Breath end-tidal gas monitor

• US 9,936,897 B2
• Filed: 07/29/2015
• Issued: 04/10/2018
• Est. Priority Date: 06/19/2003
• Status: Active Grant

• Current Assignee: Capnia, Inc.
• Original Assignee: Capnia, Inc.
• Inventors: Carlson, Lee R., McClatchie, Edward A., Martinosky, Joe, Walden, Ralph, Causevic, Elvir
• Primary Examiner(s): JANG, CHRISTIAN YONGKYUN
• Application Number:
  US14/812,822
• Publication Number:
  US 20150327793A1
• Time in Patent Office: 986 Days
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/082 Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath A61B5/083, A61B5/091 take precedence
• CPC Class Codes: A61B 5/083 Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption
• CPC Class Codes: A61B 5/0833 Measuring rate of oxygen consumption
• CPC Class Codes: A61B 5/0836 Measuring rate of CO2 production
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/097 Devices for facilitating collection of breath or for directing breath into or through measuring devices
• CPC Class Codes: G01N 33/004 CO or CO2
• CPC Class Codes: G01N 33/497 of gaseous biological material, e.g. breath
• CPC Class Codes: Y10S 436/90 Breath testing

Abstract

An improved apparatus and method for capturing and analyzing the end-tidal portion of an exhalation. The CO₂ level of air drawn into the system (10) is monitored to distinguish inhalation and exhalation of breath. Upon detection of a decrease in the CO₂ level in the air drawn into the system (10), indicating a transition between exhalation and inhalation a pair of flow selector valves (26, 28) are operated to capture the end-tidal volume of air drawn into the system (10) immediately prior to the detection of the decrease in the CO₂ level. Incoming air is diverted around the captured volume of air, and the CO₂ levels are continually monitored to ensure that the captured volume of air corresponds to the end-tidal portion of an exhalation. Once the captured volume of air is positively identified as the end-tidal portion of an exhalation, the captured volume is routed through a gas analyzer (44) for analysis of one or more predetermined gas levels.

Claims

1. A breath gas analyzer system including:

an air inlet configured to receive aspirated air from the respiratory system of a subject;

a capnograph coupled to said air inlet, said capnograph adapted to identify a transition point between an exhalation and an inhalation of air in the respiratory system;

a plurality of flow selector valves;

a sample volume coupled to said capnograph, said sample volume configured to selectively isolate a sample of aspirated air using the plurality of flow selector valves, said plurality of flow selector valves configured to selectively control a flow of air between said air inlet, said capnograph, said sample volume, and said at least one gas analyzer; and

at least one gas analyzer coupled to and downstream from, at least one of the plurality of flow selector valves, and configured to receive a sample of aspirated air from said sample volume; and

wherein said at least one gas analyzer is further configured to measure at least one gas concentration in said sample of aspirated air.

2. The breath gas analyzer system of claim 1 further including a pump, said pump configured to draw said aspirated air through said air inlet, said capnograph, and into said sample volume;

and wherein said pump is further configured to expel said sample of aspirated air from said sample volume, and through said at least one gas analyzer.

3. The breath gas analyzer system of claim 1 further including at least one exhaust port configured to discharge air;

and an airflow bypass pathway configured to selectively route an airflow from said capnograph to said exhaust port, bypassing said sample volume.

4. A method for capturing and analyzing the end-tidal portion of an exhalation, including the steps of:

drawing a flow of air from the respiratory system of patient;

identifying a point of transition representative of a change from exhalation to inhalation in the breath of said patient;

upon identification of said transition point, isolating a sample volume of said flow of air drawn prior to said transition point air using a plurality of flow selector valves configured to selectively control the flow of air between said sample volume, and at least one gas analyzer, wherein the gas analyzer is coupled to and downstream from, at least one of the plurality of flow selector valves;

confirming said change from exhalation to inhalation in the breath of said patient;

measuring, upon confirmation of said change from exhalation to inhalation in the breath of said patient, at least one gas level in said isolated sample volume using the gas analyzer.

5. The method of claim 4 for capturing and analyzing the end-tidal portion of an exhalation wherein the step of identifying a point of transition includes monitoring changes in a concentration of gas in of said flow of air to identify a point of transition.

6. The method of claim 5 for capturing and analyzing the end-tidal portion of an exhalation wherein the step of identifying a point of transition includes monitoring changes in a concentration of CO₂ in of said flow of air, said point of transition corresponding to a transition from an increasing CO₂ level to a decreasing CO₂ level in said flow of air.

7. The method of claim 4 for capturing and analyzing the end-tidal portion of an exhalation wherein said step of measuring includes measuring a CO concentration in said isolated sample volume.