Gut Microbiota Structure, Functional and Metabolic Profiles, and Composite Biomarkers in ICU Adults With Refractory Enteral Feeding Intolerance

Some adults in the intensive care unit (ICU) cannot receive enough nutrition through a feeding tube because of persistent digestive problems, even after standard measures to improve feeding. This condition is called refractory enteral feeding intolerance. The community of microorganisms living in the gut, known as the gut microbiota, and the substances produced by these microorganisms and the body may be associated with feeding tolerance and recovery. This prospective observational study will enroll approximately 180 adults with refractory enteral feeding intolerance at a single hospital. It aims to describe changes in their gut microbiota and metabolic profiles over time and identify combinations of microbial markers associated with improved feeding tolerance and adequate nutritional intake. Stool samples or rectal swabs will be collected at enrollment, on days 3-5 and day 7, and, when feasible, near the end of the ICU stay. The samples will be used to examine the types of microorganisms present. Selected samples will also be analyzed for metabolic substances. Clinical information about nutrition, digestive symptoms, medications, illness severity, and treatments will be collected. Participants will be followed for up to 90 days to assess survival and unplanned hospital readmissions. The study will examine whether microbial and metabolic patterns provide additional information about feeding improvement by day 7 beyond routine clinical assessments. Where suitable public datasets are available, findings will also be evaluated in other patient groups. Participants will continue to receive usual medical care. The study does not assign treatments or change feeding decisions. Its findings may help guide future research on feeding intolerance, but participants are not expected to receive a direct medical benefit from taking part.