Different effects of early endotoxaemia on hepatic and small intestinal oxygenation in pigs

Objective Study on simultaneous O₂ supply/uptake relationships in liver and gut during endotoxaemia, to determine whether signs of dysoxia develop uniformly in the splanchnic region.Design Animal study to assess the early effects of endotoxaemia on oxygenation of both liver and small intestine.Interventions Eight anaesthetized pigs received a continuous portal venous infusion of lipopolysaccharide (0.5 g·kg^–1·h^–1) for 6 h. Systemic, pulmonary and splanchnic haemodynamics as well as systemic and splanchnic O₂ supply/uptake relationships were determined.Results There was a multiphasic haemodynamic response pattern characterized by an early (within the 1st h) and a subsequent more prolonged phase (between the 2nd and 6th h) of decreases and recovery of hepatic arterial, portal venous and superior mesenteric arterial blood flows (electromagnetic flow probes) and splanchnic O₂ deliveries. Unrelated to perfusion pressure and O₂ delivery, there were early and sustained decreases in ileal mucosal surface partial pressure of oxygen (PO₂) (multiwire PO₂ electrode) and pH (tonometry). This was not reflected by ileal serosal surface PO₂, O₂ uptake and arteriomesenteric venous pH and partial pressure of carbon dioxide (PCO₂) gradients. There was little evidence of concomitant hepatic dysoxia as evaluated by surface PO₂.Conclusions The study demonstrates early and sustained regional (mucosa) intestinal hypoxia with little evidence of simultaneous hepatic dysoxia during initial endotoxaemia.