A simplified plethysmographic system for the measurement of systemic arterial pressure and peripheral blood flow

Abstract

A mercury strain-gauge plethysmographic system which employs an inexpensive, battery-powered, transistorized DC amplifier and a portable electrocardiographic recorder for the measurement of systolic arterial pressure and blood flow in the limbs is described. The accuracy of the plethysmographic method for determining systemic arterial pressure was demonstrated by comparing it with methods which simultaneously determined direct arterial pressures. The applicability to a variety of clinical problems of both the DC and AC amplifying systems was discussed. The technique has been found to be particularly useful in the preoperative and postoperative study of patients with coarctation of the aorta, in the study of newborn infants and older infants, and in patients of all ages who are in shock or in whom vasoconstriction is marked. It is also anticipated that the plethysmographic system utilizing the transistorized DC amplifier will simplify the measurement of blood flow in the limbs of patients with peripheral vascular disease.