An experimental treatment for severe emphysema that involves placing one-way valves in airways leading to damaged lung tissue can help patients breathe easier and exercise longer, according to a new study from the Netherlands

The technique is designed to replace risky surgery in which doctors remove a damaged lobe of the lung to literally give healthier areas more breathing room. Once the expandable valves are in place, fresh air can't flow in and old air flows out, collapsing the inefficient area.

"We now have proof that this is a workable therapy," chief author Karin Klooster of the University of Groningen told Reuters Health. "We can't cure the patient, but we can relieve symptoms. These patients really have life-changing benefits."

The technique only works in patients whose badly-damaged lung tissue is isolated, and air isn't sneaking in from healthier tissue. That's why an earlier test of the valves only produced modest results, she said. A new screening test can determine if the damaged lung tissue is isolated.

In part because of that limitation, only about one in 10 patients with severe emphysema would be candidates for the implanted valves, Klooster estimated.

"It's a limited group, but the benefit will be real," Dr. Norman Edelman, senior scientific advisor for the American Lung Association, who was not involved in the research, told Reuters Health. "It's hardly the Holy Grail. It's not likely to extend life or anything like that. But if patients are carefully selected, it will help them get less short of breath for at least six months," which was the duration of the study.

Klooster speculated that, if approved, the therapy would cost roughly 20,000 to 25,000 euros ($22,000 to $27,500), including costs of screening to make sure the therapy is likely to be effective, along with follow-up care.

"We've known for a while that among people with really bad emphysema, if we can take out the big air sacs and reduce the total lung volume, it will make people feel better, less short of breath," Edelman said. "This is a way to do that without actually opening up the chest."

The results of the trial, known as STELVIO, are based on 68 patients, 34 of whom received valves in the airways leading to the least-healthy lung tissue. The rest were in the control group, receiving standard medical care, but not lung reduction surgery.

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Improvements in breathing - when they came - often appeared within days. With the valves in place, patients released 21 percent more air in the first second when they tried to exhale. With standard care the increase was just 3 percent, according to the results in the New England Journal of Medicine.

The distance patients could walk improved by nearly 20 percent. It declined by more than 3 percent in the control group.

But 23 serious problems were reported in the valve group, compared to only five among those who received standard care. The biggest problem was unwanted air in the chest, which happened in 18 percent of patients. The condition, known as pneumothorax, can be deadly.

Twelve percent of the volunteers who received the valves needed them replaced, and 15 percent of the patients required removal. The one death during the study was in the valve group.

"The nice thing about this treatment is that it's reversible, so if you get complications it is possible to remove the valves," Klooster said.

The findings were originally released in May at a meeting of the American Thoracic Society.

The valves have not been approved in the U.S. They are being tested at 21 U.S. centers as part of the LIBERATE study, for which doctors are still seeking volunteers.

Pulmonx, the valve manufacturer, is financing LIBERATE. It was not involved in STELVIO.