Pulse Oximeters May Overestimate Blood Oxygen Levels in Ethnic Groups
Pulse oximeters are routinely used to monitor blood oxygen levels in patients. But a new study in the European Respiratory Journal calls these devices into question when measuring blood oxygen in people of color. The reason? The light wave technology used in pulse oximeters is modified by skin pigmentation.
In the study, investigators from the University of Nottingham and Nottingham University Hospitals NHS Trust compared blood oxygen levels measured by pulse oximeters and those measured by arterial blood gas tests within a half-hour of each other in COVID-19 patients. Results showed differences in oxygen saturations between the two tests in all groups in the study. Still, the highest difference was seen in the Mixed ethnicity group, which had nearly 7% higher pulse oximetry readings when compared with the arterial blood gas.
Black participants had a 5.4% higher reading with pulse oximetry, and Asians had a 5.1% higher reading. Whites in the study had a 3.2% higher reading. The differences seen in blood oxygen levels often occurred in the 85-89% range, which is generally considered the clinically important range and is used to make treatment decisions.
Since people of color have suffered disproportionally from COVID-19 in particular, the authors believe these findings suggest more study is needed to see how less accurate blood oxygen levels determined by pulse oximetry can be accounted for in the care of patients.
“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,” said study author Dr. Andrew Fogarty. “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.” Read More
How Long-Term Immunity to COVID-19 Forms
Studies have shown that long-lived memory T cells can protect against severe disease in people who have been vaccinated against COVID-19 or had a natural infection. Now researchers from Switzerland shed some light on how this long-term immunity forms.
The investigators explain that virus-specific CD8-T cells play a critical role in the cellular immune response to SARS-CoV-2 by eliminating viruses and helping to prevent the spread of newly formed viruses. Unfortunately, these T cells are short-lived. Long-lived memory T cells that can be called into action quickly when faced with the virus are needed for immunological memory.
Their study tracked individual clones of SARS-CoV-2-specific CD8+ T cells in patients with COVID-19, from the time of the initial viral infection up to one year after recovery. Signaling pathways responsible for the transition of CD8+ T cells from short-lived killers to long-lived memory cells were identified, and the researchers found a distinct molecular signature of long-lived memory CD8+ T cells that was already present during the acute SARS-CoV-2 infection.
“The distinct signature of memory cells contained signals of immune messengers, such as interferons, which are an important part of the immune response against SARS-CoV-2 and also contribute to controlling viral infections,” said study author Onur Boyman, from the University of Zurich. “While everyone responds differently to the virus or a vaccine, cellular immunity plays a crucial role in preventing severe cases of COVID-19 in both vaccinated and recovered people.”
The study was published by Nature. Read More
Are RSV Deaths More Common Than We Think?
Infant deaths from the respiratory syncytial virus (RSV) may be higher than thought, report researchers from Boston University who tested 2,286 deceased infants in hospitals and the community in Zambia to see if they harbored the virus.
They found RSV in 7-9% of infants under six months of age, with the most affected group being those under age three months. Two-thirds of the fatalities occurred not in the hospital but in the community.
The researchers concluded that RSV caused at least 2.8% of all infant deaths, with 4.7% of those occurring outside the hospital setting. Previous research has suggested RSV causes about 120,000 infant deaths each year, but that figure is based on hospital-based surveillance data alone.
“Managing RSV infections tend to rely heavily on supportive care such as supplemental oxygen and suction, but we suspect that the majority of the young infants in our study are dying before accessing even basic care,” said study author Rachel Pieciak. “While no small feat, public health interventions aimed at addressing common barriers to care could have the potential to prevent these infant deaths.”
The study was published by The Lancet Global Health. Read More
COVID-19 Lung Transplant Patients Fare Well
It’s no secret that COVID-19 patients who end up on a ventilator or extracorporeal membrane oxygenation (ECMO) are deathly ill. Traditional wisdom would have it that these patients are not good candidates for a lung transplant.
New research in The New England Journal of Medicine shows otherwise. According to the authors, 7% of the lung transplants performed from Aug. 1, 2020 to Sept. 30, 2021 went to patients with COVID-19, and more than half of that group received ECMO prior to their transplant.
Overall, 214 COVID-19 patients received a lung transplant during the study period, 140 for COVID-19 ARDS and 74 for COVID-19 pulmonary fibrosis. The average patient age was 52, and 21% were female. Hispanic patients accounted for 21% of the group. The three-month survival rate was 95.6%.
“Our experience treating COVID-19 has shown us that ECMO can be used in carefully selected patients, either as a bridge to lung transplantation or to allow a patient’s own lungs to heal,” said study author Joanna Chikwe, MD, from the Smidt Heart Institute at Cedars-Sinai in Los Angeles, CA. “Most of these COVID-19 patients would have been considered too ill to transplant a few years ago, and the surprising finding of our research was how well they did after lung transplantation.” Read More
Cell Study Reveals New Changes Related to COPD
Using single-cell RNA sequencing, researchers from Baylor College of Medicine, Yale University, and other institutions have identified cellular changes and changes in gene expression in three types of cells involved in COPD, epithelial cells found in the lungs, endothelial cells found in the blood vessels, and macrophage cells found in the immune system.
Specifically, they found that endothelial cells in capillary blood vessels in the lungs of people with COPD are inflamed and that a subpopulation of macrophages expresses high levels of proteins called metallothioneins, which regulate the balance of certain metals found in the body. An abnormal expression of genes involved in metabolic, antioxidant, and cellular stress responses was found in a subpopulation of epithelial cells.
The investigators believe all these changes contribute to the condition, and they have now organized the cells identified in their study into a cell atlas that will help other researchers looking at gene expression in lung diseases.
The research appeared in Nature Communications. Read More
On the Track to a Universal Flu Vaccine for Kids
Here’s another good reason to give kids the seasonal flu shot year after year: the shots help them develop antibodies against new flu strains and even those capable of causing pandemics.
That’s the take-home message from researchers at McMaster University in Canada who looked at the immune response of children between the ages of six months and 17 years over a three-year period. Both the nasal flu vaccine and the flu shot were able to generate the protective antibodies.
Unfortunately, the investigators say the same thing doesn’t happen in adults.
“When we give adults vaccines, they make a very specific immune response against seasonal strains,” said study author Matthew Miller. “Adults simply don’t generate immune responses to seasonal flu vaccines capable of protecting them from pandemic viruses like children can.”
They believe their findings may be helpful in efforts to develop a universal flu vaccine for kids.
“We now know that children’s immune systems are much more flexible than adults’ when it comes to being able to teach them how to make these broadly protective responses,” said Miller.
The study appeared in Cell Reports Medicine. Read More
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