Eligible volunteers provide written, informed consent prior to participating in the research. The protocol was carried out in accordance with the Declaration of Helsinki, approved by the Hospital of Chengdu University of Traditional Chinese Medicine's Medical Ethics Committee (ethics approval number: 2022KL-006).

1. Screening and diagnostics

1. Screen patients according to the inclusion and exclusion criteria with AGI in the initial phase of this study. Use the following diagnostic standards; class II-III on AGI as of the 2012 European Society for Intensive Care Medicine (ESICM)¹.
   1. AGI grade II (gastrointestinal dysfunction): the GI tract is unable to sufficiently complete digestion and absorption to meet the body's needs for nutrients and fluids. Regarding GI issues, the patient's overall condition has not changed.
   2. AGI grade III (gastrointestinal failure): the loss of GI function, in which case GI function is not restored despite interventions, and the overall state is not getting better.
2. Use the following inclusion criteria for this study. Add patients who match all of these requirements to the trial.
   1. Compliance with the diagnostic standards for AGI I-III grades.
   2. Informed consent to the treatment protocol described above.
3. Use the following exclusion criteria for this study. Exclude patients from the trial who met any of these requirements.
   1. An ICU stay of less than three days. These patients are unsuitable for acupuncture because they have damaged skin at the acupuncture site.
   2. Women who have childbearing needs within the previous 6 months, including those who are pregnant or breastfeeding. Also, patients whose life expectancy has been considerably reduced due to advanced malignant cancers.
   3. Patients with severe gastrointestinal conditions that prevent them from receiving routine therapy medications through the intestines, such as acute gastrointestinal hemorrhage, mechanical intestinal obstruction, major abdominal surgery, and abdominal compartment syndrome; patients whose unstable hemodynamics make it impossible to administer typical treatment medications orally.
   4. Individuals taking part in other clinical trials.
4. Obtain informed approval from those patients who satisfy the requirements and will thereafter be a part of the investigation. Ensure to get written informed permission before beginning any study procedures.

2. Patient grouping

1. Use a random number table by a non-affiliated third party to determine the random sequence number.
2. Create a card out of the random number sequence and insert it into the associated coded envelope.
3. Ask the patients who have been enrolled to choose an envelope at random. Assign odd numbers to the control group and even numbers to the treatment group, and number each patient corresponding to the random number.

3. Interventions

1. Start the intervention by an acupuncturist. After 24 hours, the groups are assigned. It is important to note that only acupuncture professionals with at least 1 year of clinical experience and a certificate as a physician are qualified to administer the treatments.
2. For the control group, administer standard care, including infection control, careful selection of antibiotics, correction of shock (maintaining intraperitoneal perfusion pressure > 60 mmHg), improvement of tissue perfusion and oxygen supply, elimination of factors that increase oxygen consumption as much as possible, early enteral nutrition, and protection of gastric mucosa. Additionally, treat symptoms such as diarrhea, abdominal distension, gastric retention, and vomiting.
3. For the treatment group, administer acupuncture according to standard medical practice.
   1. Prior to the procedure, prepare surgical masks and hats. Wash hands with a chlorine-containing disinfectant and dry them. Disinfect the hand that will hold the needle using an iodophor cotton swab.
   2. Prepare the patient by continuously monitoring their heart rate, blood pressure, respiratory rate, oxygen saturation, and changes in consciousness. Ask the patient to lie down in a supine position and fully expose the area for needle administration.
   3. Select the acupuncture points according to the WHO standard shown in Table 1, which include Zhongwan (CV 12), Tianshu (ST 25), Zusanli (ST 36), Hegu (LI 4), Shangjuxu (ST 37), and Xiajuxu (ST 39). Prior to acupuncture, clean the patient's skin using povidone-iodine cotton swabs.
   4. Use a disposable stainless-steel needle with a size of 0.30 mm x 40 mm. Hold the needle in the right hand and use the index and middle finger of the left hand to press the skin around the acupuncture point or hold the needle body to assist in its insertion.
   5. Rotate the needle in the right hand next to the nail surface of the left hand and insert the needle at the specified angle and depth. The penetration depth for Hegu is 0.5 cun, and for Zhongwan, Tianshu, Zusanli, Shangjuxu, and Xiajuxu, it is 1.5 cun. Keep all acupuncture directions perpendicular to the skin (90°). Leave the needle in place for 30 minutes.
   6. After the 30-minute treatment, remove the needle and gently press the needle hole with a sterile cotton swab. If there is any bleeding, continue to apply pressure for a few minutes until the bleeding stops.

4. Ultrasonic analysis

1. Perform abdominal ultrasound on the first day before treatment and the seventh day after treatment.
2. Ask the patient to lie on the bed on their back.
3. Scan the abdomen using an ultrasonic machine and choose a convex array probe with a skilled intensivists. The scan should include the colon, ileum, jejunum, and gastric antrum.
4. In the short-axis view of the stomach antrum, locate the abdominal aorta in the lower portion of the screen and keep the angle annular.
5. Position the convex array ultrasonic probe longitudinally on the midline beneath the xiphoid process with the probe mark pointed toward the head. This position is referred to as the stomach antrum. Measure the greatest antrum diameters (D1 and D2) using two vertical lines and average them over three subsequent measurements to determine the antrum area.
   Antrum area = π x (D1 x D2)/4
6. At the same time, observe the frequency of stomach movements per minute.
7. For the ileum section, use a convex array ultrasound probe to scan the right lower abdomen in a clockwise direction. Measure the thickness of the intestinal wall and the maximal diameter of the small intestine.
8. For the colon section, position the convex array ultrasound probe along the course of the colon on either the left or right side of the abdomen and scan vertically or horizontally from top to bottom. Measure the thickness of the intestinal wall and the largest diameter of the colon.