Oxygen extraction in pigs subjected to low-dose infusion of endotoxin after major abdominal surgery

Abstract

Background: Sepsis may impair O2 extraction due to blood flow redistribution or decreased utilization of the available oxygen. Methods: We assessed the effect of endotoxemia on systemic and regional O2 extraction and lactate handling in pigs, randomized to receive either endotoxin (0.4 μg kg-1 h-1; n = 10) or saline infusion (controls; n = 9) for 12h. Results: High baseline regional and systemic O2 extraction in the endotoxin group (median 56%, range 45-77%) and in the controls (67%, 49-72%) was maintained until the end of the experiment (endotoxin group: 60%, 50-71%; controls: 60%, 50-74%) despite hypotension and a decrease in stroke volume in endotoxic animals. Hepatic lactate exchange decreased during endotoxemia from 14 μmol kg-1 min-1 (range 10-28 μmol kg-1 min-1) to 10 (range 3-15) μmolkg -1 min-1; P < 0.01), but remained stable in the controls, with 13 μmol min-1 (4-18 μmol min-1) at baseline and 7 μmol min-1 (3-17 μmol min-1) after 12h of saline infusion. Conclusions: The high and sustained oxygen consumption and oxygen extraction in this endotoxemic model speak against any major impairment of hepatosplanchnic or systemic oxygen extraction and oxidative metabolism. The reduced hepatic lactate exchange despite an unchanged hepatic lactate influx suggests altered metabolic activities independent of oxygen consumption. © Acta Anaesthesiologica Scandinavica (2005).