Oral clonidine premedication preserves heart rate variability for patients undergoing larparoscopic cholecystectomy

Background: Clonidine has been shown to reduce perioperative circulatory instability. This postoperative analgesic effect of clonidine was also known in previous studies. The aim of the study was to investigate the clinical efficiency of oral clonidine premedication in anesthesia and analgesia in patients undergoing laparoscopic cholecystectomy. Methods: Thirty-two patients scheduled for elective laparoscopic cholecystectomy were recruited for a prospective, randomized, double-blinded comparative study. They were allotted randomly to two groups: placebo or clonidine. Patients in the placebo group (n=16) were premedicated with oral antacid (alugel hydroxide 300 mg), while those in the clonidine group (n=16) were premedicated with oral clonidine 150 μg before anesthesia. Analysis of heart rate variability was used to quantify the control of heart rate at baseline, and during the pneumoperitoneum and recovery periods. Time of the first request for postoperative analgesic and cumulative analgesic requirements in 24h were recorded. Data are expressed as mean ± SD. Results: Heart rate variability was reduced in the pneumoperitoneum and postoperative period in the placebo group. Clonidine resulted in a greater perioperative (pneumoperitoneum period) power at all frequency ranges compared with placebo (671.5±470.5 vs. 55.1±51.6ms²/Hz for total power variability, 170.1±94.4 vs. 16.9±21.1 ms²/Hz for low-frequency variability and 206.1±95.7 vs. 16.4±15.1 ms²/Hz for high-frequency variability, P<0.05). The postoperative analgesic requirement was less (2.3±0.8 vs. 3.2±1.2 dose, P<0.05) in comparison with the placebo group. Conclusion: Clonidine preserves heart rate control in pneumoperitoneum and recovery periods. Oral clonidine premedication also reduces the requirement for postoperative analgesia.