The median effective dosage of 0.5% ropivacaine for ultrasound-guided lateral popliteal sciatic nerve block / 中华麻醉学杂志

ABSTRACT

Objective To determine the median effective dosage of 0.5% ropivacaine for ultrasoundguided lateral popliteal sciatic nerve block. Methods Twenty-three ASA Ⅰ or Ⅱ patients of both sexes, aged 19-20 yr weighing 52-90 kg received lateral popliteal nerve block guided with ultrasound for foot and ankle surgery.The volume of 0.5% ropivacaine injected was determined by the response of the previous patient using an up-anddown technique. The initial volume was 18 ml. Each time the volume increased/decreased by 2 ml.Successful nerve block was defined as complete loss of pinprick sensation in both tibial and common peroneal nerve distribution with concomitant inability to perform plantar or dorsal flexion of the foot 30 min after injection. Results The median effective dosage of 0.5% ropivacaine resulting in complete block of the sciatic nerve in 50% patients was 13 ml (95% confidence interval 11.3-14.9 ml).Conclusion The median effective dosage of 0.5% ropivacaine for ultrasound-guided lateral popliteal sciatic nerve is 13.0 ml.