Hypoxemia in COVID-19
Silent hypoxemia in COVID-19 was initially described in elderly patients but shortly was reported in younger, previously healthy individuals(1). Although perplexing at first glance, silent hypoxemia can be elucidated through the lens of the basic principles of respiratory physiology(2). In contrast, normocapnia until later stages of the disease is less understood(3). With progressive hypoxemia, increased minute ventilation and cardiac output occur as a compensatory mechanism. As the ventilatory response is limited due to normocapnia, the cardiovascular system becomes the central adaptive mechanism. Its failure to compensate is the proximal cause of tissue injury in profound hypoxemia(4).