By Debbie Bunch
July 1, 2024
Removing Race from Lung Function Calculations Impacts Kids Too
Several studies have confirmed that removing race-based adjustments from lung function calculations increases the number of Black adults who are diagnosed with chronic lung conditions. Now researchers from Vanderbilt University Medical Center (VUMMC), the University of Pittsburgh Medical Center (UPMC), and Indiana University find the same is true for Black children.
In a study involving 24,630 children and young adults between the ages of six and 21 who were treated at Monroe Carell Jr. Children’s Hospital at Vanderbilt and the UPMC Children’s Hospital of Pittsburgh between 2012 and 2022, they found the number of tests with a normal lung function pattern decreased by 19.5% among Black children and increased by 7.3% among White children when race-neutral equations were applied rather than race-based equations.
Most of the change in Black children resulted from a reclassification from a dyanapsis pattern to an obstructive pattern, such as that seen in asthma. The authors believe their results point to a possible underreporting of chronic lung conditions like asthma and cystic fibrosis in Black children.
“Our results will help health care providers understand what to expect when removing race from spirometry interpretation in children,” said study author Christian Rosas-Salazar, MD, MPH, an assistant professor of pediatrics at VUMC. “This is important, as race-neutral equations are relatively new, and the current recommendation is not to use race-based adjustment when interpreting spirometry results in children or adults.”
The authors believe using race-neutral equations for spirometry could lead to additional testing for some children and an escalation of therapy for others who are already diagnosed.
The study was published by JAMA Pediatrics. Read Article Read Abstract
Happy Hypoxia, Explained
Respiratory therapists saw it time and time again during the pandemic: patients with critically low blood oxygen saturation levels who nonetheless were talking on their phones, engaging with caregivers, and otherwise breathing normally.
It was dubbed “silent or happy hypoxia” and no one could figure out what was happening. U.S. investigators have now conducted computational modeling research that they believe offers an explanation.
The team adapted a previous mathematical model described as a “closed-loop control system” that can simulate the effects of silent hypoxemia on the respiratory system for their study. The adapted model allowed the researchers to systematically investigate how different aspects of the system affect the partial pressure of oxygen in the blood and the point at which the respiratory system collapses as metabolic demand is increased.
After manipulating various parameters, the team pinpointed hematocrit — the concentration of hemoglobin in the bloodstream — as a crucial factor in inducing silent hypoxemia.
“Our study suggests that COVID-19 patients with silent hypoxemia might also have elevated levels of hemoglobin in their blood, which might be a protective response to the infection,” said study author Christopher Wilson, from Loma Linda University School of Medicine.
Fellow author Peter Thomas, from Case Western Reserve University, took it a step further, explaining that elevated levels of hemoglobin in populations living at high altitude are part of the body’s attempt to keep muscles, organs, and the brain supplied with enough oxygen despite the lower levels of oxygen in the air. “When the effects of COVID-19 make it harder to get oxygen out of the air and into the tissues, even at sea level, it could be that increasing hemoglobin levels offers a similar benefit,” he said.
Author Casey Diekman, from the New Jersey Institute of Technology, notes most emergency departments do not measure hematocrit levels in COVID-19 patients, but suggests they should, noting that it would “not be too difficult to do.”
The study was published by Biological Cybernetics. Read Press Release Read Full Paper
Outcomes Differ Between Lungs Procured from Hospital DCUs and Independent DCUs
While deceased donors in the U.S. have traditionally received care on general hospital wards, over the past couple of decades more and more of them have been transferred to donor care units (DCUs) to receive care instead. These DCUs may be located within a hospital, or they may be located outside of the hospital in an independent facility.
Researchers from the Perlman School of Medicine recently analyzed lung donation and lung transplant survival rates among nearly 11,000 deceased donors who underwent organ recovery procedures between April of 2017 and June of 2022 to find out how outcomes would compare between the two types of DCUs. The investigators speculated that no differences would be seen, but results showed the opposite.
Independent DCUs generally had higher donation rates, but lung recipients at hospital-based DCUs lived longer. Overall, graft survival was nearly four months longer for lungs recovered in hospital-based DCUs than independent DCUs. The finding held true even after the researchers accounted for factors like transplant program, transplant year, and donor and recipient factors associated with graft and recipient survival.
The authors cited three potential differences between the two types of DCUs that could be coming into play: donor selection, donor management, and relationships with transplant programs. They specifically noted that “critical care nurses, respiratory therapists, and physician consultants available in hospital-based DCUs may improve graft survival over lungs recovered from independent DCUs.”
Study author Emily Vail, MD, MSc, believes the study findings hold important implications for the future of organ transplantation in the U.S. “These insights could drive improvements in organ donor management practices nationwide, ultimately enhancing the quality and availability of donated organs,” she said.
The study was funded by several government agencies, including the National Heart, Lung and Blood Institute, and published by JAMA Network Open. Read Press Release Read Full Paper
