Transcutaneous Electrical Acupoint Stimulation Versus Sham Stimulation Combined With Dexamethasone Versus Amisulpride for Preventing Postoperative Nausea and Vomiting After Laparoscopic Gynecological Surgery: A Randomized Controlled Factorial Trial

1. Background Postoperative nausea and vomiting (PONV) is a common complication after general anesthesia, with an incidence as high as 80% in gynecological laparoscopic surgery. Transcutaneous electrical acupoint stimulation (TEAS) has shown potential as a non-invasive, side-effect-free intervention. Combining pharmacological agents (dexamethasone or amisulpride) with TEAS may provide a synergistic preventive effect, aligning with enhanced recovery after surgery (ERAS) principles.
2. Study Objectives To evaluate the preventive effect of TEAS on PONV in patients undergoing gynecological laparoscopic surgery, compared with sham stimulation.

To explore the synergistic effect of dexamethasone or amisulpride when combined with TEAS, and to optimize PONV prevention strategies.

To assess the impact of multimodal intervention on postoperative recovery quality, length of hospital stay, and patient satisfaction.

To evaluate the safety of the combined interventions and record any adverse events. 3. Study Design Design type: 2×2 factorial, randomized, double-blind (participants, outcome assessors, and data analysts blinded to group assignment).

Randomization: 1:1:1:1 allocation using an online randomization tool.

3.1 Study Groups Group Intervention A TEAS + Dexamethasone B TEAS + Amisulpride C Sham stimulation + Dexamethasone D Sham stimulation + Amisulpride 3.2 Participants Inclusion criteria: Age 18-65 years; ASA physical status I-II; scheduled for elective gynecological laparoscopic surgery (e.g., ovarian cystectomy, myomectomy) under general anesthesia; willing to provide informed consent.

Exclusion criteria: Severe cardiac, hepatic, renal, or pulmonary disease; allergy or skin disease at TEAS application site; Receipt of antiemetics within 24 h before surgery; Implanted cardiac pacemaker, cardioverter-;pregnancy or lactation; vulnerable populations (e.g., critically ill, psychiatric disorders, cognitive impairment, illiteracy); any condition deemed unsuitable by the investigator.

3.3 Interventions A wearable transcutaneous electrical acupoint stimulation (TEAS) wristband will be applied to the P6 (Neiguan) acupoint on the dominant upper extremity. The P6 acupoint is located approximately 3-5 cm proximal to the distal wrist crease, between the tendons of the flexor carpi radialis and palmaris longus. The device integrates the stimulating electrodes within the wristband and does not require external adhesive electrodes.

TEAS or sham stimulation will be administered at three time points: 30 minutes before surgery and 24 and 48 hours after surgery, with each session lasting 30 minutes.

Dexamethasone 5 mg (off-label for PONV; approved for inflammatory/allergic conditions).

Amisulpride 5 mg.

3.4 Outcome Measures

Primary outcomes (0-48 h postoperatively):

PONV incidence (proportion of patients with nausea, vomiting, or retching). PONV severity (0 = none, 1 = nausea only, 2 = vomiting/retching, 3 = refractory nausea/vomiting).

Secondary outcomes:

Recovery quality: time to first flatus, first ambulation, hospital stay, bowel function recovery.

Patient satisfaction: Visual Analogue Scale (VAS, 0-10) and QoR-15 score (0-150).

Rescue antiemetic use. Management needs for severe PONV. Postoperative pain (VAS at rest and on movement) and opioid consumption. Device-related adverse events (skin irritation, burning, allergy). Drug-related adverse events (e.g., hyperglycemia, hypotension, headache, dizziness, QT prolongation).

Intraoperative hemodynamics and postoperative complications (e.g., infection, shivering, urinary retention).

3.5 Follow-up Schedule Postoperative day 1 (24 h): PONV assessment, time to first flatus and ambulation.

Postoperative day 2 (48 h): PONV incidence/severity, rescue medication. At discharge: Satisfaction, hospital stay (via in-person or telephone follow-up). 4. Sample Size Calculation Assumptions: PONV incidence 50% in control groups, 30% in TEAS groups; two-sided α = 0.05; power = 80%.

Each main effect level requires ~93 patients. For a 2×2 factorial design with 1:1:1:1 allocation, this translates to 47 patients per group (total 188). Accounting for a 10% dropout rate, final sample size = 212 patients (53 per group). 5. Data Management and Confidentiality Electronic Data Capture (EDC) system with unique coding (no direct identifiers).

Access restricted to authorized research team members. 6. Informed Consent Written informed consent will be obtained from each participant after full explanation of the study purpose, procedures, risks, and benefits. Participants are informed of their right to withdraw at any time. 7. Adverse Event Management Dexamethasone-related AEs (transient hyperglycemia, blood pressure fluctuation, gastrointestinal discomfort, rare allergic reactions).

Amisulpride-related AEs (headache, dizziness, constipation/diarrhea, QT prolongation, allergic reactions).

TEA-related AEs (local skin discomfort, redness, itching, rare blisters or mild burns).