US 4,729,383 A · Method and apparatus for automatically determining blood pressure measurements

Abstract

A blood pressure monitor which automatically and noninvasively measures a patient's systolic, diastolic, and mean arterial blood pressure. Measurements are based on the oscillometric principle. Cuff pressure oscillations are monitored as cuff pressure decreases from a value higher than systolic pressure, down to a value below diastolic pressure. The oscillometric method is the most widely used clinical method of automated noninvasive blood pressure monitoring. The apparatus utilizes a conventional pressure cuff placed about an extremity of the body of the subject and the pressure of air in the cuff is measured at a very low frequency steady pressure, which is called "cuff pressure". A second measurement, which is the oscillation signal after passing through a band pass filter, gives the oscillations in the wall of the artery about which the cuff is placed. The method utilizes an inflatable occlusive cuff which controls the pressure placed on the artery. The signal information that is diagnostically used is the oscillation period and oscillation amplitude as the cuff pressure is reduced monatonically from a value above the systolic pressure to a value below the diastolic pressure. From this data the subject's blood pressure and heart rate values can be determined.

Claims11

Dependent claims

A method for automatically determining, by noninvasive blood pressure measurements, the mean arterial pressure of a person, comprising the steps of:

(a) placing a pressure cuff around an extremity of said person's body and inflating said cuff to a selected cuff pressure;
(b) measuring and storing the amplitude of cuff pressure oscillations (PCA) with each heartbeat of said person;
(c) bleeding down the cuff pressure at a selected substantially linear rate and recording the first amplitude of oscillation (PCA1) at a first cuff pressure;
(d) repeating step (c) for a second lower cuff pressure on the succeeding heartbeat to obtain a second amplitude of oscillation (PCA2) at a second cuff pressure;
(e) determining the difference in amplitudes between PCA2 and PCA1, whereby as long as (PCA2) - (PCA1) is within a selected range of K where K is a predicted differential amplitude the determination is made that no amplitude artifact is present and the amplitude values are valid;
(f) continuing to bleed down the cuff pressure until a peak value of PCA is reached and the amplitude begins to decrease;
(g) continuing to monitor the PCA for a selected period and comparing the successive values of amplitude with the previously observed peak value to determine that said peak value has, in fact, been reached in that at the end of said selected period, the amplitudes have all been less than said peak values;
and
(h) determining the value of the cuff pressure at the time of said peak value of PCA and recording this value of cuff pressure as the mean arterial pressure.

6 more elements

A method for automatically determining the blood pressure of a person, comprising the steps of:

(a) placing a pressure cuff around an extremity of said person's body and inflating said cuff to a selected cuff pressure;
(b) measuring and storing the amplitude of cuff pressure oscillations with each heartbeat of said person;
(c) bleeding down the cuff pressure at a selected substantially linear rate and recording the first amplitude of oscillation at a first cuff pressure;
(d) repeating step (c) for a second lower cuff pressure on the succeeding heartbeat to obtain a second amplitude of oscillation at a second cuff pressure;
(e) for each heart beat prdicting the amplitude of oscillation for the next heart beat;
(f) determining the different in amplitude of oscillation of the next heart beat with the predicted amplitude;
(g) determining whether the difference in measured amplitude of oscillation of the succeeding heart beat and the predicted amplitude is within a preselected range;
(h) if the difference determined in step (g) is within said predicted range, continuing to bleed down the cuff pressure, and if the difference determined in step (g) is not within said predicted range, terminating the cuff pressure bleed down until the difference is within said selected range and the continuing to bleed down the cuff pressure;
(i) means of determining the blood pressure measurements of the person using the cuff pressure;
and
(j) continuing to bleed down the cuff pressure until the desired blood pressure measurements have been made.

8 more elements

Dependencies are inferred from the claim text.

Method and apparatus for automatically determining blood pressure measurements

Life of this patent

Method and apparatus for automatically determining blood pressure measurements

Life of this patent

Abstract

Claims11