Changes in total peripheral resistance during experimental shock

Abstract

The question as to whether the peripheral resistance is increased or decreased in experimental shock has been submitted to repeated investigations, but with contradictory results. 1 On the basis of changing contours of the aortic pressure curves found during the course of experimental shock, Wiggers 1 came to the conclusion that a reduced peripheral resistance obtained early in shock. Apparently contradictory results were however soon reported by Erlanger, Gasser and Gesell 1 who employed, in modified form, the procedure described by Bartlett 2 —a method which measures essentially the rate of saline inflow into the main artery of an organ or limb temporarily isolated from the rest of the arterial circulation. In view of the investigations of Dale and Richards 3 who found that the normal reactions of capillaries are not maintained when an organ is perfused with saline solution, whereas the reactions of the arterioles are retained, it seemed not impossible that Erlanger, Gasser and Gesell by their method tested largely the reaction of the peripheral arterioles in shock, whereas the optical curves analyzed by Wiggers determined peripheral resistance changes due in part also to alterations in the caliber of the capillaries, viscosity of blood, etc. Since evidence has accumuated that the capillaries are particularly affected in shock it is quite possible that their dilation might decrease the total resistance early in shock in spite of the fact that a contraction of their supplying arterioles occurs. If this be true the discordant finds of Wiggers and Erlanger et al. would be explained.

At the suggestion of Doctor Wiggers, we therefore attempted to determine by direct methods how the total peripheral resistance behaved during the course of experimental shock-particular attention being directed to early phases. To do this we employed the method described by Cope 4 which essentially determines the rate that the animal's own blood flows through a limb temporarily isolated from the rest of the arterial circulation.