Automatic oscillometric apparatus and method for measuring blood pressure

• US 6,440,080 B1
• Filed: 09/25/2001
• Issued: 08/27/2002
• Est. Priority Date: 09/25/2001
• Status: Expired due to Fees

• Current Assignee: GE Medical Systems Information Technologies Incorporated (GE Healthcare Technologies, Inc.)
• Original Assignee: GE Medical Systems Information Technologies Incorporated (GE Healthcare Technologies, Inc.)
• Inventors: Booth, John W., Friedman, Bruce A.
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US09/962,380
• Time in Patent Office: 336 Days
• Field of Search: 600/490, 600/493-6
• US Class Current: 600/494
• 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

Abstract

Blood pressure of an human being is read by a process that places a cuff around a portion of the human being'"'"'s body. The cuff is inflated to a predefined pressure which occludes the flood of blood and then the cuff is deflated in a controlled manner. At a plurality of deflation pressure levels, pressure pulses that occur in the cuff are integrated to produce a plurality of integral values. A diastolic pressure of the human being is derived in response to the deflation pressure level at which occurred the integral value that is greatest in magnitude.

Claims

1. A method for indirectly measuring blood pressure comprising:

placing a cuff around a portion of a human being;

varying pressure within the cuff to produce a plurality of cuff pressure levels;

while at a given cuff pressure level, measuring and storing the given cuff pressure level and a plurality of pressure oscillation amplitude values to produce a pressure oscillation waveform, thereby producing a plurality of measurements;

integrating a plurality of pressure oscillations of the pressure oscillation waveform to produce a plurality of integral values; and

deriving a first estimate of diastolic pressure for the human being in response to the cuff pressure level which occurred coincident with the pressure oscillation which produced the integral value that is greatest in magnitude.

2. The method as recited in claim 1 wherein the integrating comprises individually summing pressure oscillation amplitude values which correspond to each of the plurality of pressure oscillations.

3. The method as recited in claim 1 wherein varying pressure within the cuff comprises inflating the cuff.

4. The method as recited in claim 1 wherein varying pressure within the cuff comprises inflating the cuff to a predetermined pressure, and thereafter deflating the cuff to produce the plurality of pressure levels which decrease with time.

5. The method as recited in claim 1 further comprising:

determining a peak value for each pressure oscillation;

identifying a peak value of greatest magnitude;

deriving a second estimate of diastolic pressure which corresponds to the cuff pressure level which occurred coincident with the pressure oscillation that has the peak value of greatest magnitude; and

calculating a diastolic, pressure value as a function of the first estimate of diastolic pressure and the second estimate of diastolic pressure.

6. The method as recited in claim 5 wherein calculating a diastolic pressure value averages the first estimate of diastolic pressure and the second estimate of diastolic pressure.

7. The method as recited in claim 1 further comprising determining an estimated mean arterial pressure for the human being from the plurality of measurements.

8. The method as recited in claim 1 further comprising determining an estimated systolic pressure for the human being from the plurality of measurements.

9. A method for indirectly measuring blood pressure comprising the steps of:

(a) placing a cuff around a portion of a human being'"'"'s body;

(b) inflating the cuff to a predetermined pressure;

(c) periodically measuring pressure in the cuff thereby producing an oscillation pressure waveform;

(d) deflating the cuff by a predetermined increment of pressure, which results in a deflation pressure in the cuff;

(e) repeating the steps (c) and (d) for a plurality of times thereby producing a plurality of oscillation pressure waveforms;

(f) utilizing an oscillometric technique to estimate a systolic pressure and a mean arterial pressure for the human being from a plurality of oscillation amplitudes derived from the oscillation pressure waveforms;

(g) integrating the plurality of measurements taken during each different deflation pressure to derive an integral value for each different deflation pressure; and

(h) deriving a first estimate of diastolic pressure of the human being from the deflation pressure associated with the greatest integral value.

10. The method as recited in claim 9 further comprising:

identifying a separate peak value for each of the plurality of oscillation pressure waveforms;

identifying a peak value of greatest magnitude;

deriving a second estimate of diastolic pressure which corresponds to the deflation pressure which occurred coincident with the oscillation pressure waveform that has the peak value of greatest magnitude; and

calculating a diastolic pressure value as a function of the first estimate of diastolic pressure and the second estimate of diastolic pressure.

11. The method as recited in claim 10 wherein calculating a diastolic pressure value averages the first estimate of diastolic pressure and the second estimate of diastolic pressure.

12. The method as recited in claim 9 wherein the step of integrating the plurality of measurements comprising separately summing a plurality of measurements.

13. The method as recited in claim 9 wherein the step of inflating the cuff to a predetermined pressure comprising activating an electrically operated pump.

14. The method as recited in claim 9 wherein the step of deflating the cuff comprises opening an electrically controlled valve for a period of time.

15. The method as recited in claim 9 wherein deflating the cuff comprises opening an electrically controlled valve, measuring pressure in the cuff, and closing the electrically controlled valve when the pressure in the cuff has decreased by the predetermined increment.

16. An apparatus for producing information indicative of blood pressure of an human being through indirect measurement comprising:

an inflatable cuff;

a pump connected to the cuff, for inflating the cuff to a pressure above systolic pressure of the human being;

a deflating valve connected to the cuff to release fluid from within the cuff thereby varying pressure within the cuff;

a transducer that measures pressure oscillations in the cuff caused by heartbeats of the human being; and

a controller responsive to the transducer for initially energizing the pump to inflate the cuff and subsequently energizing the deflating valve incrementally to deflate the cuff at predetermined pressure increments, wherein the controller integrates the pressure oscillations occasioned by successive heartbeats to produce a plurality of integral values and identifies as a diastolic pressure, the pressure which occurs in the cuff when the pressure oscillations have an integral value of greatest magnitude.

17. The apparatus as recited in claim 16 wherein the controller integrates the pressure oscillations by summing a plurality of measurements of pressure in the cuff acquired from the transducer during each heart beat.

18. The apparatus as recited in claim 16 wherein the controller further includes:

a mechanism that identifies a peak value for the pressure oscillations during each heartbeat,

a calculator that derives a value which is a predefined fraction of the greatest peak value;

means for identifying, as a systolic peak value, a peak value that is closest arithmetically to the greatest peak value; and

an element that determines a systolic pressure of the human being in response to the deflation pressure which occurred during the same heart beat as the systolic peak value.

19. The apparatus as recited in claim 16 wherein the controller activates the deflating valve periodically to deflate the cuff at predetermined pressure increments.

20. The apparatus as recited in claim 16 wherein further including a mechanism that responds to an excessive pressure in the cuff by activating the deflating valve.