Effect of Semi-elemental Enteral Nutrition on Gastrointestinal Tolerance in Patients With Traumatic Brain Injury.

Inclusion Criteria: * Aged 18-75 years; * Clinically diagnosed with closed traumatic brain injury; * Glasgow Coma Scale (GCS) score ≤ 8; * Ability to initiate enteral nutrition within 48 hours post-injury; * Expected need for enteral nutrition support ≥3 days based on clinical assessment (Nutritional Risk Screening 2002 \[NRS2002\] score ≥3). Exclusion Criteria: * GCS=3 with bilateral fixed and dilated pupils; * Hemodynamic instability or respiratory failure: mean arterial pressure \<70mmHg, PaO2/FiO2\<150, PaCO2\<30 mmHg or \>45 mmHg, or lactate \>5 mmol/l; * Contraindications to both nasogastric and nasojejunal tube placement, or inability to complete tube placement within 48 hours of onset; * Contraindications to enteral nutrition therapy or semi-recumbent positioning; * Pre-existing intellectual disability or physical disability affecting outcome assessment; * Gastrointestinal abnormalities likely to affect gastrointestinal function, such as short bowel syndrome (defined as total small bowel length ≤122 cm), ulcerative colitis, Crohn's disease, or any form of ostomy; * Body mass index (BMI) \<18kg/m2; * Concomitant abdominal injury or extracranial injury with AIS score \>3 in any region; * Presence of malignancy, severe cardiac insufficiency (ejection fraction \<50%), severe hepatic failure (Child-Pugh score ≥7), or severe renal failure (glomerular filtration rate ≤30 mL/min or serum creatinine ≥4mg/dL) at NICU admission; * Concurrent severe disease with expected survival ≤14 days; * Pregnancy, within 30 days postpartum, or breastfeeding; * Refusal of treatment or receipt of palliative care; * Patient or family declines informed consent; * Current participation in another interventional clinical trial.