The influence of isoflurane on peri-operative endocrine and metabolic stress responses.

Trauma and surgery profoundly affect the circulating concentrations of metabolites and so-called stress hormones, and may thereby directly or indirectly influence recovery. This stress response on the other hand is subject to modification by the anaesthetics employed. We investigated the effects of isoflurane on selected stress parameters in 10 patients undergoing major abdominal surgery and compared them to those in 10 patients receiving halothane. Plasma levels of adrenaline, noradrenaline, cortisol, ACTH, and beta-endorphin, as well as glucose, non-esterified fatty acids (NEFA), and lactate were determined during a pre-operative anaesthesia period as well as intra- and post-operatively. The levels of all parameters remained stable or decreased during the pre-operative anaesthesia period. They increased intra- and/or post-operatively, reaching peak values in the recovery period. Although the changes in both groups were basically similar, we observed lower serum concentrations of cortisol and lactate in the isoflurane group. We conclude that isoflurane and halothane have similar effects on peri-operative changes of endocrine and metabolic parameters, and that neither can effectively block the stress response to major surgery. We found no firm evidence for a stimulatory effect of isoflurane on the parameters studied.