Epidural combination of ropivacaine with sufentanil for postoperative analgesia after total knee replacement: a pilot study

Background and objective: We assessed the analgesic efficacy of postoperative epidural infusions of ropivacaine 0.1 and 0.2% combined with sufentanil 1 mug mL(-1) in a prospective, randomized, double-blinded study. Methods: Twenty-two ASA I-III patients undergoing elective total-knee replacement were included. Lumbar epidural blockade using ropivacaine 0.75% was combined with either propofol sedation or general anaesthesia for surgery. After surgery, the epidural infusion was commenced. Eleven patients in each group received either an epidural infusion of ropivacaine 0.1% with 1 mug mL(-1) sufentanil (Group 1) or ropivacaine 0.2% with 1 mug mL(-1) sufentanil (Group 2) at a rate of 5-9 mL h(-1). All patients had access to intravenous pirinatrimide (piritramide) via a patient-controlled analgesia (PCA) device. Results: Motor block was negligible for the study duration in both groups. There was no significant difference with the 100 mm visual analogue scale (VAS) scores, with the consumption of rescue analgesia or with patient satisfaction. Patients in Group I experienced significantly less nausea (P < 0.05) than those in Group 2. Both treatment regimens provided effective postoperative analgesia with only a minimal use of supplemental opioid PCA. Conclusions: We recommend the use of ropivacaine 0.1% with 1 mu g mL(-1) sufentanil for postoperative analgesia after total knee replacement as it provides efficient pain relief with no motor block of the lower limbs. In addition, compared with 0.2% ropivacaine with sufentanil, the mixture reduces local anaesthetic consumption without compromise in patient satisfaction or VAS scores. Patients even experience less nausea.