A Transducer for the Continuous External Measurement of Arterial Blood Pressure

The objective of the research was to develop a transducer to measure arterial blood pressure. It was required that the transducer provide a continuous measure of blood pressure, that it not encumber the subject and that it not require cannulation. Two basic techniques were investigated both analytically and experimentally. First, an indirect measurement of blood pressure based on arterial deflection was attempted. Difficulties of calibration; and sensitivity to physiological changes of skin and tissue around the artery led to the decision to attempt a more direct measurement of arterial blood pressure. In this second approach, arterial deflection is restrained by the transducer and the resultant restraining force is measured. A mathematical model of the transducer artery system was developed and was used as a guide for the design of the experimental prototype transducers. Tests performed on these experimental transducers gave results consistent with the predictions of the model. These transducers have been used to measure blood pressure at large superficial arteries, with results comparable to sphygmomanometer determinations.