Usefulness of oral hypnotic premedication for volatile induction of anesthesia in adults

Purpose. We investigated the effects of oral hypnotic premedication for smooth anesthetic induction and for the patient's comfort under anesthesia, using sevoflurane without nitrous oxide. Methods. Adult patients were divided into four groups: control (n= 12), triazolam (0.25 mg; n= 12), zopiclone (7.5 mg; n= 12), and clonidine (0.15 mg; n= 12) groups. Each premedication was given to each patient 1 h before the anesthesia. The patients breathed out to residual volume and then the anesthetic mask was fitted. The repeated vital capacity breathing technique was used, with 5% sevoflurane in 10 l·min⁻¹ oxygen. Induction time, specific induction side effects, and acceptability of this technique by the patients were recorded by an independent observer. Results. Induction time in the premedicated groups ranged from 66 ± 12 s (mean ± SD) to 76 ± 14 s, and these values were significantly shorter than that in the control group (92 ± 16 s). The number of patients in whom adverse effects occurred during anesthetic induction was significantly greater in the control group (4 patients; 33%) than in the premedicated groups (1 patient each; 8%). Acceptability of the smell of sevoflurane was significantly higher in the premedicated groups (8–10 patients; 67%–83%) than in the control group (5 patients; 42%). Conclusion. Oral hypnotic premedications with either triazolam (0.25 mg), zopiclone (7.5 mg), or clonidine (0.15 mg) are recommended for smoother volatile anesthetic induction and for the patient's comfort in adults. Received: January 28, 2002 / Accepted: April 26, 2002