Acetaminophen improves analgesia but does not reduce opioid requirement after major spine surgery in children and adolescents

Abstract

Study design: A randomized, placebo-controlled, double-blind study to evaluate the effect of intravenously (IV) administered acetaminophen on postoperative pain in children and adolescents undergoing surgery for idiopathic scoliosis or spondylolisthesis.

Objective: To evaluate effectiveness of IV-administered acetaminophen on postoperative analgesia, opioid consumption, and acetaminophen concentrations after major spine surgery in adolescents.

Summary of background data: Scoliosis surgery is associated with severe postoperative pain, most commonly treated with IV-administered opioids. Nonsteroidal anti-inflammatory drugs (NSAIDs), as adjuvant to opioids, improve analgesia and reduce the need for opioids. However, by inhibiting cyclo-oxygenase enzymes peripherally, NSAIDs may inhibit bone healing. Acetaminophen, a centrally acting analgesic, does not have the adverse effects of NSAIDs and has improved analgesia in children after another orthopedic surgery.

Methods: In an institutional review board approved study, 36 American Society of Anesthesiology patient classification I to III patients of 10 to 18 years of age were analyzed. Acetaminophen 30 mg/kg, administered IV or 0.9% NaCl was administered at the end of scoliosis or spondylolisthesis surgery, and thereafter twice at 8-hour intervals. Timed blood samples for acetaminophen determination were taken between 0.25 and 20 hours after the first dose. All patients received standard propofol-remifentanil anesthesia. Pain scores (visual analogue scale [VAS], 0-10), opioid consumption, and adverse effects were recorded.

Results: In the surgical ward, 7 (39%) patients in the acetaminophen and 13 (72%) in the placebo group had a VAS pain score 6 or more (P < 0.05). There were fewer hours with VAS score 6 or more in the acetaminophen group compared with the placebo group (8.7% vs. 17.8% of the hours, P < 0.05). There was no difference in oxycodone consumption during the 24-hour follow-up between the 2 groups.

Conclusion: IV-administered acetaminophen 90 mg/kg/day, adjuvant to oxycodone, did improve analgesia, but did not diminish oxycodone consumption during 24 hours after major spine surgery in children and adolescents. All acetaminophen concentrations were in nontoxic levels.