Efficacy of repeated pronations in patients affected by COVID-19-related acute respiratory distress syndrome: think it twice!

Abstract

Prone position is widely used to ameliorate gas exchange in severe COVID-19-related ARDS (CARDS), through its beneficial effects on shunt and dead space. However, the effectiveness of repeated pronation has never been explored in this category of patients. We then retrospectively analyzed the changes of the alveolar-arterial oxygen gradient (A-aO2grad), as shunt index, and the ratio EtCO2/paCO2 ratio, as dead space index, during repeated pronation cycles in 7 patients with CARDS admitted to our Intensive Care Unit. The A-aO2grad decreased significantly more during the first pronation than the second (-43.6% vs -12.2% - p0.008) and, similarly, the improvement was maintained only after the first supination (-26.2% vs +9% - p0.04). The EtCO2/paCO2 ratio showed similar behavior but did not achieve statistical significance. Considering our findings, with the inherent limitations of the study, since pronation entails risks for the patient, as well as requiring a lot of effort from the nursing staff, further caution appears to be necessary in indicating pronation.

Keywords

• COVID-19
• pronation
• pulmonary shunt
• ventilation/perfusion mismatch
• ARDS
• CARDS