Blood pressure monitoring system

Abstract

Apparatus is disclosed for long-term ambulatory monitoring of blood pressure by an auscultation method, employing a pressurizable cuff and requiring no intervention by the patient. Heartbeats are sensed by ECG electrodes, and a microphone is used to sense the Korotkow sounds as the pressure in the cuff is varied. The presence or absence of a Korotkow sound within a preset interval following each heartbeat is used in determining when the cuff pressure equals the systolic and diastolic pressures. Those pressures are determined in each cycle of operation and are recorded on a continuously-running portable tape recorder, along with the ECG signals. In each cycle of operation, the initial pressure to which the cuff is inflated is based on the systolic pressure measured in the immediately preceding cycle. The pressure in the inflated cuff is thereafter stepped downward in small discrete decrements triggered by successive heartbeats during the measurement phase of each cycle. After both the systolic and diastolic pressures have been determined, the remaining cuff pressure is vented through the same valve that was used to produce the stepwise pressure reduction. After a number of cycles of operation, the magnetic tape is removed from the portable recorder and inserted into an analyzer for high-speed playback and automated plotting of the heart rate and accompanying blood pressure readings on a common chart.