Impact of Intraoperative Clonidine on Postoperative Opioid Use in Patients With Endometriosis: A Randomized Controlled Trial

BACKGROUND: Patients with endometriosis undergoing surgery are at risk of moderate-to-severe postoperative pain. Clonidine, an alpha-2 agonist with analgesic properties, may improve multimodal pain management in these patients. METHODS: We conducted a randomized, blinded, placebo-controlled trial to investigate the effect of a single intraoperative dose of clonidine on postoperative opioid consumption and pain intensity. Patients undergoing endometriosis surgery at Aarhus University Hospital, Denmark, were randomized 1:1 to receive either intravenous clonidine (150 µg) or placebo intraoperatively. Our primary outcome was cumulative opioid consumption (intravenous morphine equivalents) 3 hours after surgery. Secondary outcomes included opioid consumption at 6 hours, pain intensity at rest and during coughing, shivering, postoperative nausea and vomiting, and sedation within the first 2 postoperative hours. The length of stay in the postanesthesia care unit was also recorded. RESULTS: A total of 120 women (mean ± standard deviation [SD] age 37 ± 7 years) were included in the final analysis, with 57 receiving clonidine and 63 receiving placebo. Mean (interquartile range [IQR]) postoperative intravenous morphine consumption during the first 3 hours was lower in the clonidine group with 5 mg (0–10) compared to 10 mg (0–16.5) in the placebo group ( P = .032). Shivering was less frequent in the clonidine group (3 vs 18 patients, P = .001). Sedation was more common in the clonidine group (21 vs 12 patients, P = .029). No differences were found between groups for pain intensity at rest and during coughing, postoperative nausea and vomiting, or length of stay in the postanesthesia care unit (PACU). CONCLUSIONS: A single intraoperative dose of clonidine is hemodynamically safe in patients undergoing endometriosis surgery and is associated with reduced postoperative opioid consumption and shivering, but increased sedation.