Comparison of the effects of clonidine and hydroxyzine on haemodynamic andcatecholamine reactions to microlaryngoscopy

Background and objective This study compares the effect of oral clonidine v s. hydroxyzine on the haemodynamic and catecholamine responses to microlary ngoscopy. Methods Thirty-five ASA II-III patients were included in this double-blind randomized trial. The patients received either hydroxyzine 1 mg kg(-1) (n=1 8) or clonidine 3 mug kg(-1) ( n = 17) for their oral premedication 100 min before an intravenous induction of anaesthesia using propofol (2-3 mg kg(- 1)) and fentanyl (2 mug kg(-1). Arterial pressure and heart rate were measu red before premedication, and throughout the procedure and recovery. Plasma catecholamine levels were determined before premedication, after induction , and 1.5, 30 and 120 min after laryngoscopy. Results Mean arterial pressure was significantly lower after clonidine, whe reas there was no difference in heart rate and plasma catecholamine levels between the two groups. Conclusions Clonidine for premedication significantly decreased mean arteri al pressure during microlaryngoscopy and the following recovery phase but d id not modify the overall haemodynamic response to the suspension microlary ngoscopic nociceptive stimulus.