The effectiveness of oral clonidine as a sedative/anxiolytic and as a drug to blunt the hemodynamic responses to laryngoscopy.

STUDY OBJECTIVE

To determine the effects of oral clonidine premedication on sedative, anxiolytic, and hemodynamic responses during the immediate preoperative period, laryngoscopy/intubation, and postanesthetic recovery.

DESIGN

Randomized double-blind assignment to one of four treatment groups (clonidine 0.1 mg, clonidine 0.2 mg, triazolam 0.25 mg, or placebo); n = 10 per group.

SETTING

Inpatient surgery in a university-staffed tertiary center.

PATIENTS

Forty ASA physical status I and II adults of both sexes scheduled for a variety of procedures requiring general anesthesia.

INTERVENTIONS

Anxiety and sedation scored on ordinal scale at time of treatment and 90 minutes later, just prior to anesthetic induction. Standardized induction protocol with automated hemodynamic monitoring at 1-minute intervals and a 45-second laryngoscopy to ensure a vigorous stress response.

MEASUREMENTS AND MAIN RESULTS

Triazolam and both doses of clonidine increased sedation at 90 minutes both absolutely and compared with a placebo. Clonidine 0.2 mg decreased anxiety absolutely at 90 minutes but no more than a placebo. Clonidine 0.2 mg decreased systolic, mean, and diastolic blood pressures (BPs) but not heart rate (HR) at 90 minutes. Clonidine 0.2 mg also blunted the increase in systolic blood pressure (SP) [but not in diastolic blood pressure (DP) or HR] that accompanied laryngoscopy. There were no treatment differences in postanesthetic hemodynamics or duration of recovery.

CONCLUSIONS

Oral clonidine 0.2 mg was effective in reducing the level of behavioral and hemodynamic responses preoperatively and in blunting systolic hypertension produced by prolonged laryngoscopy.