Effect of Transcutaneous Auricular Vagus Nerve Stimulation on Gastrointestinal Function After Colorectal Surgery: A Double-Blind, Randomized Controlled Trial

INTERVENTION: Fake stimulation group (Group F):Transcutaneous Auricular Vagus Nerve Stimulation (taVNS);taVNS group (Group T):Transcutaneous Auricular Vagus Nerve Stimulation (taVNS); CONDITION: gastrointestinal function after colorectal surgery. PRIMARY OUTCOME: Time of first postoperative exhaust; SECONDARY OUTCOME: pain level;Time of first bowel movement after surgery;sleep quality;delirium incidence; INCLUSION CRITERIA: 1. Age 18 years or older; 2. ASA class I‐III; 3. Scheduled for elective laparoscopic colorectal surgery under general anesthesia; 4. Hb > 70 g/L.