Method and apparatus for detection of breathing gas interruptions

• US 4,550,726 A
• Filed: 07/15/1982
• Issued: 11/05/1985
• Est. Priority Date: 07/15/1982
• Status: Expired due to Term

• Current Assignee: Abatis Medical Technologies Limited
• Original Assignee: Saltwater West Research Limited
• Inventors: McEwen, James A.
• Primary Examiner(s): Recla, Henry J.
• Application Number:
  US06/398,716
• Time in Patent Office: 1,209 Days
• Field of Search: 128/202.22, 128/204.21, 128/204.22, 128/204.23
• US Class Current: 128/202.22
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/1025 the O2 concentration
• CPC Class Codes: A61M 2230/43 Composition of exhalation

Abstract

A method for detecting an interruption in the supply of breathing gas to a patient, and apparatus adapted to carry out the method by:

(a) during a reference time period, sensing the pressure in the patient'"'"'s breathing gas;

(b) storing, in memory apparatus, reference breathing information derived from the pressure sensed during the reference time period;

(c) after the reference time period, sensing the pressure in the patient'"'"'s breathing gas;

(d) comparing active breathing information derived from the pressure sensed after the reference time period with the reference breathing information; and,

(e) producing an alarm signal upon detection, during the comparing step, of predetermined variations between the reference breathing information and the active breathing information.

Claims

1. A method for detecting an interruption in the supply of breathing gas to a patient, comprising the steps of:

during a predetermined time period within at least one breathing cycle of a patient initiated solely by an operator and significant of a reference time period during which a normal breathing cycle of the patient occurs, sensing the pressure in the patient'"'"'s breathing gas;

deriving from the pressure sensed during the reference time period, reference breathing information including a reference breathing cycle waveform parameter,

storing, in memory apparatus, the reference breathing information including said reference breathing cycle waveform parameter derived from the pressure sensed during said reference time period;

after said reference time period, sensing the pressure in the patient'"'"'s breathing gas and deriving from the pressure sensed after said reference time period, active breathing information including an active breathing cycle waveform parameter;

comparing the active breathing information including said active breathing cycle waveform parameter derived from the pressure sensed after said reference time period with said reference breathing information including said reference breathing cycle waveform parameter; and

,

producing an alarm signal upon detection, during said comparing step, of a predetermined variation between the breathing cycle waveform parameters of said reference breathing information and said active breathing information, respectively.

2. A method as defined in claim 1, further comprising:

before said storing step, referentially comparing;

the reference breathing information derived from the pressure in the patient'"'"'s breathing gas during a first referential breathing cycle of the patient; and

,

second reference breathing information derived from the pressure in the patient'"'"'s breathing gas during a second referential breathing cycle of the patient which follows said first referential breathing cycle;

proceeding to said storing step if said breathing information derived from said pressure sensed during said first referential breathing cycle differs, by no more than a selected amount, from said breathing information derived from said pressure sensed during said second referential breathing cycle; and

,

repeating said referential comparing step if said reference breathing information derived from said pressure sensed during said first referential breathing cycle differs, by more than a selected amount, from said second reference breathing information derived from said pressure sensed during said second referential breathing cycle.

3. A method as defined in claim 2, further comprising producing said alarm signal upon detection, during said reference time period, of ten successive referential breathing cycles, each having an average pressure which differs, by more than about ten percent, from the average pressure of the immediately following referential breathing cycle.

4. A method as defined in claim 1, wherein said breathing information includes the average breathing gas pressure sensed during the breathing cycle in respect of which said breathing information is derived.

5. A method as defined in claim 4, further comprising producing said alarm signal upon detection, for at least 15 seconds during an active breathing cycle, of breathing gas pressures less than the greater of:

(a) 5 cmH₂ O; and

,

(b) the average breathing gas pressure of said representative normal breathing cycle.

6. A method as defined in claim 1, wherein said breathing information includes the maximum breathing gas pressure sensed during the breathing cycle in respect of which said breathing information is derived.

7. A method as defined in claim 1, wherein said breathing information includes the minimum breathing gas pressure sensed during the breathing cycle in respect of which said breathing information is derived.

8. A method as defined in claim 1, wherein said breathing information includes the ratio of the time, during the breathing cycle in respect of which said breathing information is derived, the patient inspires breathing gas, to the time, during the breathing cycle in respect of which said breathing information is derived, the patient expires breathing gas.

9. A method as defined in claim 1, wherein said breathing information includes the period of the breathing cycle in respect of which said breathing information is derived.

10. A method as defined in claim 1, further comprising producing said alarm signal upon detection of an active breathing cycle having a period longer than about 30 seconds.

11. Apparatus for detecting an interruption in the supply of breathing gas to a patient, said apparatus comprising:

pressure sensing means for sensing the pressure in the patient'"'"'s breathing gas during a breathing cycle of a patient and for producing an output signal representative thereof;

means for deriving breathing information including a reference breathing cycle waveform parameter from said output signal during a predetermined time period within at least one of said breathing cycles significant of a reference time period during which a normal breathing cycle of a patient occurs;

memory means for storing said reference breathing information including said reference breathing cycle waveform parameter derived from said output signal during said reference time period;

means solely actuable by an operator for initiating the reference time period to cause storage of said reference breathing information including said reference breathing cycle waveform parameter;

means for deriving active breathing information including an active breathing cycle waveform parameter from said output signal after said reference time period;

signal comparison means for comparing;

active breathing information including said active breathing cycle waveform parameter derived from said output signal after said reference time period;

with

said reference breathing information including said reference breathing cycle waveform parameter derived from said output signal; and

,

alarm means for producing an alarm signal upon detection, by said comparison means, of a predetermined variation between said breathing cycle waveform parameters of said active breathing information and said reference breathing information.

12. Apparatus as defined in claim 11, wherein said pressure sensing means is an electronic pressure transducer.

13. Apparatus as defined in claim 11, wherein said alarm means comprises an audible alarm for producing an audible alarm signal.

14. Apparatus as defined in claim 13, further comprising alarm suppression means for suppressing said audible alarm signal.

15. Apparatus as defined in claim 14, wherein said alarm suppression means suppresses said audible alarm signal for no more than about 30 seconds.

16. Apparatus as defined in claim 11 or 13, wherein said alarm means further comprises display means for displaying a visible message representative of said predetermined variation, upon detection thereof.

17. Apparatus as defined in claim 11, further comprising status indicator means for indicating an absence of detection, by said comparison means, of said predetermined variation.

18. Apparatus as defined in claim 11, further comprising control means for enabling replacement of said reference breathing information with revised reference breathing information derived from said output signal.

19. Apparatus as defined in claim 18, wherein storage of reference breathing information is prevented while said alarm signal is produced.