Measurement of intraluminal pressure from external pressure with strain transducers

¹ Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington

In an effort to find a means of recording absolute systemic arterial pressure from the skin surface, steady pressures in rubber-walled models were recorded with external pressure-sensing devices. The recorded pressure at which a plateau appeared was dependent on the degree of stretch in the wall of the pressure source. Distortion of the wall of the source by the pressure sensor resulted in a recorded curve with no plateau. The area of the sensor was critical; those with diameters greater than that of the source recorded only part of the internal pressure. When the diameter of the sensor was less than that of the source, a fairly linear relationship between recorded and source pressure could be obtained, but interposition of sponge rubber to simulate tissues lying between the artery and the body surface produced nonlinear responses. It was concluded that external sensors are adequate to record the waveforms of arterial pressure but cannot be reliably calibrated to provide accurate measurement of its level.

Submitted on July 8, 1963