Abstract: Objective To compare the clinical effect of ultrasound-guided suprascapular nerve block (SSB) combined with general anesthesia and interscalene brachial plexus block (ISB) combined with general anesthesia in arthroscopic shoulder surgery. 
Methods In total, 91 patients who underwent arthroscopic shoulder surgery at People′s Hospital of Xindu District in Chengdu, Sichuan Province and First Affiliated Hospital of Chengdu Medical College were selected and randomly divided into the ISB group (ultrasound-guided ISB combined with general anesthesia, n=45) and the SSB group (ultrasound-guided SSB combined with general anesthesia, n=46) using a computer-generated random number table. The heart rate (HR), mean arterial pressure (MAP), anesthetic dosage, surgical duration, and length of recovery room stay between the two groups at the time of entry, at 30 min after surgery, and after surgery were compared. The pain levels, wrist flexion strength, and elbow flexion strength between the two groups at 1, 6, 12, and 24 h after surgery were compared. The stress response and differences in inflammatory mediator indicators between the two groups before and at 24 h after surgery and complications in the two groups were compared. 
Results HR and MAP in both groups were decreased at 30 min after the initiation of surgery compared with preoperative levels, and then increased at the end of the surgery. There was no significant difference between the two groups, but there were significant differences in the interaction between time points, groups, and time points between groups (P＜0.001). The success rate of nerve block in both groups was 100%, with no occurrence of nerve block failure or repeated nerve block. There was no significant difference in the dosage of propofol and remifentanil, surgical duration, and the length of recovery room stay between the two groups (P＞0.05). The visual analogue scale (VAS) scores of postoperative pain in the two groups showed a decreasing trend with the prolongation of time, with the ISB group showing a more significant downward trend than the SSB group. There were significant differences in the interaction between groups, time points, and time points between groups (P＜0.001). The wrist and elbow flexion strength of the two groups were gradually increased with the prolongation of time; there was no significant difference between groups (P＞0.05), but there were significant differences in the interaction between time points, groups, and time points between groups (P＜0.001). The differences in aldosterone (ALD) and adrenocorticotropic hormone (ACTH) levels before and at 24 h after surgery in the ISB group were significantly higher than those in the SSB group, showing significant differences (P＜0.05). The difference in interleukin-6 (IL-6) and prostaglandin E2 (PGE2) levels before and at 24 h after surgery in the ISB group was higher than that in the SSB group, suggesting significant differences (P＜0.05). Both groups did not experience nerve damage or arterial injury. The incidence of phrenic nerve paralysis in the SSB group was lower than that in the ISB group, showing significant differences (P＜0.05). There was no significant difference in the incidence of recurrent laryngeal nerve paralysis and stellate ganglion block between the two groups (P＞0.05). 
Conclusion Compared with ultrasound-guided ISB combined with general anesthesia, SSB combined with general anesthesia in arthroscopic shoulder surgery can reduce postoperative stress and inflammatory responses, enhance wrist and elbow flexion strength, and reduce fewer complications. However, its early postoperative analgesic effect is less pronounced than that of ISB combined with general anesthesia. 

Key words: arthroscopy, suprascapular nerve block, interscalene brachial plexus block