For educational purposes only.
New Clues About
Acidity in Lungs Worsen Asthma Symptoms
WebMD Medical News
By Jeanie Davis
March 24, 2000 (Atlanta) -- Quite by accident, researchers
have uncovered a clue that might someday lead to effective
asthma treatments with fewer side effects.
Acidity in the lungs -- which increases up to a thousandfold
during asthma attacks -- may cause the symptoms of the disease,
a small study published in this month's American Journal of
Respiratory and Critical Care Medicine has shown.
[Please Note: Victims of chemical injury suffer changes in
metabolism which disrupt the body's ability to "buffer" itself
against acidic conditions.]
Calling the finding preliminary but potentially significant, study
author Benjamin Gaston, MD, tells WebMD that "it's too early
to know for sure what's going to come of it in terms of diagnosis
and treatment. But it certainly is a completely different way of
looking at asthma. The question is, what's causing low pH
[acidity]?" Gaston is an associate professor of medicine in
allergy, asthma, and immunology at the University of Virginia
Health System in Charlottesville.
An estimated 14 million Americans, including 4 million to 5
million children, suffer from asthma, a chronic respiratory
disease that causes mild-to-severe breathing difficulties and
Severe asthma can result in death. While current treatments
are effective, the long-term use of steroids to reduce inflammation
of airways can cause serious side effects.
"For a long time, people have been looking for different
treatment and looking for other clues to ways to manage
asthma without using so much steroids," Gaston says.
"The new information provides clues as to why steroids
The UVA researchers looked at 22 hospital patients who
had been undergoing treatment for acute asthma for less
than 48 hours, using steroid medications. Twelve of the
patients' conditions had stabilized. Each was asked to
breathe into a breathalyzer-like device.
"What we found was that when getting ready for an asthma
attack, pH levels in the breath decreased significantly -- from
100- to 1,000-fold," meaning an increase in acidity, Gaston
tells WebMD. The sudden decrease triggered other chemical
reactions in the airways. "We were really quite surprised to
see how dramatic it was," he says.
The researchers speculate that this increased acidity could
contribute to inflammation in asthma sufferers' airways. The
steroid medications, they found, normalized acidity levels.
Gaston says that measuring pH levels was a last-minute
addition to the study. The researchers' original intent was
to better understand chemical activity in the airway during
asthma attacks. "Measuring pH was just added as a control,"
Gaston says. "It turns out that pH affects the other chemicals
we were measuring."
What's known about acidity levels in other parts of the body
could give clues about what's happening in the lungs, Gaston
says. "Certainly, you can put a lot of things in your mouth,
and the stomach is good at preventing those things from causing
infection because of low pH levels. Most bacteria don't survive
in a low pH environment. When you think about the stuff dogs
eat, at least my dog, that's an example of the kinds of antibacterial
effects of low pH, that he doesn't get sick. ... I think it's fair to
say that the same things that go on in the stomach and kidney
may also be going on in the lungs."
In an editorial accompanying the study, Harvey E. Marshall,
of Howard Hughes Medical Center, and Jonathan S. Stamler,
of Duke University Medical Center, both in Durham, N.C.,
"The key discovery is ... the finding that pH is low in the
airway lining fluid. The lung, like most other tissues, does
not handle acid well." They say it would be interesting to
know whether airway acidification occurs in other obstructive
lung diseases, such as emphysema. "Hunt and colleagues have,
at the very least, opened a new area of research," they write.
"Enter the era of antacid therapy of the lung?"
After reviewing what he called a fascinating study, H. James
Wedner, MD, professor of medicine in allergy and clinical
immunology, tells WebMD: "The real question that has to
be answered: Is it a chicken-and-egg problem? Is the decreased
pH the cause of or the result of the acute asthmatic episode?"
Nonetheless, Wedner says, "This is a very important, breakthrough
study in the sense that it asks a question that no one has asked
before. Certainly, I think there's going to be a lot of work directed
to this particular aspect of asthma."
*Researchers were surprised
to discover that when patients
are about to undergo an asthma attack, their lungs become
more acidic by 100 to 1,000 times.
may one day help scientists understand what
causes the disease and develop new treatments.
treatments are effective, but the long-term
use of steroids to control the disease is associated with
adverse side effects.