The Effects of Intravenous Adenosine Infusion on Intraoperative Remifentanil Requirements and Postoperative Pain in Elective Tonsillectomies Are Influenced by the Time of Day the Operation Is Performed

ABSTRACT

BACKGROUND: The chronobiology of postoperative pain is an interesting topic. This study was performed to evaluate the effects of adenosine on inta-operative remifentanil requirements and on postoperative pain in patients undergoing tonsillectomies and how those effects change with changing time of day the surgery is performed. METHODS: For this study, 120 patients were randomly allocated into four groups. Patients in groups B and D received adenosine at a dose of 50microgram/kg/min, and those in group A and C received an equal volume of saline from 10 minutes after the induction of anesthesia until the end of surgery. Group A (saline) and B (adenosine) patients entered the operating room after 08:30 and finished before 11:00, Group C (saline) and D (adenosine) patients entered the operating room after 13:30 and finished before 16:00. We evaluated the intraoperative time-weighted mean remifentanil dose, and postoperative pain scores at 1, 6, 12, and 24 hours, and the analgesic dose required during the following 24 hours. RESULTS: Time-weighted mean remifentanil doses during the intraoperative period and the analgesic requirement during the following 24 hours in group D was significantly lower than in the other groups. The numeric rating scale for pain at 1, and 6 hours in group D was significantly lower (P < 0.01) than that of group A. There were no significant differences in side effects among groups. CONCLUSIONS: Use of intraoperative adenosine infusion provides perioperative analgesia. Postoperative pain is affected by the time of day the operation is performed.