METABOLIC ANALYZER

• US 3,799,149 A
• Filed: 12/26/1972
• Issued: 03/26/1974
• Est. Priority Date: 12/26/1972
• Status: Expired due to Term

• Current Assignee: Cortes L. Perry, John A. Rummel
• Original Assignee: Cortes L. Perry, John A. Rummel
• Inventors: Rummel, John A., Perry, Cortes L.
• Primary Examiner(s): Howell, Kyle L.
• Application Number:
  US05/318,152
• Time in Patent Office: 455 Days
• Field of Search: 128/2.07,2.08 73/421.5R,23
• US Class Current: 600/531
• CPC Class Codes: A61B 5/083 Measuring rate of metabolism by using breath test, e.g. measuring rate of oxygen consumption

Abstract

An apparatus for the measurement of metabolic rate and breathing dynamics in which inhaled and exhaled breath are sensed by sealed, piston-displacement type spirometers. These spirometers electrically measure the volume of inhaled and exhaled breath. A mass spectrometer analyzes simultaneously for oxygen, carbon dioxide, nitrogen and water vapor. Computation circuits responsive to the outputs of the spirometers, mass spectrometer, temperature, pressure and timing signals compute oxygen consumption, carbon dioxide production, minute volume and respiratory exchange ratio. A selective indicator provides for read-out of these data at predetermined cyclic intervals.

Claims

1. A metabolic analyzer for measurement of a subject'"'"''"'"'s metabolic rate by respiratory gas analysis, said metabolic analyzer comprising:

inspiration spirometer means adapted to sense and measure the volume of a subject'"'"''"'"'s inhaled breath and provide a voltage signal output indicative of said volume;

expiration spirometer means adapted to sense and measure the volume of a subject'"'"''"'"'s exhaled breath and provide a voltage signal output indicative of said volume of exhaled breath;

means for receiving a sample of the exhaled breath sensed and measured by said expiration spirometer means and providing a voltage signal output indicative of the proportion of CO2 in the subject'"'"''"'"'s exhaled breath;

means for receiving a sample of the ambient air being breathed by said subject and providing a voltage signal output indicative of the proportion of CO2 in said ambient air;

computation means responsive to said voltage signal outputs for computing the volume of the CO2 produced by said subject during a specific time interval;

control means responsive to the completion of an expired breath as sensed by said expiration spirometer means to commence said time interval for computation and for controlling said computation means to compute the volume of CO2 produced by said subject during said time interval; and

indication means responsive to said computation means for indicating the computation performed by said computation means.

2. A metabolic analyzer as set forth in claim 1 further comprising CO2 stabilizIng means connected to said expiration spirometer means for passing moisture in vapor form only into said expiration spirometer means.

3. A metabolic analyzer as set forth in claim 1 including recycle logic means connected to each of said spirometer means for providing a discrete voltage at the completion of an inhalation and an exhalation, for controlling a said spirometer means whereby an operating cycle of each said spirometer means is commenced upon the occurrence of a said discrete voltage for that spirometer means.

4. A metabolic analyzer as set forth in claim 1 wherein:

said means for receiving a sample of exhaled breath further comprises means for providing a voltage signal output indicative of the proportion of O2 in said exhaled breath;

said means for receiving a sample of ambient air being breathed by said subject further comprising means for providing a voltage signal output indicative of the proportion of O2 in ambient air; and

said computation means is further responsive to said voltage signal output indicative of the proportion of O2 in exhaled breath and in ambient air for computing the volume of O2 consumed during a said time interval.

5. A metabolic analyzer as set forth in claim 1 wherein said indication means includes means responsive to said expiration spirometer means for selectively indicating the volume of a said exhaled breath.

6. A metabolic analyzer as set forth in claim 4 wherein said means for receiving a sample of the exhaled breath further comprises means for providing a voltage output signal indicative of the proportion of H2O in the subject'"'"''"'"'s exhaled breath and said indication means is further responsive to said means for receiving a sample of exhaled breath for selectively indicating the proportions of H2O, CO2 and O2 in the exhaled breath.

7. A metabolic analyzer as set forth in claim 6 wherein said means for receiving a sample of ambient air being breathed further comprises means for providing a voltage output signal indicative of the proportion of H2O in the subject'"'"''"'"'s exhaled breath and said indication means is further responsive to said means for receiving a sample of ambient air being breathed for selectively indicating the proportions of H2O, CO2 and O2 in the ambient air.

8. A metabolic analyzer as set forth in claim 7 further comprising calibration means including a source of CH2D2 (dideuteromethane) diluted with N2 to have the apparent properties of water vapor and including means for coupling said source to said means for receiving samples of ambient air, whereby said indication means may be calibrated in terms of water vapor.

9. A metabolic analyzer as set forth in claim 8 wherein the percentage of said CH2H2 is 20% and N2 is 80%.

10. A metabolic analyzer as set forth in claim 8 wherein:

said means for receiving a sample of ambient air being breathed by a subject includes means for providing a voltage signal output indicative of the precentage of N2; and

said analyzer further comprises calibration means for selectively providing a known mixture of N2, O2 and CO2 as a substituted input to said means for receiving samples of ambient air, whereby said indication means may be calibrated to indicate the percentage of N2, O2 and CO2 to correspond to the known percentages of each present in said source.

11. A metabolic analyzer as set forth in claim 10 wherein inspiration spirometer means comprises:

a cylinder having a closed end;

a piston positioned for travel within said cylinder;

a convoluted, flexible diaphragm coupling and providing a seal between said piston and said cylinder;

breath input means for coupling ambient air from the compartment in said cylinder formed between said piston and said closed end to a subject; and

potentiometEr means mechanically coupled to said piston for providing an output voltage proportional to the displacement of said piston from a preselected position, whereby the movement of said piston caused by an inspired breath is electrically sensed by said potentiometer and said output voltage is fed to said computation means.

12. A metabolic analyzer as set forth in claim 11 wherein said expiration spirometer means comprises:

a second cylinder having a closed end;

a piston positioned for travel within said second cylinder;

a convoluted flexible diaphragm coupling and providing a seal between said last named piston and said second cylinder;

breath output means adapted to couple breath exhaled by a subject to the compartment in said second cylinder formed between said last named piston and said last named closed end; and

potentiometer means mechanically connected to said last named piston for providing to said computation means an output voltage proportional to the displacement of said last named piston from a selected position.

13. A metabolic analyzer for measurement of metabolic rate by respiratory gas analysis, said metabolic analyzer comprising:

expiration spirometer means adapted to sense and measure the volume of a subject'"'"''"'"'s exhaled breath and provide a voltage signal output indicative of the volume of exhaled breath;

means for receiving a sample of the exhaled breath sensed and measured by said expiration spirometer means and providing voltage signal outputs indicative of the porportion of O2 and N2, respectively, in the subject'"'"''"'"'s exhaled breath;

means for receiving a sample of the ambient air being breathed by said subject and providing voltage signal outputs indicative of the proportion of O2 and N2, respectively, in said ambient air;

computation means responsive to said voltage signal outputs for computing the volume of the O2 consumed by said subject during a specific time interval;

control means responsive to the completion of an expired breath as sensed by said expiration spirometer means to commence said time interval for computation and for controlling said computation means to compute the volume of O2 consumed by said subject during said time interval; and

indication means responsive to said computation means for indicating the volume of O2 consumed by subject during said time interval.

14. A metabolic analyzer for measurement of metabolic rate by respiratory gas analysis, said metabolic analyzer comprising:

expiration spirometer means adapted to sense and measure the volume of a subject'"'"''"'"'s exhaled breath and provide a voltage signal output indicative of the volume of exhaled breath;

means for receiving a sample of the exhaled breath sensed and measured by said expiration spirometer means and providing voltage signal outputs indicative of the proportion of CO2 and N2, respectively, in the subject'"'"''"'"'s exhaled breath;

means for receiving a sample of the ambient air being breathed by said subject and providing voltage signal outputs indicative of the proportion of N2 and CO2, respectively, in said ambient air;

computation means responsive to said voltage signal outputs for computing the volume of the CO2 produced by said subject during a specific time interval;

control means responsive to the completion of an expired breath as sensed by said expiration spirometer means to commence said time interval for computation and for controlling said computation means to compute the volume of CO2 produced by said subject during said time interval; and

indication means responsive to said computation means for indicating the volume of CO2 produced by subject during said time interval.

15. A metabolic analyzer for measurement of metabolic rate by respiratory gas analysis, said metabolic analyzer comprising:

expiration spirometer means adapted to senSe and measure the volume of an exhaled breath and provide a signal output indicative of said volume of exhaled breath;

mass analysis means for receiving a sample of ambient air being breathed and a sample of exhaled breath sensed by said expiration spirometer means and providing signal outputs comprising outputs representative of proportions of chemical constituents in said samples including the proportion of one constituent from the group of O2 and CO2 in each sample;

computation means responsive to said outputs of said mass analysis means and expiration spirometer means for computing the volume of one of the signs of metabolic rate from the group consisting of O2 consumed and CO2 produced by a subject during a specific time interval;

control means responsive to the completion of an expired breath as sensed by said expiration spirometer means to commence said time interval for computation and for controlling said computation means to compute the volume of at least one of said signs of metabolic rate during said time interval; and

indication means responsive to said computation means for indicating the said volume computed by said computation means.