Early in the COVID-19 pandemic, the scientific community questioned whether this infection led to typical ARDS or not. Gattinoni et al1 proposed a subdivision of COVID-19 ARDS into 2 phenotypes: L for low elastance, ventilation-perfusion ratio, lung weight, and recruitability; and H for high elastance, right-to-left shunt, lung weight, and recruitability. However, numerous studies failed to confirm these findings, leading authors to contest this classification.2 Nevertheless, the correct identification of the respiratory phenotype of COVID-19 ARDS seems of critical importance. Indeed, the use of high PEEP is expected to be beneficial in phenotype H, whereas a deleterious effect is expected in phenotype L. We conducted a study to describe early respiratory and hemodynamic modifications in response to high PEEP in subjects with COVID-19, using a pulmonary artery catheter for intrapulmonary shunt (Q̇S/Q̇T) determination and the recruitment-to-inflation (R/I) ratio to assess the lung recruitment potential. The primary objective of the study was to assess the effect of high PEEP on Q̇S/Q̇T in comparison with low PEEP. Secondary objectives were to evaluate whether high R/I correlated with a drop in Q̇S/Q̇T with low versus high PEEP and to describe advanced physiologic variables at each PEEP.