Method and Apparatus for Analyzing Pulmonary Performance

Abstract

A method for pulmonary testing includes, while a patient inspires through the testing device, injecting a test gas at a selected flowrate toward an open end of the testing device. The method also includes measuring a flow rate of the inspired gas, which comprises the test gas. The method further includes measuring a concentration of a selected test gas component in the inspired gas.

What is claimed is: 
     
         1 . A pulmonary testing device, comprising:
 a body with first and second ends, the first end comprising a mouthpiece for a patient and the second end being open to the ambient atmosphere;   a test gas injector positioned on the body of the device;   a gas cartridge coupled containing a test gas and coupled with the test gas injector, whereby the test gas is introduced into the body via the test gas injector at a direction away from the first end;   a flow rate measuring device operable to determine a flow rate of gas being at least one of inspired and expired by the patient;   a gas analyzer operable to measure a concentration the test gas in an inspired gas during inhalation by the patient; and   a controller operable to determine a volume of the test gas in the inspired gas, wherein the controller determines a volume of the test gas by measuring the gas flow rate and using the concentration of the test gas measured by the gas analyzer.   
     
     
         2 . The testing device of  claim 1 , wherein the controller is configured to change a composition of the test gas while the mouthpiece is in the patient's mouth. 
     
     
         3 . The testing device of  claim 1 , wherein the controller is configured to change a flow rate of the test gas. 
     
     
         4 . The testing device of  claim 1 , wherein the controller comprises a logical circuit operable to determine an inspired volume of a selected gas component of the test gas using the following equation:
 determining an inspired volume of the test gas using the following equation:   
       
         
           
             
               
                 V 
                 X 
               
               = 
               
                 
                   
                     Σ 
                     ⁡ 
                     
                       [ 
                       
                         
                           
                             dV 
                             1 
                           
                           dt 
                         
                         ⁢ 
                         
                           F 
                           X 
                         
                       
                       ] 
                     
                   
                   i 
                 
                 ⁢ 
                 Δ 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 
                   T 
                   i 
                 
               
             
           
         
         where V X  is a total volume of the test gas inspired by the patient, 
       
       
         
           
             
               
                 dV 
                 1 
               
               dt 
             
           
         
          is a volumetric flow rate of the inspired gas over a sample interval, F X  is a fraction of the test gas in the inspired gas during the sample interval, ΔT i  is the sample interval, and i is a reference indicating which member the sample interval represents in a set of sample intervals. 
       
     
     
         5 . The testing device of  claim 1 , wherein the injectors each being angled away from the first end and toward the second end at an angle measured relative to a centerline of the body. 
     
     
         6 . The testing device of  claim 1 , wherein the open end is open to ambient atmosphere while the patient inspires through the testing device. 
     
     
         7 . The testing device of  claim 1 , wherein:
 the open end is open to ambient atmosphere while the patient inspires through the testing device; and   the testing device includes a mouthpiece opposite the open end.   
     
     
         8 . The testing device of  claim 1 , wherein:
 the open end is open to ambient atmosphere while the patient inspires through the testing device;   the testing device includes a mouthpiece opposite the open end;   the testing device includes a breathing conduit fluidically coupling the open end to the mouthpiece; and   a volumetric flow rate at which the test gas is injected is greater than a volumetric flow rate of gas flowing through the mouthpiece, such that the test gas prevents or inhibits ambient atmosphere from being inspired.   
     
     
         9 . The testing device of  claim 1 , wherein:
 the open end is open to ambient atmosphere while the patient inspires through the testing device;   the testing device includes a mouthpiece opposite the open end;   the testing device includes a breathing conduit fluidically coupling the open end to the mouthpiece such that while the patient inspires, the stream of gas flows in a first direction from the open end, through the breathing conduit, and to the mouthpiece, the breathing conduit defining a centerline of the testing device.   
     
     
         10 . The testing device of  claim 1 , wherein:
 the open end is open to ambient atmosphere while the patient inspires through the testing device;   the testing device includes a mouthpiece opposite the open end; and   the testing device includes a breathing conduit fluidically coupling the open end to the mouthpiece.   
     
     
         11 . A method for controlling a testing device, the method comprising:
 while a patient inspires through the testing device such that the patient causes a stream of gas to flow from an open end of the testing device and through the testing device, releasing, by a controller of the testing device, a test gas from a gas cartridge of the testing device into the stream of gas via an injector directed towards the open end of the testing device;   measuring, by the controller of the testing device, using a gas flow sensor, a flow rate of the inspired gas, the inspired gas including at least a portion of the test gas;   measuring, by the controller of the testing device, a concentration of the test gas in the inspired gas; and   adjusting, by the controller of the testing device, for each sampling time interval from the plurality of successive sampling time intervals, a volumetric flow rate of the test gas that is greater than a volumetric flow rate of gas inspired by the patient.   
     
     
         12 . The method of  claim 11 , further comprising:
 changing, by the controller of the testing device, a composition of the test gas while a mouthpiece of the testing device is in the patient's mouth.   
     
     
         13 . The method of  claim 11 , further comprising:
 changing, by the controller of the testing device, the volumetric flow rate of the test gas for each sampling time interval from the plurality of successive sampling time intervals.   
     
     
         14 . The method of  claim 11 , further comprising:
 determining, by the controller of the testing device, an inspired volume of the test gas using the following equation:   
       
         
           
             
               
                 V 
                 X 
               
               = 
               
                 
                   
                     Σ 
                     ⁡ 
                     
                       [ 
                       
                         
                           
                             dV 
                             1 
                           
                           dt 
                         
                         ⁢ 
                         
                           F 
                           X 
                         
                       
                       ] 
                     
                   
                   i 
                 
                 ⁢ 
                 Δ 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 
                   T 
                   i 
                 
               
             
           
         
         where V X  is a total volume of the test gas inspired by the patient, 
       
       
         
           
             
               
                 dV 
                 1 
               
               dt 
             
           
         
          is a volumetric flow rate of the inspired gas over a sample interval, F X  is a fraction of the test gas in the inspired gas during the sample interval, ΔT i  is the sample interval, and i is a reference indicating which member the sample interval represents in a set of sample intervals. 
       
     
     
         15 . The method of  claim 14 , wherein the determining the inspired volume of the test gas is performed by the processor. 
     
     
         16 . The method of  claim 11 , wherein the open end is open to ambient atmosphere while the patient inspires through the testing device. 
     
     
         17 . The method of  claim 11 , wherein:
 the open end is open to ambient atmosphere while the patient inspires through the testing device; and   the testing device includes a mouthpiece opposite the open end.   
     
     
         18 . The method of  claim 11 , wherein:
 the open end is open to ambient atmosphere while the patient inspires through the testing device;   the testing device includes a mouthpiece opposite the open end;   the testing device includes a breathing conduit fluidically coupling the open end to the mouthpiece; and   a volumetric flow rate at which the test gas is injected is greater than a volumetric flow rate of gas flowing through the mouthpiece, such that the test gas prevents or inhibits ambient atmosphere from being inspired.   
     
     
         19 . The method of  claim 11 , wherein:
 the open end is open to ambient atmosphere while the patient inspires through the testing device;   the testing device includes a mouthpiece opposite the open end;   the testing device includes a breathing conduit fluidically coupling the open end to the mouthpiece such that while the patient inspires, the stream of gas flows in a first direction from the open end, through the breathing conduit, and to the mouthpiece, the breathing conduit defining a centerline of the testing device; and   the injector is directed such that the test gas is injected along an injection direction that has an angle that is less than 90 degrees relative to the centerline.   
     
     
         20 . The method of  claim 11 , wherein:
 the open end is open to ambient atmosphere while the patient inspires through the testing device;   the testing device includes a mouthpiece opposite the open end; and   the testing device includes a breathing conduit fluidically coupling the open end to the mouthpiece, the breathing conduit defining a centerline of the testing device, the injector disposed at an angle that is less than 90 degrees relative to the centerline.