Infiltration of the sternotomy wound and the mediastinal tube sites with 0.25% levobupivacaine as adjunctive treatment for postoperative pain after cardiac surgery

Background and objective: This study aimed to investigate the effect of 0.25% levobupivacaine infiltration of the sternotomy wound and the mediastinal tube sites on postoperative pain, morphine consumption and side-effects in patients undergoing cardiac surgery. Methods: After obtaining Ethics Committee approval and informed consent, 50 patients aged 18-65 yr, undergoing coronary artery bypass grafting, were included in this study. Anaesthesia was induced with 5 mu g kg(-1) fentanyl, 0.3 mg kg(-1) etomidare, 1 mg kg(-1) lidocaine, 0.1 mg kg(-1) vecuronium and maintained with 1-2%, sevoflurane, 50% oxygen in air and fentanyl. Patients were randomized into two groups before sternal wire placement: sternotomy and mediastinal tube sites were infiltrated with either 60mL 0.25% levobupivacaine (infiltration group, n = 2 5) or 60 mL saline placebo (control group, n = 2 5). All patients received intravenous morphine patient-controlled analgesia (bolus dose: 2 mg, lock-out time: 15 min, 4 h limit: 20 mg) after extubation. Postoperative pain at rest and on coughing was assessed by a visual analogue scale (0-10). Pain scores, sedation scores (Ramsay scale), haemodynamic and respiratory parameters, arterial blood gases and morphine consumption were recorded. Results: The times to extubation and visual analogue scale scores were similar between groups. Morphine consumption at 24 h was significantly lower in the infiltration group compared with the control group (29.5 +/- 5.1 vs. 42.8 +/- 4.7 mg, respectively, P < 0.05). The sedation scores were found to be significantly higher in the control group when compared with the infiltration group at 1, 2 and 4 h after extubation (P < 0.05), whereas sedation scores after 4 h were similar between groups. Conclusion: Infiltration of the median sternotomy incision and the mediastinal tube insertion sites with 0.25% levobupivacaine in addition to morphine patient-controlled analgesia was found to be effective in reducing postoperative morphine consumption when compared with morphine patient-controlled analgesia atone during the initial 24 h after cardiac surgery.