Maintenance of and recovery from anaesthesia in elderly patients. A clinical comparison between sevoflurane and isoflurane.

BACKGROUND: The goal of this multicenter, prospective, randomized clinical investigation was to compare the clinical efficacy and safety of sevoflurane and isoflurane during the maintenance of and the recovery from general anaesthesia in elderly patients. METHODS: With the approval of the Ethical Committee and the patient informed consent, 104 ASA physical status II-III patients, aged more than 65 years, were randomized in order to receive either isofluorane (n = 54) or sevoflurane (n = 50) as the main general anaesthetic. After an oral diazepam (0.1-0.2 mg kg-1) and intramuscular atropine (0.007-0.01 mg kg-1) premedication, anaesthesia was induced intravenously and then maintained by adjusting the end-tidal concentrations of the inhalation agent for the maintainance of cardiovascular stability. At the moment of the last skin suture the inhalational agents were discontinued and the neuromuscular block was reversed. The following times were recorded: time of extubation, time of eyes opening, time of command response and readiness for discharge. The occurrence of untoward event throughout the study was also recorded. Before surgery and 24 hr after the procedure, blood was collected in order to assess renal function. RESULTS: No differences in demography, duration of surgery, exposure to the volatile anaesthetic, and renal function laboratory values were observed between the two groups. The time of extubation (median: 8 min versus 11 min, p 30% of baseline values) was observed in 16 patients receiving isoflurane (29%) and only in 5 patients receiving sevoflurane (10%) (p < 0.02). DISCUSSION: When used in elderly patients undergoing operations of intermediate duration, sevoflurane provides a more rapid emergence from anaesthesia with a faster fulfillment of discharging criteria, and a more stable cardiovascular homeostasis than isoflurane. Renal function also appears to be equally well preserved with both anaesthetics.