Comparison of the efficacy of two doses of dexmedetomidine in attenuating the hemodynamic response to intubation in patients undergoing elective cardiac surgery: A randomized double-blinded study

Background and Aims: Transient tachycardia and hypertension associated with laryngoscopy and intubation may be hazardous to patients presenting for cardiac surgery. The α 2 agonist dexmedetomidine may blunt this stress response, but the optimal dose which will accomplish this without causing hypotension and bradycardia is not well established. The primary objective of this study was to compare the efficacy of two doses of dexmedetomidine (0.5 and 1 μg/kg) as a 15 min infusion in attenuating the hemodynamic stress response to laryngoscopy and endotracheal intubation in elective cardiac surgery. Material and Methods: Seventy six patients scheduled for elective cardiac surgery received a single preoperative dose of dexmedetomidine of either 0.5 μg/kg (low dose) or 1 μg/kg (high dose) as a 15-min infusion prior to induction. The hemodynamic response to laryngoscopy and endotracheal intubation (heart rate, systolic blood pressure, mean arterial pressure, and diastolic blood pressure) were recorded at different times. Independent sample t-test, Chi-square test of association, and repeated measures analysis of variance were used to analyze the collected data. Results: The incidence of hypertension following intubation was significantly more in the low-dose group. Administration of 1 μg/kg dexmedetomidine was not accompanied by hypotension or bradycardia. Conclusion: Dexmedetomidine in a dose of 1 μg/kg is more effective than 0.5 μg/kg for attenuation of hemodynamic stress response to intubation in cardiac surgery. A more graded increase in the dose of dexmedetomidine may lead to an optimum dose in attenuating the hemodynamic response to intubation.