System and method for controlling the flow of exhaled breath during analysis

Abstract

A system and method for controlling the flow rate of a gaseous sample in an exhaled breath analysis system is disclosed. Two embodiments are described in this patent: a single pump embodiment and a dual pump embodiment. In each of these embodiments, a pump or pumps are used to control the flow rate of the breath sample as it moves through the analysis system. Also, the system includes means to conduct side stream, stopped flow analysis.

1 . A system for analysis of exhaled breath, comprising: 
 a. a device for capturing breath from a subject's mouth and for measuring a gaseous analyte in said breath;    b. a sensing element in said device, wherein said sensing element is responsive to trace gases in said exhaled breath; and    c. a pump associated with said device, wherein said pump maintains a substantially constant flow rate from said subject.    
   
   
       2 . The system according to  claim 1 , wherein said pump is downstream from said sensing element.  
   
   
       3 . The system according to  claim 1 , wherein said device captures an entire breath stream from said subject.  
   
   
       4 . The system according to  claim 1 , wherein said flow rate is between 40 and 60 ml/s.  
   
   
       5 . The system according to  claim 1 , wherein said device additionally comprises: 
 a. a primary stream;    b. a side stream, said side stream containing said sensing element;    and    c. a joinder point wherein said primary stream joins said side stream.    
   
   
       6 . The system according to  claim 5 , wherein said pump is downstream from said joinder point.  
   
   
       7 . The system according to  claim 1 , additionally comprising: 
 a. a blow tube for capturing said exhaled breath;    b. a pressure sensor downstream from said blow tube;    c. a primary stream downstream from said pressure sensor;    d. a resistor on said primary stream;    e. a side stream downstream from said pressure sensor, wherein said sensing element is on said side stream;    f. a side stream valve for opening said side stream; and    g. a joinder point wherein said primary stream joins said side stream, and wherein said pump is downstream from said joinder point.    
   
   
       8 . The system according to  claim 1 , wherein said sensing element comprises a bioactive molecule.  
   
   
       9 . The system according to  claim 1 , wherein said bioactive molecule comprises cytochrome-c in a sol-gel.  
   
   
       10 . The system according to  claim 1 , wherein said gaseous analyte is nitric oxide.  
   
   
       11 . A system for analysis of exhaled breath, comprising: 
 a. a device for measuring a gaseous analyte in exhaled breath;    b. a primary stream in said device;    c. a first pump in said primary stream for controlling a primary stream flow rate;    d. a side stream in said device; and    e. a second pump in said side stream for controlling a side stream flow rate.    
   
   
       12 . The system according to  claim 11 , additionally comprising a joinder point wherein said primary stream joins said side stream, and wherein said first pump and said second pump are upstream from said joinder point.  
   
   
       13 . The system according to  claim 11 , wherein said side stream and said primary stream have separate exhaust points.  
   
   
       14 . The system according to  claim 11 , wherein said analyte is a trace gas.  
   
   
       15 . The system according to  claim 14 , wherein said analyte is nitric oxide.  
   
   
       16 . The system according to  claim 15 , additionally comprising a sensing element, and wherein said sensing element comprises cytochrome-c in a sol-gel.  
   
   
       17 . A system for analysis of exhaled breath, comprising: 
 a. a primary stream for travel of said exhaled breath;    b. a side stream for travel of said exhaled breath; and    c. a variable resistor associated with said system for attaining a desired constant side stream flow rate.    
   
   
       18 . The system according to  claim 17 , wherein said side stream flow rate is between 5 ml/s and 11 ml/s.  
   
   
       19 . The system according to  claim 18 , wherein said side stream flow rate is between 6 ml/s and 10 ml/s.  
   
   
       20 . The system according to  claim 19 , wherein said side stream flow rate is between 7 ml/s and 9 ml/s.  
   
   
       21 . The system according to  claim 17 , wherein said primary stream has a flow rate of 40-45 ml/s when said side stream is open.  
   
   
       22 . A system for analysis of exhaled breath, comprising: 
 a. a primary stream for travel of said exhaled breath;    b. a side stream for travel of said exhaled breath; and    c. a variable pump associated with said system for attaining a desired constant side stream flow rate.    
   
   
       23 . The system according to  claim 22 , wherein said side stream flow rate is between 5 ml/s and 11 ml/s.  
   
   
       24 . The system according to  claim 22 , wherein said side stream flow rate is between 6 ml/s and 10 ml/s.  
   
   
       25 . The system according to  claim 24 , wherein said side stream flow rate is between 7 ml/s and 9 ml/s.  
   
   
       26 . The system according to  claim 22 , wherein said primary stream has a flow rate of 40-45 ml/s when said side stream is open.  
   
   
       27 . A system for analysis of exhaled breath, comprising: 
 a. a primary stream for travel of said exhaled breath;    b. a side stream for travel of said exhaled breath;    c. means for opening said side stream; and    d. a sensor in said side stream for measuring an analyte in said exhaled breath.    
   
   
       28 . The system according to  claim 27 , wherein exhaled breath flows through said side stream at a rate between 5 ml/s and 11 ml/s when said side stream is open.  
   
   
       29 . The system according to  claim 27 , wherein exhaled breath flows through said side stream at a rate between 6 ml/s and 10 ml/s when said side stream is open.  
   
   
       30 . The system according to  claim 27 , wherein exhaled breath flows through said side stream at a rate between 7 ml/s and 9 ml/s when said side stream is open.  
   
   
       31 . The system according to  claim 30 , wherein said primary stream has a flow rate of 40-45 ml/s when said side stream is open.  
   
   
       32 . The system according to  claim 27 , wherein said side stream is opened between 5 and 9 seconds after exhalation begins.  
   
   
       33 . The system according to  claim 27 , wherein said side stream is opened between 6 and 8 seconds after exhalation begins.  
   
   
       34 . The system according to  claim 27 , wherein said side stream is opened approximately 7 seconds after exhalation begins.  
   
   
       35 . The system according to  claim 32 , wherein said side stream remains open for between 1 and 10 seconds.  
   
   
       36 . The system according to  claim 35 , wherein said side stream remains open for between 1 and 7 seconds.  
   
   
       37 . The system according to  claim 36 , wherein said side stream remains open for between 1 and 5 seconds.  
   
   
       38 . The system according to  claim 37 , wherein said side stream remains open for between 2 and 4 seconds.  
   
   
       39 . The system according to  claim 38 , wherein said side stream remains open for approximately 3 seconds.  
   
   
       40 . The system according to  claim 27 , wherein said sensor comprises cytochrome-c in a sol-gel.  
   
   
       41 . The system according to  claim 27 , wherein said means for opening said side stream comprises a side stream valve.  
   
   
       42 . The system according to  claim 27 , wherein said means for opening said side stream comprises a pump.  
   
   
       43 . A method for analysis of exhaled breath, comprising: 
 a. providing a device comprising: 
 i. a sensor, said sensor having a sensing element;  
 ii. a first stream for supplying flowing exhaled breath to said sensor;  
   b. supplying exhaled breath to said device;    c. stopping a portion of said flowing exhaled breath in said first stream;    d. allowing said portion to interact with said sensing element for an analysis period; and    e. measuring concentration of an analyte in said portion after said analysis period.    
   
   
       44 . The method according to  claim 43 , wherein said device additionally comprises a second stream.  
   
   
       45 . The method according to  claim 43 , wherein said first stream is opened between 5 and 9 seconds after exhalation begins.  
   
   
       46 . The method according to  claim 45 , wherein said first stream is opened between 6 and 8 seconds after exhalation begins.  
   
   
       47 . The method according to  claim 46 , wherein said stopping step occurs between 7 and 13 seconds after exhalation begins.  
   
   
       48 . The method according to  claim 43 , wherein said stopping step occurs between 9 and 11 seconds after exhalation begins.  
   
   
       49 . The method according to  claim 43 , wherein said analysis period has a duration of between 30 and 90 seconds.  
   
   
       50 . A system for analysis of an analyte in exhaled breath, comprising: 
 a. means for capturing a stream of exhaled breath from a subject;    b. means for dividing said stream into a primary stream and a side stream;    c. means for causing said side stream to flow at a substantially constant flow rate; and    d. means for stopping the flow of said side stream for an analysis period.    
   
   
       51 . A method of analyzing exhaled breath, comprising: 
 a. capturing an exhaled breath sample from a subject;    b. flowing said sample through a breath analysis device;    c. ensuring a constant flow rate through said device without monitoring said flow rate.    
   
   
       52 . A method of analyzing exhaled breath, comprising: 
 a. capturing an exhaled breath sample from a subject;    b. dividing said sample into a primary stream and a side stream;    and    c. analyzing said side stream to determine concentration of an analyte in said side stream.    
   
   
       53 . A method of analyzing exhaled breath, comprising: 
 a. capturing an exhaled breath sample from a subject;    b. flowing said sample through a gas sensing device;    c. stopping the flow of said sample for an analysis period; and    d. analyzing said sample to determine concentration of an analyte, wherein said analyzing step occurs after said analysis period.