied through the nasal cannula and a total flow rate of air and oxygen supplied though the nasal cannula. However, in other arrangements, the controller may control the operation of the ventilator system differently, e.g. by changing the output control parameters from the controller in a different order and/or by changing two or more of the output control parameters simultaneously or substantially simultaneously.

Claim 1:
A ventilator system (<NUM>) comprising:
a nasal cannula for supplying a flow of air and/or oxygen (<NUM>) to one or both nares of the user;
an air and oxygen supplying apparatus (<NUM>) configured to supply flows of air and oxygen to the nasal cannula (<NUM>);
a mouthpiece (<NUM>), to be received within a user's mouth, wherein the mouthpiece comprises:
a passage (<NUM>) for permitting a flow of gases through the mouthpiece between a first side (202a) of the passage to be inside the user's mouth and a second side (202b) of the passage to be outside the user's mouth;
a passage adjustment component (<NUM>) for selectively adjusting a flow area of the passage (<NUM>); and
one or more sensors (<NUM>) mounted on the mouthpiece, wherein the sensors comprise a pressure sensor (<NUM>) configured to measure a pressure at the first side (202a) of the passage; and
a controller (<NUM>) configured to control, based on the pressure measured by the pressure sensor:
a flow rate and/or concentration of oxygen supplied to the user through the nasal cannula (<NUM>);
a total flow rate of air and oxygen supplied through the nasal cannula; and
the flow area of the passage.