A Comparative Study of Labetalol and Fentanyl on the Sympathomimetic Response to Laryngoscopy and Intubation in Vascular Surgeries

Background: Stress response to laryngoscopy and intubation causes autonomic or endocrine disturbance such as hypertension, tachycardia, and arrhythmias that may be potentially dangerous in cardiovascular disease patients. These changes are maximum at 1 min after intubation and last for 5‑10 min. Labetalol is a selective α1‑ and nonselective β1‑ and β2‑adrenergic antagonist. It lowers blood pressure (BP) by decreasing systemic vascular resistance by α1‑blockade and reflex tachycardia attenuated by simultaneous β‑blockade. Fentanyl is a potent synthetic opioid agonist with rapid onset and short duration of action. It blocks afferent nerve impulses resulting from stimulation of the pharynx and larynx during intubation. This is a prospective, randomized, control trial carried out to compare the effect of labetalol and fentanyl on sympathomimetic response to laryngoscopy and intubation in vascular surgeries. Materials and Methods: Eighty four patients [American Society of Anesthesiologists (ASA) grade I and II] scheduled for vascular surgeries were divided into three groups (28 each). Group A received fentanyl 2 μg/kg intravenous (IV), Group B received labetalol 0.25 mg/kg IV, and Group C received 10 mL saline IV. The groups were compared for heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and rate pressure product (RPP). Results: The groups were comparable as per their demographic data and preoperative vitals. All the vitals decreased significantly (P < 0.05) in Group A and Group B from just before intubation (5 min after the study drug) to 15 min after intubation compared to the control group. Labetalol decreased SBP, DBP, and MAP significantly at 1 min and 3 min after intubation and RPP at 1 min and 15 min after intubation. In HR, the difference was not significant (P > 0.05). The incidence of hypertension and tachycardia was higher in Group C. No hypotension, bradycardia, and abnormal electrocardiogram (ECG) were recorded in any group. Conclusion: In lower doses, labetalol is a better agent than fentanyl in attenuating the sympathomimetic response to laryngoscopy and intubation but the difference is not significant. However, both effectively blunt the pressure response