Oral clonidine premedication reduces induction dose and prolongs awakening time from propofol-nitrous oxide anesthesia

Abstract

Purpose: To evaluate whether oral clonidine premedication affects the induction dose of propofol and awakening time from epidural and propofol anesthesia. Methods: Thirty-nine female patients (ASA I or II) were randomly allocated to receive 5 μg·kg-1 clonidine po or no clonidine 90 min before induction of anesthesia. After epidural anesthesia was achieved with lidocaine, general anesthesia was induced with continuous iv infusion of propofol at a rate of 50 mg·min-1 until loss of eyelash reflex and responses to verbal commands, which were judged by a blinded observer. After a laryngeal mask airway was inserted, anesthesia was maintained with N2O 67%, O2 33% and propofol adjusted to maintain hemodynamic stability. After completion of surgery, a blinded observer recorded the time from discontinuance of propofol and N2O until the patient was awake and responsive (awakening time), and then, the laryngeal mask airway was removed. Results: The induction dose of propofol in the clonidine group (1.4 ± 0.3 mg) was less than that in the control group (1.9 ± 0.4 mg, P < 0.05), while the awakening time of the clonidine group (470 ± 145 sec) was longer than that of the control group (329 ± 123 sec. P < 0.05). Conclusion: Premedication with 5 μg·kg-1 clonidine po reduced the induction dose of propofol, but delayed emergence from propofol anesthesia.