Duration of Intrathecal morphine effect in children with idiopathic scoliosis undergoing posterior spinal fusion

Objective: Intrathecal (IT) morphine improves pain control and decreases opioid requirements in children following thoracic and abdominal surgery. However, studies in children report variable durations of analgesia following IT morphine. The purpose of this study is to describe the duration of analgesia in children undergoing surgical correction of idiopathic scoliosis. Design: Retrospective chart review. Setting: Pediatric hospital within a tertiary care academic medical center. Participants: Forty-four pediatric patients with idiopathic scoliosis who received IT morphine following posterior spinal fusion (PSF). Main outcome measure(s): Mean opioid exposure 0-12 hours and 13-24 hours post-IT morphine. Results: Mean opioid exposure was significantly increased during the 13-24-hour compared to the 0-12-hour time period (23.0 ± 12.5 mg parenteral morphine vs 15.9 ± 1.7 mg; p = 0.0006). The only factors significantly associated with morphine exposure during the 0-12-hour period included the median pain score (0-12 hours) (odds ratio [OR], 1.92; 95% confidence interval [CI], 0.033-3.80; p = 0.046) and total acetaminophen dose (OR, 0.003; 95% CI, 0.0008-0.005; p = 0.011). Conclusions: These data indicate that patients experienced improved analgesia for at least 12 hours following IT morphine. Increased use of adjuvant analgesics such as acetaminophen may reduce opioid requirements following PSF procedures. More studies are needed to investigate the combination of adjuvants and IT morphine to reduce postoperative pain in this population.