Whole-body and organ Vo2 changes with enflurane, isoflurane, and halothane

This study was designed to determine the effects of enflurane on canine whole-body and individual organ oxygen consumption (Vo2). Whole-body, myocardial, splanchnic, renal, and skeletal muscle Vo2 were determined at enflurane concentrations equivalent to those used in previous studies with halothane and isoflurane. With increasing enflurane concentrations, whole-body Vo2 decreased progressively. The major component of the decrease was a reduction in myocardial Vo2 resulting from a decrease in myocardial external work as a result of a decrease in cardiac output and arterial pressure. Other organs contributed to a lesser extent to the overall decrease in whole-body Vo2. In each respect the findings with enflurance were not significantly different from those with halothane and isoflurane. These findings did support to the view that anaesthetic agents are not general metabolic depressants and that observed changes in whole-body Vo2 reflect the summated changes in individual organ Vo2 occasioned by an anaesthetic-induced change in organ function and metabolic requirements.