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Oral clonidine premedication reduces induction dose and prolongs awakening time from propofol-nitrous oxide
T Goyagi1, M Tanaka, T Nishikawa
1Department of Anesthesia, Akita University School of Medicine, Akita-city, Japan. t-goyagi@doc.med.akita-u.ac.jp
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 microg x kg(-1) clonidine p.o. or no clonidine 90 min before induction of anesthesia. After epidural anesthesia was achieved with lidocaine, general anesthesia was induced with continuous i.v. infusion of propofol at a rate of 50 mg x 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 microg x kg(-1) clonidine p.o. reduced the induction dose of propofol, but delayed emergence from propofol anesthesia.