Abstract
Silent hypoxemia is common in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In this article, the possible pathophysiological mechanisms underlying respiratory symptoms have been reviewed, and the presence of hypoxemia without hypoxia is also discussed. The experience we have gained since the start of the Coronavirus disease 19 (COVID-19) pandemic has changed our point of view about which patients with respiratory involvement should be admitted to the intensive care unit/high-dependency unit for mechanical ventilation and monitoring. In patients with clinically well-tolerated mild to moderate hypoxemia (silent hypoxemia), regardless of the extent of pulmonary opacities found in radiological studies, the administration of supplemental oxygen therapy may increase the risk of endothelial damage. The risk of sudden respiratory arrest during emergency intubation, which could expose healthcare workers to infection, should be considered along with the risks of premature intubation. Criteria for intubation need to be revisited based on updated evidence showing that many patients with severe hypoxemia do not show increased work of breathing. This has implications in patient management and may explain in part reports of broad differences in outcomes among intubated patients.