Resting Peripheral Blood Flow in Hypertensive Subjects.

Abstract

In the course of plethysmographic studies on the peripheral vascular responses of hypertensive patients, it was noted that in about 50% of the cases the resting blood flow in the forearm was much greater than that in subjects with normal blood pressure. Such findings differ from those presented previously by Prinzmetal and Wilson using a similar method, and from those obtained by Pickering, who utilized Stewart's calorimetric procedure. These investigators found that the average blood flow reading for the forearm in a series of hypertensive subjects was no greater than that in a normal group, and on the basis of these observations, together with some confirmatory studies, they concluded that the increased vascular resistance in hypertension is generalized throughout the systemic circulation rather than confined to the splanchnic area. Pickering subsequently pointed out, as did also Stead and Kunkel, that in the light of Grant and Pearson's work, the data included in the two investigations represented not only arterial inflow to the forearm, but also venous return from the hand. It is well known that blood flow through the hand can be affected by a variety of stimuli, and hence readings obtained under such conditions cannot be considered representative of peripheral blood flow generally. Further, as Prinzmetal and Wilson indicated, the opposite conclusion to the one presented by them, namely that the hypertonus is limited to the splanchnic region, could have been drawn if an increase in blood flow had been found in the forearm of hypertensive subjects of the magnitude of 1.5 times the normal figure, i.e., approximately 2.65 cc per min. per 100 cc of limb volume instead of 1.7 cc.