Even though many Americans might not even know what pulse oximeters are, the tiny devices are flying off pharmacy shelves as high-risk folks worry about COVID-19.
That's because they perform a critical function, measuring the concentration of oxygen in the blood. How? Just clip the device onto a patient's finger for a reading.
A healthy blood level of "oxygen saturation" normally measures 95-100% on a pulse oximeter, and readings lower than 90% are considered dangerously low.