Methadone in Pediatric Anesthesia II

Randomized, controlled, modified dose-escalation design. Patients receive standard monitoring for anesthesia and postoperative care. Surgical and anesthesia (except for opioid use) care are not altered for study purposes. All patients are induced by propofol and muscle relaxants. In the first cohort (n=30 evaluable), subjects are randomized 1:2 to either control (standard intraop opioid at anesthesiologists' discretion) or methadone HCl (0.4 mg/kg ideal body weight, IBW). In the second cohort (n=30 evaluable), subjects are randomized 1:2 to either control (standard intraop opioid) or methadone HCl (0.3 mg/kg ideal body weight, IBW). Subjects in the study groups will receive methadone (IV bolus, after induction of anesthesia) as their primary intraoperative opioid, rather than leaving the choice of intraoperative opioid to the anesthesiologist. Intraoperative breakthrough pain will be treated at the discretion of the anesthesiologist with fentanyl. In the control groups, intraoperative opioid administration will be left at the discretion of the anesthesia providers. Patient controlled analgesia as prescribed by the clinical team, using hydromorphone or morphine, will be used to treat postoperative pain relief.