Punch Newspapers Sections A new study published in the New England Journal of Medicine says pulse oximeter results are three times likely to give misleading results in patients with black skin. A pulse oximeter is a small device attached to the thumb which tells healthcare workers a person’s level of blood oxygenation. A pulse oximeter works by a process that senses the level of oxygen in the blood by passing light through the skin. It’s thought that the wrong result in black skin could be because darker skin pigments absorb light differently. Since the COVID-19 pandemic, there has been an increase in the use of the device. It helps to know the patients who are in critical conditions and who might benefit from the use of oxygen, or to make a decision to transfer a patient to the intensive care units. Those who are isolating at home can also use it to monitor their own condition too, to know if they need to go to hospital urgently.