Pathophysiological and neurochemical mechanisms of postoperative nausea and vomiting.
BACKGROUND AND OBJECTIVE To compare induction, pre- and post-discharge recovery characteristics and patient preferences between four anaesthetic regimens in adult day-surgery. METHODS Randomized controlled trial. In all, 1158 adults assigned to: propofol induction and maintenance, propofol induction with isoflurane/N2O, or sevoflurane/N2O maintenance, or sevoflurane/N2O alone. We prospectively recorded induction and pre-discharge recovery characteristics, collected 7-day post-discharge recovery characteristics using patient diaries and patient preferences by telephone follow-up. RESULTS Recruitment rate was 73%--of the 425 refusals, 226 were not willing to risk a volatile induction. During induction, excitatory movements and breath holding were more common with sevoflurane only (P < 0.01). Injection pain and hiccup were more common with propofol induction (P < 0.01). In the recovery room and the postoperative ward, both nausea and vomiting were more common with sevoflurane only (P < 0.01). This difference disappeared within 48 h. There was no difference between groups in the mental state on awakening, recovery time, time to discharge or overnight admissions; then was also no difference in pain between the four groups for each of the seven postoperative days (P < 0.01), nor any differences in concentration or forgetfulness. Patients took 6.5 days (95% CI: 6.0-7.0, n = 693) to resume normal activities. Patients who received sevoflurane only were more likely to recall an unpleasant induction and least likely to want the same induction method again (P < 0.01). CONCLUSION Differences in outcome between the four regimens are transient; sevoflurane is not an ideal sole agent for adult day case anaesthesia and, in this setting, patients base their preferences for future anaesthetics on the method of induction.