Blood pressure measuring system

• US 4,751,930 A
• Filed: 06/24/1986
• Issued: 06/21/1988
• Est. Priority Date: 07/12/1985
• Status: Expired due to Term

• Current Assignee: Asahi Matsushita Electric Works Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Asahi Matsushita Electric Works Ltd. (Panasonic Holdings Corporation)
• Inventors: Ishino, Kouichi, Terada, Haruhiro, Iwai, Nobuo
• Primary Examiner(s): Jaworski, Francis J.
• Application Number:
  US06/878,081
• Time in Patent Office: 728 Days
• Field of Search: 128/680-683, 128/687-690, 364/415, 364/417
• 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

An improved blood pressure measuring system based on oscillometric methods utilizes a pressure transducer which provides a varying cuff pressure for occluding the artery of a test subject. The cuff pressure is sampled at a suitable sampling rate to provide a consistent waveform including arterial or blood pressure pulses appearing in sequence during the period of decreasing the occluding pressure. Each blood pressure pulse superimposed upon the cuff pressure is extracted as a pulsating quantity for analyzing the characteristic behavior of such arterial pulse train in order to determine required blood pressure measurements. The pulsating quantity is defined to be an integral of each pulse which value is much larger than the height of the pulse and accordingly, represents an index more readily discernable from possible artifacts having a level in the vicinity of the height level of the pulse.

Claims

1. A blood pressure measuring system comprising:

an occluding cuff attachable to a test subject for applying a varying occluding pressure thereto in the vicinity of an artery;

pressure bleeding means for gradually decreasing the occluding pressure;

pressure transducer means communicating with said occluding cuff for producing an instantaneous cuff pressure measurement which is the sum of an instantaneous static cuff pressure plus an instantaneous pulsating blood pressure indicative of each blood pressure pulse superimposed on said static cuff pressure;

an analog-digital converter coupled to the pressure transducer means for sampling and converting said instantaneous cuff pressure measurement at a suitable sampling rate substantially more frequent than a rate of said blood pressure pulses into corresponding cuff pressure data in digital form, said cuff pressure data being monitored during the course of decreasing the occluding pressure from a point of substantially occluding the artery to a point of substantially unoccluding the artery so that said cuff pressure data are obtained from said instantaneous cuff pressure measuraement including said instantaneous pulsating blood pressure superimposed thereon and showing a generally decreasing relationship with respect to elapsed time;

static cuff pressure deriving means for extracting from said sampled cuff pressure digital data instantaneous static cuff pressures corresponding to the onset of each blood pressure pulse during the course of decreasing the occluding pressure;

arterial pulse component deriving means for extracting from said sample cuff pressure digital data a pulsating quantity representing the intensity of each of said blood pressure pulses appearing in sequence during the courase of decreasing the occluding pressure, said arterial pulse component deriving means operating to integrate values of sampled cuff pressure data for each blood pressure pulse above an offset value corresponding to the instantaneous static cuff pressure at the onset of the pulse over a time period of a portion of the blood pressure pulse so that said pulsating quantity is derived in terms of an integral of each blood pressure pulse above said offset pressure valaue corresponding to the static blood pressure at onset of the associated blood pressure pulse, for a time period starting from the onset of said blood pressure pulse to at least the peak of said blood pressure pulse;

memory means for storing said pulsating quantitites and said sampled values of static cuff pressures associated with each pulsating quantity;

blood pressure determining means which analyzes changes in the successive train of said pulsating quantities and said sampled values so as to determine values of systolic and diastolic pressures which are, respectively, static cuff pressures corresponding to each of said changes in said pulsating quantities; and

display means for displaying the respective values of systolic and diastolic pressures.

2. A blood pressure measuring system as set forth in claim 1, wherein said pulsating quantity is derived as an integral of the entire blood pressure pulse above said offset pressure value.

3. A blood pressure measuring system as set forth in claim 1, wherein said pulsating quantity is derived as an integral of said blood pressure pulse above said offset pressure value for a time period starting from the onset of said blood pressure pulse to the peak of said blood pressure pulse.

4. A blood pressure measuring system as set forth in claim 1, wherein said pulsating quantity is derived as the quotient of an integral of said entire blood pressure pulse above said offset pressure value divided by a limited time interval, said integral of said entire blood pressure pulse being calculated for a time period starting from the onset of said blood pressure pulse to a point at which said blood pressure pulse decreases to the level of said offset pressure value, and said limited time interval corresponding to said time period.

5. A blood pressure measuring system as set forth in claim 1, wherein said pulsating quantity is derived as the quotient of an integral of said blood pressure pulse above said offset pressure value divided by a limited time interval, said integral of said blood pressure pulse being calculated for a time period starting from the onset of said blood pressure pulse to the peak thereof, and said limited time interval corresponding to said time period.