Pulse signal extraction apparatus for an automatic blood pressure gauge

摘要

An automatic blood pressure gauge generates a signal representing the instantaneous pressure levels in a blood pressure cuff. This pressure signal includes a slowly changing component representing a deflating cuff and a more rapidly changing component representing blood pressure pulses that are mechanically coupled to the cuff. The pressure signal is DC coupled to a microprocessor. The microprocessor filters the pressure signal using a minimum order-statistic filter coupled in cascade with a median order-statistic filter to generate an auxiliary signal having peaks at the starting points of the pulses. This auxiliary signal is used to generate a signal representing the slowly changing component of the pressure signal. The slowly changing component of the pressure signal is subtracted from the pressure signal, leaving only the blood pressure pulse signal. The microprocessor then generates a function representing peaks of the blood pressure pulses versus a corresponding cuff pressure at which they occur. From this function, the microprocessor calculates mean, systolic and diastolic pressures using extrapolation and/or interpolation.