APPLIED RECORDING FORCE AND NONINVASIVE ARTERIAL PULSES

Arterial pressure pulses are often measured noninvasively, but the inf luence of external recording forces has not been well documented. Acco rdingly, the main goal was to delineate pulse contour and amplitude di stortion with progressively compressive forces applied to an external transducer. Ten young normal male subjects were studied while supine. Pulses were recorded at the end of a normal expiration over a range of forces (0.45-4.29, 0.42N increments) applied in a randomized order ov er first the brachial and then the radial artery. Pulse contours were Fourier analyzed and harmonic powers were normalized to the peak power at the fundamental frequency. Brachial artery pulse amplitudes progre ssively decreased (p = 0.013), whereas, those at the radial artery pea ked at a recording force of 1.79 +/- 0.01N (p < 0.001) and subsequentl y decreased parallel to the brachial data with larger forces. No signi ficant pulse contour distortions occurred at either the brachial or ra dial artery with applied forces of up to 2.18 +/- 0.02 and 2.59 +/- 0. 02N, respectively, as indicated by the similarity of the relative powe r for harmonics 2-7. Radial artery pulses were distorted at and beyond a force of 2.99 +/- 0.01N as indicated by the increased relative powe r of harmonics 3-7 (p < 0.05). Therefore, despite significant alterati ons in pulse amplitude, the relative shape of pulses remains similar o ver a large range of lower recording forces.