'Silent' Presentation of Hypoxemia and Cardiorespiratory Compensation in COVID-19

Philip E. Bickler, M.D., Ph.D.; John R. Feiner, M.D.; Michael S. Lipnick, M.D.; William McKleroy, M.D.


Anesthesiology. 2021;134(2):262-269. 

In This Article


COVID-19 is bringing large numbers of severely hypoxemic patients to medical care and highlighting a known phenomenon of "silent hypoxia." The variability in human breathing response to hypoxemia, as well as the preponderance of shunt physiology early in the course of COVID pneumonia, likely explains lack of dyspnea in some hypoxemic COVID-19 patients. Cardiovascular compensation to hypoxemia is critical for preservation of tissue oxygen delivery. The limits of cardiovascular compensation to hypoxemia are more likely to define clinical outcomes in COVID-19 than is the degree of hypoxemia per se.