Cardiopulmonary effects of sevoflurane in cats: comparison with isoflurane, halothane, and enflurane

The cardiopulmonary effects of sevoflurane (mean, 2·6, 3·8–3·9 and 5·2 per cent) were compared with those of halothane (1·2, 1·8 and 2·4 per cent), enflurane (2·4, 3·6 and 4·8 per cent) and isoflurane (1·6, 2·4 and 3·2–3·3 per cent) at end-tidal concentrations equivalent to 1, 1·5 and 2 minimal alveolar concentrations (macs) during spontaneous or controlled ventilation (sv or cv) in 57 cats. Cats were assigned to four groups of nine animals each in sv trial and four groups of five or six animals each in cv trial. During sv, respiration rate was decreased by sevoflurane and isoflurane at 2 mac and by enflurane at each mac multiple when compared with control values, whereas halothane increased respiration rate at 2 mac. The degree of hypercapnia and acidosis induced by sevoflurane was not different from that induced by isoflurane and was less than that induced by halothane at 1 to 1·5 mac or enflurane at 2 mac. During sv and cv, four anaesthetics decreased heart rate at 2 mac when compared with control values, but there was no significant difference between anaesthetics. Sevoflurane, like halothane and isoflurane, induced hypotension at 2 mac when compared with 1 mac.