Methods and apparatus for respiratory treatment

Abstract

Apparatus and methods provide control for generation of a flow of air to a patient's airways for different respiratory therapies. The pressure and a flow rate may be simultaneously controlled so as to provide a pressure therapy and a flow therapy. The system may include one or more flow generators, in which the control of the pressure and flow rate may include altering the output of one or more of the flow generators and/or an optional adjustable vent. The pressure and flow rate may each be held at a constant. One or both of the pressure and flow rate may also vary in accordance with a desired therapy. The air may be provided via a patient interface that includes a vent to atmosphere, which may be the adjustable vent. The vent may be actuated by a controller to implement the simultaneous control of pressure and flow rate of the air.

1 . A system for delivery of a flow of air to a patient's airways comprising:
 a flow generator configured to provide air to a patient via an air circuit and a patient interface;   an adjustable vent; and   one or more controllers configured to:
 determine a pressure and a flow rate of the air being provided to the patient via the patient interface with a plurality of sensors; and 
 control the flow generator and the adjustable vent so as to simultaneously control the pressure and the flow rate of the air at the patient interface to correspond with a predetermined pressure and a predetermined flow rate, respectively. 
   
     
     
         2 . The system of  claim 1  further comprising the patient interface, wherein the patient interface comprises a projection portion configured to conduct a flow of the air into a naris of a patient and a mask portion configured to apply pressure of the air to the patient. 
     
     
         3 . The system of  claim 2 , wherein the adjustable vent is part of the mask portion of the patient interface. 
     
     
         4 . The system of  claim 2 , wherein the plurality of sensors comprise:
 a pressure sensor for determining a measured pressure of the air; and   a flow rate sensor for determining a measured flow rate of the air through the projection portion of the patient interface.   
     
     
         5 . The system of  claim 4 , wherein at least one of the pressure sensor and the flow rate sensor is located at an output of the flow generator. 
     
     
         6 . The system of  claim 4 , wherein at least one of the pressure sensor and the flow rate sensor is located at the patient interface. 
     
     
         7 . The system of  claim 1 , wherein the one or more controllers are further configured to maintain at least one of the predetermined pressure and the predetermined flow rate at a constant value for a period of time. 
     
     
         8 . The system of  claim 1 , wherein the one or more controllers are further configured to vary the predetermined pressure in accordance with a breathing cycle of the patient. 
     
     
         9 . The system of  claim 1 , wherein the simultaneous control of the pressure and the flow rate of the air provides the patient with a positive airway pressure therapy and a deadspace therapy. 
     
     
         10 . The system of  claim 9 , wherein the positive airway pressure therapy is a ventilation therapy. 
     
     
         11 . The system of  claim 1 , wherein the one or more controllers are configured to determine the predetermined pressure and the predetermined flow rate to restrict the predetermined pressure and the predetermined flow rate to a curve of equal efficacy. 
     
     
         12 . The system of  claim 1  further comprising a variable resistance in the air circuit, wherein the one or more controllers are configured to control one or more of the pressure and the flow rate of the air by adjusting the resistance of the variable resistance. 
     
     
         13 . The system of  claim 1 , wherein a controller of the one or more controllers is configured to compute a target ventilation based on anatomical deadspace information and a deadspace therapy reduction value. 
     
     
         14 . The system of  claim 1 , wherein a controller of the one or more controllers is configured to generate a cardiac output estimate by controlling a step change in the predetermined flow rate of the air and determining a change in a measure of ventilation in relation to the step change. 
     
     
         15 . The system of  claim 14 , wherein the controller of the one or more controllers is configured to initiate control of the step change in the predetermined flow rate of the air in response to a detection of sleep. 
     
     
         16 . A method for controlling a supply of air to a patient's airways for a respiratory therapy, the method comprising:
 identifying, by one or more controllers, a predetermined pressure and a predetermined flow rate of the air to be provided to a patient via an air circuit and a patient interface;   determining, with a plurality of sensors, a pressure and a flow rate of the air being provided to the patient via the patient interface; and   controlling, by the one or more controllers, a flow generator configured to provide the air to the patient interface, and an adjustable vent so as to simultaneously control the pressure and the flow rate of the air at the patient interface to correspond with the predetermined pressure and the predetermined flow rate, respectively.   
     
     
         17 . The method of  claim 16 , wherein the patient interface comprises a projection portion configured to conduct a flow of the air into a naris of the patient and a mask portion configured to apply pressure of the air to the patient. 
     
     
         18 . The method of  claim 17 , wherein the flow generator provides the flow of the air through the projection portion of the patient interface thereby applying pressure of the air to the mask portion of the patient interface. 
     
     
         19 . The method of  claim 16  further comprising maintaining, by the one or more controllers, at least one of the predetermined pressure and the predetermined flow rate at a constant value for a period of time. 
     
     
         20 . The method of  claim 16  further comprising varying, by the one or more controllers, the predetermined pressure in accordance with a breathing cycle of the patient. 
     
     
         21 . The method of  claim 16 , wherein the simultaneous control of the pressure and the flow rate of the air comprises control of a positive airway pressure therapy and a deadspace therapy. 
     
     
         22 . The method of  claim 21 , wherein the positive airway pressure therapy is a ventilation therapy. 
     
     
         23 . The method of  claim 16  further comprising determining, by the one or more controllers, the predetermined pressure and the predetermined flow rate so as to restrict the predetermined pressure and the predetermined flow rate to a curve of equal efficacy. 
     
     
         24 . The method of  claim 16 , wherein controlling the adjustable vent comprises adjusting, by the one or more controllers, a venting characteristic of the adjustable vent in synchrony with the patient's breathing cycle so as to maintain the pressure of the air at the patient interface to correspond with the predetermined pressure. 
     
     
         25 . The method of  claim 16  further comprising adjusting, by the one or more controllers, a resistance of a variable resistance in the air circuit so as to control one or more of the pressure and the flow rate of the air. 
     
     
         26 . The method of  claim 16  further comprising calculating, in the one or more controllers, a target ventilation based on anatomical deadspace information and a deadspace therapy reduction value. 
     
     
         27 . The method of  claim 16  further comprising generating, in the one or more controllers, a cardiac output estimate by controlling a step change in the predetermined flow rate of the air and determining a change in a measure of ventilation in relation to the step change. 
     
     
         28 . The method of  claim 27  further comprising initiating, by the one or more controllers, the controlling of the step change in the predetermined flow rate of the air in response to a detection of sleep.