Pulse oximeter measurements of blood oxygen levels are unreliable in
assessing severity of COVID-19 pneumonia across different ethnic groups, study finds

Date:
January 27, 2022
Source:
University of Nottingham
Summary:
The severity of COVID-19 pneumonia can be difficult to assess in
people from different ethnic groups, due to inaccurate readings
from a device that measures the level of oxygen in the blood of
patients, a new study has found.



FULL STORY ==========================================================================
The severity of Covid-19 pneumonia can be difficult to assess in people
from different ethnic groups, due to inaccurate readings from a device
that measures the level of oxygen in the blood of patients.


==========================================================================
The findings of the research, published in the European Respiratory
Journal, show that pulse oximeters gave false readings of nearly 7%
higher in a group of patients of Mixed ethnicity with Covid-19, compared
to White patients at just over 3%. There were also falsely high readings
in patients with both Black and Asian ethnicity, which could delay
patients receiving the best and most timely treatment for the virus.

Pulse oximetry is a non-invasive test that measures the oxygen saturation
level of the blood. It can rapidly detect even small changes in oxygen
levels. These levels show how efficiently blood is carrying oxygen
to the extremities furthest from the heart, including the arms and
legs. Medical professionals routinely use them in primary care and
critical care settings like emergency rooms or hospitals to monitor the clinical status of their patients.

The light wave transmission that this technology uses is modified by
skin pigmentation and may vary by skin colour. A recent study reported different outputs in patients with Black skin compared to patients
with White skin, which has the potential to adversely affect patient
care. This led to the Food and Drink Administration in the USA releasing
an expression of concern about the accuracy of pulse oximeters in 2021,
which led to the current study.

The study was delivered by a consortium of multidisciplinary teams from
the University of Nottingham and Nottingham University Hospitals NHS
Trust. They made use of the electronic datasets that are collected for
clinical use in real time, but archived and available to answer important clinical questions and improve both patient care and patient safety
in the future. The NUH Covid-19 Patient Safety Database is anonymised
to allow lessons to be learned without compromising individual patient confidentiality. The team included clinicians, managers, statisticians, computer analysts, software coders and data warehouse archivists.

The team of experts from Nottingham used data from patients with Covid-19 infection to look at the difference in blood oxygen levels as measured
by pulse oximetry and arterial blood gas tests, spilt into different
ethnic groups over a wide range of oxygen saturations. Arterial blood
gas tests measure the levels of oxygen in the blood from an artery,
and represent the gold standard measurement for oxygen levels.

The team used electronic data for patients admitted to Nottingham
University Hospitals NHS Trust between February 2020 and September 2021
with Covid-19 infection. Pulse oximetry measurements with a paired blood
gas measurement within a half an hour window were compared.

Mean differences between pulse oximetry and blood gas oxygen saturations
were recorded by ethnicity of White, Mixed, Asian, and Black patients,
and were also split up by level of oxygen saturation as measured by
arterial blood gases.

There were differences in oxygen saturations (amounts of oxygen in the
blood), between the pulse oximetry arterial blood gas readings in all
groups. The highest difference was in the Mixed ethnicity group which
was nearly 7% higher in the oximetry reading, with the lowest in the
White group at 3.2% higher than the true measurement from arterial blood
gases. A reading of 5.4% higher using pulse oximetry was found in the
Black group of participants and 5.1% higher in the Asian population.

The difference between the readings also increased in the clinically
important range of 85 to 89%, when many clinical decisions are made. Mean values as measured by pulse oximeter were higher than reality in
individuals with a recorded Black and Asian ethnicity, compared to those
of a White ethnicity.

The findings of the research are important as high levels of skin
pigmentation are associated with ethnic groups who have a poorer outcome
from Covid-19 infection, and would require the most accurate oxygen measurements available in order to deliver the most appropriate and
timely treatment.

Dr Andrew Fogarty, from the School of Medicine at the University and
the lead author of the study, said: "This data builds on what we know,
which is that patients with darker skin have less accurate oxygen
measurements using the pulse oximeters. Any error of measurement of
oxygen levels will make assessing the severity of Covid-19 infection
more difficult, and may delay delivery of timely medical care. We are now exploring the impact of this on clinical outcomes to see if it may have
led to any issues in escalating treatment intensity for our patients." ========================================================================== Story Source: Materials provided by University_of_Nottingham. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Colin J Crooks, Joe West, Joanne R Morling, Mark Simmonds, Irene
Juurlink, Steve Briggs, Simon Cruickshank, Susan Hammond-Pears,
Dominick Shaw, Timothy R Card, Andrew W Fogarty. Pulse oximeters'
measurements vary across ethnic groups: An observational study in
patients with Covid- 19 infection. European Respiratory Journal,
2022; 2103246 DOI: 10.1183/ 13993003.03246-2021 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220127104222.htm

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