Non-white patients get less ICU oxygen because of flawed device: study

A flaw in a widely used medical device that measures oxygen levels causes critically ill Asians, blacks and Hispanics to receive less supplemental oxygen to help them breathe than white patients, according to data from a large study published on Monday.

Pulse oximeters clip onto a fingertip and pass red and infrared light through the skin to gauge oxygen levels in the blood. It has been known since the 1970s that skin pigmentation can throw off readings, but the discrepancies were not believed to affect patient care.

Among 3,069 patients treated in a Boston intensive care unit (ICU) between 2008 and 2019, people of colour were given significantly less supplemental oxygen than would be considered optimal compared to white people because of inaccuracies in pulse oximeter readings related to their skin pigment, the study found.

“Nurses and doctors make the wrong decisions and end up giving less oxygen to people of colour because they are fooled” by incorrect readings from pulse oximeters, said Dr Leo Anthony Celi of Harvard Medical School and the Massachusetts Institute of Technology, who oversaw the study.

For the study published in JAMA Internal Medicine, pulse oximetry readings were checked against direct measurement of blood oxygen levels, which is not practical in the average patient because it requires a painful invasive procedure.

The authors of a separate study involving patients with Covid-19 published recently in the same journal saw “occult hypoxaemia” – an oxygen saturation level below 88 per cent despite pulse oximeter readings of 92 per cent to 96 per cent – in 3.7 per cent of blood samples from Asian patients, 3.7 per cent of samples from black patients, 2.8 per cent of samples from non-black Hispanic patients versus just 1.7 per cent of samples from white patients. Whites accounted for only 17.2 per cent of all patients with occult hypoxaemia.