Inclusion Criteria: All those critically ill patients with anticipated ICU stay for more than 2 days Exclusion Criteria:Patients will be excluded if they have any of the following situations: patients who have not signed the informed consent; Unable to tolerate intra-abdominal pressure monitoring; pregnant woman; Patients after bladder surgery; Systemic diseases and recent use of related drugs; He had a history of infectious diseases, such as tuberculosis or PPD positive. History of hypertension and poor blood pressure control (SBP / DBP > = 140mmHg); Patients with severe mental illness; Long term use of traditional Chinese medicine, probiotics, gastric mucosal protective agents, proton pump inhibitors, chemotherapy or immunosuppressive drugs, etc. were not included if the drug was not stopped within one month before admission.  -