Abstract:Objective To explore the analgesic effects of brachial plexus block (BPB) guided by ultrasound versus localized by nerve stimulator in elderly patients who underwent humeral surgery. Methods Ninety nine elderly patients scheduled for open reduction and internal fixation of humeral fractures in Tongling Municipal Hospital from May 2020 to May 2023 were selected ,and randomly divided into ultrasound group (55 cases) and stimulator group (54 cases) based on a random number table method. The ultrasound-guided BPB was performed in ultrasound group, and the nerve stimulator localization for BPB was performed in stimulator group. The blocking effect, diaphragmatic function, hemodynamics indexes, stress indexes and perioperative adverse anesthesia reactions were compared between the two groups. Results The onset time［(4.82±1.44)min vs(6.95±1.87)min， t=6.675］ and improvement time ［(17.62±2.57)min vs(20.54±3.79)min， t=4.689］, and dosage of 0.75% bupivacaine hydrochloride ［(21.33±2.05)mL vs(25.54±2.52)mL， t=9.592］ in ultrasound group were lower than those in stimulator group (P＜0.01). After injecting drugs for 30min, the diaphragm mobility at calm breathing position ［(1.52±0.23)cm vs(1.24±0.22)cm］and at 〖JP2〗maximum breathing position ［(4.01±0.44)cm vs(3.19±0.49)cm］in ultrasound group were higher than those in stimulator group(P＜0.01). From entering the operating room to the end of surgery, heart rate (HR) and mean arterial pressure (MAP) of the two groups decreased first and then increased (P＜0.01), and the HR and MAP of ultrasound group were significantly higher than those of stimulator group from 10 min before the start of surgery to the end of the surgery (P＜0.05). Before surgery, on the day and 2 days after surgery, levels of serum epinephrine, norepinephrine and cortisol in the two groups showed a trend of first increasing and then decreasing (P＜0.01), but no significant difference was found between the two groups at each time point (P＞0.05). There was no significant difference in the incidence of perioperative adverse anesthesia reactions (agitation, nausea and vomiting, lethargy) between the two groups (P＞0.05). Conclusion Ultrasound-guided BPB has a fast block onset time, few effects on diaphragmatic function, stable hemodynamics and little stress response in elderly patients undergoing humeral surgery.