Role of melatonin in attenuation of haemodynamic responses to laryngoscopy and intubation

BACKGROUND AND AIMS Laryngoscopy and endotracheal intubation are considered as potent stimuli which lead to an increase in heart rate and blood pressure. Melatonin (N-acetyl-5-methoxytryptamine) has been studied for pre-operative anxiolysis and sedation in Intensive Care Unit. We made a hypothesis that melatonin can provide haemodynamic stability during laryngoscopy and intubation when given 120 min before the procedure. METHODS Sixty American Society of Anesthesiologists physical status Grade I and II patients of either gender, 20-45 years old, 40-65 kg body weight, scheduled to undergo elective surgical procedures under general anaesthesia were assigned into two equal groups - Group C (control) and Group M (melatonin). They received oral placebo or melatonin tablets 6 mg, respectively, 120 min before surgery. The haemodynamic parameters were recorded preoperatively, during laryngoscopy and endotracheal intubation and thereafter at 1, 3, 5 and 10 min. Unpaired t-test was used for between-group comparison of ratio and interval scale data. For within-group comparison of ratio and interval scale data, repeated-measures ANOVA and post hoc Bonferroni t-tests were used. RESULTS It was observed that in the control group, there was a significant increase in heart rate and blood pressure at laryngoscopy and intubation and persisted till 10 min post-intubation. In melatonin group, there was an insignificant increase in heart rate at the time of laryngoscopy and intubation which however settled within 1 min post-intubation. CONCLUSION Melatonin is an effective drug for attenuation of cardiovascular responses to laryngoscopy and endotracheal intubation.