Intraoperative Methadone in Adult and Pediatric Cardiac Surgery: A Narrative Review

Background/Objectives: Intraoperative methadone has emerged as a significant pharmacological strategy in cardiac surgery to improve postoperative analgesic outcomes and reduce the reliance on rescue short-action opioids. This review aims to synthesize evidence regarding the safety and efficacy of intravenous methadone compared to other strategies for postoperative pain control in adult and pediatric cardiac surgeries. Methods: This narrative review relied on electronic searches in PubMed, Web of Science, Cochrane Library, and EMBASE up to January 2026. From 199 articles retrieved, 41 were included, focusing on analgesic efficacy, safety, pharmacokinetic variations during cardiopulmonary bypass (CPB), and cost-effectiveness. Results: The implementation of methadone results in up to 70% reduction in postoperative opioid requirements. Patients experience significantly lower pain scores from 24 to 72 h and improvement in satisfaction regarding pain management. In pediatric populations (neonates and children), the use of methadone leads to a significant reduction in opioid needs and a high rate of extubation in the operating room. Pharmacokinetically, a 48% drop in methadone concentration occurs during CPB due to hemodilution and sequestration. Safety data confirms that intraoperative use does not prolong mechanical ventilation; however, doses exceeding 0.25 mg/kg are linked to an increased incidence of delirium. Economically, methadone can be cost-effective, resulting in savings of up to $6355 per patient. Conclusions: Intraoperative methadone improves postoperative analgesia, opioid consumption, patient satisfaction, and costs after cardiac surgery. Its opioid-sparing effects make it particularly attractive for ERAS protocols, although vigilance against dose-related delirium and QT prolongation remains essential. Further research, especially in pediatrics, is needed to refine dosages and safety protocols.