Ear-Vagus Nerve Stimulation and Body Acupuncture for Gut Motility in Elderly ICU Patients

• Standard Care (Other): Standard ICU care including hemodynamic management, enteral nutrition support per protocol (energy target: 25 kcal/kg ideal body weight/day; protein target: 1.3 g/kg ideal body weight/day), and management of feeding complications such as diarrhea, abdominal distension, and gastric retention. Enteral nutrition is initiated within 24-48 hours of ICU admission.
• Body Acupuncture (Behavioral): Acupuncture at body acupoints including CV13 (Shangwan), CV12 (Zhongwan), CV10 (Xiawan), ST21 (Liangmen), ST25 (Tianshu), SP15 (Daheng), CV4 (Guanyuan), CV6 (Qihai), CV7 (Yinjiao), LI4 (Hegu), TE6 (Zhigou), ST36 (Zusanli), ST37 (Shangjuxu), ST41 (Jiexi), and LR3 (Taichong). Sterile disposable needles (0.25mm × 40mm) are inserted 1-1.5 cun to achieve deqi sensation, retained for 30 minutes per session, once daily.
• Transcutaneous Auricular Vagus Nerve Stimulation (Device): Medium-frequency electrical stimulator (SNM-FDCM01, Ningbo Maida Medical Instruments Co., Ltd.) applied to the cymba concha region of the ear. Parameters: active period 2 seconds, rest period 3 seconds; pulse width 0.5 ms; frequency 25 Hz; intensity 0-2 mA (maximum tolerable by patient); 30 minutes per session, once daily.

Primary outcomes

• Time to Achieve Enteral Nutrition Target [From ICU admission up to 28 days]

Secondary outcomes

• Change in Acute Gastrointestinal Injury (AGI) Grade [Baseline Day3 Day 7]
• Change in Feeding Intolerance Score (FIS) [Baseline Day3 Day 7]: Minimum Value: 0 (The lowest score, where all evaluation items are scored as 0). Maximum Value: 15. The score is calculated by summing three items (abdominal distension and/or pain + nausea and/or vomiting + diarrhea). Since each item has a maximum score of 5, the theoretical maximum total score is 5 + 5 + 5 = 15. Interpretation (Higher vs. Worse): Higher scores indicate a worse outcome. A higher score represents more severe feeding intolerance (e.g., severe abdominal distension, frequent vomiting, massive diarrhea), requiring stricter clinical management. According to the notes in the image: 0-2 points: Continue enteral nutrition, increase or maintain the original rate, and provide symptomatic treatment. 3-4 points: Continue enteral nutrition, slow down the rate, and reassess after 2 hours. ≥5 points: Suspend enteral nutrition and take corresponding management measures.
• Change in Gastrointestinal Dysfunction Score (GIDS) [Baseline Day3 Day 7]: Minimum Value: 0 (0 - No risk: No symptoms, or any of the listed conditions present at the time of oral intake). Maximum Value: 4 (4 - Life-threatening: One of the listed conditions present). Interpretation (Higher vs. Worse): Higher scores indicate a worse outcome. Higher scores represent more severe gastrointestinal dysfunction and a higher risk of mortality. The specific grades are as follows: 0 (No risk): No symptoms, or any of the following conditions present at the time of oral intake (e.g., absent bowel sounds, vomiting, gastric residual volume >200ml, etc.). 1. (Increased risk): Two of the following symptoms are present (e.g., no oral intake, absent bowel sounds, vomiting, gastric residual volume >200ml, etc.). 2. (Gastrointestinal dysfunction): Three or more symptoms scored as 1, OR two of the following symptoms (severe diarrhea, gastrointestinal bleeding requiring transfusion, intra-abdominal pressure >20 mmHg). 3. (Gastrointestinal failure): Three or more of the followin
• Change in Intra-Abdominal Pressure (IAP) [Baseline Day3 Day 7]
• Change in Plasma Levels of Intestinal Injury Biomarkers (I-FABP） [Baseline Day 7]: ng/mL
• Change in Plasma Levels of Intestinal Injury Biomarkers (DAO） [Baseline and Day 7]: ng/mL
• Proportion of Participants Requiring Supplemental Parenteral Nutrition (SPN) [Day 7]
• Incidence of Secondary Intestinal Infections [Up to 28 days from ICU admission]
• Duration of Mechanical Ventilation [Up to 28 days from ICU admission]
• Length of ICU Stay [Up to 28 days from ICU admission]
• 28-Day Mortality [Day 28]
• Change in Plasma Levels of Citrulline [Baseline and Day 7]: μmol/L

Sex: All, ages: 65 Years to any

Inclusion Criteria:

1. Age ≥ 65 years.
2. Critically ill patients admitted to the ICU with APACHE II score ≥ 15.
3. NRS 2002 score ≥ 3 at ICU admission, indicating risk of malnutrition and requiring nutritional support.
4. Presence of gastrointestinal dysfunction or at risk, with AGI grade I-II.
5. Condition considered reversible.
6. Written informed consent obtained from the participant or legal representative before any study procedures.

Exclusion Criteria:

1. ICU length of stay less than 7 days.
2. Presence of severe gastrointestinal disease with contraindications to enteral nutrition and inability to receive conventional medications via the enteral route, such as acute gastrointestinal bleeding, mechanical intestinal obstruction, post-abdominal surgery, or abdominal compartment syndrome.
3. Skin lesions at the acupuncture sites that are not suitable for acupuncture treatment.
4. Advanced malignancy with significantly shortened life expectancy.
5. Participation in another clinical trial.
6. The treating clinician determines that the intervention is not in the patient's best interest.