Mesenteric Circulation in Hemorrhagic Shock

The effect of hemorrhage and of reinfusion on the mesenteric circulation of dogs was determined. During the control period, the average mesenteric vascular resistance was 0.6 P.R.U., and the average mesenteric plasma volume was 100 ml. Hemorrhagc produced an early reduction in mesenteric plasma volume, averaging 50 per cent, without any accompanying change in mesenteric vascular resistance. As the hemorrhagie period progressed, mesenteric vascular resistance rose to a level 120 per cent above control coincidental with the autoinfusion of blood from the hemorrhagc reservoir. With the elevation in mesenteric vascular resistance, mesenteric plasma volume displayed a slight additional decline. Reinfusion produced only a slight and transient recovery of mesenteric vascular resistance and plasma volume. A comparison of mesenteric vascular resistance changes with those of mesenteric plasma volume indicates that no uniform relationship exists. Similar dissociation was seen between mesenteric plasma volume and portal venous pressure. No evidence of pooling of blood in the mesenteric circulation during the induction and development of normovolemic hemorrhagie shock was observed.