Transdermal buprenorphine in cardiac surgery: Results of a randomized doubleblind clinical trial

Introduction: Moderate to severe pain has been reported in about 75% of patients after cardiac surgery and predisposes to complications. We evaluated whether a 5 µg/h transdermal buprenorphine patch applied immediately before surgery improves analgesia within a standardized multimodal protocol. Materials and Methods: Singlecenter, randomized, doubleblind, placebocontrolled trial. Adults 18-75 years, BMI 21-35 kg/m² and LVEF > 35% undergoing coronary revascularization, singlevalve surgery or cardiac tumor resection were allocated 1:1 to buprenorphine 5 µg/h or placebo patch; all received multimodal analgesia. Primary outcome: pain (static and dynamic NRS > 3) at 12, 24, 48, 72 h and day 7, analyzed with multilevel logistic regression. Secondary outcomes: rescue opioid use and adverse events (nausea/vomiting, constipation, urinary retention). Results: No differences were observed in static NRS (OR 1.2, 95% CI 0.7-2.2) or dynamic NRS (OR 1.7, 95% CI 0.9-3.3) between groups. Secondary outcomes were also comparable. No serious patchrelated adverse events occurred. Conclusions: Immediate application of a 5 µg/h buprenorphine patch did not improve analgesia or reduce rescue opioid use; routine use in this setting is not supported by these data. Discussion: Lack of effect may relate to the low dose, absence of a preoperative (12-24 h) uptake window to achieve steady levels, and the high analgesic ceiling of the multimodal protocol. The rigorous design supports internal validity; future trials should assess higher doses and earlier application.