This information is mostly anecdotal, we know very little about COVID-19 and this is based on very low quality evidence. We need more studies to confirm or deny what is currently being discussed.
The following illustrations summarize the proposed phenotypes of hypoxemic patients with COVID-19. Extraordinarily, these patients exhibit at first an almost exclusive hypoxemic 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 hypoxemic viral pneumonia to ARDS. Therefore 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).
After the illustrations you will find some PDF articles used as reference. Hope you enjoy these and find them helpful!