Effect of clonidine premedication on haemodynamic responses to fibreoptic bronchoscopy

The usual haemodynamic response to fibreoptic bronchoscopy is an increase in heart rate and blood pressure. We therefore compared, in a prospective, randomised, double-blind study, the effect of two doses of oral clonidine premedication (150 mu g or 300 mu g) with placebo (control group) on the haemodynamic alterations in 62 patients who underwent elective fibreoptic bronchoscopy. Significant increases in blood pressure and heart rate were observed during fibreoptic bronchoscopy only in the control group. Clonidine 150 mu g blunted the haemodynamic response to fibreoptic bronchoscopy (p < 0.05). Significant decreases in systolic blood pressure (< 90 mmHg) were observed in all patients premedicated with 300 mu g clonidine. Throughout the study nine patients (75%) in the 300 pg clonidine group were heated at least once for hypotension. Compared with the control group, time to awakening was significantly longer only in patients premedicated with 300 mu g clonidine. In conclusion, premedication with 150 mu g oral clonidine attenuates haemodynamic responses to fibreoptic bronchoscopy, without causing excessive haemodynamic depression and sedation. These data encourage the administration of clonidine as premedication in patients undergoing fibreoptic bronchoscopy, particularly in those with, or at risk for, coronary artery disease.