Background: Previous studies have documented that single injection nearby the sciatic nerve bifurcation would influence the anesthesia and analgesia effect. But this is uncertain for preoperative continuous popliteal sciatic nerve block. This trial was conducted to compare two paths (proximal to the bifurcation and at the bifurcation) of ultrasound-guided continuous popliteal sciatic nerve block in foot and ankle surgery.
Methods: Forty recruited objects were randomly assigned to receive ultrasound-guided continuous popliteal sciatic nerve block at the puncture path proximal to the nerve bifurcation either at the nerve bifurcation. Subjects received an injection using a novel nerve block needle with external indwelling cannula guided by ultrasound invented by the corresponding author. The external indwelling cannula was inserted for postoperative analgesia. The primary outcome was NRS scores (at rest and during movement) times at 24 hours after surgery. The secondary outcomes included the measurements related to the performance of the nerve block and efficacy of analgesia, such as anesthesia effect grade, grade of nausea and vomiting, case number of patients with cannula leaking, occlusion or slipping, patient satisfaction, etc. RESULTS: During the surgery, six subjects in the proximal group needed additional analgesic, significantly different from one in the at bifurcation group (P<0.05). There was significant difference on anesthesia effect rating, 1.6±0.8 in the proximal group and 1.1±0.4 in another (P<0.05). The proximal group got 2.1±1.6 of NRS on rest at 24 hours and 1.7±1.5 at 48 hours, and the at bifurcation group got 0.9±1.4 at 24 hours and 0.7±1.1 at 48 hours (P<0.05). The proximal group got more PCA times during 6-24 hours and 24-48 hours and lower satisfaction scores.
Conclusions: Continuous popliteal sciatic nerve block at nerve bifurcation could receive better analgesia effect and more patients' satisfaction, rather than proximal to the bifurcation.