To Discuss CE₅₀of Ropivacaine When Popliteal Fossa Sciatic Nerve Block Disspeared Guided By Peripheral Nerve Stimulator Continuously

Objective: The purpose of this essay is to discuss half-effective concentration ofropivacaine when popliteal fossa sciatic nerve block disspeared guided by peripheralnerve stimulator continuously. Methods: American Society of Anesthesiologists (ASA),Ⅰ~Ⅱselected patients aged from18to65with22cases of ankle surgery of single lowerlimb, to guide popliteal fossa sciatic nerve block by peripheral nerve stimulator. Byadopting sequential test and preparing30ml ropivacaine with the concentration of0.27%,0.30%,0.33%,0.36%,0.39%, inject the first patient with the concentration of0.33andgraded differential of0.03%. Set the block at grade2and the motor block at or abovegrade2within30minutes after injection. If there is no referred pain in surgery noadjuvant intravenous injection is needed to make effect to patient. If it is effective, thelower concentration can be used to next case; if it isn’t effective, the higher concentrationwould be applied in the next case. With the method of probability unit regression, tocalculate the half-effective concentration of EC50and95%CI andEC95. Results: Whenthe ropivacaine in continuous popliteal fossa sciatic nerve block disspeared, the EC50is0.318%and CI95is0.284%-0.351%,while EC95is0.37%and CI95is0.342%-0.625%.Conclusion: The CE50is0.318%when ropivacaine for continuous popliteal fossa nerveblock disspeared.