Working in the dark

摘要

SOME THINGS, you might think, are obvious. For example, if you design a device which shines light through someone's fingertip to measure the oxygen level of their blood, then the colour of the skin through which that light is shining should be a factor when the device is calibrated. But no. Research suggests that, with honourable exceptions, pulse oximeters, the machines which do this, overestimate oxygen levels three times more frequently (12% of the time) in people with black skin rather than white. When this informs decisions on whom to admit to hospital during a pandemic, more black than white patients are sent home on the mistaken conclusion that their blood-oxygen levels are within a safe range. This could have fatal consequences (see Science section).