An odd condition that the New York Post says seems to "defy basic biology" is popping up among coronavirus patients, and no one has yet figured out how or why it's happening. Some COVID-19 patients are exhibiting abnormally low oxygen levels—ones that would typically cause someone to fall unconscious or even die—but don't appear to be in much distress. The Guardian notes that normal blood-oxygen saturation lies at around 95%, but doctors are reporting patients in the 70%-80% range, and even some below 50%. A University of Colorado pulmonary expert tells Live Science that once those oxygen levels drop below 90%, it becomes problematic, as the brain becomes deprived of oxygen; at that point, patients typically start becoming confused and lethargic. Dip below 80%, and vital organs can begin to suffer damage.
Yet Science Magazine notes those suffering from "happy" hypoxia (aka "silent" hypoxia) can be seen talking normally, checking their phones, and not reporting much discomfort. "There is a mismatch [between] what we see on the monitor and what the patient looks like," says an ER physician at NYC's Maimonides Medical Center. Doctors do have some ideas on what's causing oxygen levels to fall in virus patients, including possible blood clotting—tiny lung vessels that collect and transport oxygen can become easily stopped up. As for why happy hypoxics don't seem distressed by their condition, some experts theorize their otherwise healthy lungs are still inflating well (despite the lack of oxygen circulation in the body) or that they're used to feeling lethargic from low oxygen levels if they already deal with other conditions. "We just don't understand it," a UK anesthetist tells the Guardian. Much more here and here. (More coronavirus stories.)