Method and apparatus for breathing assistance

Abstract

Methods and system for treating obstructive sleep apnea and snoring are disclosed. The system generally comprises a mask for delivering pressurized air to patient's breathing orifice, a sensing mechanism for continuously assessing the state of patient's breathing and a pressure generator for generating the pressurized air in the mask. The pressurized air is applied to the breathing orifice only during selected portions of the breathing cycle, when such pressure might be required to prevent occlusion of the airway or to restore patency of the airway after such occlusion occurs.

What is claimed is: 
     
         1 . A system to maintain upper airway patency of a subject during sleep, comprising:
 a mask adapted to be applied to at least one breathing orifice of the subject;   a valve arrangement including at least one controllable breathing valve associated with said mask and configured to be connected between the at least one breathing orifice and ambient atmosphere, the at least one controllable breathing valve having an open state and at least one flow-restricting state;   a controller adapted to control the at least one controllable breathing valve; and   a sensor for providing to said controller an input indicative of a waveform of at least one of the subject's breathing cycles, said controller processing said waveform so as to identify within said waveform at least one spontaneous inspiration phase during at least part of which a pressure within said mask is negative and at least one spontaneous expiration phase,   wherein said valve arrangement and said controller are configured to:
 (a) allow substantially unrestricted spontaneous inspiration via the valve assembly; 
 (b) allow spontaneous expiration via said at least one controllable breathing valve in said open state for a first part of said expiration phase; and 
 (c) control said at least one controllable breathing valve to restrict flow during a second part of said spontaneous expiration phase, thereby achieving a temporarily elevated pressure within said mask. 
   
     
     
         2 . The system of  claim 1 , wherein said controller is configured to vary a flow restriction of said controllable breathing valve dynamically during said second part of said spontaneous expiration phase. 
     
     
         3 . The system of  claim 1 , wherein said controller is configured to initiate said flow restriction in timed relation to a characteristic reference point in said waveform. 
     
     
         4 . The system of  claim 3 , wherein said controller is configured to identify occurrences of an upper airway occlusion, and wherein a time of initiation of said flow restriction relative to said characteristic reference point in said waveform is varied as a function of a frequency of occurrence of upper airway occlusions. 
     
     
         5 . The system of  claim 3 , wherein said characteristic reference point in said waveform is a peak expiration pressure. 
     
     
         6 . The system of  claim 3 , wherein said characteristic reference point in said waveform is crossing of a threshold value during decline of pressure within said mask from a peak expiration pressure. 
     
     
         7 . The system of  claim 1 , wherein said controller is configured to maintain said controllable breathing valve in said open state for multiple breathing cycles to allow unimpeded spontaneous breathing until a sleeping-subject criterion is satisfied, and then to initiate said control of said at least one controllable breathing valve to restrict flow during said second part of said spontaneous expiration phase. 
     
     
         8 . The system of  claim 7 , wherein said sleeping-subject criterion includes a time delay. 
     
     
         9 . The system of  claim 7 , wherein said sleeping-subject criterion includes detection of an upper airway occlusion. 
     
     
         10 . The system of  claim 1 , further comprising a gas accumulator and a pump deployed for introducing pressurized air into said gas accumulator, said gas accumulator being interconnected via a surge control valve to said mask, and wherein said controller is configured to be responsive to an upper airway occlusion condition to actuate said at least one controllable breathing valve to assume a fully-closed state and to open said surge control valve, thereby generating a pressure surge within said mask, and then close said surge control valve. 
     
     
         11 . The system of  claim 10 , wherein said gas accumulator and said pump are integrated with a headgear. 
     
     
         12 . A system to maintain upper airway patency of a subject during sleep, comprising:
 a mask adapted to be applied to at least one breathing orifice of the subject;   a valve arrangement including at least one controllable breathing valve associated with said mask and configured to be connected between the at least one breathing orifice and ambient atmosphere, the at least one controllable breathing valve having a plurality of flow-restricting states;   a controller adapted to control the at least one controllable breathing valve; and   a sensor for providing to said controller an input indicative of a waveform of at least one of the subject's breathing cycles, said controller processing said waveform so as to identify within said waveform breathing cycles including an inspiration phase during at least part of which a pressure within said mask is negative and an expiration phase, wherein said valve arrangement and said controller are configured to:
 (a) allow substantially unrestricted spontaneous inspiration via the valve assembly; and 
 (b) control said at least one controllable breathing valve to provide sequentially at least two different levels of flow restriction within the expiration phase of each breathing cycle, thereby achieving a temporarily elevated pressure within said mask.