The effects of positive end expiratory pressure (PEEP) in COVID-19-related acute respiratory distress syndrome (ARDS) are similar to those reported in classical ARDS, according to study results published in the American Journal of Respiratory and Critical Care Medicine.

Assessment of lung ventilation and perfusion of COVID-19-related ARDS is scarce, especially in response to positive end expiratory pressure (PEEP) and prone positioning. Therefore, researchers sought to describe the physiologic effects of PEEP and prone positioning on respiratory mechanics, ventilation, and pulmonary perfusion in patients with COVID-19-related ARDS.

Of 41 patients with COVID-19-related ARDS admitted during the study period, only 9 completed full explorations and could be analyzed. The effects of PEEP in COVID-19-related ARDS were demonstrated to be close to those reported in classical ARDS. The increase in PEEP resulted in alveolar recruitment associated with a significant decrease in severe shunt, mainly in the dorsal regions, driven by the increase in dorsal ventilation. Additionally, increasing PEEP resulted in less severe alveolar dead space in the ventral regions, because ventilation decreased more than perfusion.

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However, the better ventilation/perfusion ratio (V/Q) matching at high PEEP was at the expense of hyperdistension, as suggested by the respiratory mechanics data and in particular by a decrease in ventral compliance and ventilation. Turning the patient from supine to prone position increased the PaO2/FiO2 ratio by 64 mm Hg, induced recruitment in the dorsal regions and collapse in ventral regions, but did not change the dorsal predominance of pulmonary perfusion. Proning also decreased ventral dead space and dorsal shunt.

“Prone positioning, and to a lesser extent increased PEEP, shifted ventilation from ventral to dorsal regions in [patients with COVID-19-related] ARDS, but did not change perfusion, which remained predominantly dorsal, resulting in a better V/Q matching,” the study authors concluded.


Perier F, Tuffet S, Maraffi T, et al. Effect of PEEP and proning on ventilation and perfusion in COVID-19 ARDS. Am J Respir Crit Care Med. Published online October 19, 2020. doi:10.1164/rccm.202008-3058LE