RESUMO
BACKGROUND:Clonidine, an alpha2-adrenergic receptor agonist, has been shown to have a sedative effect and to suppress hemodynamics when used as a premedicant. We evaluated the change of AEP index and hemodynamics after clonidine premedication and induction with propofol. METHODS:The study design was a prospective, randomized, double-blind study. 90 patients who were scheduled for elective surgery were randomly assigned in 3 groups (Group 1, 2 and 3). In groups 2 and 3, the patients were administered 2 microgram/kg or 4 microgram/kg of i.v. clonidine 30 minutes before the induction of propofol anesthesia, respectively. We measured A-lineTM ARX index (AAI), systolic blood pressure, mean arterial pressure, diastolic blood pressure and heart rate at the ward; before the administration of clonidine premedication, before induction, just before intubation and 1 minute after endotracheal intubation, and compared these parameters among the 3 groups. RESULTS:Each dose of clonidine had a suppressive effect before the induction of anesthesia and suppressed hemodynamics successfully during intubation. In groups 2 and 3, the AAI was lower than in group 1 (P < 0.05), but 7 patients had bradycardia and 3 patients had been hypotensive in group 3. CONCLUSIONS: Intravenous injection of 2 microgram/kg clonidine as a premedicant reduced AAI significantly (P < 0.05) compared to the control group, with good hemodynamic stability. Therefore, we believe that AAI can be used to predict hypnotic state during propofol anesthesia.