OAKLAND, Calif. — The patient was in his 60s, an African American man with emphysema. The oximeter placed on his fingertip registered well above the 88% blood oxygen saturation level that signals an urgent risk of organ failure and death. Yet his doctor, Noha Aboelata, believed the patient was sicker than the device showed. So she sent him for a lab test, which confirmed her suspicion that he needed supplemental oxygen at home. Months later, in December 2020, Aboelata thought back to her patient as she read a New England Journal of Medicine article showing that pulse oximeters were three times…