Covid-19 Does Not Lead to a “Typical” Acute Respiratory Distress Syndrome

Am J Respir Crit Care Med. 2020 Mar 30. Online ahead of print

Relatively high compliance indicates well preserved lung gas volume in this patient cohort, in sharp contrast to expectations for severe ARDS.

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In northern Italy an overwhelming number of patients with Covid-19 pneumonia and acute respiratory failure have been admitted to our Intensive Care Units. Attention is primarily focused on increasing the number of beds, ventilators and intensivists brought to bear on the problem, while the clinical approach to these patients is the one typically applied to severe ARDS, namely high Positive End Expiratory Pressure (PEEP) and prone positioning. However, the patients with Covid-19 pneumonia, fulfilling the Berlin criteria of ARDS, present an atypical form of the syndrome. Indeed, the primary characteristics we are observing (confirmed by colleagues in other hospitals), is the dissociation between their relatively well preserved lung mechanics and the severity of hypoxemia. As shown in our first 16 patients (Figure 1), the respiratory system compliance of 50.2 ± 14.3 ml/cmH2O is associated with shunt fraction of 0.50 ± 0.11. Such a wide discrepancy is virtually never seen in most forms of ARDS. Relatively high compliance indicates well preserved lung gas volume in this patient cohort, in sharp contrast to expectations for severe ARDS.