Redistribution of Intraorgan Blood Flow in Acute, Hyperdynamic Porcine Endotoxemia

Abstract

In a standardized porcine model of acute, hyperdynamic endotoxemia the distribution of intraorgan blood flow within heart, kidney and brain was analyzed. Twelve pigs received either short-term (23 min) or long-term (205 min) continuous intravenous infusion of endotoxin (Salmonella abortus equi). A high cardiac output/low peripheral resistance state was maintained throughout the 3.5 h observation period. Total organ blood flow in heart, kidney and brain remained high; however, already small amounts of endotoxin provoked a significant redistribution of intraorgan blood flow within the left ventricle and the kidney. These characteristic alterations were absent in a control group of 5 animals subjected to the same protocol, but receiving 0.9% saline instead of endotoxin. Deterioration of respiratory function developed exclusively after continuous intravenous endotoxin infusion over 205 min, indicating incipient organ failure. Using electron microscopy, endothelial cells swelling and entrapment of blood cells in capillaries of the midmyocardium as well as severe ultrastructural damage in the kidney could be demonstrated already after 90 min of endotoxemia in two additional animals. It is concluded that already in the initial phase of acute endotoxemia, in the presence of high cardiac output and high global organ blood flow microcirculatory deterioration and organ failure develops. As small amounts of endotoxin are capable of inducing these alterations, earliest possible diagnosis of endotoxemia should be achieved in critically ill patients.