System and method for identifying and correcting abnormal oscillometric pulse waves

• US 5,865,756 A
• Filed: 06/06/1997
• Issued: 02/02/1999
• Est. Priority Date: 06/06/1997
• Status: Expired due to Term

• Current Assignee: Omron Healthcare Company Limited (Omron Corporation)
• Original Assignee: Southwest Research Institute
• Inventors: Peel, Harry H. III
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US08/870,648
• Time in Patent Office: 606 Days
• Field of Search: 600/485, 600/490, 600/492, 600/494, 600/495, 600/515
• US Class Current: 600/490
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts

Abstract

A system and method for identifying and correcting abnormal oscillometric pressure pulse waves detects oscillometric pressure pulse waves produced by a cardiac muscle of a living subject, identifies abnormal oscillometric pressure pulse waves and corrects the amplitudes of oscillometric pressure pulse waves produced by arrhythmias. Thus, the arrhythmic oscillometric pressure pulse waves may be retained by an oscillometric blood-pressure measurement system for use in determining a living subject'"'"'s blood pressure. The system and method of this invention preferably identify abnormal oscillometric pressure pulse waves not produced by arrhythmias as artifacts. The oscillometric pressure pulse waves identified as artifacts may then be rejected by an oscillometric blood-pressure measurement system to improve the accuracy of a blood-pressure measurement.

Claims

1. A system for identifying and correcting abnormal oscillometric pressure pulse waves, comprising:

an oscillometric pulse-wave detection device that detects oscillometric pressure pulse waves produced by a cardiac muscle of a living subject during an oscillometric-blood-pressure measurement, the oscillometric pressure pulse waves propagating through an artery of the living subject; and

an abnormal-pulse correcting circuit that identifies abnormal oscillometric pressure pulse waves detected by the oscillometric pulse-wave detection device and corrects amplitudes of the abnormal oscillometric pressure pulse waves, the oscillometric pressure pulse-wave detection device being operationally coupled to the abnormal-pulse correcting circuit.

2. The system of claim 1, wherein the oscillometric-pulse-wave detection device comprises a constriction device that applies a changing constriction pressure to a portion of the living subject.

3. The system of claim 2, wherein the constriction device comprises:

a cuff wrapable around the portion of the living subject and capable of applying a constriction pressure to the portion of the living subject when the cuff is wrapped around the portion of the living subject; and

a cuff-pressure regulating circuit that controls the constriction pressure applied by the cuff to the portion of the living subject, the cuff pressure regulating circuit changing the constriction pressure applied by the cuff to the portion of the living subject during an oscillometric-blood-pressure measurement.

4. The system of claim 1, further comprising:

a first pulse-wave detection device that detects first pulse waves from a first portion of the living subject;

a second pulse-wave detection device that detects second pulse waves from a second portion of the living subject;

a pulse-period measuring circuit that determines pulse periods based on a time difference between predetermined periodic points on successive pulse waves detected by the first pulse-wave detection device;

a pulse-wave-area determining circuit that determines a pulse-wave area for each pulse wave detected 10 by the second pulse-wave detection device;

a pulse-period-abnormality judging circuit that determines whether the pulse periods determined by the pulse-period measuring circuit are normal or abnormal; and

a pulse-wave-area-abnormality judging circuit that determines whether a pulse-wave area determined by the pulse-wave-area determining circuit is normal or abnormal.

5. The system of claim 4, wherein the abnormal-pulse correcting circuit comprises means for identifying the abnormal oscillometric pressure pulse waves based on the determinations of the pulse-period-abnormality judging circuit and the pulse-wave-area-abnormality judging circuit.

6. The system of claim 4, wherein the first pulse-wave detection device comprises an electrocardiographic waveform detection device.

7. The system of claim 6, wherein the abnormal-pulse-correcting circuit determines an abnormal oscillometric pressure pulse wave was produced by an arrhythmia based on a shape of a corresponding pulse wave detected by the electro-cardiographic waveform device.

8. The system of claim 4, wherein the second pulse-wave detection device comprises an oximeter sensor.

9. The system of claim 8, wherein the oximeter sensor comprises a photoelectric pulse-wave detector.

10. A method of identifying and correcting abnormal oscillometric pressure pulse waves, comprising:

detecting oscillometric pressure pulse waves from a first portion of a living subject;

determining whether a detected oscillometric pressure pulse wave is normal or abnormal;

determining whether the detected abnormal oscillometric pulse wave was produced by an arrhythmia; and

correcting an amplitude of the detected oscillometric pressure pulse wave when it is determined that the detected abnormal oscillometric pressure pulse wave was produced by an arrhythmia.

11. The method of claim 10, further comprising identifying the detected oscillometric pressure pulse wave as an artifact if the detected abnormal oscillometric pulse wave was not produced by an arrhythmia.

12. The method of claim 10, wherein determining whether the detected oscillometric pressure pulse wave is normal or abnormal comprises:

determining pulse periods corresponding to the detected oscillometric pressure pulse waves;

determining pulse-wave areas corresponding to the detected oscillometric pressure pulse waves; and

determining whether a detected oscillometric pressure pulse wave is normal or abnormal based on its corresponding pulse period and pulse-wave area.

13. The method of claim 12, wherein determining pulse periods comprises:

detecting first pulse waves from a second portion of the living subject; and

determining time differences between predetermined periodic points on successive first pulse waves detected from the second portion of the living subject.

14. The method of claim 13, wherein detecting first pulse waves from the second portion of the living subject comprises detecting an electrocardiographic waveform from the second portion of the living subject.

15. The method of claim 14, wherein determining if a detected abnormal oscillometric pressure pulse wave was produced by an arrhythmia comprises:

determining a shape of the electrocardiographic waveform corresponding to the detected abnormal oscillometric pressure pulse wave; and

determining, based on the shape of the corresponding electrocardiographic waveform, whether the detected abnormal oscillometric pressure pulse wave was produced by an arrhythmia.

16. The method of claim 12, wherein determining pulse-wave areas comprises:

detecting first pulse waves from a second portion of the living subject; and

determining a pulse-wave area for each pulse wave detected from the second portion of the living subject.

17. The method of claim 16, wherein detecting first pulse waves from the second portion of the living subject comprises detecting a plethysmographic pulse wave from the second portion of the living subject.

18. The method of claim 16, wherein correcting the amplitude of a detected abnormal oscillometric pressure pulse wave comprises:

determining an amplitude of a previous normal pulse wave detected from the second portion of the living subject;

determining an amplitude of a current pulse wave detected from the second portion of the living subject; and

correcting the amplitude of the detected oscillometric pressure pulse wave based on the amplitude of the previous normal pulse wave and the amplitude of the current pulse wave detected from the second portion of the living subject.

19. The method of claim 18, wherein correcting the amplitude of the detected oscillometric pressure pulse wave uses the relationship:

space="preserve" listing-type="equation">SM.sub.1 (c)=SM.sub.1 (a) Δ

V.sub.f (n)/Δ

V.sub.f (a)!,

where;

SM₁ (c) is a corrected amplitude of the detected oscillometric pressure pulse wave;

SM₁ (a) is the amplitude of the detected oscillometric pressure pulse wave;

Δ

V_f (n) is the amplitude of the previous normal pulse wave detected from the second portion of the living subject; and

Δ

V_f (a) is the amplitude of the current pulse wave detected from the second portion of the living subject.

20. The method of claim 16, further comprising:

determining, when a current oscillometric pressure pulse wave is determined to be normal, if a previous oscillometric pressure pulse wave was produced by an arrhythmia; and

adjusting the amplitude of the current oscillometric pressure pulse wave when it is determined that the previous oscillometric pressure pulse wave was produced by an arrhythmia.

21. The method of claim 20, wherein adjusting the amplitude of the current oscillometric pressure pulse wave comprises:

determining an amplitude of a previous normal pulse wave detected from the second portion of the living subject;

determining an amplitude of a current pulse wave detected from the second portion of the living subject; and

adjusting the amplitude of the current oscillometric pressure pulse wave based on the amplitude of the previous normal pulse wave and the amplitude of the current pulse wave detected from the second portion of the living subject.

22. The method of claim 21, wherein adjusting the amplitude of the current oscillometric pressure pulse wave uses the relationship:

space="preserve" listing-type="equation">SM.sub.1 (c)=SM.sub.1 (a) Δ

V.sub.f (n)/Δ

V.sub.f (a)!,

where;

SM₁ (c) is an adjusted amplitude of the current oscillometric pressure pulse wave amplitude;

SM₁ (a) is the amplitude of the current oscillometric pressure pulse wave;

Δ

V_f (n) is the amplitude of the previous normal pulse wave detected from the second portion of the living subject; and

Δ

V_f (a) is the amplitude of the current pulse wave detected from the second portion of the living subject.

23. A method of identifying and correcting abnormal oscillometric pressure pulse waves, comprising:

detecting oscillometric pressure pulse waves from a first portion of a living subject;

detecting first pulse waves corresponding to the detected oscillometric pressure pulse waves from a second portion of the living subject;

detecting second pulse waves corresponding to the detected oscillometric pressure pulse waves from a third portion of the living subject;

determining time differences between predetermined periodic points on successive first pulse waves detected from the second portion of the living subject;

determining corresponding pulse periods from the determined time differences;

determining corresponding pulse-wave areas from the second pulse waves detected from the third portion of the living subject;

determining whether a detected oscillometric pressure pulse wave is normal or abnormal based on its corresponding pulse period and its corresponding pulse-wave area;

determining whether a detected abnormal oscillometric pressure pulse wave was produced by an arrhythmia; and

correcting the amplitude of the detected oscillometric pressure pulse wave when it is determined that the detected abnormal oscillometric pressure pulse wave was produced by an arrhythmia.

24. The method of claim 23, further comprising identifying the detected oscillometric pressure pulse wave as an artifact if the abnormal oscillometric pressure pulse wave was not produced by an arrhythmia.

25. The method of claim 23, wherein detecting first pulse waves from the second portion of the living subject comprises detecting an electrocardiographic waveform from the second portion of the living subject.

26. The method of claim 25, wherein determining if a detected oscillometric pressure pulse wave was produced by an arrhythmia comprises:

determining a shape of the electrocardiographic waveform corresponding to the detected oscillometric pressure pulse wave; and

determining, based on the shape of the corresponding electrocardiographic waveform, whether the oscillometric pressure pulse wave was produced by an arrhythmia.

27. The method of claim 23, wherein detecting second pulse waves from the third portion of the living subject comprises detecting a plethysmographic pulse wave from the third portion of the living subject.

28. The method of claim 23, wherein correcting the amplitude of a detected oscillometric pressure pulse wave comprises:

determining an amplitude of a previous normal pulse wave detected from the third portion of the living subject;

determining an amplitude of a current pulse wave detected from the third portion of the living subject; and

correcting the amplitude of the detected oscillometric pressure pulse wave based on the amplitude of the previous normal pulse wave and the amplitude of the current pulse wave detected from the third portion of the living subject.

29. The method of claim 28, wherein correcting the amplitude of the detected oscillometric pressure pulse wave uses the relationship:

space="preserve" listing-type="equation">SM.sub.1 (c)=SM.sub.1 (a) Δ

V.sub.f (n)/Δ

V.sub.f (a)!,

where;

SM₁ (c) is a corrected amplitude of the detected oscillometric pressure pulse wave;

SM₁ (a) is the amplitude of the detected oscillometric pressure pulse wave;

Δ

V_f (n) is the amplitude of the previous normal pulse wave detected from the third portion of the living subject; and

Δ

V_f (a) is the amplitude of the current pulse wave detected from the third portion of the living subject.

30. The method of claim 23, further comprising:

determining, when a current oscillometric pressure pulse wave is determined to be normal, if a previous oscillometric pressure pulse wave was produced by an arrhythmia; and

adjusting the amplitude of the current oscillometric pressure pulse wave when it is determined that the previous oscillometric pressure pulse wave was produced by an arrhythmia.

31. The method of claim 30, wherein adjusting the amplitude of the current oscillometric pressure pulse wave comprises:

determining an amplitude of a previous normal pulse wave detected from the third portion of the living subject;

determining an amplitude of a current pulse wave detected from the third portion of the living subject; and

adjusting the amplitude of the current oscillometric pressure pulse wave based on the amplitude of the previous normal pulse wave and the amplitude of the current pulse wave detected from the third portion of the living subject.

32. The method of claim 31, wherein adjusting the amplitude of the current oscillometric pressure pulse wave uses the relationship:

space="preserve" listing-type="equation">SM.sub.1 (c)=SM.sub.1 (a) Δ

V.sub.f (n)/Δ

V.sub.f (a)!,

where;

SM₁ (c) is a corrected amplitude of the current oscillometric pressure pulse wave;

SM₁ (a) is the amplitude of the current oscillometric pressure pulse wave;

Δ

V_f (n) is the amplitude of the previous normal pulse wave detected from the third portion of the living subject; and

Δ

V_f (a) is the amplitude of the current pulse wave detected from the third portion of the living subject.