Enteral Nutrition Delivery in Prone Position Ventilated Patients With Moderate to Severe ARDS

• enteral nutrition through nasojejunal tube (Procedure): place nasojejunal tube for enteral nutrition
• enteral nutrition through nasogastric tube (Procedure): place nasogastric tube for enteral nutrition

Primary outcomes

• Cumulative Enteral Nutrition intake to target ratio [follow-up till 7-day]: The ratio of total calorie and protein intake through EN to target calorie and protein respectively.

Secondary outcomes

• Incidence of new Infections [follow-up till 28-day]: New infections occur after admission to ICU within 28 days after admission to this study
• Ventilator-free days within 28 days [follow-up till 28-day]: the number of days within a 28-day period that a patient does not require mechanical ventilation.
• ICU Length of Stay [up to 24 weeks]: Duration of time a patient spends in the ICU from admission to discharge.
• ICU Mortality Rate [up to 24 weeks]: The proportion of patients who die in the Intensive Care Unit (ICU) of a hospital
• 28-Day Mortality Rate [28 days]: The proportion of patients who die within 28 days.
• 60-Day Mortality Rate [60 days]: The proportion of patients who die within 60 days.
• Incidence Rate of Enteral Nutrition Intolerance [28 days]: The frequency at which patients experience intolerance to enteral feeding.
• Daily Enteral Nutrition Intake Rate [7 days]: It is calculated as the total volume of enteral nutrition fed to a patient each day, divided by the total prescribed enteral nutrition for that day, multiplied by 100%.

Sex: All, ages: 18 Years to 85 Years

Inclusion Criteria:

* ARDS patients who meet the Berlin criteria for ARDS and have a P/F ratio ≤ 200mmHg.
* Patients receiving invasive mechanical ventilation and clinically judged to require prone ventilation, with an anticipated daily prone positioning time of ≥12 hours and a duration of prone ventilation therapy of ≥3 days.
* Patients planned to receive enteral nutrition.
* Age ≥18 and ≤85 years.
* Consent to sign an informed consent form.

Exclusion Criteria:

* Contraindications to enteral nutrition, such as severe intestinal ischemia, active upper gastrointestinal bleeding, high-output intestinal fistula without a distal feeding route, abdominal compartment syndrome, severe diarrhea, intestinal obstruction, etc.
* Presence of shock with hemodynamic instability (norepinephrine or equivalent vasopressor dosage ≥0.5ug/kg.min) or tissue hypoperfusion (lactate >3mmol/L).
* Life-threatening hypoxemia, hypercapnia, and acidosis.
* Inability to tolerate prone ventilation (e.g., pregnant women, limb contractures, recent fractures, recent thoracic or abdominal surgery, pacemaker insertion within 48 hours, spinal instability, pelvic fractures, facial fractures, anticipated difficult airway).
* Conditions preventing nasogastric or nasojejunal tube placement (e.g., esophageal rupture, severe esophageal varices).
* Anticipated inability to start enteral nutrition within 48 hours.
* Use of prokinetic agents within 48 hours prior to starting enteral nutrition.
* Enteral nutrition via gastrostomy or jejunostomy.
* Expected ICU stay or survival time less than 3 days.
* Patients refusing further resuscitative treatment.
* Pregnant or breastfeeding women.
* Patients already enrolled in other interventional clinical studies or deemed unsuitable for the study by the clinician.