Early Versus Delayed Parenteral Nutrition in Abdominal Surgical Patients

Patients after abdominal surgery will attempt enteral nutrition support for 2 days, if she/he can not tolerate 30% of target energy, then she/he will be randomized to early PN group or late PN group at day 3. Patients in early PN group will receive supplemental parenteral nutrition at day 3 while patients in late PN group will not receive supplemental parenteral nutrition until day 8 after abdominal surgery. Both groups will receive SPN except 80% of target energy delivered by EN or oral or patients are discharged from hospital. The primary and secondary outcomes will be collected.

Inclusion criteria

• Informed consent of patients or their legal representatives to participate in this study.
• Patients undergoing selective operation without trauma
• Patients following medium or major abdominal surgery
• NRS 2002≥ 3

Exclusion criteria

• Psychiatric disorders
• Pregnancy or breast-feeding women
• Malnutrition

• Weight loss >10%-15% in 6 months
• BMI<18.5
• SGA score with stage C
• Albumin <30g/L
• Unstable vital signs or unstable hemodynamics (such as systolic blood pressure < 90 mmHg or mean arterial pressure < 70 mmHg after rapid 500 ml crystal or 200 ml gel infusion, or the 50% increase of vascular active drug infusion rate in an hour, etc)
• Refuse to participate in the study
• Mortality rates expected to more than 50% in 6 months with malignant or irreversibility diseases

• Cancer in terminal stage
• HIV positive at end-stage or CD4 < 50/mm3
• Cardiopulmonary resuscitation (CPR) before cardiac arrest and nervous system function not fully recovery
• Four levels of physical activity of the patients defined by New York heart association
• Rely on breathing machine because of chronic diseases
• Life expectancy less than 24 hours of dying patients
• Refractory shock to meet any of the following article

• The infusion rate of dopamine > 15 ug/kg/min
• The infusion rate of dobutamine > 15 ug/kg/min
• The infusion rate of epinephrine and norepinephrine > 30 ug/min
• The infusion rate of phenylephrine > 50 ug/min
• The infusion rate of milrinone > 0.5 ug/kg/min
• The infusion rate of vasopressin > 0.04 U/min
• Inter aortic ballon pump (IABP)
• Hepatic insufficiency (alanine/aspartate transaminase 200% above normal range)
• Renal insufficiency(creatinine 200% above normal range)
• Metabolic diseases（hyperthyroidism/ hypothyroidism, adrenal cortex disorders)
• EN can reach 30% of target energy in 48 hours after surgery
• Burn area exceeding 20% of the patient's body surface
• Autoimmune diseases or immune dysfunction or history of organ transplantation
• International standardization ratio (INR) more than 3.0 or platelet count < 30000 cells/mm3 or other hemorrhagic diathesis
• Intracranial hemorrhage one month before enrolment
• General contraindications to infusion therapy or history of severe allergy against ingredients of enteral and parenteral nutrition
• Has already participated in another clinical trial
• Has started to nutritional support therapy before enrolment
• Diabetes mellitus (anamnestic and/or under medical treatment)