Stage 2 - IFABP as biomarker of feeding intolerance in critically ill children in the PICU (IFABP in PICU) Critically ill children are at increased risk for intestinal injury, gastrointestinal dysfunction and feeding intolerance, which are associated with delayed recovery and increased morbidity and mortality during their course in the pediatric intensive care unit. In critically ill children, there is little data on the factors influenced the enteral nutrition. Feeding intolerance in the critically ill children may be due to in part to alterations in gastrointestinal motility secondary to the underlying disease process or administrations of medication.It is also known the role of hyperglycemia, caloric density of enteral nutrition and gastrointestinal feedback mechanism, and routine intensive care management such as sedation, analgesia and catecholamines on the feeding intolerance in critically ill children. We hypothesise that IFABP might be used as a biomarker which shows that the early intestinal damage due to these medications.