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


CONCLUSIONS
Premedication with 5 microg x kg(-1) clonidine p.o. reduced the induction dose of propofol, but delayed emergence from propofol anesthesia.
Goyagi
T
T
Department of Anesthesia, Akita University School of Medicine, Akita-city, Japan. t-goyagi@doc.med.akita-u.ac.jp
Tanaka
M
M
Nishikawa
T
T
D000316:Adrenergic alpha-Agonists; D000328:Adult; D015360:Analgesia, Epidural; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D003000:Clonidine; D004562:Electrocardiography; D005260:Female; D013509:Gynecologic Surgical Procedures; D006801:Humans; D008875:Middle Aged; D009609:Nitrous Oxide / Q000008:administration & dosage; D011229:Preanesthetic Medication; D015742:Propofol / Q000008:administration & dosage; D013997:Time Factors
D000316:Adrenergic alpha-Agonists; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D009609:Nitrous Oxide; D003000:Clonidine; D015742:Propofol