The effect of two different doses of remifentanil on postoperative pain and opioid consumption after cardiac surgery - a randomized controlled trial

Background Remifentanil, an ultra‐short‐acting opioid, provides intensive analgesia without prolonged respiratory depression and is widely used in cardiac surgery. Diminished dosing may also offer stable hemodynamics, even during sternotomy and sternal retraction. However, increased postoperative pain and induced opioid tolerance after remifentanil dosing during abdominal surgery was reported. We tested whether remifentanil 0.3 μg/kg/min infusion increased postoperative opioid consumption and pain compared to 0.1 μg/kg/min dosing. Methods Ninety coronary artery bypass grafting or heart valve surgery patients were randomized to remifentanil 0.1 μg/kg/min or 0.3 μg/kg/min infusions during surgery. All patients received oxycodone bolus 0.15 μg/kg postoperatively, and patient‐controlled analgesia (PCA) with oxycodone thereafter. Postoperative pain was estimated thrice daily by visual analogue scale, and 48‐h opioid consumption was recorded from the PCA‐device. Results Total remifentanil dosing was 64 μg/kg in the higher and 22 μg/kg in the lower dosing group during the 3‐h cardiac operations. Mean postoperative opioid consumption was 107 (SD 36) mg in the lower and 104 (SD 33) mg in the higher dose remifentanil groups. Postoperative pain did not differ between groups, at rest or during deep breathing, at any time (P = 0.110 and 0.941, respectively). Conclusions Remifentanil 0.3 μg/kg/min infusion did not increase postoperative pain or opioid consumption after cardiac surgery compared to the 0.1 μg/kg/min infusion. Remifentanil infusion 0.1–0.3 μg/kg/min during cardiac surgery was safe, with no exaggerated postoperative pain or opioid consumption.