Background: Laryngoscopy and intubation are frequently associated with hypertension and tachycardia, sometimes arrhythmia due to a sympathetic response to epipharyngeal and laryngopharyngeal stimulation. This study aimed to evaluate the efficacy of intravenous clonidine as an adjuvant to general anesthesia in blunting the sympathetic response to intubation in adult patients for thyroidectomy.
Methodology: This is a randomized double blind controlled trial conducted on patients scheduled for thyroidectomy. Sixty patients who consented were randomly assigned to receive lidocaine 30 mg IV or clonidine 75 mcg IV as a premedication prior to anesthesia. Parameters measured were blood pressure, heart rate and mean arterial pressure, average minimum alveolar concentration, need for rescue pain medications and visual analogue scale scores. Data was analyzed using SPSS Version 20.0 Trial Version. Frequency, percentage, and mean were the main statistical tools used. Independent-samples t-test was also used to determine association of blood pressure, heart rate, mean arterial pressure, need for rescue pain medication and intubation outcomes; while Cramer's V coefficient was used to compare VAS scores between the groups.
Results and Conclusion: The clonidine group had significantly lower blood pressure at the first minute post-intubation, lower mean arterial pressure (MAP) at 1 and 3 minutes post intubation, lower heart rate at 1, 3, 5, 10 and 15 minutes post intubation and significantly lower minimum alveolar concentration (MAC). The percentage of patients with VAS score of 0 was significantly higher in the clonidine group (83.33% vs 50%) compared to the percentage of patients with higher VAS scores (1-6) in the lidocaine group. There was no difference in the outcome of intubation and no rescue pain medication was needed for both groups postoperatively. A single dose clonidine given intravenously was superior in blunting sympathetic response to intubation and had decreased intraoperative anesthetic requirements with decreased post operative pain.