Effects of xenon anaesthesia on intestinal oxygenation in acutely instrumented pigs.
Xenon is a narcotic gas that might be able to replace volatile anaesthetics or nitrous oxide due to its favourable pharmacological properties, such as providing haemodynamic stability. Intestinal oxygenation is affected by most volatile anaesthetics as a result of cardiodepressive effects. Reducing oxygenation of the gut might be a factor leading to perioperative organ dysfunction. This animal study was designed to assess the effects of xenon on intestinal oxygenation. After ethical approval, 24 anaesthetized, acutely instrumented pigs were randomly assigned to three groups: nine animals received xenon anaesthesia with inspiratory concentrations of 0, 20, 50 and 65% in addition to their basic i.v. anaesthesia, nine animals served as a study control group, and five animals were used to assess model stability. Measurement of systemic and regional haemodynamic and oxygenation parameters was made 30 min after changing the xenon concentration. Xenon elicited dose-dependent systemic haemodynamic changes: heart rate and cardiac output decreased by 30%, while mean arterial pressure was stable. Superior mesenteric artery blood flow was lower in the xenon group. Vascular resistance of the superior mesenteric artery increased. The small intestinal oxygen supply decreased with increasing xenon concentration; the mucosal tissue oxygen partial pressure decreased but did not reach hypoxic (<5 mm Hg) values. Serosal tissue oxygen partial pressure was maintained. Xenon, in addition to basic i.v. anaesthesia, elicited a decrease in cardiac output and maintained mean arterial pressure. Intestinal oxygenation was maintained, although regional macrohaemodynamic perfusion decreased. Xenon does not impair intestinal oxygenation under physiological conditions.