Subcutaneous gas tensions closely track ileal mucosal gas tensions in a model of endotoxaemia without anaerobism.

Abstract

OBJECTIVE: Few comparative data exist on the responses of the subcutaneous and splanchnic circulations to evolving endotoxic shock. We therefore compared continuous subcutaneous pO(2) (pO(2sc)) and pCO(2) (pCO(2sc)) with simultaneous continuous gut luminal pCO(2) (pCO(2gi)) in an animal model of endotoxaemia and examined whether changes in gas tensions track tissue energy charge (EC). DESIGN: Prospective observational study. SUBJECTS: Fourteen anaesthetized rats, 7 controls and 7 experimental. INTERVENTIONS: Controls were injected with saline, the experimental group with 20 mg/kg Klebsiella endotoxin. pCO(2sc), pO(2sc), and pCO(2gi) were measured continuously. Plasma lactate concentrations were measured at defined periods during the study. After 2 h ileal segments were snap frozen and assayed for tissue EC. MEASUREMENTS AND RESULTS: Endotoxaemia resulted in a significant decrease in mean arterial blood pressure (132+/-9 to 71+/-20 mmHg) and pO(2sc) (71+/-23 to 33+/-22 torr) and a significant increase in pCO(2gi) (58+/-10 to 90+/-20 torr) and pCO(2sc) (56+/-6 to 81+/-25 torr). During endotoxaemia pCO(2gi) was directly correlated with pCO(2sc) (R (2)=0.5) and inversely correlated with pO(2sc) (R (2)=0.63). Plasma lactate concentrations were significantly elevated from baseline in the endotoxin limb. The mean EC was not significantly different in the two groups. CONCLUSIONS: Both subcutaneous tissue gas tensions and intestinal luminal carbon dioxide tensions are rapidly responsive during evolving hypodynamic endotoxic shock. Alterations in tissue gas tensions were not associated with dysoxia.