Patent Description:
A patient dealing with respiratory illness, for example chronic obstructive pulmonary disease (COPD), can have difficulty engaging in effective respiration. This difficulty may be the result of a variety of physiological faults, including a breakdown of lung tissue, dysfunctions of the small airways, excessive accumulation of sputum, infection, genetic disorders, or cardiac insufficiency. With such illnesses, it is useful to provide the patient with a therapy that can improve the ventilation of the patient. In some situations, the patient can be provided with a respiratory therapy system that includes a gas source, an interface that may be used to transmit gas to an airway of a patient, and a conduit extending between the gas source and the interface. Gas delivered to an airway of the patient from the gas source can help to promote adequate ventilation of the patient. The gas source may, for example, be a container of air and/or another gas suitable for inspiration, for example, oxygen or nitric oxide, a mechanical blower capable of propelling a gas through the conduit to the interface, or some combination of both. The respiratory therapy system may include structure used to heat and/or humidify gases passing through the system to improve patient comfort and/or improve the prognosis of the patient's respiratory illness.

A patient suffering from respiratory conditions may benefit from reducing the volume of air that he inhales that does not take part in the normal gas exchange of oxygen (O<NUM>) and carbon dioxide (CO<NUM>). This volume of air is contributed to by anatomical dead space, which is gas that includes exhaled CO<NUM> captured in the patient's airways that is rebreathed upon inspiration. To reduce dead space, the patient can be treated with high flow therapy, which can involve the administration of gas to the airways of a patient at a relatively high flow rate and at a relatively low pressure. The high flow of gases reaching the patient's airways can be beneficial for flushing out the patient's airways, which can reduce the volume of anatomical dead space. High flow therapy is often delivered with an unsealed patient interface such as, for example, a nasal cannula.

<CIT> discloses a nasal cannula having a structure that allows for insufflation and monitoring of co2 in the exhaled breath. <CIT> discloses a dual lumen cannula. <CIT> discloses a divided cannula with each nare communicating with each flow path. <CIT> discloses several nasal and oral patient interfaces for co2 sampling and oxygen delivery. <CIT> discloses a breathing gas delivery system and method. <CIT> discloses an expiratory limb for a breathing circuit.

It is an object of certain embodiments disclosed herein to provide an improved or alternative system and method for respiratory therapy that might overcome or ameliorate problems with existing systems or methods, or at least provide the public with a useful choice.

The present invention provides a non-sealing patient interface in accordance with the claims.

Although high flow therapy may be useful for reducing the level of anatomical dead space in the airways of a patient, the level of dead space clearance may be limited by the flow rate of gases supplied to the patient and/or by the path taken by gases expelled from the patient's airways. For example, if the patient is receiving high flow therapy and is using a nasal cannula, if the patient's mouth is open, exhaled gases may travel up the airways and leave the patient's body through the mouth or through the nares. However, if the patient's mouth is closed, exhaled gases may leave the patient's body substantially through the nares. The level of anatomical dead space present if the patient's mouth is closed may be greater than the level of anatomical dead space present if the patient's mouth is open because the exhaled gases may be required to travel further along the patient's airways to escape the body. Additionally, for some patients, the respiratory effort necessary for inhalation and/or exhalation is difficult to meet. More respiratory effort may be required to force the exhaled gases from the nares relative to the respiratory effort required to force the exhaled gases from both the mouth and nares. This additional respiratory effort may be difficult to achieve for a patient with impaired respiratory function.

Thus, in accordance with certain features, aspects and advantages at least some of the arrangements disclosed herein, but not independently claimed, a respiratory therapy system is disclosed that provides additional and/or alternative anatomical dead space respiratory clearance assistance. The respiratory therapy system may comprise a non-sealed gas flow generating arrangement. A first gas passageway may be adapted to pneumatically link at least a part of the gas flow generating arrangement to an airway of the patient. A second gas passageway may be adapted to pneumatically link at least a part of the gas flow generating arrangement to an airway of the patient. The gas flow generating arrangement may be configured to simultaneously deliver gases at a positive flow rate through the first gas passageway and draw gases at a negative flow rate through the second gas passageway. The first gas passageway may be substantially pneumatically isolated from the second gas passageway. The negative flow rate can provide additional and/or alternative anatomical dead space clearance. The negative flow may provide additional clearance. The negative flow may allow for a reduction in positive flow without compromising the anatomical dead space clearance. This can provide greater physical comfort to a patient.

In some arrangements disclosed herein, not independently claimed, a respiratory therapy system is disclosed. The system has a positive gas flow source, a negative gas flow source, at least one gas passageway adapted to provide a non-sealed pneumatic link between an airway of a patient and the positive and negative gas flow sources, and a hardware controller which controls the positive gas flow source to deliver a positive flow of gas to a subject via the at least one gas passageway and control the negative gas flow source to provide a negative flow of gas configured to draw gas from the airway of a patient at a sufficient flow rate to reduce a concentration of an exhaled gas in a physiological dead space of a subject. In some embodiments, the positive gas flow source and the negative gas flow source are provided simultaneously. In some embodiments, the positive flow of gas comprises a rate of at least <NUM> liters per minute. In some embodiments, the positive flow of gas comprises a rate of about <NUM> liters per minute to about <NUM> liters per minute. In some embodiments, the negative flow of gas comprises a rate of at least <NUM> liters per minute. In some embodiments, the negative flow of gas comprises a rate that is at least <NUM>% of a rate of the positive flow of gas. In some embodiments, the system comprises a first gas passageway adapted to provide a non-sealed pneumatic link between an airway of a patient and the positive gas flow source and a second gas passageway adapted to provide a non-sealed pneumatic link between an airway of a patient and the negative gas flow source. In some embodiments, the first and second gas passageways are both in a single conduit. In some arrangements, the first gas passageway is in a first conduit and the second gas passageway is in a second conduit. In some arrangements, the first gas passageway interfaces with a first patient interface and the second gas passageway interfaces with a second patient interface. In some arrangements, the first patient interface is a nasal interface and the second patient interface is an oral interface, or wherein the first patient interface is an oral interface and the second patient interface is a nasal interface. In some embodiments, the first gas passageway and the second gas passageway interface with a patient interface that substantially maintains pneumatic isolation of the positive and negative flows of the first gas passageway and the second gas passageway. In some embodiments, the patient interface is a nasal cannula. In some embodiments, the nasal cannula comprises a first nasal prong and a second nasal prong, the first and second nasal prongs adapted to be fitted into the nares of the patient, and a manifold in pneumatic communication with the nasal prongs, the first gas passageway, and the second gas passageway. In some arrangements, a first side of the manifold accepts the first gas passageway, and wherein a second side of the manifold accepts the second gas passageway. In some embodiments, the first gas passageway extends into the first nasal prong and the second gas passageway extends into the second nasal prong. In some embodiments, both the first and second gas passageways extend into each of the first nasal prong and the second nasal prong. In some embodiments, both the first and second gas passageways enter the manifold on a single side of the manifold. In some embodiments, also includes a humidifier adapted to heat and/or humidify gases passing through the first gas passageway. In some embodiments, the system also has a transfer module configured to transfer moisture and/or heat from the second gas passageway to the first gas passageway. In some embodiments, the transfer module comprises a wick or absorbent material. In some embodiments, non-sealed pneumatic link comprises an occlusion of less than <NUM>% of the airway of the patient. In some embodiments, the non-sealed pneumatic link comprises an occlusion of less than <NUM>% of the airway of the patient. In some embodiments, the non-sealed pneumatic link comprises an occlusion of between <NUM>% and <NUM>% of the airway of the patient. In some embodiments, the airway is one or more of a nare or mouth. In some embodiments, the non-sealed pneumatic link delivers <NUM> or less of pressure per <NUM>/min of flow. In some embodiments, the non-sealed pneumatic link delivers <NUM> or less of pressure per <NUM>/min of flow.

A method of delivering gas to the airway of a subject in need thereof is also disclosed, but not independently claimed. The method improves the ventilation of a subject in need thereof, reducing the volume of anatomical dead space within the volume of the airway of a subject in need thereof, and/or treating a respiratory condition or a sleep disorder in a subject in need thereof. The method can include providing a positive gas flow source, delivering, using the positive gas flow source, a continuous flow of positive gas to the airway of a subject via at least one gas passageway adapted to provide a non-sealed pneumatic link between an airway of a patient and the positive gas flow source, providing a negative gas flow source, and drawing gas, using the negative gas flow source, from the airway of the subject at a flow rate sufficient to reduce a concentration of an exhaled gas in a physiological dead space of a subject's airways. In some embodiments, the delivering and the drawing are performed simultaneously. In some embodiments, the delivering the continuous flow of gas comprises delivering a positive flow of gas at a rate of at least <NUM> liters per minute. The delivering the continuous flow of gas may comprise delivering a positive flow of gas at a rate of at least <NUM> liters per minute. In some embodiments, drawing gas using the negative flow source comprises drawing gas at a rate of at least <NUM> liters per minute. Drawing gas using the negative flow source may comprise drawing gas at a rate of at least <NUM>% of a rate of the positive glow of gas. In some embodiments, gas is delivered to the airway of the subject through a first gas passageway and gas is drawn from the airway of the subject through a second gas passageway that is substantially pneumatically isolated from the first gas passageway. In some arrangements, the first and second gas passageways are pneumatically connected to one or more patient interfaces that substantially maintain the pneumatic isolation of the flow of gas in each passageway. In some embodiments, the first and second gas passageways are in separate conduits or a single conduit. In some arrangements, gas is delivered to the airway of the subject through a first patient interface and gas is drawn from the airway of the subject through a second patient interface. In some embodiments, gas is delivered to the airway of the subject through a first patient interface and gas is drawn from the airway of the subject through the same patient interface. In some arrangements, the first patient interface is a nasal interface and the second patient interface is an oral interface, or the first patient interface is an oral interface and the second patient interface is a nasal interface. In some embodiments, the first patient interface is a nasal interface. In some embodiments, the nasal interface is a nasal cannula. In some embodiments, the nasal cannula comprises a first nasal prong that delivers a continuous flow of gas to the airway and a second nasal prong that simultaneously draws gas from the airway. In some embodiments, the nasal cannula comprises a first nasal prong and a second nasal prong, each nasal prong delivering a continuous flow of gas to the airway and simultaneously drawing gas from the airway. The subject's mouth may be closed or sealed. The subject's mouth may be open. The gas pressure in the subject's airway may be measured. The gas pressure in the subject's airway may be maintained at a level of less than about <NUM> H<NUM>O, preferably at a level of less than about <NUM>, <NUM>, <NUM>, <NUM> or <NUM> H<NUM>O, preferably with the subject's mouth open or closed, preferably with the subject's mouth closed. The oxygen concentration of the subject's airway may be measured. The oxygen concentration of the subject's airway may be maintained at a substantially constant level or increased. The carbon dioxide concentration of the subject's airway may be measured. The carbon dioxide concentration of the subject's airway may be maintained at a substantially constant level or reduced. The molar fraction of carbon dioxide in the upper airway of the subject may be reduced by at least about <NUM> molar % compared to the molar fraction of carbon dioxide in the upper airway of the subject when breathing without assistance. The molar fraction of carbon dioxide in the upper airway of the subject may be reduced by at least about <NUM> molar % compared to nasal high flow therapy conducted at an equivalent flow rate when the subject's mouth is open. The molar fraction of carbon dioxide in the upper airway of the subject may be reduced by at least about <NUM> molar % compared to nasal high flow therapy conducted at an equivalent flow rate when the subject's mouth is closed. The peripheral capillary oxygen saturation of the subject may be measured. The peripheral capillary oxygen saturation of the subject may be maintained at a substantially constant level or increased. The peripheral capillary oxygen saturation of the subject may be increased compared to nasal high flow therapy conducted at an equivalent flow rate. In some embodiments, the non-sealed pneumatic link provides less than <NUM>% occlusion of the airway of the patient. In some embodiments, the non-sealed pneumatic link provides less than <NUM>% occlusion of the airway of the patient. In some embodiments, the non-sealed pneumatic link provides between <NUM>% and <NUM>% occlusion of the airway of the patient. In some embodiments, the airway is a nare. In some embodiments, the delivering delivers gas at <NUM> or less of pressure per <NUM>/min of flow. The delivering may deliver gas at <NUM> or less of pressure per <NUM>/min of flow. The subject may be hypoxic or hypoxemic or hypercapnic before the method is carried out. The respiratory condition may be chronic obstructive pulmonary disease, asthma, pneumonia, bronchitis, or emphysema. The sleep disorder may be obstructive sleep apnoea. In some arrangements, the method is carried out using a system of any one of the above embodiments or arrangements.

In some configurations, a gas flow generating arrangement is disclosed which may comprise a first flow generator adapted to deliver gases at a positive flow rate, and may comprise a second flow generator adapted to draw gases at a negative flow rate. In some configurations, the gas flow generating arrangement may comprise a single flow generator configured to simultaneously deliver gases through the first gas passageway and draw gases through the second gas passageway. The flow of gases can be provided using a non-sealed or non-occluded interface. In some such configurations, the flow generator may comprise a motor. The motor may comprise a shaft. The shaft may be coupled to a first impeller and a second impeller. The motor may cause the shaft to rotate, and the first and second impellers may rotate concurrently with the shaft. The first impeller may be substantially pneumatically isolated from the second impeller. In some configurations, the first impeller may have a first housing, and the second impeller may have a second housing. In some configurations, the first and second impellers may share a single housing having individual compartments for each of the first and second impellers. The compartments may be sealed or pneumatically isolated from one another through the use of an internal partition. The respiratory therapy system may be configured such that, in use, the motion of the first impeller may deliver gases through the first gas passageway, and such that, in use, the motion of the second impeller may draw gases through the second gas passageway and may guide the gases to a flow generator outlet.

In some configurations, the first gas passageway may be in a first conduit and the second gas passageway may be in a second conduit. In some configurations, the first and second gas passageways may lie in a single conduit. The conduit may comprise a first second and a second section. The first section may accommodate the first gas passageway and the second section may accommodate the second gas passageway. The first and second sections may be pneumatically isolated from one another. The conduit may comprise a barrier. The barrier may pneumatically isolate the first and second gas passageways.

In some configurations, the first gas passageway may interface with a first patient interface and the second gas passageway may interface with a second patient interface. In some such configurations, the first patient interface may comprise a nasal interface and the second patient interface may comprise an oral interface. In some such configurations, the first patient interface may comprise an oral interface and the second patient interface may comprise a nasal interface. One or both of the first patient interface and the second patient interface may comprise a non-sealing interface.

In some configurations, the first gas passageway and the second gas passageway may interface with a patient interface that may substantially maintain pneumatic isolation of the positive and negative flows of the first gas passageway and the second gas passageway. The patient interface may comprise a non-sealing interface. The non-sealing interface may comprise a nasal cannula. The nasal cannula may comprise a first nasal prong and may comprise a second nasal prong. The first and second nasal prongs may be adapted to be fitted into the nares of the patient. The nasal cannula may comprise a manifold that may be in pneumatic communication with the nasal prongs, the first gas passageway, and the second gas passageway. In some configurations, a first side of the manifold may accept the first gas passageway, and a second side of the manifold may accept the second gas passageway. In some configurations, both the first and second gas passageways may be pneumatically linked to a single side of the manifold. In some configurations, the first gas passageway may extend into the first nasal prong, and the second gas passageway may extend into the second nasal prong. In some configurations, both the first and second gas passageways may extend into each of the first nasal prong and the second nasal prong.

In some configurations, the respiratory therapy system may comprise a humidifier. The humidifier may be adapted to heat and/or humidify gases passing through the first gas passageway. The humidifier may be positioned in-line between the gas flow generating arrangement and an airway of the patient. In some configurations, the respiratory therapy system may comprise a transfer module. The transfer module may be used to remove moisture and/or heat from the second gas passageway, and may transfer this moisture and/or heat to the first gas passageway. In some such configurations, the transfer module may comprise a wick or absorbent material. The wick or absorbent material may extend between the first gas passageway and the second gas passageway. In some such configurations, the wick or absorbent material may be present in a patient interface, e.g. a nasal cannula. In some configurations, the wick or absorbent material may be a component of the gas flow generating arrangement.

In accordance with certain features, aspects and advantages of at least one of the arrangements disclosed herein, a method of delivering gas to the airway of a subject is also disclosed, but not independently claimed. The method may comprise delivering gas to the airway of a subject in need thereof, improving the ventilation of a subject in need thereof, reducing the volume of anatomical dead space within the volume of the airway of a subject in need thereof, and/or treating a respiratory condition or a sleep disorder in a subject in need thereof. The method may comprise.

In various embodiments gas may be delivered to the airway of the subject through a first gas passageway and gas may be drawn from the airway of the subject through a second gas passageway that is substantially pneumatically isolated from the first gas passageway. In various arrangements the first and second gas passageways may be pneumatically connected to one or more patient interfaces that substantially maintain the pneumatic isolation of the flow of gas in each passageway. In various embodiments the first and second gas passageways may be in a single conduit.

In various arrangements gas may be delivered to the airway of the subject through a first patient interface and gas may be drawn from the airway of the subject through a second patient interface. In various embodiments gas may be delivered to the airway of the subject through a first patient interface and gas may be drawn from the airway of the subject through the same patient interface. In various arrangements the first patient interface may be a nasal interface and the second patient interface may be an oral interface, or the first patient interface may be an oral interface and the second patient interface may be a nasal interface. In various embodiments the first patient interface is a nasal interface. In various embodiments the nasal interface may be a nasal cannula. In various embodiments the nasal cannula comprises a first nasal prong that delivers a continuous flow of gas to the airway and a second nasal prong that simultaneously draws gas from the airway, as described herein. In various arrangements the nasal cannula comprises a first nasal prong and a second nasal prong, each nasal prong delivering a continuous flow of gas to the airway and simultaneously drawing gas from the airway, as described herein. In various embodiments, a patient interface may comprise a non-sealing interface where no seal is formed at the nares and/or mouth of a subject.

The subject's mouth may be closed or sealed. The subject's mouth may be open.

The gas pressure in the subject's airway may be measured. The gas pressure in the subject's airway may be maintained at a level of less than about <NUM> H<NUM>O, preferably at a level of less than about <NUM>, <NUM>, <NUM>, <NUM> or <NUM> H<NUM>O, preferably with the subject's mouth open or closed, preferably with the subject's mouth closed.

The oxygen concentration of the subject's airway may be measured. The oxygen concentration of the subject's airway may be maintained at a substantially constant level or increased.

The carbon dioxide concentration of the subject's airway may be measured. The carbon dioxide concentration of the subject's airway may be maintained at a substantially constant level or reduced.

The molar fraction of carbon dioxide in the upper airway of the subject may be reduced by at least about <NUM> molar % compared to the molar fraction of carbon dioxide in the upper airway of the subject when breathing without assistance. The molar fraction of carbon dioxide in the upper airway of the subject may be reduced by at least about <NUM> molar % compared to nasal high flow therapy conducted at an equivalent flow rate when the subject's mouth is open. The molar fraction of carbon dioxide in the upper airway of the subject may be reduced by at least about <NUM> molar % compared to nasal high flow therapy conducted at an equivalent flow rate when the subject's mouth is closed.

The peripheral capillary oxygen saturation of the subject may be measured. The peripheral capillary oxygen saturation of the subject may be maintained at a substantially constant level or increased. The peripheral capillary oxygen saturation of the subject may be increased compared to nasal high flow therapy conducted at an equivalent flow rate.

The method may be carried out using a system for delivering and drawing gas that is not a closed system and is vented to the surrounding atmosphere.

The subject may be hypoxic or hypoxemic or hypercapnic before the method is carried out.

The respiratory condition may be chronic obstructive pulmonary disease, asthma, pneumonia, bronchitis, or emphysema.

The sleep disorder may be obstructive sleep apnoea.

The method may be carried out using a system described herein.

Specific embodiments and modifications thereof will become apparent to those skilled in the art from the detailed description herein having reference to the figures that follow, of which:.

Certain features, aspects and advantages of at least one of the configurations disclosed herein include the realization that a non-sealed respiratory therapy system may be configured such that a positive gas flow may be delivered to an airway of a patient and a negative gas flow may be drawn from an airway of a patient, wherein the respiratory therapy system may be configured to simultaneously generate both the positive and negative gas flows. `Positive flow,' 'positive gas flow,' `positive flow rate,' or other similar or derivative phrases as referenced in this disclosure may be interpreted to refer to gas flow that substantially progresses in a direction towards an airway of the patient. 'Negative flow,' 'negative gas flow,' 'negative flow rate,' or other similar or derivative phrases as referenced in this disclosure may be interpreted to refer to gas flow that substantially progresses in a direction away from an airway of the patient. 'Non-sealed,' 'unsealed,' 'non-occluded,' 'unoccluded,' or other similar or derivative phrases as referenced in this disclosure may be interpreted to refer to a system that allows for gas exchange with ambient air in order to provide high flow rates at relatively low pressures. A further explanation of such a system is provided below.

With reference to <FIG>, a configuration for a respiratory therapy system <NUM> is shown. In the illustrated configuration, the respiratory therapy system <NUM> may comprise a gas flow generating arrangement <NUM>. The gas flow generating arrangement <NUM> may be configured to generate a positive gas flow and a negative gas flow. The gas flow generating arrangement <NUM> may be configured to simultaneously generate a positive gas flow and a negative gas flow. The gas flow generating arrangement <NUM> may comprise a first flow generator <NUM> configured to generate a positive flow. The first flow generator <NUM> may comprise a first gas inlet <NUM> and a first gas outlet <NUM>. The first flow generator <NUM> may comprise a first blower <NUM>. The first blower <NUM> may comprise a motor. The motor may comprise a stator and a rotor. The rotor may comprise a shaft. An impeller may be linked to the shaft. In use, the impeller may rotate concurrently with the shaft to draw in gas from the first gas inlet <NUM>. The first flow generator <NUM> may comprise a user interface <NUM>, which may comprise one or more buttons, knobs, dials, switches, levers, touch screens, speakers, displays, and/or other input or output modules that a user might use to input commands into the first flow generator <NUM> to view data and/or control its operation and/or the operation of other aspects of the respiratory therapy system <NUM>. Operation of the first flow generator <NUM> may result in the generation of a positive flow of gas that may exit the first flow generator <NUM> through the first gas outlet <NUM>. The gas may move along a first gas passageway <NUM> that may extend from the first flow generator <NUM> to an airway of the patient. The first gas passageway <NUM> may be in a first conduit <NUM>. Optionally, a humidifier <NUM> may be located along the first gas passageway <NUM>. The humidifier <NUM> may comprise a humidifier inlet <NUM> and a humidifier outlet <NUM>. The humidifier <NUM> may comprise water or another moisturizing agent (hereinafter referred to as water). The humidifier <NUM> may comprise a heating element (not shown). The heating element may be used to heat the water in the humidifier <NUM> to encourage water vaporization and/or entrainment in the gas flow and/or increase the temperature and/or humidity of gases passing through the humidifier <NUM>. The humidifier <NUM> may comprise a user interface <NUM> which may comprise one or more buttons, knobs, dials, switches, levers, touch screens, speakers, displays and/or other input or output modules that a user might use to input commands into the humidifier <NUM> to view data and/or control its operation and/or the operation of other aspects of the respiratory therapy system <NUM>. The first conduit <NUM> may comprise a heater. The heater may be used to add heat to gases passing through the first conduit <NUM>. The heat may prevent the condensation of water entrained in the gas stream along a wall of the first conduit <NUM>. This heat may be useful if, for example, the humidifier <NUM> is utilized. The heater may comprise one or more resistive wires located in, on, around or near a wall of the first conduit <NUM>. Gas passing through the first gas passageway <NUM> may be passed to a patient interface <NUM>. The patient interface <NUM> may comprise a non-sealing interface. As demonstrated in <FIG>, the patient interface <NUM> may comprise a nasal cannula. However, the patient interface <NUM> may comprise other interfaces, including but not limited to nasal mask, an oral mask, an oro-nasal mask, a full face mask, a nasal pillows mask, a nasal cannula, an endotracheal tube, a nasogastric tube, a combination of the above or some other gas conveying apparatus or system.

A sealed nasal interface is an interface which substantially occludes a respiratory opening of a patient, such as one or more nares and/or the mouth such that either or both of inhalation and/or exhalation are forced through the cannula. The pressure of gasses delivered to a patient in a sealed system is substantially different than a non-sealed system, and thus the air flow dynamics are substantially different between the two systems such that the considerations applicable in a sealed system do not apply to a non-sealed system. Moreover, sealed systems are used for different types of patients suffering different types of respiratory problems than a non-sealed system.

For example, <CIT> (the '<NUM> patent) describes a high pressure / high flow rate sealed interface system. <NUM>, lines <NUM>-<NUM> of the '<NUM> patent describes creating a peak gas flow rate at the gas delivery device <NUM> (for example, a mask), of <NUM>/min by providing a pressure of about <NUM> H2O. This type of high pressure / high flow system that includes gas pressures in the realm of <NUM>-<NUM>, can be useful for ventilated patients when delivered for short periods of time, for example during recruitment manoeuvres, but can be dangerous when delivered for anything longer than short periods of time. Moreover, sealed systems force can for exhaled gas back into the patient's lungs as opposed to flushing the exhaled air. Such systems, although useful for certain types of clinical situations, are not useable for prolonged administration.

High flow therapy, including nasal high flow therapy, is generally provided using a non-sealed or non-occlusive system in order to allow for a large flow of gases without an associated significant increase in pressure. For example, for nasal high flow therapy using an adult non-occlusive cannula delivering flows of <NUM>, <NUM> and <NUM>/min of humidified oxygen can generate nasopharyngeal mean gas pressures of about <NUM>, <NUM>, and <NUM> respectively. This is roughly about <NUM> litres of flow per <NUM> pressure. In a sealed or occluded system, the gas pressure for a given flow increases rapidly as the occlusion of the area of the orifice, such as a nare, becomes quite high, for example, at around <NUM>-<NUM>% occlusion of the oriface. A non-sealed interface, on the other hand, would generate, for example, about <NUM> or less of pressure per <NUM>-<NUM>/min of flow.

A non-sealing nasal prong is generally designed to provide less than <NUM>% occlusion of the nares, and preferably less than <NUM>% occlusion of the nares. The actual size and shape of the nasal prongs depends greatly on nare size of the patient. For example, pediatric nasal cannula prongs will be significantly smaller in size than adult nasal cannula prongs, despite providing an equivalent amount of occlusion in the nares. In some embodiments, the nasal prong is designed to provide only about <NUM>-<NUM>% occlusion to account for potential deformation of a prong against the inner surface of the nare. This much smaller occlusion design is particularly useful for neonate designs, but is still applicable to pediatric and adult designs as well. In an embodiment, the nasal prong in an adult non-occlusive nasal cannula is about <NUM> in diameter. In other embodiment, the diameter of nasal cannula can range from about <NUM> in diameter to about <NUM> in diameter, depending on the size and shape of the nasal passages of the patient. Similar non-sealing considerations are also applicable to masks that cover the mouth and masks that cover both the mouth and nose as would be understood by a person of skill in the art from the present disclosure.

With further reference to <FIG>, the respiratory therapy system <NUM> may comprise a second flow generator <NUM>. The second flow generator <NUM> may comprise a second inlet <NUM> and a second outlet <NUM>. Likewise, the second flow generator <NUM> may comprise a second blower <NUM> that may comprise a motor. The motor may comprise a stator and a rotor. The rotor may comprise a shaft. An impeller may be linked to the shaft. In use, the impeller may rotate concurrently with the shaft to draw in gas from the second gas inlet <NUM>. The second flow generator <NUM> may comprise a user interface <NUM> which may comprise one or more buttons, knobs, dials, switches, levers, touch screens, speakers, displays and/or other input or output modules that a user might use to input commands into the second flow generator <NUM> to view data and/or control its operation and/or the operation of other aspects of the respiratory therapy system <NUM>. Operation of the second flow generator <NUM> may result in the generation of a negative flow of gas that may move from an airway of a patient and through a second gas passageway <NUM>. The first gas passageway <NUM> and the second gas passageway <NUM> may be substantially pneumatically isolated from one another. The negative flow of gas may pass through the same interface <NUM> or a different patient interface. The second gas passageway <NUM> may be in a second conduit <NUM>. The airway of the patient that is pneumatically linked to the second gas passageway <NUM> may be the same airway that is pneumatically linked to the first gas passageway <NUM>, or may be a different airway than the airway that is pneumatically linked to the first gas passageway <NUM>. For example, if the airways are different, the first gas passageway <NUM> may be pneumatically linked to a nasal airway and the second gas passageway <NUM> may be pneumatically linked to an oral airway, or alternatively the first gas passageway <NUM> may be pneumatically linked to an oral airway and the second gas passageway <NUM> may be pneumatically linked to a nasal airway. Operation of the second flow generator <NUM> may result in the generation of a negative flow of gas that may pass from an airway of the patient, pass through the second gas passageway <NUM>, through the second gas inlet <NUM>, and out the second gas outlet <NUM>.

In the illustrated configuration, and as implied above, the respiratory therapy system <NUM> may operate as follows. Gas may be drawn into the first flow generator <NUM> through the first gas inlet <NUM> due to the rotation of an impeller of the motor of the first blower <NUM>. Gas may then pass out of the first gas outlet <NUM> at a positive flow rate and through the first gas passageway <NUM>, which may be in a first conduit <NUM>. The gas may enter the humidifier <NUM> through the humidifier inlet <NUM>. The humidifier <NUM> may be located along the first gas passageway <NUM> between the first flow generator <NUM> and an airway of the patient. Once in the humidifier <NUM>, the gas may pick up moisture. Water in the humidifier <NUM> may be heated by the heating element, which may aid in the humidification and/or heating of the gas passing through the humidifier <NUM>. The gas may then leave the humidifier <NUM> through the humidifier outlet <NUM> and progress further through the first gas passageway <NUM>. Gas may then be passed to an airway of the patient, where it may be taken into a patient airway to aid in the treatment of a respiratory disorder. The gas may pass through a patient interface <NUM> on its way to the airway, which may be a nasal cannula. Preferably simultaneously, the second flow generator <NUM> may draw gases at a negative flow rate out of an airway of the patient and through the second gas passageway <NUM>, which may be in a second conduit <NUM>. The gases may be drawn through the second inlet <NUM> of the second flow generator <NUM> and out the second outlet <NUM>. The airway in pneumatic communication with the second gas passageway <NUM> may be the same airway as the airway in pneumatic communication with the first gas passageway <NUM>, and gases moving between the patient airway and the second flow generator <NUM> may pass through a patient interface, which may be the same patient interface <NUM> in pneumatic communication with the first gas passageway <NUM>.

The negative flow provides for additional or alternative anatomical dead space clearance. Positive high flow therapy significantly reduces CO<NUM> build up in anatomical dead spaces of the patient. Negative flow can also provide additional anatomical dead space clearance. When used together, a combination of positive and negative flow in a high flow therapy system provides for a greater reduction in CO<NUM> in the anatomical dead spaces of a patient then just using positive flow. In addition, negative flow can be used to reduce the positive flow rate required to achieve a desired level of anatomical dead space clearance. For example, a certain positive flow rate used to provide a certain level of anatomical dead space clearance can be reduced by using a combination of positive and negative flow in order to achieve the same level of clearance. A lower positive flow rate, in some situations, can reduce patient discomfort that can occur from higher flow rates in a high flow therapy system.

Referring again to <FIG>, it should be understood that the illustrated configuration should not be taken to be limiting, and that many other configurations for the respiratory therapy system <NUM> are possible. In some configurations, the first flow generator <NUM> may, for example, comprise a source or container of compressed gas (for example, air). The container may comprise a valve that may be adjusted to control the flow of gas leaving the container. In some configurations, the first flow generator <NUM> may use such a source of compressed gas and/or another gas source in lieu of the first blower <NUM>. In some configurations, the first blower <NUM> may be used in conjunction with another gas source. In some configurations, the first flow generator <NUM> may draw in atmospheric gases through the first gas inlet <NUM>. In some configurations, the first flow generator <NUM> may be adapted to both draw in atmospheric gases through the first gas inlet <NUM> and accept other gases (for example, oxygen, nitric oxide, carbon dioxide, etc.) through the same first gas inlet <NUM> or a different gas inlet. In some configurations, the first flow generator <NUM> and the second flow generator <NUM> may have individual housings or may share a single housing <NUM>. In some configurations, the first flow generator <NUM> and the humidifier <NUM>, if present, may share a single housing <NUM>. In some configurations, the first flow generator <NUM>, the second flow generator <NUM>, and the humidifier <NUM> may all share a single housing. In some configurations, the respiratory therapy system <NUM> may comprise a single user interface located on the first flow generator <NUM>, the second flow generator <NUM>, the humidifier <NUM>, the patient interface <NUM>, or another component of the respiratory therapy system <NUM>. In some configurations, the operation of components of the respiratory therapy system <NUM> may be actuated wirelessly using a user interface located on a remote computing device, which may be a tablet, a mobile phone, a personal digital assistant, or another computing device. In some configurations, the operation of the first flow generator <NUM>, of the second flow generator <NUM>, of the humidifier <NUM>, or of other components or aspects of the respiratory therapy system <NUM> may be controlled by a controller. The controller may comprise a microprocessor. The controller may be located in or on the first flow generator <NUM>, the second flow generator <NUM>, the humidifier <NUM>, or other components of the respiratory therapy system <NUM> or on a remote computing device. In some configurations, multiple controllers may be used. In some configurations, the respiratory therapy system <NUM> may comprise one or more sensors for detecting various characteristics of gases in the respiratory therapy system <NUM>, including pressure, flow rate, temperature, absolute humidity, relative humidity, enthalpy, oxygen concentration, breath composition and/or carbon dioxide concentration, or one or more sensors for detecting various characteristics of the patient or of the health of the patient, including heart rate, EEG signal, EKG/ECG signal, blood oxygen concentration, blood CO<NUM> concentration, and blood glucose. One or more of the sensors may be used to aid in the control of components of the respiratory therapy system <NUM> through the use of a closed or open loop control system. In some configurations, there may be no user interface or a minimal user interface for components of the respiratory therapy system <NUM>. In some such configurations, the respiratory therapy system <NUM> may utilize a sensor to determine if the patient is attempting to use the respiratory therapy system <NUM> and automatically operate (e.g., the first flow generator <NUM> may generate a positive flow, the second flow generator <NUM> may generate a negative flow, the humidifier <NUM> may humidify gases, etc) according to one or more predetermined parameters if data obtained from the sensor indicates that the patient is attempting to use the respiratory therapy system <NUM>. In some configurations, preferably, the first flow generator <NUM> may generate a positive flow of gas and the second flow generator <NUM> may simultaneously generate a negative flow of gas. In some configurations, the first flow generator <NUM> and the second flow generator <NUM> may be actuated at different times. For example, in some configurations, the first flow generator <NUM> may be configured to generate a positive flow of gas while the patient is inhaling, and the second flow generator <NUM> may be configured to generate a negative flow of gas while the patient is exhaling. The first flow generator <NUM> and/or the second flow generator <NUM> may be configured to generate pulsed positive and/or negative flows at frequencies that may be equal to, higher or lower than the patient's rate of respiration.

In some configurations, the first flow generator <NUM> and/or the second flow generator <NUM> may be configured to alternatively generate positive and negative flows. For example, the first flow generator <NUM> may be switchable between a positive flow mode and a negative flow mode, and likewise the second flow generator <NUM> may be switchable between a positive flow mode and a negative flow mode. Thus, in some such configurations, two separate positive flows or two separate negative flows may be administered to one or more airways of a patient. Furthermore, it should be understood that in some configurations the flows for the first flow generator <NUM> and/or the second flow generator <NUM> may be adjustable. For example, in some configurations, the first flow generator <NUM> may generate a positive gas flow at rates of about <NUM> to about <NUM>/minute, or about <NUM> to about <NUM>/minute. Similarly, the second flow generator <NUM> may generate a negative gas flow at rates of about <NUM> to about <NUM>/minute, or about <NUM> to about <NUM>/minute. In some configurations, the ranges of deliverable gas flow rate for each flow generator may encompass both positive and negative flow rates. For example, one or both of the flow generators may generate gas flows at rates of about -<NUM> to +<NUM>/minute (where -<NUM>/minute implies generation of a negative flow of <NUM>/minute and +<NUM>/minute implies generation of a positive flow of <NUM>/minute). In some configurations, the gas flow generation arrangement <NUM> may be configured in such a way that the positive flow rate is set to a function of the negative flow rate, e.g., the positive flow rate may be set to a value that is <NUM> times greater than the negative flow rate. In some configurations, if desired, one of the flow generators may be temporarily deactivated and gas therapy may proceed with only one of the flow generators active. In some configurations, the on/off state of one or more of the flow generators or the flow rates generated by one or more of the flow generators may be adjusted according to a function of one or more characteristics of the gases in the respiratory therapy system <NUM>, of the patient, or of the health of the patient. The characteristics may include some or all of the characteristics listed above. In some such configurations, the adjustment may occur automatically. In some such configurations, the respiratory therapy system <NUM> may instead suggest adjustments (for example, through a user interface) that may be selected or confirmed by a user of the respiratory therapy system. In some configurations, more than one flow generator may be utilized to generate a positive flow or to generate a negative flow. In some configurations, a flow generator may be used together with a single gas passageway, where the flow generator may be configured to alternatively generate positive and negative flows. The delivery of positive and negative flows may be synchronized with the patient's respiratory cycle. For example, the flow generator may generate a positive flow during at least a portion of an inspiratory period and may generate a negative flow during at least a portion of an expiratory period.

Attention is given towards various configurations of the respiratory therapy system <NUM> where a patient interface <NUM> in pneumatic communication with a nasal airway of the patient is used. The patient interface <NUM> may be a nasal cannula <NUM>. <FIG> demonstrate various configurations in which a nasal cannula <NUM> is used with the respiratory therapy system <NUM>, wherein <FIG> illustrate embodiments of the present invention. It should be understood that the nasal cannula illustrated should not be taken to be limiting, and that other cannula configurations may be utilized. For example, in some configurations, a nasal cannula with two left prongs and one right prong may be used, and/or the prongs used may have different lengths, and/or the prongs may have different orientations (for example, one prong may at least partially extend up along an internal surface of a nare and another prong may not substantially extend along an internal surface of a nare). <FIG> illustrates a nasal cannula <NUM> comprising a pronged section <NUM> and a manifold <NUM>. The pronged section <NUM> may comprise a first nasal prong 134A and a second nasal prong 134B. A barrier <NUM> may be used to substantially pneumatically isolate sections of the nasal cannula <NUM>. Gases passing through the first gas passageway <NUM> may enter the nasal cannula <NUM> through a side of the manifold <NUM> and enter the nasal airway of the patient through the first nasal prong 134A. Gases may also be drawn out of the nasal airway of the patient through the second nasal prong 134B and leave another side of the manifold <NUM> through the second gas passageway <NUM>. The barrier <NUM> may aid in substantially pneumatically isolating the positive gas flow moving through the first nasal prong 134A and the negative gas flow moving through the second nasal prong 134B.

Although the configuration illustrated in <FIG> shows that the first gas passageway <NUM> and the second gas passageway <NUM> may be pneumatically linked to different sides of the manifold <NUM>, the sides being roughly perpendicular to the nasal prongs 134A, 134B of the pronged section <NUM>, other configurations are possible. <FIG> demonstrates that the first gas passageway <NUM> and the second gas passageway <NUM> may interface with the nasal cannula <NUM> on a single side of the manifold <NUM>. According to the present invention, the first and second gas passageways <NUM>, <NUM> interface with the manifold <NUM> on a side that is roughly coaxial with the nasal prongs 134A, 134B of the pronged section <NUM> of the nasal cannula <NUM>. Additionally, <FIG> may demonstrate that the first and second gas passageways <NUM>, <NUM> may be in a single conduit. The conduit may comprise the same barrier <NUM> or another partition that may substantially pneumatically isolate the first and second gas passageways <NUM>, <NUM>. <FIG> may demonstrate that the first and second gas passageways <NUM>, <NUM> may be in different conduits that may interface with the same side of the manifold <NUM>. It is to be understood that the cannula examples disclosed in the present disclosure describe non-sealing interfaces as explained above. Thus, for example, the prongs 134A and/or 134B are designed such that they provide less than <NUM>% occlusion of the nares, less than <NUM>% occlusion or about <NUM>%-<NUM>% occlusion of the nares as explained above in greater detail.

Advantageously, in some configurations, the respiratory therapy system <NUM> in combination with the nasal cannula <NUM> may be configured such that both positive and negative flows may be delivered/drawn with each prong 134A, 134B of the pronged section <NUM> of the nasal cannula <NUM>. Similarly, preferably but not necessarily, the positive and negative flows may be administered simultaneously. The administration of both positive and negative flows in each prong 134A, 134B of the nasal cannula <NUM> may be more comfortable and/or more effective relative to administering a positive flow in the first prong 134A and a negative flow in the second prong 134B. As seen in <FIG>, the first and second gas passageways <NUM>, <NUM> may be received in a single conduit interfacing with the manifold <NUM> that may split the positive and negative flows using a pair of barriers 138A, 138B that may extend into the prongs 134A, 134B. The flows may be split in such a way that both prongs 134A, 134B are pneumatically linked with both the positive and negative flows. <FIG> demonstrate that the positive and negative flows may move in/out of the nasal cannula <NUM> from a single side of the manifold <NUM>. While <FIG> demonstrates that a pair of barriers 138A, 138B may be used to split the flows, <FIG> illustrates that the first gas passageway <NUM> (and barrier <NUM>) may be split at or near the manifold <NUM> into two compartments such that positive flow moving through the first gas passageway <NUM> may move into both nasal prongs 134A, 134B of the nasal cannula <NUM>. Negative flow may be drawn out of the patient airway and through the second gas passageway <NUM> through the sections of the prongs 134A, 134B that are not being utilized to deliver positive flow to the patient airway. For example, the second gas passageway <NUM> and the nasal cannula <NUM> may be configured such that the negative flow of gas passes under or around the compartments that carry the positive flow of gas. Similarly, <FIG> demonstrates that the first and second gas passageways <NUM>, <NUM> may interface with the manifold <NUM> of the nasal cannula <NUM> on different sides of the manifold <NUM> (e.g. on opposing sides of the manifold <NUM> roughly perpendicular to the prongs 134A, 134B). <FIG> demonstrates that each of the first gas passageway <NUM> and the second gas passageway <NUM> may be divided into compartments using, for example, the barriers 138A, 138B to deliver/draw the positive and negative flows through the nasal prongs 134A, 134B. <FIG> demonstrates that the first and second gas passageways <NUM>, <NUM> may enter the manifold <NUM> of the nasal cannula <NUM> through a single side of the manifold <NUM>, where the single side may be roughly perpendicular to the nasal prongs 134A, 134B of the nasal cannula <NUM>. It should be understood that more than one of each of the positive and negative gas flows may be delivered to one or more airways of the patient (e.g. fed into each prong of the nasal cannula <NUM>). For example, in some configurations, two negative gas flows and one positive gas flow may be used in a prong of the nasal cannula <NUM>, or two negative gas flows and two positive gas flows may be used in a prong of the nasal cannula <NUM>. Additionally, it should be understood that, in some configurations, the pronged section <NUM> may comprise only one prong adapted to be fitted into a single nare of the patient. In some configurations, the pronged section <NUM> may comprise more than two prongs. In some such configurations, more than one prong may be fitted into a single nare of the patient. In some configurations, one prong is larger and/or taller than the other prong. In any of the above nasal cannula <NUM> configurations, the positive and negative flows may be fixed or variable as implied above. Moreover, in some configurations, if more than one positive or more than one negative flow is utilized, the flow rate of each positive or negative flow may be adjusted (e.g., through a valve arrangement or some other means).

In some configurations, moisture and/or heat may be removed from the negative flow of the second gas passageway <NUM> and added to the positive flow of the first gas passageway <NUM>. In some such configurations, the nasal cannula <NUM> may comprise a transfer module <NUM>. The transfer module <NUM> may be configured to aid in transferring heat and/or moisture from the negative flow (e.g. from the second gas passageway <NUM>) to the positive flow (e.g. to the first gas passageway <NUM>). The transfer module <NUM> may comprise a wick or absorbent material (hereinafter referred to as a wick). The wick may comprise, for example, natural or artificial sponge, melamine foam, metal (e.g. sodium) polyacrylates, calcium chloride, or other materials exhibiting a relatively high capacity for retaining and/or transferring heat and/or moisture. The wick may comprise anti-pathogenic materials or additives such as silver or zinc-based substances. The transfer module <NUM> may be positioned such that it extends between the first gas passageway <NUM> and the second gas passageway <NUM>. Preferably, the transfer module <NUM> may act as a seal between the first gas passageway <NUM> and the second gas passageway <NUM>, or may substantially prevent pneumatic communication between the first gas passageway <NUM> and the second gas passageway <NUM>. <FIG> illustrates a nasal cannula <NUM> configuration in which a transfer module <NUM> is placed. The transfer module <NUM> be used to remove heat and/or moisture from exhaled/drawn gases passing through the second nasal prong 134B and through the second gas passageway <NUM>. The heat and/or moisture may then be transferred across the transfer module <NUM> such that the heat and/or moisture may be entrained in the flow of gases passing through the first gas passageway <NUM> and into the first nasal prong 134A. <FIG> illustrates a nasal cannula <NUM> configuration in which nasal prong 134A is longer than nasal prong 134B. <FIG> illustrates a nasal cannula <NUM> in which the nasal prong 134B is removed, providing only an opening centered about the opening of the nare with negative flow. <FIG> illustrates a nose <NUM> with nares <NUM>. The prongs 134A and 134B of cannula <NUM> are designed, as described above, to be non-sealing such that an exchange of air can occur at the point where the prongs 134A and 134B interact with the nares <NUM>. This allows for a release of pressure such that a pressure build-up, either from positive or negative flow does not occur.

Other configurations for respiratory therapy systems capable of simultaneously delivering positive and negative flows are possible. <FIG> demonstrates a respiratory therapy system <NUM> comprising a gas flow generating arrangement <NUM> comprising a single flow generator <NUM> that may be configured to simultaneously deliver gases through a first gas outlet <NUM> and through a first gas passageway <NUM> (which may be in a first conduit <NUM>) and draw gases through a second gas passageway <NUM> and through the second gas inlet <NUM>. However, and as illustrated in <FIG>, it should be understood that the first and second gas passageways <NUM>, <NUM> may be in a single conduit <NUM> that may extend between the flow generator <NUM> and a patient airway. The first and second gas passageways <NUM>, <NUM> in the conduit <NUM> may be substantially pneumatically separated by a partition <NUM> that may lie between the first and second gas passageways <NUM>, <NUM>. In some configurations, the first and second gas passageways <NUM>, <NUM> may be arranged such that they are in parallel (e.g. side-by-side) or arranged such that they are coaxial (e.g. one above another) with respect to one another. Similarly to the respiratory therapy system presented in paragraphs [<NUM>]-[<NUM>], the respiratory therapy system <NUM> may comprise a user interface <NUM>, a first gas inlet <NUM>, a blower <NUM>, a gas exhaust <NUM> and a patient interface <NUM> which may comprise a non-sealing interface and which may comprise a nasal cannula. Likewise, many of the alternative configurations suggested above or elsewhere in the specification may be adapted to be used with the respiratory therapy system <NUM>. It should be understood that in this embodiment, while they share a common gas flow generating arrangement <NUM>, the first and second gas passageways <NUM>, <NUM> are substantially pneumatically isolated from each other to the extent that the flow of gas through the first gas passageway <NUM> is substantially unaffected by flow of gas through the second gas passageway <NUM>.

<FIG> demonstrates a configuration for a respiratory therapy system <NUM> involving a flow generating arrangement <NUM> comprising a flow generator <NUM> comprising a blower <NUM> capable of generating simultaneous positive and negative flows in further detail. The blower <NUM> may comprise a motor <NUM> that may comprise a stator <NUM> and a rotor <NUM>. The rotor <NUM> may be, for example, a motor shaft. A first impeller <NUM> and a second impeller <NUM> may be coupled to the rotor <NUM>. The first and second impellers <NUM>, <NUM> may comprise a housing <NUM> that may pneumatically isolate the first and second impellers <NUM>, <NUM>. The housing <NUM> may comprise an internal partition <NUM> that may help to substantially seal or substantially pneumatically isolate the space around the first and second impellers <NUM>, <NUM>. In some configurations, each of the first and second impellers <NUM>, <NUM> may have separate housings. In use, the concurrent rotation of the first impeller <NUM> with the rotor <NUM> due to the action of the motor <NUM> may cause gas to enter the blower <NUM> through the first gas inlet <NUM>. Gas may be propelled out the first outlet <NUM> and through the first gas passageway <NUM> (which may pass through a humidifier <NUM> and which may be in a single conduit <NUM> as described above). The gas may be introduced into an airway of the patient using one of the interface systems demonstrated in <FIG> and in the above paragraphs, or using another interface or combination of interfaces. Likewise, the concurrent rotation of the second impeller <NUM> with the rotor <NUM> due to the action of the motor <NUM> may draw gases out of a patient airway, through the second gas passageway <NUM>, through the second gas inlet <NUM> and out the gas exhaust <NUM>. Valve arrangements may be used to further control the flows administered to the patient (e.g., the flow rates of gases passing through sections of the first gas passageway <NUM> and/or gases passing through sections of the second gas passageway <NUM>). Advantageously, the use of a single blower <NUM> in the flow generating arrangement <NUM> as demonstrated in <FIG> may be more efficient and more cost effective than using multiple blowers. In some configurations, and as seen in <FIG>, the respiratory therapy system <NUM> may comprise a first transfer module <NUM> (e.g., in a patient interface) and/or a second transfer module <NUM> (e.g., in the blower <NUM>, extending between the sections of the housing <NUM>). The first transfer module <NUM> and/or second transfer module may be configured to aid in transferring heat and/or moisture from the negative flow (e.g., from the second gas passageway <NUM>) to the positive flow (e.g., to the first gas passageway <NUM>). The configurations suggested above may be equally applicable to some such transfer modules <NUM>, <NUM>. It should be understood that in the embodiments of <FIG> and <FIG>, while they share a common gas flow generating arrangement <NUM>, the first and second gas passageways <NUM>, <NUM> are substantially pneumatically isolated from each other to the extent that the flow of gas through the first gas passageway <NUM> is substantially unaffected by flow of gas through the second gas passageway <NUM>.

As discussed above, also disclosed herein is a method of delivering gas to the airway of a subject. In various embodiments the method may comprise delivering gas to the airway of a subject in need thereof, improving the ventilation of a subject in need thereof, reducing the volume of anatomical dead space within the volume of the airway of a subject in need thereof, and/or treating a respiratory condition or a sleep disorder in a subject in need thereof.

For example, <FIG> illustrates a method of providing positive and negative flow of gases in a high flow therapy system. The method includes the step <NUM> of providing a positive high flow rate of respiratory gases to the airway of a patient. The method also includes the step <NUM> of providing negative pressure to the airway of the patient. The high flow therapy system of <FIG> is a non-sealed system such that pressure does not build up in the system.

In various embodiments, the method may comprise delivering a continuous flow of gas to the airway of a subject. For example, the flow of gas may be delivered at a first flow rate of at least about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>/min, and useful ranges may be selected between any of these values (for example, about <NUM> to about <NUM>, about <NUM> to about <NUM>, or about <NUM> to about <NUM>/min).

In various embodiments, the method may comprise simultaneously drawing gas from the airway of the subject. In some embodiments gas may be drawn from the airway of the subject at a second flow rate that is the same as or less than or greater than the first flow rate. In some embodiments the second flow rate may be at least about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>%, or more, of the first flow rate, and useful ranges may be selected between any of these values (for example, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>%). In some embodiments the second flow rate may be at least about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>/min, and useful ranges may be selected between any of these values (for example, about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>/min). In some embodiments the second flow rate may be about <NUM> to about <NUM>% of the first flow rate, provided that the second flow rate is at least about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>/min.

In various embodiments the method may be carried out using a system as described herein or an equivalent system that is adapted to carry out the described method.

With reference to <FIG>, testing apparatus comprises lung pump <NUM>, computer <NUM> to control pump <NUM> to simulate breathing, computer <NUM> to record sensor output, airway model <NUM>, connecting tube <NUM>, aluminum base block <NUM>, CO<NUM> bleed valve <NUM>, CO<NUM> rotameter <NUM>, CO2 sensor <NUM>, nasal high flow (NHF) rotameter <NUM>, and NHF cannula <NUM>.

A method and system described herein was assessed using the testing apparatus. The airway CO<NUM> levels were assessed of (A) an untreated control model subject, (B) a model subject treated with standard NHF therapy at a flow rate of <NUM>/min, (C) a model subject treated with negative NHF therapy drawing gas from the airway of the model subject using a standard two-prong nasal canula at <NUM>/min, and (D) a model subject treated with an exemplary embodiment of the presently disclosed method, using negative NHF therapy drawing gas from the airway of the model subject at a flow rate of <NUM>/min and positive NHF therapy simultaneously delivering gas to the airway of the model subject at a flow rate of <NUM>/min, using a cannula of <FIG> described above. All scenarios were run with the mouth of the airway model <NUM> in the open position and in the closed position.

The results are shown in Table <NUM> and <FIG> and indicate that standard NHF therapy (B) reduced the CO<NUM> levels in the upper airway by <NUM>% and <NUM>% for mouth open and mouth closed, respectively, compared to the untreated control (A). Use of negative NHF therapy (C) reduced the CO<NUM> levels by <NUM>% and <NUM>% for mouth open and mouth closed, respectively, compared to the untreated control (A). Used of both negative and positive pressure (D) reduced the CO<NUM> levels by <NUM>% and <NUM>% for mouth open and mouth closed, respectively, compared to the untreated control (A).

Testing is carried out with combinations of positive and negative flow rates, including positive flow rates of from about <NUM> to about <NUM>/min, and negative flow rates of about <NUM> to about <NUM>/min, including specific flow rate combinations of +<NUM>/-<NUM>, +<NUM>/-<NUM>, +<NUM>/-<NUM>, +<NUM>/-<NUM>, +<NUM>/-<NUM>, +<NUM>/-<NUM>, +<NUM>/-<NUM>, +<NUM>/-<NUM>, and +<NUM>/-<NUM>/min.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to.

Where, in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers or components are herein incorporated as if individually set forth.

The disclosed methods, apparatus and systems may also be said broadly to comprise the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

Claim 1:
A non-sealing patient interface (<NUM>) for a respiratory therapy system (<NUM>) com prising:
first and second nasal prongs (134A,134B);
a manifold (<NUM>);
a first passageway (<NUM>) associated with the first nasal prong (134A) and second passageway (<NUM>) associated with the second nasal prong (134B), the first and second passageways (<NUM>,<NUM>) in a single conduit (<NUM>) and interfacing with a single side of the manifold (<NUM>);
wherein the first passageway (<NUM>) is adapted to deliver a gas flow to the manifold (<NUM>) and the first nasal prong (134A) and wherein the second passageway (<NUM>) is adapted to draw out an expiratory gas flow from a patient through the second nasal prong (134B) and the manifold (<NUM>); and
a barrier (<NUM>) adapted to isolate the gas flow in the first passageway (<NUM>) from the expiratory gas flow in the second passageway (<NUM>);
characterized in that
the first and second passageways (<NUM>,<NUM>) in the single conduit (<NUM>) interface with the single side of the manifold (<NUM>) at a position substantially coaxial with the nasal prongs (134A,134B).