Prognostic Value of the Veno-Arterial Carbon Dioxide Difference in COVID-19-Associated Acute Hypoxemic Respiratory Failure: A Retrospective Cohort Study

Background/Objectives: In acute hypoxemic respiratory failure, hyperventilation and alterations in oxygenation can influence CO2 kinetics via the Haldane effect, potentially modifying the venous-to-arterial carbon dioxide partial pressure gradient (PvaCO2) irrespective of tissue perfusion, thereby complicating its prognostic significance. This study assessed the predictive importance of PvaCO2 in critically ill patients experiencing acute respiratory failure linked to COVID-19.

Methods

This retrospective bicentric study included critically ill patients with hypoxemic COVID-19 (PaO2/FiO2 < 300 mmHg) admitted to the intensive care unit (ICU) during the first and second waves of the Belgium epidemic, with at least one PvaCO2 assessment within 5 days of admission. PvaCO2 was assessed early after ICU admission using paired arterial and central venous blood gases. The highest daily value was registered. The first registered value was considered as a baseline. The primary outcome was ICU death within 28 days.