Impact of perioperative transcutaneous auricular vagus nerve stimulation on pain and sleep quality after glaucoma surgery

Objective: To investigate the effects of perioperative transcutaneous auricular vagus nerve stimulation (taVNS) on postoperative pain and early sleep quality in patients undergoing glaucoma surgery under general anesthesia. Methods: A total of 94 hospitalized patients scheduled for elective glaucoma surgery under general anesthesia at Beijing Tongren Hospital, Capital Medical University, from April to August 2024 were prospectively enrolled and randomly assigned using a random number table to either the taVNS group (n=47) or the sham stimulation group (s‐taVNS group) (n=47). In the taVNS group, active electrical stimulation was applied to the left auricular concha area starting from 2 days before surgery, while the s‐taVNS group received electrode placement without current output. Stimulation was performed twice daily for 30 min each session until the first postoperative day. The primary outcome was the incidence of moderate to severe pain within 24 hours after surgery, defined as a Numeric Rating Scale (NRS) score≥4 score. Secondary outcomes included NRS scores at different time points, use of rescue analgesics, insomnia severity index (ISI) scores. Comparisons were made between the two groups regarding the primary and secondary outcome measures. Results: The taVNS group included 27 males and 20 females, aged (56.5±11.3) years; the s‐taVNS group included 26 males and 21 females, aged (58.4±9.7) years, with no significant differences in age or gender between the two groups (all P>0.05). The incidence of moderate to severe pain within 24 hours after surgery was lower in the taVNS group than in the s‐taVNS group [14.9% (7/47) v. 38.3% (18/47), P=0.010]. The proportion of patients requiring acetaminophen for rescue analgesia within 24 hours postoperatively was lower in the taVNS group than in the s‐taVNS group [8.5% (4/47) vs 23.4% (11/47), P=0.049]. The ISI score on the first postoperative night was lower in the taVNS group than in the s‐taVNS group [(3.1±2.7) score vs (5.7±4.3) score, P=0.018]. Conclusion: Perioperative taVNS can effectively reduce the incidence of moderate to severe postoperative pain and improve early postoperative sleep quality in patients undergoing glaucoma surgery under general anesthesia.