Effects of Delayed Enteral Nutrition on Inflammatory Responses and Immune Function Competence in Critically Ill Patients With Prolonged Fasting

Inclusion Criteria: * having a fasting time of more than 14 days * American Society of Anesthesiologists (ASA) physical status ranging between 1 and 3, and their condition allows enteral nutrition therapy. Exclusion Criteria: * chronic renal failure (peritoneal or hemodialysis or creatinine \> 2.5 mg/dl) * history of chronic obstructive pulmonary disease * hepatic dysfunction or cirrhosis or a bilirubin value \> 3 mg/dl * metabolic diseases,severe anemia * blood coagulation dysfunction * pregnancy lactation * history of psychiatric illness * patients underwent immunosuppressive therapy