Impact of carbapenem-resistant infections on mortality in mechanically ventilated acute respiratory distress syndrome patients: A comparison with hypoxemia severity – An observational study

<h2>Abstract</h2><h3>Introduction</h3> There has been a shift in predicting adverse outcomes in acute respiratory distress syndrome (ARDS) from pulmonary to extra-pulmonary organ dysfunction. With rising multi-drug resistance, carbapenem-resistant infections (CRI) may complicate ARDS. The significance of CRI as an outcome predictor is crucial. This study aimed to assess the impact of CRI in ARDS patients. <h3>Methods</h3> This secondary analysis included 355 adult ARDS patients on invasive mechanical ventilation from two prospective observational studies conducted between September 2020 and July 2024 at a single-center tertiary care facility. The primary outcome was ICU mortality. Demographic details, organ dysfunction scores, oxygenation values, ARDS classification based on the Berlin criteria, inflammatory biomarkers, and ICU outcomes were noted from clinical records. Patients' culture sensitivity reports were reviewed for CRI, and the association of CRI with mortality outcomes was analyzed. Univariate and multivariable logistic regression analyses and artificial neural network model, were employed to analyze mortality outcomes. <h3>Results</h3> CRI was present in 32.9 % of ARDS patients. Multivariable logistic regression identified CRI as an independent predictor of ICU mortality (P-value<0.001, adjusted OR 3.13, 95%CI [1.752–5.588]). Artificial neural network analysis showed that acute physiology and chronic health evaluation (APACHE) II score, sequential organ failure assessment (SOFA) score, and CRI had the normalized importance (100 %, 84.5 %, and 83.4 %, respectively) in predicting mortality. Independent predictors—CRI, APACHE II score ≥ 17, and SOFA score ≥9—were combined to create the "CARAS" categorization, which had a higher mortality (76.6 %, P-value<0.001). Mortality in mild-moderate ARDS with CRI was 59.4 % versus 41.1 % without CRI (P-value = 0.013, Chi-Square test). <h3>Conclusion</h3> CRI is an independent predictor of mortality in ARDS patients, compared to hypoxemia severity. "CARAS" positive patients (CRI with APACHE II score ≥17 and SOFA score ≥9) had significantly higher mortality than non-CARAS. CRI significantly increases mortality in mild-moderate ARDS compared to increase in mortality in severe ARDS.