Evaluation of the Effect of Oral Clonidine Premedication on PR- interval, in Rhinoplasty and Functional Endoscopic Sinus Surgery

Background: Clonidine, an alpha-2-agonist, attenuates the sympathetic response during general anesthesia and improves intra-operative hemodynamic stability. Clonidine has been associated with certain adverse cardiopulmonary effects. Aim: This study aimed to investigate the impact of oral clonidine, administered as premedication, on the post-operative PR interval of the electrocardiogram (ECG) in patients who underwent rhinoplasty or Functional Endoscopic Sinus Surgery (FESS). Methods: This study enrolled 50 patients scheduled for rhinoplasty or FESS under general anesthesia. Before arriving at the operation room, each patient received 300µg of oral clonidine 30 minutes before the standard 12-lead ECG was obtained. Induction of anesthesia was performed using the same standard protocol in all patients. Any changes in ECG monitoring during operation and in the recovery, room were registered. Six hours after clonidine administration, the standard 12-lead ECG was obtained and compared with the first ECG. Results: The PR interval was prolonged in 23 cases (46%). In 21 cases, the prolongations were in the normal range (0.12-0.2 Sec.), and in two cases were in abnormal ranges (> 0.2 Sec.). (P value < 0.001). Conclusion: It seems that premedication with oral clonidine can prolong the PR interval.