[Comparison of postoperative analgesia with methadone versus morphine in cardiac surgery]

Pain is an aggravating factor of postoperative morbidity and mortality. The aim of this study was to compare the effects of methadone versus morphine using the numerical rating scale of pain and postoperative on-demand analgesia in patients undergoing myocardial revascularization.

A randomized, double-blind, parallel clinical trial was performed with patients undergoing coronary artery bypass grafting. The subjects were randomly divided into two groups: Morphine Group (MoG) and Methadone Group (MeG). At the end of cardiac surgery, 0.1 mg.kg^-1 adjusted body weight of methadone or morphine was administered intravenously. Patients were referred to the ICU, where the following was assessed: extubation time, time to first analgesic request, number of analgesic and antiemetic drug doses within 36 hours, numerical pain scale at 12, 24, and 36hours postoperatively, and occurrence of adverse effects.

Each group comprised 50 patients. Methadone showed 22% higher efficacy than morphine as it yielded a number-needed-to-treat (NNT) score of 6 and number-needed-to-harm (NNH) score of 16. The MeG showed a mean score of 1.9 ±2.2 according to the numerical pain scale at 24hours after surgery, whereas as the MoG showed a mean score of 2.9 ±2.6 (p =0.029). The MeG required less morphine (29%) than the MoG (43%) (p =0.002). However, the time to first analgesic request in the postoperative period was 145.9 ±178.5 minutes in the MeG, and 269.4 ±252.9 in the MoG (p =0.005).

Methadone was effective for analgesia in patients undergoing coronary artery bypass grafting without extracorporeal circulation.