Abstract
BACKGROUND: Laryngoscopy and tracheal intubation (LTI) are known to release catecholamines resulting in rise in heart rate (HR) and blood pressure. Various drugs have been studied till date to attenuate the sympathomimetic effects of laryngoscopy and intubation. AIMS: The aim is to study the effect and safety of esmolol, diltiazem, and their combination on pressor response of laryngoscopy and intubation. SETTING AND DESIGN: This prospective, randomized double-blind study was designed to assess the efficacy of the combination of esmolol and diltiazem and compare it with esmolol and diltiazem when used alone, for attenuating the pressor response to laryngoscopy and intubation. MATERIALS AND METHODS: One hundred twenty-four adult patients of physical status American Society of Anesthesiologists Classes I and II posted for elective surgery under general anesthesia requiring endotracheal intubation were randomly allocated (using computer-generated random numbers) into four groups of 31 each, in a double-blind fashion, to receive the test drug, i.e., saline (control), diltiazem (0.2 mg/kg), esmolol (1.5 mg/kg), or a combination (diltiazem [0.1 mg/kg] and esmolol [0.75 mg/kg]). The test drug was administered intravenously as a bolus after 1 min of injecting the muscle relaxant. LTI was performed after 2 min of the test drug. Hemodynamic data - HR, systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) - were recorded at 1 min intervals after induction, until laryngoscopy and intubation, and at 1, 2, 3, 4, 5, and 10 min thereafter. STATISTICAL ANALYSIS: Statistical analysis was performed using one-way analysis of variance (ANOVA) for comparison among and between the groups. The Bonferroni's correction was applied when a significant difference was found between groups after applying ANOVA. Results were considered statistically significant at P ≤ 0.05. RESULTS: In the control and diltiazem groups, a significant increase in HR (P ≤ 0.05) was observed after laryngoscopy. Esmolol and combination groups were associated with a significant fall in HR after administration of the test drug, and no significant rise was noted after laryngoscopy. HR was significantly less in the combination and esmolol groups as compared to the control till 5 min after LTI. As compared with the control, all the other groups were associated with a fall in SBP after the test dose, and this lasted for 5 min (P < 0.001) after laryngoscopy in the esmolol and combination groups and for 1 min (P < 0.001) in the diltiazem group. All groups were associated with a significant rise in DBP and MAP for 1-2 min after LTI (P < 0.001), except the combination group in which no change was noted. DBP and MAP were significantly less in the combination group as compared to the control, from 1 min after giving the test dose till 5 min (P < 0.001) after LTI. CONCLUSION: Although esmolol and combination groups were both effective in controlling the increase in HR and SBP, only the combination group was effective in controlling the rise in DBP and MAP after LTI. HR, SBP, DBP, and MAP were significantly less in the combination group as compared to the control till 5 min after LTI. We recommend a combination of esmolol and diltiazem in appropriate doses for effectively attenuating the rise in HR and blood pressure responses during LTI.