SEVOFLURANE FOR OUTPATIENT ANESTHESIA - C OMPARISON WITH ISOFLURANE

A multicenter, randomized, comparative phase III study evaluating the effect of sevoflurane versus isoflurane in adult outpatients was perfo rmed. The aim of the study was to compare (1) maintenance of anaesthes ia and (2) how rapidly and easily the patients emerge from the anaesth etic and recover. Methods. Outpatients were included who underwent sch eduled surgical procedures of an anticipated duration of up to 3 h and an anticipated length of hospitalization of less than 24 h post-anaes thesia. Five hundred patients were randomly selected to receive either sevoflurane (n = 247) or isoflurane (n = 253), each administered with oxygen (30-50%) in nitrous oxide. Efficacy was evaluated through the measurement of times of recovery parameters and tests like the objecti ve pain-discomfort scale, the visual analogue scale, and the digit sym bol substitution test. Safety was evaluated by monitoring adverse expe rience, clinical laboratory and non-laboratory testing and physical as sessments. Results. No statistical differences were observed between t he two treatment groups with respect to demographics and ASA class. Al l study drug concentrations during each anaesthetic phase were statist ically lower in the sevoflurane (average concentration 0.61 MAC) compa red to the isoflurane (average concentration 0.70 MAC) group. The mean time to emergence was statistically shorter in the sevoflurane group (8.2 min) than in the isoflurane group (9.3 min). The mean time to res ponse to commands (8.5 min vs 9.8 min) and the mean time to orientatio n (10.6 min vs 13.0 min) were also statistically shorter in the sevofl urane than in the isoflurane group. The EEG results showed a faster de crease in delta activity and a faster increase in alpha activity in th e sevoflurane group than in the isoflurane group, indicating faster aw akening. No statistical differences were observed between the two trea tment groups for the mean time to any of the remaining postanaesthesia events. Bradycardia was observed in a statistically higher percentage of patients in the sevoflurane group (6%) than in the isoflurane grou p (2%). No other statistical differences were observed between the two treatment groups concerning the incidence of study drug-related adver se experience. The most common adverse experiences were nausea and vom iting. At all postanaesthesia time points, higher serum inorganic fluo ride concentrations were observed in the sevoflurane (maximum 30.2 mu mol/1) than in the isoflurane group. No clinical or laboratory renal i nsufficiency was noted. Eighty-seven percent of patients in the sevofl urane group would request the same anaesthetic technique compared to o nly 79% of patients in the isoflurane group. Conclusions. Sevoflurane was as safe as isoflurane for anaesthesia in adult outpatients. Patien ts who received sevoflurane had statistically significantly shorter re covery parameters than isoflurane patients.