Prolonged Perioperative Low-Dose Ketamine Does Not Improve Short and Long-term Outcomes After Pediatric Idiopathic Scoliosis Surgery

STUDY DESIGN.Randomized, double-blind, placebo-controlled study, with a six-month follow-up period. OBJECTIVES.To test the hypothesis that a 72-hour dose of subanesthetic ketamine in this surgical procedure reduces postoperative morphine use; To assess if there are fewer adverse effects, if postoperative recovery is faster, if there is less peri-incisional hyperalgesia or if there is lower incidence of persistent postsurgical pain. SUMMARY OF BACKGROUND DATA.Tissue injury and high opioid requirements following posterior spinal fusion surgery produce central sensitization, which can in turn be associated with hyperalgesia and chronic pain. Clinical trials involving this type of procedure using subanesthetic ketamine doses have assessed pain and morphine requirements with contradictory results. The effects of prolonged subanesthetic ketamine doses on postoperative recovery, mechanical hyperalgesia and the incidence of chronic pain are unknown. METHODS.A total of 48 pediatric patients between 10 and 18 years diagnosed with idiopathic scoliosis were randomized to receive perioperative low-dose ketamine or placebo for 72 hours. They received general anesthesia, intraoperative remifentanil and morphine postoperatively (patient-controlled analgesia). We measured morphine consumption, pain at rest and during movement (coughing), undesirable effects and sedation during morphine treatment. The onset of oral intake, ambulation and hospital stay were recorded. The extent of the peri-incisional hyperalgesia was measured at 72 hours and pain controls were conducted post-surgery. RESULTS.Primary endpoint results (total cumulative morphine consumption while admitted) were obtained in 44 patients. Results were 2.72 (SD 1.13) in the placebo group and 3.13 (SD 1.13) in the study group (P = 0.2903), with no significant differences. Moreover, differences were not found between the experimental group and the placebo group in the secondary endpoints analyzed. CONCLUSIONS.Our findings do not support the routine combining of prolonged subanesthetic ketamine doses with opioids in posterior fusion surgery in children with idiopathic scoliosis.Level of Evidence2