Efficacy of lateral femoral approach to continuous sciatic nerve block for patient-controlled analgesia after foot and ankle surgery

Abstract

Objective To evaluate the efficacy of lateral femoral approach to continuous sciatic nerve block for patient-controlled analgesia after foot and ankle surgery. Methods One hundred American Society of Anesthesiologists physical status Ⅰ-Ⅲ patients of both sexes, aged 18-60 yr, weighing 50-100 kg, with body height of 145-190 cm, scheduled for elective foot and ankle surgery, were divided into 2 groups (n=50 each) using a random number table: patient-controlled nerve block analgesia (PCNA) group and patient-controlled intravenous analgesia (PCIA) group.In group PCNA, the lateral femoral approach to sciatic nerve block was performed under the guidance of ultrasound and a neurostimulator, 0.2% ropivacaine 20 ml was injected after successful location, the catheter was inserted, and 0.2% ropivacaine 10 ml was injected again.In group PCIA, 0.2% ropivacaine 30 ml was injected after successful location of the sciatic nerve.General anesthesia was performed using laryngeal mask airway in both groups.In group PCNA, PCNA was performed with 0.2% ropivacaine (diluted to 200 ml in normal saline) at the end of surgery, and the PCNA pump was set up with a 0.5 ml bolus dose, a 15-min lockout interval and background infusion at a rate of 5 ml/h.In group PCIA, PCIA was performed with sufentanil 100 μg, tramadol 500 mg and tropisetron 10 mg (diluted to 200 ml in normal saline) at the end of surgery, and the PCIA pump was set up with a 0.5 ml bolus dose, a 15-min lockout interval and background infusion at a rate of 2 ml/h.The visual analog scale score was maintained≤3, and postoperative analgesia lasted until postoperative 72 h. When visual analog scale scores ≥ 4, tramadol 100 mg was intramuscularly injected as rescue analgesic.The requirement for rescue analgesia and development of adverse effects such as nausea and vomiting, insomnia, puncture site infection and bleeding were recorded within 72 h after surgery. Results The requirement for rescue analgesia and incidence of nausea and vomiting were significantly lower in group PCNA than in group PCIA (P<0.05). Conclusion The lateral femoral approach to continuous sciatic nerve block can be safely and effectively used for patient-controlled analgesia after foot and ankle surgery. Key words: Nerve block; Sciatic nerve; Analgesia, patient-controlled