Birmingham study tests ear sensor for fairer oxygen readings

Researchers in Birmingham are testing a new device that measures blood oxygen from inside the ear, to find out whether it can give more accurate readings for people with darker skin.

The clinical investigation is being led by University Hospitals Birmingham, working with the National Institute for Health and Care Research HealthTech Research Centre in Devices, Digital and Robotics and the Medical Devices Testing and Evaluation Centre.

A known problem

Pulse oximeters, the small clips placed on a fingertip to measure oxygen levels, are used every day in hospitals, GP surgeries and homes. But they shine light through the skin, and their readings can be affected by skin pigmentation. Studies have found they can overestimate oxygen levels in people with darker skin, which means low oxygen could be missed.

Professor Dhruv Parekh, the principal investigator and medical director for research and innovation at the trust, said: "The monitors we use to measure oxygen can sometimes be inaccurate in people with darker pigmentation."

Nick Gompertz, chief executive of EarSwitch Ltd, which developed the new device, said: "During COVID-19, it became very clear that pulse oximeters were not working adequately for people with brown and black skin."

The new device

The EarMetrics Oximeter measures oxygen from inside the ear canal, using light to detect changes in blood flow. The ear canal has less pigment than the fingertip, which the developers hope will make readings more consistent across skin tones.

How the study works

Healthy adult volunteers breathe specially controlled gases that gently reduce the oxygen level in their blood, under close medical supervision. Researchers compare the readings from the ear device with measurements taken from blood samples, which are the gold standard.

So far, 29 volunteers have taken part. Professor Tom Clutton-Brock, clinical director of the Medical Devices Testing and Evaluation Centre, said the team had "been able to recruit volunteers across a range of different skin tones", helped by the community outreach organisation PROBr.

Who is paying

The study is funded mainly by the charity Asthma and Lung UK, with support from a regional health technology innovation accelerator.

Why it matters

Oxygen readings help doctors decide who needs extra oxygen, who should be admitted to hospital and who is well enough to go home. If readings are less accurate for some groups, those patients could receive worse care. Birmingham's diverse population means getting this right is particularly important in the city's hospitals.

An independent review commissioned by the Government after the pandemic looked at bias in medical devices, including pulse oximeters, and called for action to make sure devices work equally well for everyone.

Patient safety awards

The study comes as University Hospitals Birmingham won three awards at the HSJ Patient Safety Awards on 28 September, including two for its Alfa system for managing controlled drugs and one for Listen, Learn, Share, a programme encouraging staff to learn from experience. Chief executive Jonathan Brotherton said the wins were "an outstanding endorsement of the innovation, expertise and commitment of our colleagues".

Taking part in research

Health research depends on volunteers, and researchers say it is important that the people who take part reflect the whole population, so that new treatments and devices work for everyone. People in Birmingham who want to get involved can find out about studies through the NHS Be Part of Research website, which lists trials recruiting near them.