Effect of Fluctuations in Arterial Pressure on the Validity of Automatic Pulse Count Records

Abstract

For a normal person alighting from a step several inches high, fluctuations of his bodily acceleration were shown to be of the order of 3 g. Simple hydrodynamical theory would predict a resulting fluctuation in arterial pressure in the carotid arteries of the order of 70 mm. Hg, after allowing for fractional losses, and of a slightly lower value in the brachial artery. The latter prediction was experimentally verified. Serious artefacts may arise from this, caused by the use of automatic ear-lobe pulse-counters which count fluctuations in ear capillary blood flow.