Abstract
OBJECTIVES: To determine if functional residual capacity (FRC) and elastic power (EP) could predict outcomes in patients with acute respiratory distress syndrome (ARDS). METHODS: This retrospective study included 353 ARDS patients admitted to our hospital between 2018 and 2025. Patients were categorized into good (n=251) and poor (n=102) prognosis groups based on their 28-day outcomes. FRC was measured using nitrogen washout, and EP was calculated using the formula: 0.098 × VT × RR × ½(PEEP + Pplat). After comparing these parameters between groups, multivariate regression and ROC analyses were performed to identify predictors. We validated our findings in an external cohort of 101 patients. RESULTS: Poor outcome patients had significantly lower FRC and higher EP (both P<0.001). A positive correlation between EP and mortality was observed (rho=0.298, P<0.001), while FRC showed a significant inverse relationship (rho=-0.177, P<0.001). Multivariate analysis confirmed that EP (OR=1.251, P<0.001), FRC (OR=0.956, P=0.039), ARDS severity (OR=8.421, P<0.001), and PEEP (OR=1.338, P=0.011) were independent predictors of outcomes. A predictive model combining FRC and EP showed strong performance, with an AUC of 0.809 in internal validation and 0.819 in the external cohort. EP alone exhibited a high specificity of 0.944 at a cutoff value of 21.535 J/min. CONCLUSIONS: ARDS patients with low FRC and high EP face an increased risk of mortality. Combining these measures enhances prognostic accuracy and can help tailor ventilation strategies for improved outcomes.