PEEP-induced alveolar recruitment in patients with COVID-19 pneumonia: take the right time

In case of adverse evolution of COVID-19 pneumonia and high stress ventilation as for patient-self-inflicted lung-injury induced by vigorous negative pressure developed during spontaneous breathing or non-invasively assisted breath, “low” phenotype may worsen in “high” phenotype with low respiratory system compliance, high right-to-left shunt, high lung weight, and good response to lung recruitment. [...]while assuring a protective ventilation, a high positive end-expiratory pressure (PEEP) strategy, similar to that employed in managing severe COVID-19-free ARDS, can be pursued when a predominant “high” phenotype is observed [1]. [...]the assessment of lung recruitment through CT-scan was performed 1 min following the application of 16 cmH2O-PEEP. [...]despite promising initial reports, randomized trials failed to show benefits when compared to strategies aiming at maintaining oxygenation with the use of lower PEEP levels [6, 7]. [...]we believe that the use of higher PEEP and recruitment maneuvers should be limited to selected patients based on clinical and physiological reasoning [7], including in COVID-19 pneumonia. [...]we were able to detect a clear recruitment effect in some patients, as illustrated in Fig. 1a, b. On the other hand, patients with low recruitment had either diffuse ground glass opacities with few non-aerated areas (Fig. 1c) or large opacities with early fibrotic progression (Fig. 1d), two conditions which might explain the lack of response to PEEP.