HEMODYNAMIC COMPARISON OF SEVOFLURANE AND ISOFLURANE ANESTHESIA IN SURGICAL PATIENTS

Purpose: To compare the haemodynamic responses to surgical incision du ring sevoflurane and isoflurane anaesthesia and to compare the haemody namic effects of each anaesthetic alone with those obtained using an e quipotent mixture of each anaesthetic plus N2O during steady-state sur gical stimulation. Methods: Twenty-four patients undergoing gastrectom y were randomized to receive sevoflurane (n = 12) or isoflurane (n = 1 2). At 1.5 MAC, haemodynamic measurements were performed before and af ter surgical incision. During intestinal anastomosis, patients in each group were given (in random order) either 1.5 MAC of the designated a naesthetic or 0.85 MAC of the volatile plus 0.65 MAC N2O. Haemodynamic measurements were repeated under each condition. Results: One patient in the sevoflurane group and two in the isoflurane group were exclude d from the incision study because of hypotension. in both groups, inci sion increased the heart rate (HR), mean arterial pressure, mean pulmo nary arterial pressure (MPAP), pulmonary capillary wedge pressure (PCW P), cardiac index, and systemic vascular resistance index (SVRI). Ther e 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 differenc es in the effects of N2O. Conclusions: At 1.5 MAC, sevoflurane and iso flurane do not prevent the haemodynamic response to incision. The haem odynamic effects of each volatile anaesthetic with N2O are minimal com pared with those of equi-MAC volatile alone.