Intraoperative Clonidine in Spine Surgery: A Randomised Controlled Trial

Patients undergoing spine surgery often experience post-operative pain. In this context, clonidine, an alpha-2 agonist, may be relevant due to its analgesic properties. We conducted a randomised, double-blinded, placebo-controlled trial to evaluate the effect of a single dose of intraoperative intravenous clonidine on post-operative opioid consumption, pain intensity and side effects. Patients undergoing spine surgery at Aarhus University Hospital, Denmark, were randomised to receive intraoperative clonidine (3 μg/kg) or placebo. The primary outcome was opioid consumption within the first 3 h after surgery. Secondary outcomes included opioid consumption within the first 6 h, pain intensity at rest and during coughing, post-operative nausea and vomiting (PONV), and sedation in the post-anaesthesia care unit (PACU). Additional outcomes included time to discharge from the PACU, length of hospital stay and daily opioid consumption after 1 month. Data from 120 patients (49 females, 71 males, mean age 65 ± 14 years) were available for analysis; 61 received clonidine and 59 received placebo. Post-operative intravenous morphine equivalents within 3 h were similar in the clonidine group 5 mg (0-15) and the placebo group 10 mg (0-15) (p = 0.58). Pain intensity at rest was 4 (0-5.5) in the clonidine group and 3 (0-5) in the placebo group upon arrival at the PACU (p = 0.20). No differences were observed between the clonidine and placebo groups regarding any secondary outcomes, except for hypotension, which was more frequent in the clonidine group (24 vs. 13 patients). A single dose of intraoperative clonidine did not reduce post-operative opioid consumption or pain intensity in patients undergoing spine surgery.