• T Goyagi, M Tanaka, and T Nishikawa.
• Department of Anesthesia, Akita University School of Medicine, Akita-shi, Akita-ken, Japan.
• Can J Anaesth. 2000 Jul 1;47(7):627-30.

PurposeTo determine the effect of oral clonidine premedication on propofol requirement (ED(50)) for the insertion of the laryngeal mask airway (LMA) in healthy patients undergoing abdominal hysterectomy.MethodsAfter ethics committee approval and informed consent, 41 patients were randomly assigned to receive 5 microg x kg(-1) clonidine po premedication 90 min before entering the operating room (n = 22), or no clonidine (n = 19). To alleviate pain associated with iv propofol, 3 ml lidocaine 2%iv were administered. General anesthesia was induced, 30 sec later, with propofol at a rate of 100 mg x min(-1) (600 ml x hr(-1)) iv. The dose of propofol at which insertion of the LMA was attempted was predetermined by modification of Dixon's up-and-down method with an initial dose of 2.5 mg x kg(-1) and 0.25 mg x kg(-1) as the step size. An LMA was inserted, without muscle relaxants or other adjuvants 90 sec after completion of the propofol injection, by an anesthesiologist blinded to the treatment of the patient.ResultsThe ED(50) of propofol for LMA insertion in clonidine-treated patients (2.0 +/- 0.2 mg x kg(-1), 1.8-2.3 mg x kg(-1) [95% confidence interval]), was less than that in patients without clonidine (2.5 +/- 0.1 mg x kg(-1), 2.4-2.6 mg x kg(-1), P < 0.01).ConclusionOral clonidine premedication reduces propofol requirement for LMA insertion.

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