Objective: Various drugs including hydroxyzine are preoperatively administered to facilitate the induction of general anaesthesia. We investigated the effect of hydroxyzine premedication on BIS-based etomidate induction of general anaesthesia.
Patients and methods: Sixty-seven ASA I-II consecutive patients were randomly allocated to receive oral hydroxyzine 1.5 mg/kg or placebo, 90 min prior to inducing general anaesthesia using intravenous etomidate alone 0.3 mg/kg. BIS values were continuously recorded. The times for the BIS to decrease to 50 and to loss of eyelid reflex; the evolution of arterial pressure and heart rate; and myoclonia rate and grade were investigated and compared.
Results: The results for the hydroxyzine and placebo groups were similar with respect to: a) time [median (range) (seconds)] to a BIS decrease to 50 [100 (21-266) versus 113 (30-510), P=0.1] and to loss of eyelid reflex [83 (21-210) versus 97 (30-300), P=0.1]; b) myoclonia frequency (yes/no) (9/26 versus 4/28, P=0.2) and grade (P=0.3); the evolution of mean arterial pressure and heart rate (P=0.3).
Conclusion: Oral weight-related hydroxyzine premedication does not alter BIS-based etomidate induction of GA.