Impact of prone position on dead-space fraction in COVID-19 related acute respiratory distress syndrome.

INTRODUCTION: COVID-19 Related Acute Respiratory Syndrome (C-ARDS) is characterized by a mismatch between respiratory mechanics and hypoxemia, suggesting increased dead-space fraction (DSF). Prone position is a cornerstone treatment of ARDS under invasive mechanical ventilation reducing mortality. We sought to investigate the impact of prone position on DSF in C-ARDS in a cohort of patients receiving invasive mechanical ventilation.

METHODS: we retrospectively analysed data from 85 invasively mechanically ventilated patients with C-ARDS in supine and in prone positions, hospitalized in Intensive Care Unit (Reims University Hospital), between November, 1st 2020 and November, 1st 2022. DSF was estimated via 3 formulas usable at patients' bedside, based on partial pressure of carbon dioxide (PaCO2) and end-tidal carbon dioxide (EtCO2).

RESULTS: there was no difference of DSF between supine and prone position, using the 3 formulas. According to Enghoff, Frankenfield and Gattinoni equations, DSF in supine vs. prone position was in median respectively [IQR]: 0.29 [0.13-0.45] vs. 0.31 [0.19-0.51] (p = 0.37), 0.5 [0.48-0.52] vs. 0.51 [0.49-0.53] (p = 0.43), and 0.71 [0.55-0.87] vs. 0.69 [0.57-0.81], (p = 0.32).

CONCLUSION: prone position did not change DSF in C-ARDS.