Hepato-splanchnic Blood Flow and Oxygen Extraction Capabilities during Experimental Tamponade: Effects of Endotoxin

We studied the hepato-splanchnic vascular response and changes in O2extraction capabilities to a reduction in blood flow following endotoxemia. Fourteen anesthetized and mechanically ventilated dogs were divided into two groups of seven each. Group 1 received 2 mg/kg ofE. coliendotoxin, and group 2 served as a control. After initial fluid resuscitation following endotoxic shock, regional blood flow estimated by an ultrasonic technique increased similarly in the hepatic artery, portal vein, and mesenteric artery, but microvascular blood flow estimated by a laser Doppler technique was lower in the liver than in the intestinal mucosa. When blood flow was reduced by cardiac tamponade, endotoxin-treated animals had greater whole body and regional critical O2delivery (DO2crit) and lower whole body, liver, and intestinal critical O2extraction ratios (O2ERcrit). DO2critwas higher in the liver than in intestine but O2ERcritwas similar in the two organs. Whole bodyDO2critat the onset of organ O2supply dependency was similar under control (9.4 ± 1.9 mL/kg · min for whole body, 10.3 ± 4.7 mL/kg · min for liver, and 10.0 ± 2.6 mL/kg · min for intestine) and endotoxic conditions (13.6 ± 3.2 mL/kg · min for whole body, 15.6 ± 2.7 mL/kg · min for liver, and 15.4 ± 8.7 mL/kg · min for intestine). We conclude that fluid-resuscitated endotoxic shock in dogs is characterized by blood flow redistribution within the liver and intestine. Microvascular depression may be more severe in the liver than in the intestinal mucosa, although the whole body, the liver, and the intestine became O2supply-dependent simultaneously.