This study is a prospective, multicenter, three-arm, parallel-group, randomized, sham-controlled trial conducted at 13 tertiary hospitals in Shandong Province, China. A total of 300 eligible participants scheduled for laparoscopic radical gastrectomy for stage I-III gastric cancer will be enrolled and randomly assigned in a 1:1:1 ratio to one of three groups: Peri-TEAS (transcutaneous electrical acupoint stimulation administered before, during, and after surgery), Post-TEAS (sham treatment before and during surgery, with real TEAS after surgery), or Sham-TEAS (sham treatment at all time points). Randomization will be performed using a centralized system with stratification by study center and a randomized block design with randomly assigned block sizes. Allocation concealment is ensured by the system, with group assignments revealed only after participant enrollment.
TEAS is delivered using a standardized electroacupuncture device (SDZ-V, Suzhou Medical Products Factory) with a dense-disperse wave (2 Hz alternating with 100 Hz, 5s/10s duty cycle) at individually titrated intensities. Four bilateral acupoints are selected: Hegu (LI4), Neiguan (PC6), Zusanli (ST36), and Shangjuxu (ST37), following WHO standard acupoint locations. For the Peri-TEAS group, stimulation begins 30 minutes before anesthesia induction at the individually determined maximal tolerable threshold, continues throughout surgery at the same intensity, and resumes postoperatively for 30 minutes daily on postoperative days 1 through 3. For the Post-TEAS group, sham stimulation is applied before and during surgery, with real TEAS administered postoperatively using the same protocol as the Peri-TEAS group. The Sham-TEAS group receives sham stimulation at all time points. To maintain blinding, the device screen is shielded, and operators use standardized scripts to avoid unblinding.
All participants receive a standardized enhanced recovery after surgery (ERAS) protocol, including no bowel preparation, preoperative carbohydrate loading, minimally invasive incisions, goal-directed fluid therapy, no routine nasogastric tubes, early removal of drains and urinary catheters (within 24 hours), early mobilization, and a stepwise enteral nutrition plan. Postoperative analgesia is provided via patient-controlled intravenous analgesia (PCIA) with sufentanil (2 μg/kg in 100 mL normal saline, background infusion 2 mL/h, bolus 2 mL, lockout 15 min), supplemented with flurbiprofen axetil 50 mg twice daily. Rescue analgesia (morphine 2-4 mg IV or equivalent) is administered for breakthrough pain (NRS ≥ 4), with all rescue doses converted to morphine equivalent dose for analysis.
The primary endpoint is time to first flatus after surgery. Key secondary endpoints include the area under the curve of movement-evoked pain NRS scores over 0-72 hours and total rescue analgesic consumption in morphine equivalent dose. Additional secondary endpoints encompass gastrointestinal recovery parameters (time to first bowel movement, tolerance of liquid/semi-liquid/solid diets), pain and analgesic use (resting pain AUC, time to first PCIA press, total PCIA presses, intraoperative propofol and remifentanil dosages), ambulation and recovery (time to first independent ambulation ≥5 meters, postoperative hospital stay meeting uniform discharge criteria), and safety outcomes (incidence and severity of nausea, vomiting, abdominal distension, postoperative complications graded by Clavien-Dindo classification, and 30-day readmission rate). Patient-reported outcomes are assessed using the EORTC QLQ-C30 and QLQ-STO22 questionnaires, and perioperative fatigue is evaluated using the ICFS-10, all administered preoperatively, on postoperative day 4, and at 30 days after surgery. Exploratory endpoints include inflammatory cytokines (CRP, IL-6, IL-1β, TNF-α), gastrointestinal hormones (motilin, gastrin, substance P, VIP, cholecystokinin), and immunoglobulins (IgA, IgG, IgM) measured from fasting blood samples on postoperative days 1, 3, and 5 (or at discharge if earlier).
Blinding is implemented for participants, surgeons, anesthesiologists, outcome assessors, and statisticians. TEAS operators are not blinded but are strictly prohibited from participating in any post-treatment clinical assessments or data collection. The success of blinding will be evaluated using Bang's Blinding Index. An independent Data Monitoring Committee, composed of one statistician and two external experts, will regularly review safety and compliance data.
Sample size calculation: Based on pilot data showing a mean difference of 8.22 hours in time to first flatus between Peri-TEAS and Post-TEAS (SD 18.36) and 15.35 hours between Peri-TEAS and Sham-TEAS (SD 25.74), with α = 0.05 (two-sided) and power = 80%, 80 participants per group are required. Accounting for a 20% dropout rate, the target enrollment is 300 participants (100 per group).
The statistical analysis will follow a fixed-sequence testing procedure to control the overall type I error at α = 0.05. Analyses will be performed on the full analysis set (intention-to-treat principle), with per-protocol analysis for sensitivity. All tests will be two-sided, with statistical significance set at P < 0.05, using SAS 9.4.
The study protocol and informed consent form have been approved by the Ethics Committee of the Affiliated Hospital of Qingdao University and each participating center. The results will be disseminated through peer-reviewed academic journals.
