Effects of oral clonidine premedication on haemodynamic response to laryngoscopy and tracheal intubation: a clinical trial.

The objective of this study was to evaluate the efficacy of pre-anesthetic orally administration of clonidine on pulse rate and blood stress response to laryngoscopy and tracheal intubation. In a double-blinded, randomized study, 274 ASA I and II subjects with age of 18 to 45 years scheduled for elective surgery under general anesthesia were enrolled. They were randomly allocated to receive oral clonidine (0.2 mg) or placebo as premedication 90-120 min before surgery. All the patients received Succinylcholine (1.5 mg kg(-1)) after induction of anesthesia with Fentanyl (50 microg) and Thiopentone (5 mg kg(-1)). The anesthesia was maintained with halothane (1.5 Mac) in 50% mixture of N2O/O2. Heart rate and systolic blood pressure were recorded before, immediately after and then every 5 min after intubation until 20 min. The Clonidine group showed a significant superiority over placebo in the prevention of increase in systolic blood pressure as well as heart rate over the intubation. A significant difference was observed in both heart rate and systolic blood pressures were significantly higher in Control group at three subsequent measurements following intubation. The results of this study suggest that orally administered clonidine in preanesthetic period, provides more haemodynamic stability and attenuates the stress response to laryngoscopy and intubation.