It is very important to evaluate the degree of gastrointestinal dysfunction in critical ill patients. Thus the investigators conducted transabdominal intestine ultrasonography(US) in critical ill patients to evaluated the degree of gastrointestinal dysfunction under the acute gastrointestinal injury (AGI)

Inclusion Criteria:

• aged more than 18 years
• Acute Physiology Chronic Health Evaluation II (APACHE II) score >8

Exclusion Criteria:

• uncontrolled mesenteric vascular disease
• uncontrolled chronic organ dysfunction
• advanced cancer
• any terminal stage disease

patients with severe complications after surgery and severe trauma