RESUMO
STUDY OBJECTIVE: To evaluate oral clonidine and intravenous esmolol in blunting hemodynamic changes associated with intranasal injection of an epinephrine-containing local anesthetic solution during general anesthesia. DESIGN: Prospective, randomized, double-blind, placebo-controlled study. SETTING: University Medical Center. PATIENTS: 61 consenting ASA physical status I and II outpatients undergoing endoscopic sinus and septoplasty surgery with general anesthesia. INTERVENTIONS: All patients were assigned to receive either a placebo (P) tablet or a similar-appearing tablet containing either clonidine 0.2 mg (C2) or 0.4 mg (C4) orally 1 hour prior to entering the operating room. Prior to the intranasal injection of epinephrine, patients were administered either saline, 0.03 ml.kg-1 followed by an infusion of 0.016 ml.kg-1.min-1, or esmolol (E) 300 micrograms.kg-1 followed by a continuous infusion of 160 micrograms.kg-1.min-1. MEASUREMENTS AND MAIN RESULTS: Arterial blood pressure and heart rate (HR) values were recorded preoperatively, immediately before induction of anesthesia, and at 1-minute intervals after induction of anesthesia until 15 minutes after injection of an epinephrine-containing solution. Level of sedation was assessed using a linear visual analog scale (VAS) prior to oral premedication, immediately before induction of anesthesia, and 30 minutes after anesthesia. There were no significant differences in sedation scores among the four treatment groups. HR following injection of epinephrine-containing solution was significantly less in the C2, C4, and E groups than the placebo group. Compared to P and E treatment groups, MAP values were significantly lower in the C4 treatment group. CONCLUSION: In this healthy, young, nonsmoking outpatient population, premedication with oral clonidine, 0.2 to 0.4 mg, was effective in blunting the acute hemodynamic changes associated with injection of an epinephrine-containing local anesthetic solution during endoscopic sinus or septoplasty surgery.
