Electrical Acupoint Stimulation on Gastric Reflux During I-gel Ventilation

Inclusion Criteria: * age ≥18 years old * scheduled for surgery under general anesthesia with igel ventilation Exclusion Criteria: * American society of anesthesiologists status higher than grade 3 * history of gastrointestinal surgery * Currently taking acidic medications, or medications that affect gastric acid secretion or gastrointestinal motility * High risk of reflux or aspiration (e.g., symptomatic gastroesophageal reflux disease or hiatal hernia) * History of postoperative nausea and vomiting (PONV) * Intraoperative requirement of Trendelenburg position * Expected surgery duration exceeding 4 hours * Contraindications for acupoint electrical stimulation, such as patients with implanted electrophysiological devices, or skin infection/lesions at acupoint sites