Mesenteric circulation in hemorrhagic shock.

THE relationship of portal venous to mesenteric arterial pressure during normovolemic hemorrhagic shock suggests that significant volumes of blood may be pooled out of active circulation in the mesenteric vasculature, thus contributing to the development of irreversibility. This contention has received some support from reports by Delorme et al.,who detected elevation of intestinal red cell volume during hemorrhagic shock by a method which recorded changes in the radioactivity of an intestinal segment. However, other reports have failed to corroborate this change in intestinal blood volume.' 4 Johnson and Selkurt, employing a tissue-weight method, and Reynell et al., utilizing Bromsulphalein sodium (BSP) extraction, failed to detect any frequent elevation in mesenteric and splanchnic blood volumes, respectively. This discrepancy may reflect the fact that the tissue-weight method does not distinguish between vascular and extravascular changes, and the possibility exists that alterations in blood volume may be obscured or negated by changes in extravascular volume. In addition, BSP extraction as an index of splanchnic flow and volume is of questionable value, since BSP removal by the liver is modified during hemorrhagic shock. Since irreversible shock is associated with a reduction in circulating blood volume, and the intestinal vasculature may be a site of significant vascular pooling, the alterations in mesenteric plasma volume during the induction and development of hemorrhagic shock were investigated. Methods Mongrel dogs ranging in weight from 12 to 30 Kg. were used. The animals were anesthetized