Hepato-splanchnic blood flow and oxygen extraction capabilities during experimental tamponade: Effects of endotoxin

We studied the hepato-splanchnic vascular response and changes in O-2 extra ction capabilities to a reduction in blood flow following endotoxemia. Four teen anesthetized and mechanically ventilated dogs were divided into two gr oups of seven each. Group 1 received 2 mg/kg of E. coli endotoxin, and grou p 2 served as a control. After initial fluid resuscitation following endoto xic shock, regional blood flow estimated by an ultrasonic technique increas ed 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 mucose. When blood flow was reduced by cardiac tamponade, endotoxin-treated animals had greater whole body and reg ional critical O-2 delivery (DO2crit) and lower whole body, liver, and inte stinal critical O-2 extraction ratios (O2ERcrit). DO2crit was higher in the liver than in intestine but O2ERcrit was similar in the two organs. Whole body DO2crit at the onset of organ O-2 supply dependency was similar under control (9.4 +/- 1.9 mL/kg . min for whole body, 10.3 +/- 4.7 mL/kg . min f or liver, and 10.0 +/- 2.6 mL/kg min for intestine) and endotoxic condition s (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-resusc itated endotoxic shock in dogs is characterized by blood flow redistributio n within the liver and intestine. Microvascular depression may be more seve re in the liver than in the intestinal mucosa, although the whole body, the liver, and the intestine became O-2 supply-dependent simultaneously. (C) 1 999 Academic Press.