The Effect of Early Enteral Nutrition Feeding Process Assisted by Gastrointestinal Ultrasonography

Inclusion Criteria: * The age is not less than 18 years * within 24 hours after entering ICU * Acute Physiology and Chronic Health Evaluation II (APACHE II) score \> 8 * the estimated length of stay in ICU is more than 3 days * informed consent Exclusion Criteria: * The normal anatomy of stomach, small intestine or the right colon was significantly changed (Gastrectomy, esophagectomy, pancreaticoduodenectomy, gastrointestinal bypass surgery, the presence of short bowel syndrome,etc.) * Uncontrolled gastrointestinal bleeding * Uncontrolled intestinal obstruction * Uncontrolled mesenteric vascular disease * Pregnancy * breastfeeding * Received enteral nutrition or parenteral nutrition within 24 hours prior to ICU admission * Predict death within 48 hours after ICU admission * Enrolled in this study before.