Methods and apparatus for supplying clean breathable gas

Abstract

The invention features methods and apparatus for the treatment of asthma patients. A controlled supply of breathable air delivered to a patient interface or mask ( 4 ) is controlled for patient comfort to maintain a steady pressure level in a range 2 to 4 cm H 2 O to accommodate patient respiration. The breathable air is cleaned by a high efficiency particulate arresting filter ( 10 ) to remove allergens from the air supply. The apparatus may be programmed to automatically detect asthma-related symptoms such as an asthma attack by analyzing the respiratory flow of the patient. In response to the detection of such an attack, the apparatus may provide an audible warning or if configured with a treatment delivery module ( 14 A, 14 B), the device may administer a therapeutically effective dose of a drug or substance, for example, a broncho-dilator, to alleviate the patient's breathing difficulty. Preferred mask designs allow for proper CO 2 washout to accommodate the low pressures supplied to the mask and prevent asphyxia.

1 . An apparatus for the delivery of treatment for a patient with asthma, particularly during sleep, comprising:
 a blower to generate a flow of breathable gas under pressure, with an inlet for receiving breathable gas to said blower,   a patient interface to provide said flow of breathable gas to the respiratory system of a patient,   a conduit between said interface and said blower to lead said flow of breathable gas to said interface,   a flow meter to generate a flow signal representative of flow to the patient,   a controller to control said blower's generation of said flow of breathable gas based in part on said flow signal, and   a cleaning device to clean said breathable gas to substantially prevent allergen particulates from reaching the patient.   
     
     
         2 . The apparatus of  claim 1  wherein said cleaning device is a filter. 
     
     
         3 . The apparatus of  claim 2  wherein said filter is a high efficiency particulate arresting filter. 
     
     
         4 . The apparatus of  claim 3  wherein said filter includes activated carbon. 
     
     
         5 . The apparatus of  claim 2  wherein said patient interface is a porous mask to insure CO 2  washout at low pressures that covers the patient's nose openings and has a sealing membrane thickness in the range of 0.1 mm to 0.3 mm. 
     
     
         6 . The apparatus of  claim 5  wherein said controller controls said blower so as to vary said flow of breathable gas in response to the patient's respiration to maintain a relatively constant pressure at the patient interface. 
     
     
         7 . The apparatus of  claim 5  wherein said filter is replaceable and wherein said controller is adapted to monitor said blower to assess the filter's condition and to generate a warning when the assessment indicates that said filter should be changed. 
     
     
         8 . The apparatus of  claim 7  wherein said controller detects the number of hours of use of said blower. 
     
     
         9 . The apparatus of  claim 7  wherein said controller detects the impedance of said filter to assess the filter's condition as a function of signals from said flow meter. 
     
     
         10 . The apparatus of  claim 9  wherein said impedance is determined by the controller from the power of said blower in relation to pressure and flow from the blower. 
     
     
         11 . The apparatus of  claim 10  where said warning is an alarm. 
     
     
         12 . The apparatus of  claim 7  wherein said controller is configured to control said blower to generate a range of pressure from 1.75 to 2.5 cm H 2 O at the mask. 
     
     
         13 . The apparatus of  claim 2  wherein said controller includes a processor programmed with instructions for controlling an analysis of data from said flow signal to detect a symptom of asthma. 
     
     
         14 . The apparatus of  claim 13  wherein said analysis of data is a determination of a flow pattern including the steps of:
 calculating a shape index from said data; and 
 comparing said index to a predetermined threshold. 
 
     
     
         15 . The apparatus of  claim 14  wherein said shape index is an indicator of the flatness of an inspiratory portion of patient flow. 
     
     
         16 . The apparatus of  claim 14  wherein said shape index is an indicator of the roundness of an inspiratory portion of patient flow. 
     
     
         17 . The apparatus of  claim 14  wherein said shape index is an indicator from an expiratory portion of patient flow. 
     
     
         18 . The apparatus of  claim 1  further comprising a controlled means for delivering a therapeutic substance to supplement said flow of breathable gas to the patient. 
     
     
         19 . The apparatus of  claim 18  wherein said controller controls said means for delivering the therapeutic substance to limit delivery of the substance during the patient's inspiratory cycle. 
     
     
         20 . The apparatus of  claim 19  wherein said therapeutic substance is a broncho-dilator. 
     
     
         21 . The apparatus of  claim 20  wherein said controlled means for delivering a therapeutic substance administers said therapeutic substance at said patient interface. 
     
     
         22 . The apparatus of  claim 13  further comprising a controlled means for delivering a therapeutic substance to supplement said flow of breathable gas to the patient. 
     
     
         23 . The apparatus of  claim 22  wherein said controller is further programmed with instructions for controlling a delivery of the therapeutic substance by said controlled means in response to a detection of a symptom of asthma. 
     
     
         24 . The apparatus of  claim 23  wherein said therapeutic substance is a broncho-dilator. 
     
     
         25 . The apparatus of  claim 23  wherein said therapeutic substance is a gas. 
     
     
         26 . The apparatus of  claim 25  wherein said gas is oxygen. 
     
     
         27 - 60 . (canceled)