Transducer system for the noninvasive recording of arterial pressure contours

Abstract

A transducer system is described that permits noninvasive recordings of the pressure-vs-time arterial profile at any palpable site on the body. A thin (30 μm) piezoelectric polymer film of polyvinylidene fluoride serves as the active element and as the mechanical coupler to the skin. The system has high frequency response and a low frequency cut-off of 0.16 Hz. The active element and its support provides a good mechanical impedance match with the skin. The transducer housing resembles a thick wrist watch and is strapped in place. The complete system is designed to record as many as four simultaneous profiles on a subject. Comparisons of the noninvasive transducer records with records taken with an indwelling catheter indicate congruence of the two signals and the first and second derivatives of the two signals, both when the transducer is applied directly to the skin and when a layer of fat is interposed between the skin and the transducer. The system provides a simple atraumatic means of periodically screening and/or monitoring cardiovascular changes in large populations of subjects and would provide a means of tracking changes induced by therapeutic programs.