The hepatosplanchnic contribution to hyperlactatemia in endotoxic shock: effects of tissue ischemia

We investigated the role of the hepatosplanchnic region in the hyperlactatemia observed during endotoxic shock. The study included 18 dogs anesthetized with pentobarbital and mechanically ventilated. After baseline measurements, including gut lactate production (GLP), liver lactate uptake (LLU), liver lactate extraction (LLE), and hepatosplanchnic lactate production (HSLP), each dog received 2 mg/kg of E. coli endotoxin. After a second set of measurements, cardiac tamponade was induced in 12 dogs (EDTX + Tamp) by repeated injections of normal saline into the pericardial sac to progressively reduce cardiac output and hepatic blood flow. The six remaining dogs served as septic controls (EDTX). From a net lactate consumer before endotoxin infusion, the gut became a lactate producer after the endotoxin infusion, with GLP increasing from -11.4 +/- 27.0 to 32.9 +/- 38.2 x 10(-3) mEq/min (P < 0.05). LLU increased from 48.1 +/- 26.2 to 86.6 +/- 45.2 x 10(-3) mEq/min (P < 0.05), so that LLE and HSLP did not change. In the EDTX + Tamp group, LLE became negative, and HSLP became positive only when hepatic oxygen delivery reached its critical value during cardiac tamponade. In the EDTX group, LLE remained positive and HSLP negative. In endotoxic shock, GLP is increased, but the liver can metabolize this additional load of lactate, so that the hepatosplanchnic area is not a major source of lactate unless the liver becomes profoundly hypoxic.