A SYSTEM AND METHOD FOR MONITORING A PROGRESSIVE SEQUENCE OF PHYSIOLOGICAL CONDITIONS

• US 3,584,618 A
• Filed: 03/17/1969
• Issued: 06/15/1971
• Est. Priority Date: 03/17/1969
• Status: Expired due to Term

• Current Assignee: Clyde J. Reinhard, Gordon R. Justus, Kenneth L. Kearns
• Original Assignee: Clyde J. Reinhard, Gordon R. Justus, Kenneth L. Kearns
• Inventors: Reinhard, Clyde J., Justus, Gordon R., Kearns, Kenneth L.
• Application Number:
  US04/807,861
• Time in Patent Office: 820 Days
• US Class Current: 600/536
• CPC Class Codes: A61B 5/0809 by impedance pneumography
• CPC Class Codes: A61B 5/7405 using sound
• CPC Class Codes: C10M 2201/062 Oxides; Hydroxides; Carbonates or bicarbonates
• CPC Class Codes: C10M 2205/024 Propene
• CPC Class Codes: C10M 2205/026 Butene

Abstract

An alarm circuit for a respiration monitoring system which, in response to electrical signals indicative of the occurrence of a breath, determines whether the time interval between successive breaths exceeds a first preset time interval. When this occurs, a warning indicator is activated and the circuit begins monitoring the respiration rate. If the rate during a second preset time interval is less than a first preset rate, a low rate indicator is activated and the circuit determines whether the respiration rate during the second time interval and a third preset time interval is less than a second preset rate which is greater than the first preset rate. If the rate exceeds the second preset rate, the warning and low rate indicators are deactivated. If the rate is less than the second preset rate, an apnea indicator is activated.

Claims

1. In a physiological monitoring system wherein transducer means generates successive electrical signals indicative of the occurrence of a specific physiological activity, apparatus responsive to said electrical signals for indicating a multiplicity of physiological conditions comprising timing means responsive to the time interval between said successive electrical signals for generating a first output signal when said time interval exceeds a first predetermined interval;

first rate sensing means activated upon the occurrence of said first output signal and responsive to the rate of said electrical signals for generating a second output signal when said rate exceeds a first predetermined rate and for generating a third output signal when said rate is less than said first predetermined rate; and

output means connected to said timing and rate sensing means and responsive to said first, second and third output signals for indicating the occurrence of selected physiological conditions.

2. The physiological monitoring system of claim 1 wherein said output means includes:

first output means responsive to said first and second output signals for indicating a first physiological condition upon the occurrence of said first output signal and for indicating the absence of said first physiological condition upon the occurrence of said second output signal.

3. The physiological monitoring system of claim 2 wherein said output means includes:

second output means responsive to said third output signal for indicating a second physiological condition upon the occurrence of said third output signal.

4. The physiological monitoring system of claim 3 further comprising:

second rate sensing means connected to said first rate sensing means and responsive to the rate of said electrical signals and activated upon the occurrence of said third output signal for generating a fourth output signal when said rate exceeds a second predetermined rate and for generating a fifth output signal when said rate is less than said second predetermined rate.

5. The physiological monitoring system of claim 4 wherein said second predetermined rate is greater than said first predetermined rate.

6. The physiological monitoring system of claim 4 wherein said second output means is disabled by said fourth output signal.

7. The physiological monitoring system of claim 6 further comprising:

third output means connected to said second rate sensing means, said third output means being enabled by said fifth output signal.

8. The physiological monitoring system of claim 7 wherein said first output means comprises a visual indicating device, said second output means comprises a pulsing audio tone generator, and said third output means comprises a solid audio tone generator.

9. The physiological monitoring system of claim 1 further comprising:

second rate sensing means connected to said first rate sensing means and activated by said third output signal and responsive to the rate of said electrical signals for generating a fourth output signal when said rate exceeds a second predetermined rate and fOr generating a fifth output signal when said rate is less than said second predetermined rate, said second predetermined rate being greater than said first predetermined rate.

10. The physiological monitoring system of claim 9 wherein said output means includes:

first, second and third output means, said first output means being connected to said timing means and enabled by said first output signal to indicate a first physiological condition, said second output means being connected to said first rate sensing means and enabled by said third output signal to indicate a second physiological condition, and said third output means being connected to said second rate sensing means and enabled by said fifth output signal to indicate a third physiological condition.

11. The physiological monitoring system of claim 10 wherein said first output means is disabled by said second output signal, and said second output means is disabled by said fourth output signal.

12. The physiological monitoring system of claim 11 wherein said first and second output means are automatically disabled by said second and fourth output signals, respectively, and further comprising:

manually operable means connected to said third output means for disabling said third output means.

13. The physiological monitoring system of claim 10 wherein said first, second and third output means comprise visual display devices.

14. The physiological monitoring system of claim 13 wherein said second output means further comprises a pulsing audio tone generator and wherein said third output means further comprises a solid audio tone generator.

15. The physiological monitoring system of claim 9 wherein said first rate sensing means comprises:

first bistable means having first and second stable states and first and second input terminals, said first bistable means being switched to said first stable state by a signal at said first input terminal and being switched to said second stable state by a signal at said second input terminal, said first output signal being applied to said first input terminal;

a first preset timer for timing a second predetermined time interval and for generating said third output signal at the end of said second time interval, said first timer being connected to said first bistable means and enabled when said first bistable means is switched to said first stable state, said timer being disabled when said first bistable means is switched to said second stable state; and

first accumulator means responsive to the occurrence of said first output signal for counting the number of electrical signals occurring during said second time interval, said first accumulator means generating said second output signal when the number of counted signals occurring during said second timer interval exceeds a first predetermined number, said second output signal being applied to said second input terminal of said first bistable means to switch said bistable means to said second stable state thereby disabling said first timer.

16. The physiological monitoring system of claim 15 wherein said second rate sensing means comprises:

second bistable means having first and second stable states and first and second input terminals said second bistable means being switched to said first stable state by a signal at said first input terminal switched to said second stable state by a signal at said second input terminal, said third output signal being applied to said first input terminal of said second bistable means;

a second preset timer for timing a third predetermined time interval and for generating said fifth output signal at the end of said third time interval, said second timer being connected to said second bistable means and enabled when said second bistable means is switched to said first stable state, said second timer being disabled when said second bistable means is switched to said second stable state; and

second accumulator means Responsive to the occurrence of said first output signal for counting the number of electrical signals occurring during said second and third time intervals, said second accumulator means generating said fourth output signal when the number of counted signals occurring during said second and third time intervals exceeds a second predetermined number, said fourth output signal being applied to said second input terminal of said second bistable means to switch said second bistable means to said second stable state thereby disabling said second preset timer.

17. The physiological monitoring system of claim 16 wherein said second and third time intervals are equal.

18. The physiological monitoring system of claim 1 wherein said timing means comprises:

a preset timer, said preset timer being reset upon the occurrence of each electrical signal generated in response to the occurrence of the specific physiological activity, said preset timer generating said first output signal if the time interval before the next successive electrical signal exceeds said first predetermined interval.

19. The physiological monitoring system of claim 1 wherein said first rate sensing means comprises:

bistable means having first and second stable states and first and second input terminals, said bistable means being switched to said first stable state by a signal at said first input terminal and being switched to said second stable state by a signal at said second input terminal, said first output signal being applied to said first input terminal;

a preset timer for timing a second predetermined time interval and for generating said third output signal at the end of said second time interval, said timer being connected to said bistable means and being enabled when said bistable means is switched to said first stable state, said timer being disabled when said first bistable means is switched to said second stable state; and

accumulator means responsive to the occurrence of said first output signal for counting the number of electrical signals occurring during said second predetermined time interval, said accumulator means generating said second output signal when the number of counted signals occurring during said second predetermined time interval exceeds a first predetermined number, said second output signal being applied to said second input terminal of said bistable means to switch said bistable means to said second stable state and to disable said first timer.

20. In a respiration monitoring system comprising transducer means for monitoring physiological activity in a subject including respiration and producing a correspondingly varying electrical signal, and means for identifying signal components resulting from respiration and producing a characteristic output signal for each breath, the improvement comprising an alarm circuit responsive to said characteristic output signals for determining whether the breathing pattern of the subject is normal or abnormal, said alarm circuit comprising:

timing means responsive to said characteristic output signals for determining whether the timer period between successive breaths exceeds a first predetermined interval; and

first monitoring means activated by said timing means and responsive to said characteristic output signals and operative when said time period exceeds said first predetermined interval for determining the rate of said output signals during a second predetermined time interval.

21. In a respiration monitoring system according to claim 20, the improvement further comprising:

first output means connected to said timing means and said first monitoring means, said timing means enabling said first output means when the time period between successive output signals exceeds said first predetermined interval.

22. In a respiration monitoring system according to claim 21, the improvement further comprising:

second output means connected to said first monitoring means, said first monitorinG means being operative to enable said second output means when said rate is less than a first predetermined rate during said second time interval, said first monitoring means being operative to disabled said first output means when said rate exceeds said first rate during said second time interval.

23. In a respiration monitoring system according to claim 22, the improvement further comprising:

second monitoring means activated by said timing means and responsive to said characteristic output signals and operative when said time period exceeds said first interval for determining the rate of said output signals during a third predetermined time interval, said third time interval running concurrently with but longer than said second time interval.

24. In a respiration monitoring system according to claim 23, the improvement further comprising:

means for connecting said second monitoring means to said second output means; and

third output means connected to said second monitoring means, said second monitoring means being operative to enable said third output means when said rate is less than a second predetermined rate during said third time interval, said second monitoring means being operative to disable said second output means when said rate exceeds said second rate during said second time interval.

25. In a respiration monitoring system according to claim 24, the improvement wherein said second predetermined rate is greater than said first predetermined rate.

26. In a respiration monitoring system according to claim 24, the improvement wherein said first output means comprises a visual indicating device, said second output means comprises a pulsing audio tone generator, and said third output means comprises a solid audio tone generator.

27. In a respiration monitoring system according to claim 24, the improvement wherein said first and second output means are automatically disabled by said first and second monitoring means, respectively, and further comprising:

manually operable means connected to said third output means for resetting said third output means.

28. A method for monitoring the breathing pattern of a subject and generating warning signals as a function of the extent of abnormality of said pattern comprising the steps of:

sensing the occurrence of each breath;

generating a first warning indication when no breath is sensed during a first time interval;

initiating a second time interval upon the generating of said first warning indication; and

generating a second warning indication when less than a first predetermined number of breaths are sensed during said second time interval.

29. A method according to claim 28 further comprising the steps of:

initiating a third time interval; and

generating a third warning indication when less than a second predetermined number of breaths are sensed during said third time interval.

30. A method according to claim 29 wherein said third time interval begins simultaneously with said second time interval and ends after said second time interval ends.

31. A method according to claim 30 wherein said second predetermined number of breaths is more than twice as great as said first predetermined number of breaths.

32. A method according to claim 29 wherein said third time interval immediately follows said second time interval.

33. A method according to claim 32 wherein said second predetermined number of breaths is greater than said first predetermined number of breaths.