Gut microbiota differs between ICU patients admitted for cardiac arrest and other causes: a secondary, propensity-matched cohort analysis

Background Critical illness is known to reduce gut microbiota (GM) diversity, a change associated with adverse outcomes. Among potential mechanisms, splanchnic hypoperfusion may play a key role. Cardiac arrest (CA), characterized by transient global hypoperfusion, provides a relevant model to explore this effect. Results We conducted a secondary, propensity score-matched analysis of a cohort study investigating GM changes during early intensive care unit stay. Stool samples were collected at ICU admission (S1) and at least 24 h later (S2). GM profiling was performed using 16S rRNA sequencing. Shannon diversity index and taxonomic composition were compared between CA and non-CA patients. Propensity score matching and generalized linear models (GLM) were used to adjust for confounding. A total of 26 patients were included in this analysis (13 CA, 13 matched controls). At S1, CA patients had significantly lower GM diversity (Shannon index: 3.6 [3.0–3.8] vs. 4.3 [3.9–4.8], p = 0.019). This was confirmed in the GLM ( β = − 0.30, SE 0.12, p = 0.022). At S2, diversity remained lower (3.2 [2.7–3.8] vs. 4.0 [3.7–4.3], p = 0.064). While no global compositional shifts were observed between groups, differences in the abundance of specific taxa were noted. Conclusion CA is associated with reduced GM diversity in the first few days of intensive care unit admission compared to non-CA patients, supporting a role for splanchnic hypoperfusion in GM modulation. Further research should investigate clinical consequences and evaluate microbiota-targeted interventions in this high-risk population.