Oral clonidine premedication reduces propofol requirement for laryngeal mask airway insertion.
OBJECTIVE
To 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.


METHODS
After 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.


RESULTS
The 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).


CONCLUSIONS
Oral clonidine premedication reduces propofol requirement for LMA insertion.
Department of Anesthesia, Akita University School of Medicine, Akita-shi, Akita-ken, Japan.
T
T
Goyagi
M
M
Tanaka
T
T
Nishikawa
D000284:Administration, Oral; D000328:Adult; D000700:Analgesics / Q000627:therapeutic use*; D000769:Anesthesia, Inhalation / Q000379:methods*; D018686:Anesthetics, Intravenous / Q000627:therapeutic use*; D003000:Clonidine / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D006801:Humans; D007044:Hysterectomy; D017214:Laryngeal Masks; D008875:Middle Aged; D011229:Preanesthetic Medication; D015742:Propofol / Q000627:therapeutic use*
D000700:Analgesics; D018686:Anesthetics, Intravenous; D003000:Clonidine; D015742:Propofol