Organ blood flow and the cause of death following massive hemorrhage

We tested the hypothesis that death occurring shortly after massive hemorrhage can be attributed to the development of positive feedback loops arising from deficient blood flow to one or more vital organs such as the heart, brain, and respiratory muscles. The radiomicrosphere technique was used to measure organ blood flow in unmedicated, chronically instrumented swine subjected to removal of 41 ml/kg of blood in 15 min. Ten swine survived the experiments and five died, all within 2 hr after completion of hemorrhage. Cardiac output but not blood pressure was lower in nonsurvivors (mean +/- 1 SD). No difference was found in regard to blood flows to the heart, brain, and diaphragm (flow in ml/gm/min) between survivors and nonsurvivors. Although blood flow posthemorrhage to kidney, organs of the splanchnic bed, and the carcass tended to be greater in survivors compared to nonsurvivors, the difference reached statistical significance only in the small intestine. We conclude that in this model there is no evidence that death following massive hemorrhage results from positive feedback loops arising from deficient perfusion of the coronary or cerebral circulation. It is more likely that death results from abnormalities arising in the carcass and/or splanchnic bed.