Clinical Research Directory

Inclusion Criteria: * age ≥18 years old; * ICU admission ≥72 hours with invasive mechanical ventilation ≥24 hours; * start nutrition therapy within 72 hours after ICU admission and receive enteral or parenteral nutrition support for ≥3 days; * Relatively complete nutritional intervention records and nutrition-related biomarkers test results on the 1st, 3rd, and 7th (±1) days of ICU admission; Exclusion Criteria: * women of childbearing age who have a positive pregnancy test, are pregnant or lactating; * chronic diseases with serious organ function damage or serious complications; 1. Kidney: chronic kidney disease stage 4 or 5; 2. Liver: previous history of liver failure, hepatic encephalopathy, or hepatic coma, gastrointestinal bleeding due to portal hypertension or Child-Pugh score ≥10 in recent years; * advanced malignant tumor, or chemotherapy or immunotherapy received within one month before admission; * severe immunodeficiency or current use of potent immunosuppressive agents, agranulocytosis (N\<0.5×10\^9/L), active hematologic malignancies or HIV stage III infection; Patients who were treated with immune-inducing drugs, such as antithymocyte globulin (ATG), antilymphocyte globulin (ALG), interleukin-2 receptor a chain antibody (IL-2RA), interleukin-6 receptor A antibody (IL-6RA); glucocorticoid therapy was continued for nearly 2 weeks, with a daily dose exceeding the hydrocortisone equivalent of 200mg; * critical illness, death in ICU within 1 week or palliative care only because death outcome was inevitable; * combined with severe or more severe burns: more than 30% of total body surface area burned or more than 10% of third-degree burn area; Or the total area is less than 30%, but the whole body condition is severe, or there are shock, combined injury, and respiratory tract burn.