Association of dead space fraction to mortality in patients with COVID-19-related acute respiratory distress syndrome: A historical cohort observational study

Objective: To assess the association between dead space fraction (VD/VT) measured through time capnography, corrected minute volume (CMV), and ventilation ratio (VR) with clinical outcomes in COVID-19 patients requiring invasive mechanical ventilation. Design: Observational study of a historical cohort in an university hospital in Medellin, Colombia. Participants: Patients aged 15 and above with confirmed COVID-19 diagnosis admitted to the ICU requiring mechanical ventilation; interventions: measurement of VD/VT, CMV, and VR in COVID-19 patients. Main variables of interest: VD/VT, CMV, VR, demographic data, oxygenation index, and ventilatory parameters. Results: During the study period, 1,047 COVID-19 patients on mechanical ventilation were analyzed, of whom 446 (42%) died. Deceased patients exhibited a higher prevalence of advanced age and obesity, elevated Charlson index, higher APACHE II and SOFA scores, as well as an increase in VD/VT ratio (0.27 in survivors and 0.31 in deceased) and minute ventilation volume on the first day of mechanical ventilation. Multivariate analysis revealed independent associations with in-hospital mortality, higher VD/VT (HR: 1.24; 95% CI: 1.003-1.525; P = 0.046), age (HR: 1.024; 95% CI: 1.014-1.034; P< 0.001), and SOFA score at onset (HR: 1.036; 95% CI: 1.001-1.07; P = 0.017). Conclusions: VD/VT demonstrated an association with mortality in COVID-19 ARDS patients on mechanical ventilation. These findings suggest that VD/VT measurement may serve as a severity marker for the disease.