Considering that intestinal microbiota plays a crucial role in intestinal function, fecal microbiota transplantation (FMT) may provide a new therapeutic strategy for the treatment of intestinal nutrition intolerance in critically ill ICU patients. The purpose of this study was to investigate the effects of FMT on the recovery of gastrointestinal dysfunction-induced enteral nutrition intolerance in critically ill patients admitted to ICU, and observe the effects on gastrointestinal barrier function, as well as the effects on length of stay in ICU, ICU mortality, in-hospital mortality, and 28-day mortality.

Patients in the intensive care unit (ICU) are often at risk for gastrointestinal dysfunction and malnutrition. Gastrointestinal dysfunction is associated with poorer clinical outcomes, including longer mechanical ventilation, longer ICU stay, and increased 90-day mortality. Due to the influence of primary severe diseases and the use of proton pump inhibitors (PPI) and antibiotics, ICU patients with severe illness may have severe disturbance of intestinal flora, impairment of intestinal barrier function, high incidence of gastrointestinal dysfunction-induced enteral nutrition intolerance, and severe intestinal systemic inflammation and organ function injury. Considering that intestinal microbiota plays a crucial role in intestinal function, fecal microbiota transplantation (FMT) may provide a new therapeutic strategy for the treatment of gastrointestinal dysfunction-induced enteral nutrition intolerance in critically ill ICU patients. The project plans through nasal jejunal tube way to give FMT, to investigate its effect on the recovery of gastrointestinal dysfunction-induced enteral nutrition intolerance in severe patients admitted to ICU, and to observe its effect on gastrointestinal barrier function.

Inclusion criteria:

1. 8 ≤ age ≤ 70 years old, any nationality, any gender;
2. Female patients have no potential fertility (i.e., no physical ability to conceive, including women who have been menopausal for 2 years) or no pregnancy plan;
3. Patients who have been in the ICU for at least 24 hours;
4. Patients with an expected ICU stay of at least 7 days;
5. Non-acute patients with at least one manifestation of gastrointestinal dysfunction leading to enteral nutrition intolerance;
6. Patients can cooperate or passively complete the relevant examination and complete the follow-up;
7. Informed consent is documented by means of a written, signed and dated informed consent form.

Exclusion Criteria:

1. Severe systemic infection, in early recovery period, hemodynamic instability or tissue hypoperfusion, severe imbalances in water and electrolyte status;
2. Patients who are considered by clinicians to be at high risk of death within 5 days, or who are subject to restricted treatment decisions;
3. Severe damage of intestinal barrier such as active massive bleeding and perforation of digestive tract;
4. Patients who cannot tolerate 50% of caloric calorie requirements with enteral nutrition due to severe diarrhea, significant fibrous intestinal stenosis, severe gastrointestinal bleeding, high-flow intestinal fistula and other reasons;
5. Nasal jejunal tube cannot be placed;
6. Planned or recent abdominal surgery (within 14 days);
7. Currently diagnosed with fulminant colitis or toxic megacolon;
8. Neutropenia (neutrophil count < 1500 /µL);
9. Patients with congenital or acquired immune deficiency;
10. Malignant hematologic diseases, such as lymphoma;
11. Autoimmune diseases;
12. Patients who have recently received high-risk immunosuppressive or cytotoxic drugs, such as rituximab, doxorubicin, or medium-high dose of steroid hormones (20mg/day or higher) for more than 4 weeks;
13. Pregnant or lactating women;
14. Participating in other clinical studies as a participant at the time of enrollment or within 3 months before inclusion;
15. Informed consent can not be obtained.