Electronic sphygmomanometer

Abstract

An electronic method and apparatus for automatically determining systolic and diastolic blood pressures and heart rate by accurately detecting, verifying and evaluating the full stream of korotkoff sounds produced as electrical signals from a microphone in a cuff occluding the brachial artery of a patient and the corresponding blood pressure pulse signals which accompany and are precursors to genuine korotkoff sound signals. Blood pressure is measured with the aid of a programmed data processor such as a microprocessor. Waveform analysis is first performed upon the incoming signal waveforms to initially separate true pressure pulses and korotkoff sound signals from a variety of artifact and noise signals and to provide digital pulse streams in memory correctly indicating proper pressure pulse and korotkoff sound occurrences in the time and blood pressure domains, with each pressure pulse proportional in amplitude to the amplitude of the corresponding detected precursor input pressure signal represented and each korotkoff pulse proportional to the negative slope amplitude of the corresponding detected korotkoff sound. The output pulse signal streams are then further analyzed by the digital processing subsystem and compared with each other to additionally remove any noise and artifact signals passed as otherwise misleading genuine signals, to modify and certify the resultant data as either reliable or suspect, to determine heart rate and the most probable values of systolic and diastolic blood pressure levels indicated by the pulse signal streams detected during the measurement cycle.