2.3. Randomization, blinding, and data collection
All patients were divided into 2 groups by the same anesthesia nurse according to the random number table method. The remainder was obtained by dividing the random number in the random number table by the number of groups, while the aliquot was the control group and the experimental group with the remainder, with 40 mL of unlabeled local anesthetic or 0.9% NS in a marked 1 sealed envelope and the group label in a marked 2 sealed envelope, handed to the anesthesiologist on duty, and the patients were blinded to the group assignment. Two patients refused to participate, 11 patients were excluded according to the exclusion criteria, 2 patients were lost to follow up, and 3 patients used vasoactive agents during the procedure, resulting in 122 patients being enrolled: 62 in the OFA (F) group and 60 in the control (C) group (Fig.Consort e-flowchart.