Haemodynamic comparison of sevoflurane and isoflurane anaesthesia in surgical patients

To compare the haemodynamic responses to surgical incision during sevoflurane and isoflurane anaesthesia and to compare the haemodynamic effects of each anaesthetic alone with those obtained using an equipotent mixture of each anaesthetic plus N2O during steady-state surgical stimulation.

Twenty-four patients undergoing gastrectomy were randomized to receive sevoflurane (n = 12) or isoflurane (n = 12). At 1.5 MAC, haemodynamic measurements were performed before and after surgical incision. During intestinal anastomosis, patients in each group were given (in random order) either 1.5 MAC of the designated anaesthetic or 0.85 MAC of the volatile plus 0.65 MAC N2O. Haemodynamic measurements were repeated under each condition.

One patient in the sevoflurane group and two in the isoflurane group were excluded from the incision study because of hypotension. In both groups, incision increased the heart rate (HR), mean arterial pressure, mean pulmonary arterial pressure (MPAP), pulmonary capillary wedge pressure (PCWP), cardiac index, and systemic vascular resistance index (SVRI). There were no intergroup differences in the effects of incision. Inclusion of N2O resulted in an increase of MPAP (P < 0.05) in both groups, an increase of central venous pressure and PCWP in the sevoflurane group (P < 0.005), and a decrease of HR (P < 0.005) and an increase of SVRI (P < 0.05) in the isoflurane group. There were no intergroup differences in the effects of N2O.

At 1.5 MAC, sevoflurane and isoflurane do not prevent the haemodynamic response to incision. The haemodynamic effects of each volatile anaesthetic with N2O are minimal compared with those of equi-MAC volatile alone.