A comparative study of melatonin with placebo in attenuation of hemodynamic responses to laryngoscopy & intubation.

Abstract

BACKGROUND: Laryngoscopy is invariably accompanied by sympathetic stimulation which leads to tachycardia, hypertension. Various manoeuvres such as increasing depth of anaesthesia, giving bolus doses of injection lidocaine, esmolol have been tried which do not fully obtund these responses. All surgical & anaesthesia
procedures are also associated with anxiety & pain in the perioperative period which may be alleviated by various drugs.

OBJECTIVE(S): To compare haemodynamic responses following administration of 3mg, 6mg melatonin with placebo after laryngoscopy & intubation.

To compare pain, anxiety scores following administration of 3mg, 6mg melatonin with placebo.

PARTICIPANTS: 75 patients having ASA 1/2, aged 18 - 65 years, posted for elective surgery under general anaesthesia.

STUDY DESIGN: Randomized controlled trial.

METHODS: Participants randomly divided into 3 groups. Group I melatonin 3mg, group II of melatonin 6mg & group III placebo given 90 min before induction. Heartrate (H.R), systolicBP (SBP), diastolicBP (DBP),mean arterial pressure(MAP), saturation(SpO2) were recorded preoperatively before induction & at  3min,6min,9min,12min,15min,30min after induction. Anxiety levels, pain-scales were assessed before giving medication, at time of induction, subsequently 15min, 30min, 3hrs, 6hrs, 24hrs after extubation.

RESULTS: At 3, 6 and 9 minutes, the difference in mean heart rate in the group placebo was > group M3 > group M6 (statistically significant) with p values 0.038, 0.026 and 0.012 respectively. At 3, 6, 9 & 12 minutes, the difference in mean systolic BP in the group placebo was > group M3 > group M6 (statistically significant) with p values 0.048, 0.002, 0.011 & 0.006 respectively. At 6 and 9 minutes, the difference in mean diastolic BP in the group placebo was > group M3 > group M6 (statistically significant) with p values 0.043 & 0.032 respectively whereas at 12 minutes the difference in group placebo was > group M6 > group M3 (statistically significant) with p value 0.047. At 6, 9 & 12 minutes, the difference in mean MAP in the group placebo was > group M3 > group M6 (statistically significant) with p values 0.017, 0.014 and 0.022 respectively. Mean beck anxiety inventory score was lowest in group M6. Mean behavioural rating pain score was also lowest in group M6.

CONCLUSIONS: Premedication with oral melatonin 3mg, 6mg before surgery can be safely used to attenuate haemodynamic response to laryngoscopy & intubation. Also provides analgesic, anxiolytic effects.

IMPLICATION: A dose of 6mg of melatonin blunts the haemodynamic responses during laryngoscopy & provides significant analgesia & anxiolysis in perioperative period when compared to melatonin 3mg & placebo.