Oscillometric blood pressure monitor and method employing non-uniform pressure decrementing steps

Claim 1

Apparatus for automatic measurement of systolic pressure ofa subject comprising: a) an inflatable and deflatable pressure cuff; b) means for inflating said cuff to a predetermined pressure believed to be above systolic pressure; c) pressure transducer means for sensing cuff pressure including oscillation complexes therein; d) deflate means coupled to said cuff for controllably releasing pressure in said cuff; e) and processing means responsively coupled to said cuff pressure sensing means for providing blood pressure related measurements; f) means, responsive to the pressure signalled by said transducer, for generating a signal representative of oscillations complexes; g) complex peak storing means for storing values characterizing peak amplitudes of said complexes at different cuff pressures; h) cuff pressure storing means for storing cuff pressures respectively corresponding to said stored values; and characterized by i) control means for causing said deflate means to employ deflation decrements at least during a substantial portion of the systolic measurement cycle, at a rate in excess of about 7 mmHg/sec.; and j) systolic pressure determining means including i) means for locating the largest complex peak amplitude stored in said complex storing means and the cuff pressure corresponding thereto; ii) means for generating a threshold level as a predetermined fraction of said maximum peak values; iii) means for selecting plural peak amplitudes from those stored in said cuff pressure storing means, said plural peak amplitudes having predetermined relationship to said threshold and predetermined temporal relationship with the cuff pressure corresponding to said largest complex peak amplitude; and iv) determining means for determining systolic pressure from said plural peak amplitudes.