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.