Prilocaine or mepivacaine for combined sciatic-femoral nerve block in patients receiving elective knee arthroscopy.

Aim: The aim of this study was to evaluate the onset time of surgical block, recovery of motor function and duration of post-operative analgesia of combined sciatic-femoral nerve block performed with either mepivacaine or prilocaine.

Methods: With Ethical Committee approval and written informed consent, 30 ASA physical status I-II patients, undergoing elective arthroscopic knee surgery, received a combined sciatic-femoral nerve block with 30 ml of either 2% mepivacaine (n=15) or 1% prilocaine (n=15). An independent observer recorded the onset time of sensory and motor blocks, the need for intraoperative analgesia supplementation, recovery of motor function, and first request of post-operative pain medication.

Results: Onset time of nerve block required 15+/-5 min with prilocaine and 12+/-7 min with mepivacaine (p=0.33). No patient required general anesthesia to complete surgery; 3 patients receiving prilocaine (20%) and 2 patients receiving mepivacaine (13%) required 0.1 mg fentanyl intravenously to complete surgery (p=0.99). Recovery of motor function and first request of post-operative pain medication occurred after 238+/-36 min and 259+/-31 min with prilocaine, and 220+/-48 min and 248+/-47 min with mepivacaine (p=0.257 and p=0.43, respectively). Patient satisfaction was good in all studied patients.

Conclusion: Prilocaine 1% provides adequate sensory and motor block for arthroscopic knee surgery, with a clinical profile similar to that produced by 2% mepivacaine, and may be a good option for surgical procedures of intermediate duration and not associated with severe postoperative pain.