A pulse oximeter is placed in the hand of a COVID-19 patient. A team of researchers from the University of Nottingham (UoN) have developed a laboratory-based test to assess the performance of POs under the effects of varying melanin (pigment responsible for colour) concentration and oxygen saturation (SpO2) values.
| Photo Credit: File photo

Given that the performance of pulse oximeters (POs) is known to vary with the colour of skin, a team of researchers from the University of Nottingham (UoN) have developed a laboratory-based test to assess the performance of POs under the effects of varying melanin (pigment responsible for colour) concentration and oxygen saturation (SpO2) values.

A study pertaining to this, titled ‘Pulse oximeter bench tests under different simulated skin tones’, has been published in Medical and Biological Engineering and Computing, a peer reviewed medical journal.

Pulse oximeters were the most commonly used devices during the covid pandemic as they allowed for non-invasive, painless, continuous and inexpensive real-time monitoring of oxygen levels in the blood using light (commonly, red and infrared light).

Need for caution

Suvvi K. Narayana Swamy, lead author of the study, told The Hindu that POs did not show any deviations in SpO2 readings due to skin colour in the laboratory tests. “However, the tests also did not conclusively demonstrate that melanin does not affect SpO2 measurements. So, we need to be cautious not to over interpret these results. Further research is underway,” she said.

“In the United Kingdom, the COVID Oximetry @home programme was launched as part of the National Health Service (NHS) response to the pandemic. Through this programme, commercially available peripheral POs were delivered to allow patients with COVID-19, or at high risk, to remotely monitor their SpO2 levels at home. These devices were widely used globally by healthcare professionals to make timely clinical decisions when admitting patients (particularly with the absence of any noticeable symptoms) to hospitals for critical care and treatment,” Ms. Swamy said.

The study gains significance in a context where several recent retrospective clinical studies have highlighted that SpO2 may be overestimated in patients with non-white skin types. This phenomenon is generally termed occult hypoxemia, where SpO2 measured by a PO is greater than 90%, despite true oxygen saturation value being less than 88%,” she explained. 

“In this study, the performance of POs used in the NHS COVID Oximetry @home programme and in hospitals in UK was investigated. The test enabled the POs to be subjected to low signal and varying melanin concentration, which are the two main principal effects of melanin in the skin through simulation. The effects of low signal levels were simulated by neutral density filters (NDFs) that reduced red and infrared radiation light in the same manner while the effects of melanin concentration were achieved by utilising melanin filters (MFs) that decreased both red and IR light by unequal amounts.In these tests, the SpO2 overestimation, which has often been observed clinically, was not reproduced,” she explained.

Significant variations

Stating that a laboratory simulation was used to mimic different SpO2 values (~ 70 to 100%), Ms Swamy said different neutral density and synthetic melanin filters were used to reproduce low signal and varying melanin reduction levels. “POs from six different brands were reviewed and their response documented. Significant variations were observed in the recorded SpO2 values among different POs when exposed to identical simulated signals.  Differences were greatest for lower SpO2 (<80%) where empirical data is limited,” Ms. Swamy said.

“All PO responses under low signal and melanin concentration did not change across various simulated SpO2 values. The tests do not provide conclusive evidence that melanin does not affect in vivo SpO2 measurements. Research in the areas of instrument calibration, theory and design needs to be further developed,” she added.

A multi-millionaire property developer from Australia has sparked outrage after saying that he wants unemployment to rise in his country because workers have become ”too arrogant”. Tim Gurner, CEO of Australian real estate company Gurner Group said that the Covid pandemic had changed employees’ work ethic and they need to be put in their place through unemployment, Independent reported. 

”I think the problem that we’ve had is that people decided they didn’t really want to work so much anymore through COVID. They have been paid a lot to do not too much in the last few years, and we need to see that change” he told the Australian Financial Review Property Summit in Sydney.

According to him, the key to curbing “arrogance” in the labour market is higher unemployment.

”We need to see unemployment rise. Unemployment has to jump 40, to 50 percent in my view. We need to see the pain in the economy. We need to remind people that they work for the employer, not the other way around,” he added.

”There’s been a systematic change where employees feel the employer is extremely lucky to have them, as opposed to the other way around. We’ve got to kill that attitude and that has to come through hurting the economy,” he further said. 

The unemployment rate in Australia is 3.6 per cent, or roughly 500,000 people, meaning an estimated 250,000 workers would lose their jobs in a 50 per cent increase.

A video of his controversial comments has gone viral on social media, sparking instant backlash. ”Why doesn’t he do us a favour and volunteer his job as the first step to the 50%,” one user wrote. Another said, ”Everything a business leader should not say. Kind of unbelievable.”

His comments also drew a fierce reaction from the US democrat Alexandria Ocasio-Cortez.

”Reminder that major CEOs have skyrocketed their own pay so much that the ratio of CEO-to-worker pay is now at some of the highest levels *ever* recorded,” Ocasio-Cortez wrote on X.

After receiving backlash for his statements, he said in a LinkedIn post on Thursday that he was “wrong” to say what he did. He admitted that his comments were ”deeply insensitive”.

“At the AFR Property Summit this week I made some remarks about unemployment and productivity in Australia that I deeply regret and were wrong. There are clearly important conversations to have in this environment of high inflation, pricing pressures on housing and rentals due to a lack of supply, and other cost-of-living issues. My comments were deeply insensitive to employees, tradies and families across Australia who are affected by these cost-of-living pressures and job losses. 

”I want to be clear: I do appreciate that when someone loses their job it has a profound impact on them and their families and I sincerely regret that my words did not convey empathy for those in that situation,” Mr Gurner wrote.

Mr Gurner, who has been featured in Forbes Australia, and is one of Australia’s richest men, has a net worth of $912 million as per The Australian Financial Review’s estimates.