Automatic respiratory gas monitoring system

• US 3,927,670 A
• Filed: 01/05/1973
• Issued: 12/23/1975
• Est. Priority Date: 01/05/1973
• Status: Expired due to Term

• Current Assignee: Charles Mccluggage, Cowley R. Adams, John W. Ashworth III, Samuel Wolf, Stephen Z. Turney, Walter Blumenfeld
• Original Assignee: Charles Mccluggage, Cowley R. Adams, John W. Ashworth III, Samuel Wolf, Stephen Z. Turney, Walter Blumenfeld
• Inventors: Turney, Stephen Z., Blumenfeld, Walter, Cowley, R. Adams, Wolf, Samuel, McCluggage, Charles, Ashworth, John W. III
• Primary Examiner(s): Howell, Kyle L.
• Application Number:
  US05/321,140
• Time in Patent Office: 1,082 Days
• Field of Search: 128/2.07,2.08,2.1R,2C,DIG.29 73/23.1,421.5R,422,423
• US Class Current: 600/532
• 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

Abstract

An automated system monitors and records vital signs and respiratory gases of each of several patients in an intensive care center by time-sharing the use of a mass spectrometer and hybrid instrumentation under control of an electronic programmable calculator. Automatic measurement is performed and recorded on high and low levels corresponding to inspiratory and peak expiratory values of O2 and peak expiratory CO2. Sampled gas waveforms are counted for respiratory rate and the respiratory quotient is computed for each patient. Respiratory gas flow is automatically measured and CO2 production and O2 consumption are computed and recorded. This invention is equally applicable to analysis of gases other than respiratory gases.

Claims

1. A system for monitoring respiratory gases, which comprises:

means for withdrawing respiratory gases from the airway of at least one patient, means for rapidly analyzing the withdrawn gases and for developing analog waveforms in response to the analyzation of the withdrawn gases where the waveforms are representative of fractional concentrations of the withdrawn gases, means responsive to the developed analog waveforms for developing voltage levels proportional to the maxima and minima of the developed analog waveforms where the maxima and minima of the waveforms are representative of monitored values of inspired and expired respiratory gases, and means responsive to the developed voltage levels for displaying in visual form an indication of the maxima and minima values.

2. The monitoring system as set forth in claim 1 which further comprises means for automatically controlling the withdrawing of the patients respiratory gases at selected intervals.

3. The monitoring system as set forth in claim 1 wherein said withdrawing means further comprises:

means for withdrawing the respiratory gases of a plurality of patients to sample the respiratory gases, and means for connecting the withdrawn gases of each patient, independently of the withdrawn gases of the remaining patients, to the rapid analyzing means.

4. The monitoring system as set forth in claim 3 which further comprises means for automatically controlling the connecting means to selectively connect the withdrawn gases of each patient to the rapid analyzing means so that the withdrawn gases of only one patient are connected to the rapid analyzing means at any given instant.

5. The monitoring system as set forth in claim 4 which further comprises means for feeding a calibrating gas to the rapid analyzing means to calibrate the analyzing means prior to analyzing of the respiratory gases of each patient.

6. The monitoring system as set forth in claim 1 which further comprises means responsive to the development of an O2 waveform from the rapid analyzing means for counting the respiratory rate of the patient whose respiration gases are being sampled and monitored.

7. The monitoring system as set forth in claim 1 wherein the analyzing means is a mass spectrometer.

8. The monitoring system as set forth in claim 1 which further comprises means for simultaneous measurement of respiratory gas flow.

9. The monitoring system as set forth in claim 8 wherein the means for measurement of respiratory gas flow is a pneumotachometer.

10. The monitoring system as set forth in claim 8 wherein the means for measuring respiratory gas flow is a spirometer.

11. A gas monitoring system, which comprises:

a plurality of gas sampling lines each of which is connectable to the airway of a respective one of a plurality of gas systems whose gases are to be sampled, the systems being independent of each other, means for rapidly analyzing the sampled gases and for developing waveforms in response to the analyzation of the sampled gases, means connected in each of the sampling lines for opening and closing the lines to permit and prevent, respectively, flow of the sampled gases therethrough, means for coupling each of the sampling lines to the analyzing means, means for selectively operating the opening and closing means to permit the selective linking of each of the sampling lines with the analyzing means independent of the remaining sampling lines, and means responsive to the developed waveforms for developing signal levels porportional to and representative of monitored values of the sampled gases.

12. A gas monitoring system as recited in claim 11, which further comprises means responsive to the developed signal levels for displaying in visual form an indication of such levels as a representation of the monitored values of the sampled gases.

13. A gas monitoring system as recited in claim 11, which further comprises means for automatically and periodically controlling the operating means to permit automatic monitoring of each of the plurality of gas systems independent of the remaining gas systems.

14. A gas monitoring system as recited in claim 13 wherein the controlling means includes:

means for selectively scanning the opening and closing means, and means for producing step command signals to operate the scanning means in a predetermined manner to monitor the sampling lines as desired.

15. A gas monitoring system as recited in claim 11, wherein the analyzing means is a mass spectrometer.

16. A gas monitoring system as recited in claim 11 wherein the opening and closing means includes a plurality of valves each of which is connected serially in a respective one of the sampling lines.

17. A gas monitoring system as recited in claim 16, wherein:

the operating means includes a plurality of solenoids each of which is connected to a respective one of the valves, and electrical control means for selectively operating the solenoids independently of the remaining solenoids to permit selection of one of the sampling lines.

18. A gas monitoring system as recited in claim 17, which further compriSes means for automatically operating the electrical control means in a predetermined manner to selectively operate the solenoids in a selected sequence so that sampled gases of the plurality of systems are fed to the analyzing means in a predetermined sequential manner.

19. A gas monitoring system as recited in claim 11 wherein the developed waveforms are analog waveforms and the signal levels developing means includes a plurality of analog filters which produce steady voltage levels proportional to maxima and minima levels of the waveforms developed by the analyzing means.

20. A gas monitoring system as recited in claim 11 wherein the analyzing means includes means for analyzing sampled gases which include inspired O2 gases and expired CO2 gases, and the waveforms developed by the analyzing means are analog waveforms representative of fractional concentrations of the inspired O2 gases and expired CO2 gases.

21. A gas monitoring system as recited in claim 20 wherein the signal levels developing means includes a plurality of signal conditioners which in response to the analog waveforms developed by the analyzing means develop signals representative of fractional concentrations of inspired O2 gases, end-expired O2 gases and expired CO2 gases.

22. A gas monitoring system as recited in claim 21 wherein the signals developed by the signal conditioners are in analog form, and which further comprises:

means responsive to the analog signals developed by the plurality of signal conditioners for converting the analog signals to digital signals representative of fractional concentrations of inspired O2 gases, end-expired O2 gases and expired CO2 gases, and means for scanning the plurality of signal conditioners and for selectively coupling the analog signals of the signal conditioners to the converting means.

23. A gas monitoring system as recited in claim 22, which further comprises means for automatically controlling the operation of the scanning and selective coupling means to permit the monitoring of the signal conditioners in a predetermined manner.

24. A gas monitoring system as recited in claim 21 wherein each of the plurality of signal conditioners are analog filters which produce steady voltage levels proportional to maxima and minima levels of the waveforms developed by the analyzing means.

25. A gas monitoring system as recited in claim 20, which further comprises means for computing the respiratory rate of each of the plurality of gas systems in response to the expired CO2 fractional concentration waveforms developed by the analyzing means.

26. A gas monitoring system as recited in claim 25, wherein the computing means includes:

a circuit operable at specific levels of each expired CO2 waveform for producing an output pulse representative of each respiration of the gas system being analyzed, a binary counter responsive to each pulse produced by the circuit for producing successive counts in binary digital form, and a summing circuit responsive to the binary digital counts of the counter for summing the counts and developing an analog voltage level representative of the respiratory rate of the gas system being analyzed.

27. A gas monitoring system as recited in claim 11 which further comprises means located in each of the sampling lines of each of the gas systems for measuring the flow of respiratory gases through the sampling line.

28. A gas monitoring system as recited in claim 11 which further comprises means for indicating which sampling line is linked to the analyzing means at any given instant.

29. A gas monitoring system as recited in claim 11 wherein the signal levels developed by the signal levels developing means are in analog form and which further comprises means responsive to the developed analog signal levels for converting the analog levels to digital signals representative of the monitored valueS of the sampled gases.