Method and apparatus for performing non-invasive blood pressure and pulse rate measurements

Abstract

Abstract There is disclosed a blood pressure measuring instrument which utilizes a standard cuff, a bulb for manually pumping up the cuff pressure, and a bleed hole which allows the cuff pressure to decrease at the rate of a few mm Hg per second. A single pressure transducer is in communication with the cuff interior and its output is sampled at a rate much higher than that of the blood pressure pulses. The sampled data, representing the occluding pressure which is being pumped up or bleeding down, with blood pressure pulses superimposed on it, are used to monitor the pump-up procedure and to determine when the artery is completely occluded, to analyze each blood pressure pulse for validating it and for measuring its amplitude, to determine systolic pressure only if the pulse amplitude sequence is a valid sequence, to determine diastolic pressure by comparing decreasing average pulse amplitudes with a threshold level dependent upon maximum pulse amplitude data, and to determine pulse rate in accordance with the number of pulses detected during a fixed time interval. A display circuit guides the operator as to the steps he must take in accordance with the present system state, and it displays both error messages and measurement values. The high reliability of the system is a consequence of the particular methodology employed during each processing step; the high sampling rate allows the system to follow instantaneous pressure changes, and the various analytical routines take full advantage of this capability.

Inventors

• 👤 Michael E. Croslin

Bibliographic Details