Method and apparatus for determining blood pressure using pressure pulse duty cycle

• US 6,767,328 B2
• Filed: 07/31/2002
• Issued: 07/27/2004
• Est. Priority Date: 07/31/2002
• Status: Active Grant

• Current Assignee: GE Medical Systems Information Technologies Incorporated (General Electric Company)
• Original Assignee: GE Medical Systems Information Technologies Incorporated (General Electric Company)
• Inventors: Kulik, Robert Stanley
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US10/064,622
• Publication Number:
  US 20040024323A1
• Time in Patent Office: 727 Days
• Field of Search: 600/485, 600/490, 600/493-6, 600/500
• US Class Current: 600/494
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence

Abstract

A method of processing oscillometric blood pressure pulse data taken from a subject is disclosed. In an exemplary embodiment, the method includes determining a pressure pulse period of a cardiac cycle of the subject and identifying a duration of a pressure pulse detected within the pressure pulse period. Then, a duty cycle of the pressure pulse is calculated with respect to the pressure pulse period, wherein the calculated duty cycle is used to determine selected blood pressure parameters.

Claims

1. A method of processing oscillometric blood pressure pulse data taken from a subject, the method comprising:

determining a pressure pulse period of a cardiac cycle of the subject;

identifying a duration of a pressure pulse detected within said pressure pulse period; and

calculating a duty cycle of said pressure pulse with respect to said pressure pulse period;

wherein said calculated duty cycle is used to determine selected blood pressure parameters.

2. The method of claim 1, wherein said identifying a duration of a pressure pulse within said pressure pulse period is repeated over a plurality of cuff pressure levels applied to the subject.

3. The method of claim 2, further comprising:

identifying a systolic pressure when said duty cycle is between zero and a first designated percentage.

4. The method of claim 2, further comprising:

identifying a diastolic pressure when said duty cycle is at about 100%.

5. The method of claim 2, further comprising:

identifying a mean arterial pressure (MAP) when said duty cycle is at about 50% plus or minus a second designated percentage.

6. The method of claim 1, wherein said identifying a duration of a pressure pulse within said pressure pulse period comprises applying a curve fitting algorithm to the pressure pulse data, thereby determining a pulse portion of said pulse period and a flat portion of said pulse period.

7. A method of measuring the blood pressure of a subject, the method comprising:

inflating a cuff placed over an arm of the subject, thereby applying a plurality of pressure levels thereto;

at each pressure level, obtaining pulse pressure data caused by blood pressure pulses within the arm of the subject; and

calculating, from said pulse pressure data, a duty cycle for a pressure pulse period;

wherein said duty cycle is used to determine selected blood pressure parameters.

8. The method of claim 7, further comprising:

identifying a systolic pressure when said duty cycle is between zero and a first designated percentage;

identifying a diastolic pressure when said duty cycle is at about 100%; and

identifying a mean arterial pressure (MAP) when said duty cycle is at about 50% plus or minus a second designated percentage.

9. The method of claim 8, wherein said calculating a duty cycle from said pulse pressure data comprises identifying a duration of a pressure pulse within a pressure pulse period a pressure pulse period of a cardiac cycle of the subject by applying a curve fitting algorithm to said pressure pulse data, thereby determining a pulse portion of said pulse period and a flat portion of said pulse period.

10. The method of claim 9, wherein:

said cuff is initially inflated to a cuff pressure greater than the estimated systolic pressure of the subject;

said cuff pressure is gradually decreased until said systolic pressure is identified;

said cuff pressure is further gradually decreased until said MAP is identified; and

said cuff pressure is further gradually decreased until said diastolic pressure is identified.

11. The method of claim 9, wherein:

said cuff is initially inflated to a cuff pressure less than the estimated diastolic pressure of the subject;

said cuff pressure is gradually increased until said diastolic pressure is identified;

said cuff pressure is further gradually increased until said MAP is identified; and

said cuff pressure is further gradually increased until said systolic pressure is identified.

12. An apparatus for obtaining the blood pressure of a subject, the apparatus comprising:

an inflatable and deflatable pressure cuff for placement around an arm of the subject;

an inflating apparatus for inflating and pressurizing said pressure cuff;

a deflating apparatus for selectively relieving pressure from said cuff;

a pressure sensing device coupled to said cuff for sensing pulse pressure data caused by blood pressure pulses within the arm of the subject; and

a microprocessor for processing said pulse pressure data by determining duty cycle information for a pressure pulse period at a given cuff pressure level;

wherein said duty cycle information is used to determine selected blood pressure parameters.

13. The apparatus of claim 12, wherein said microprocessor determines said duty cycle information over a plurality of cuff pressure levels applied to the subject.

14. The apparatus of claim 13, wherein:

said microprocessor identifies a systolic pressure when said duty cycle is between zero and a first designated percentage;

said microprocessor further identifies identifying a diastolic pressure when said duty cycle is at about 100%; and

said microprocessor further identifies a mean arterial pressure (MAP) when said duty cycle is at about 50% plus or minus a second designated percentage.

15. The apparatus of claim 14, wherein said microprocessor identifies a duration of a pressure pulse within said pressure pulse period by applying a curve fitting algorithm to the pressure pulse data, thereby determining a pulse portion of said pulse period and a flat portion of said pulse period.

16. The apparatus of claim 15, wherein said curve fitting algorithm is a Levenberg-Marquardt algorithm.

17. A storage medium, comprising:

a machine readable computer program code for processing oscillometric blood pressure pulse data taken from a subject; and

instructions for causing a computer to implement a method, the method further comprising;

determining a pressure pulse period of a cardiac cycle of the subject;

identifying a duration of a pressure pulse detected within said pressure pulse period; and

calculating a duty cycle of said pressure pulse with respect to said pressure pulse period;

wherein said calculated duty cycle is used to determine selected blood pressure parameters.

18. The storage medium of claim 17, wherein said identifying a duration of a pressure pulse within said pressure pulse period is repeated over a plurality of cuff pressure levels applied to the subject.

19. The storage medium of claim 18, wherein the method further comprises:

identifying a systolic pressure when said duty cycle is between zero and a first designated percentage; and

identifying a diastolic pressure when said duty cycle is at about 100%.

20. The storage medium of claim 19, wherein the method further comprises:

identifying a mean arterial pressure (MAP) when said duty cycle is at about 50% plus or minus a second designated percentage.

21. The storage medium of claim 17, wherein said identifying a duration of a pressure pulse within said pressure pulse period comprises applying a curve fitting algorithm to the pressure pulse data, thereby determining a pulse portion of said pulse period and a flat portion of said pulse period.

26. The computer data signal of claim 17, wherein said identifying a duration of a pressure pulse within said pressure pulse period comprises applying a curve fitting algorithm to the pressure pulse data, thereby determining a pulse portion of said pulse period and a flat portion of said pulse period.

22. A computer data signal, comprising:

code configured to cause a processor to implement a method for processing oscillometric blood pressure pulse data taken from a subject, the method further comprising;

determining a pressure pulse period of a cardiac cycle of the subject;

identifying a duration of a pressure pulse detected within said pressure pulse period; and

calculating a duty cycle of said pressure pulse with respect to said pressure pulse period;

wherein said calculated duty cycle is used to determine selected blood pressure parameters.

23. The computer data signal of claim 22, wherein said identifying a duration of a pressure pulse within said pressure pulse period is repeated over a plurality of cuff pressure levels applied to the subject.

24. The computer data signal of claim 23, wherein the method further comprises:

identifying a systolic pressure when said duty cycle is between zero and a first designated percentage; and

identifying a diastolic pressure when said duty cycle is at about 100%.

25. The computer data signal of claim 24, wherein the method further comprises:

identifying a mean arterial pressure (MAP) when said duty cycle is at about 50% plus or minus a second designated percentage.