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By Nancy Lapid, Health Science Editor

Hello Health Rounds readers! Today we highlight a study with potential wide ranging impact on many of us, showing that breathing roadway pollution can quickly increase blood pressure. We also look at a potential life saving paradigm shift in how first responders should deal with rapid blood loss. And we cover a study that found a link between older veterans and brain changes that could be a sign of Alzheimer’s.

In breaking news, see these stories from our Reuters journalists: U.S. FDA investigating safety risk of CAR-T cancer therapies; AIDS response ‘under threat’ amid human rights backlash; in Gaza, disease could be bigger killer than bombs; White House urges RSV vaccine makers to meet demand; Australia begins crackdown on vaping, to ban import of single-use devices; health experts decry New Zealand’s scrapping of world-first tobacco ban; and China’s respiratory illness surge not as high as pre-pandemic.

When polluted rush-hour traffic air was allowed to flow into into cars, the riders’ blood pressure rose quickly and stay higher for hours – but not during rush hour trips when air filters kept out the pollution. REUTERS/Quetzalli Nicte-Ha

Breathing air near busy highways quickly increases blood pressure comparable to the effect of a high-salt diet, according to a small study.

Researchers drove 16 healthy young and middle-aged adults on three trips through rush-hour traffic in Seattle, monitoring their blood pressure during the excursions and for 24 hours afterward.

During one of the trips, when high-quality HEPA filters were used to block out 86% of particulate pollution, passengers’ blood pressure did not change, the researchers reported on Monday in Annals of Internal Medicine.

During the other two trips, when unfiltered road air was allowed to enter the car, participants’ blood pressure increased rapidly by more than 4.5 mm Hg, peaking about an hour into the drive and remaining elevated for the duration of the study.

“There is a growing understanding that air pollution contributes to heart problems. The idea that roadway air pollution at relatively low levels can affect blood pressure this much is an important piece of the puzzle we’re trying to solve,” study leader Joel Kaufman of the University of Washington said in a statement.

Participants did not know whether they were on a clean air drive or a roadway air drive, the research team said.

Among the limitations of the study done between 2014 and 2016 include that the timing did not account for seasonal changes in air pollution levels, and all of the participants were healthy.

Still, Kaufman said: “We know that modest increases in blood pressure like this, on a population level, are associated with a significant increase in cardiovascular disease.” 

First responders faced with patients who are rapidly bleeding to death should abandon the time-honored emergency medicine approach to trauma victims and immediately deal with blood loss, according to trauma surgeons who reviewed dozens of studies on the topic.

For decades, on-the-scene management of trauma patients has been guided by the “ABC” approach: open the Airway; make sure the patient is Breathing; and restore the Circulation, meaning control any bleeding.

But a “CAB” approach that emphasizes halting bleeding and restoring circulation first can help improve survival and overall outcomes of these patients, the surgeons reported on Tuesday in the Journal of the American College of Surgeons.

Their review of published studies concludes that enough medical literature exists to support the concept of prioritizing restoring circulation in trauma patients with massive bleeding. Instead of first intubating the patient to ensure an open airway, emergency responders should restore the patient’s circulation by compressing the wounds or administering blood products intravenously.

This approach, they said, is more time effective and can make a difference in survival when seconds matter, especially in rural areas with more limited resources.

One of the more than 50 studies cited in the review found that CAB had a mortality rate of 12.4% versus 23% for patients treated using ABC. Another found that a sharp drop in blood pressure after intubation to restore the airway worsened mortality, with a 19.6% death rate for CAB patients compared with 33.2% for ABC.

The authors – 12 trauma surgeons from 10 medical centers – “have seen how this clinically affects our patients,” study leader Dr. Paula Ferrada of the University of Virginia said in a statement.

“I believe that we’re not done yet in producing evidence for this CAB approach,” Dr. Ferrada added. “I think it’s important to have a prospective study evaluating the difference in mortality between the two approaches.”

Older individuals with a history of military service are more likely than non-veterans to have changes in the brain that are the hallmark of Alzheimer’s disease, researchers have found.

Studying nearly 600 brains from older men donated after death, they found that military veterans, who accounted for 60% of the donations, had 26% higher odds for more amyloid plaque and 10% higher odds of elevated tau tangle levels compared to men who had not served in the military.

In a second analysis that included donated brains from men and women, the same pattern of brain changes was seen in those with a history of military service regardless of gender, according to a report published in Alzheimer’s & Dementia.

The study does not prove that military service caused the brain changes, the researchers note.

The researchers called the U.S. decision to pay for veterans to receive the recently approved Eisai and Biogen anti-amyloid Alzheimer’s treatment Leqembi a “landmark decision.”

The ongoing effort to develop new treatments for Alzheimer’s disease makes it even more important to understand the ways in which military service impacts Alzheimer’s disease biological processes and how many veterans are likely to be affected, they said.

This newsletter was edited by Bill Berkrot.

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