Anesthetic Effect of Ropivacaine on Local Infiltration Anesthesia in Arteriovenous Fistula Surgery

Blinding \& Drug Preparation: To maintain blinding, all anesthetic solutions were prepared by the hospital pharmacy under aseptic conditions. Both solutions were clear, colorless, and dispensed in identical 20mL syringes labeled only with the study ID and patient randomization number. Standardized Infiltration Protocol: A fixed sequence was used: subcutaneous infiltration along the planned 3-4 cm incision line, followed by targeted perivascular infiltration around the exposed radial artery and cephalic vein using a 25-gauge needle. Standardized Surgical Protocol (Per Study Procedures): All surgeries were performed by the same high-volume surgeon. With the patient in the supine position and the operative limb abducted, a 3-4 cm skin incision was made between the artery and vein. The cephalic vein and radial artery were carefully dissected. The distal cephalic vein was ligated and divided. While an assistant compressed the cubital fossa, heparinized saline (5000 IU in 500 mL saline) was injected through the proximal vein to fully dilate the forearm cephalic vein. Vascular clamps were then applied to occlude the radial artery. Parallel longitudinal incisions (0.8-1 cm) were made in both vessels. The anastomosis was completed using continuous everting sutures on both the anterior and posterior walls. After clamp release and confirmation of fistula patency, the incision was closed in layers. Intraoperative Adjuncts: All patients received the aforementioned irrigation with heparinized saline for venous dilation. Protocol-Specified Additional Monitoring \& Quality Assurance: Extended Monitoring: Beyond pre-specified outcomes, the protocol mandated daily wound assessments for the first postoperative week and monitoring for signs of local anesthetic systemic toxicity (LAST) within 24 hours. Data Quality Control: To minimize bias, a single, uniformly trained research assistant, blinded to group allocation, was responsible for collecting all intraoperative and postoperative data, including pain scores. Source data verification was performed for all primary outcome measures. Study Progress Context (as of November 2025): Patient enrollment (n=40) and all surgical procedures were completed between April 2019 and February 2020. The study is currently in the long-term follow-up phase, tracking the 5-year primary unassisted patency endpoint. Blinding has been maintained throughout follow-up. Final data collection for the 5-year endpoint is anticipated by June 2026.