Intraoperative Methadone Use in Cardiac Surgery: A Systematic Review

Abstract

Objective: To investigate the effects of intraoperative methadone in comparison with those of standard-of-care intraoperative opioids, such as fentanyl and morphine, on pain scores, opioid consumption, and adverse effects in adults undergoing cardiothoracic surgery.

Methods: The literature was reviewed in PubMed, Embase, Cochrane Library, and Google Scholar, followed by a manual search of the reference lists of the identified articles. Search terms included a combination of "intraoperative methadone," "methadone," and "cardiac surgery." Our review includes four studies published between 2011 and 2020. Quality assessment of the studies was performed.

Results: The initial search identified 715 articles, from which 461 duplicates were removed and 236 were eliminated on the basis of inclusion and exclusion criteria. Eighteen articles underwent full-text review. Four studies evaluating a total of 435 patients with various cardiothoracic procedures were included in this review. We found that intraoperative methadone decreased acute postoperative pain and reduced postoperative opioid consumption in the first 24 postoperative hours in patients who received 0.1-0.3 mg/kg intraoperative methadone in comparison with morphine and fentanyl. No difference was found in adverse effects between the groups. Quality assessment of the studies showed a low risk of bias in three of the randomized controlled trials and a high risk of bias in the retrospective review because of the baseline confounding bias in the study design.

Conclusions: Intraoperative methadone use reduces acute postoperative pain and lowers opioid consumption in comparison with morphine and fentanyl. Initial results suggest that methadone may be an equivalent opioid to be administered during cardiothoracic procedures to reduce acute postsurgical pain, though further research is warranted.

Keywords: Cardiac Surgery; Intraoperative Analgesic; Intraoperative Methadone.