Study Of Median Effective Volume Of 0.5%Ropivacaine Ultrasound-guided Erector Spinae Plane Block For Postoperative Analgesia After Thoracoscopic Lobectomy

BackgroundVideo-assisted thoracic surgery(VATS)is the most commonly used thoracic surgery method at present,for it has the advantages of small trauma area,fast recovery,fewer complications and low mortality.However,the postoperative pain is obvious,which seriously affects the ventilation function of patients,resulting in pulmonary infection,atelectasis,hypercapnia and other complications.In recent years,the technique of ultrasound-guided erector spinae plane block(ESPB)has been popularized at home and abroad,and has been gradually used for postoperative analgesia of chest,spine,abdomen and other operations,with obvious analgesic effect.At present,the minimum effective volume of 0.5%ropivacaine ESPB to provide analgesia in patients undergoing video-assisted thoracoscopic lobectomy is unclear.Therefore,in this study,the sequential method was used to determine the median effective volume(EV50)of 0.5%ropivacaine for effective postoperative analgesia of thoracoscopic lobectomy by an ultrasound(US)-guided ESPB,so as to provide clinical reference for the clinical use of local anesthetic volume for analgesia after thoracoscopic lobectomy.ObjectiveThis dose-finding study was performed to determine the EV50 of 0.5%ropivacaine for effective postoperative analgesia of thoracoscopic lobectomy by an ultrasound(US)-guided ESPB.MethodsTwenty-four patients scheduled for thoracoscopic lobectomy were selected to undergo ultrasound-guided erector spinal plane block with 0.5%ropivacaine from April 2021 to January 2022.A smaller volume of 20ml was selected as the starting dose from previous reports,and the volume gradient was 2ml.Depending on whether the previous block was successful or unsuccessful,subsequent volume decreased or increased by 2ml(10mg),until obtaining 7 negative-positive up-and-down deflection points.The plane at 5,10,15,20 and 30min after block,VAS at rest and deep breathing at 2,6,12 and 48h after operation,the total number of PCA at 0 to 12h and 13 to 48h after operation were recorded.To determine the EV50 and 95%CI of 0.5%ropivacaine ESPB for analgesia in patients undergoing thoracoscopic lobectomy using Dixon and Massey up-and-down methods.The complications of hemorrhage in puncturing area,postoperative infection and local anesthetic intoxation were recorded.ResultsTwenty-four patients(100%)were successfully blocked.The total number of PCA>3 at 0～12h after operation was significantly lower than that at 13～48h(P<0.05).EV50 of 0.5%ropivacaine was 24.45ml(95%CI 23.26～25.69ml).None of the patients occur hemorrhage and hematoma in area,postoperative infection and local anesthetic intoxation.ConclusionThe median effective volume of ultrasound-guided 0.5%ropivacaine in the ultrasound-guided erector spinal block for postoperative analgesia after video-assisted thoracoscopic lobectomy is 24.45ml.