Attenuation of pulse rate and blood pressure response to laryngoscopy and tracheal intubation by clonidine.

Forty healthy patients (ASA class 1) of both sexes, aged between 20 and 45 years, undergoing routine surgical procedures were included in this double-blind randomized study. They were divided into two groups of 20 each. Patients in group A received no pretreatment, while patients in group B received oral clonidine 5 micrograms kg-1 90 min before induction of anesthesia. All patients received thiopentone (5 mgs kg-1) followed by suxamethonium (1.5 mgs kg-1) to facilitate endotracheal intubation. Control patients showed a significant increase in heart rate and blood pressure; they were significantly lower in the clonidine treated group immediately after intubation (p less than 0.001). The data suggest that the rise in heart rate and blood pressure associated with laryngoscopy and intubation during a routine induction sequence can be attenuated by the use of oral clonidine.