Abstract
Background: Performing laryngoscopy and endotracheal intubation evokes a reflex circulatory response, which results in an increase in the blood pressure and heart rate (HR) and causes arrhythmia due to increased outflow from the sympatho-adrenal axis.

Aim and Objective: The aim of this study was to evaluate the efficacy of a single bolus dose of 0.6 mg/kg body weight dexmedetomidine, a centrally acting α-2 agonist, through intravenous route, in attenuating the hemodynamic responses to laryngoscopy and endotracheal intubation.

Materials and Methods: It was a randomized, prospective, two fold-blinded, and placebo-controlled clinical study. After obtaining Ethical Committee clearance, 100 adult patients in the age group of 18–50 years were enrolled. Blood pressure of the patients enrolled was within the normal range and they were posted for various elective surgeries. Categorization was performed with the American Society of Anaesthesiologists and Mallampatti as Class I and II Grade I and II, respectively. The patients were randomly distributed into two groups, Group A and Group B. Group A included 50 patients (n = 50) and was treated with 1 ml/kg of normal saline intravenously for about 10 min and 10 min before the induction. Group B included 50 patients (n = 50) and was treated with dexmedetomidine 1 ml/kg (0.6 μg/kg body weight), which was further diluted in 100 ml ordinary saline and given intravenously, for about 10 min and 10 min before the induction. After premedication, anesthesia was induced with injection thiopentone 5 mg/kg body weight and was given until the loss of eyelash reflex. Dose of thiopentone required was noted. It was followed by injection succinylcholine 1.5 mg/kg body weight. HR, systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were the various parameters for analysis and recorded at regular time intervals.

Results: Initiation of laryngoscopy and intubation resulted in significant rise in the HR (36.14 bpm), SBP (29.22 mmHg), DBP (20.30 mmHg), and MAP (14.46 mmHg) in patients who were grouped under Group A. In Group B (dexmedetomidine), mean of HR, SBP, DBP, and MAP decreased by 2.86 bpm, 17.66 mmHg, 1.54 mmHg, and 4.98 mmHg, respectively, when compared to basal values which is statistically highly significant (P < 0.0001).

Conclusion: Dexmedetomidine, at the dose of 0.6 μg/kg body weight when given intravenously 10 min before induction was noted to efficiently reduce the hemodynamic response to laryngoscopy and tracheal intubation.

Key words: Laryngoscopy and Tracheal Intubation; Hemodynamic Response; Intravenous Dexmedetomidine