The following illustrations (click to enlarge) summarise the proposed phenotypes of hypoxaemic patients with COVID-19. Extraordinarily, these patients exhibit at first an almost exclusive hypoxaemic respiratory failure, which respond very difficulty to high fractions of oxygen. The true cause is still unclear. We know there may be vascular and inflammatory abnormalities which make the pulmonary disease progress from a hypoxaemic viral pneumonia to ARDS.
Some experts divide patients in two separate phenotypes: The “L” phenotype characterized by a hypoxemic failure and “low elastance” lungs (high compliance) and the “H” phenotype with “high elastance and recoil” lungs (lower compliance).
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