'Respiratory dialysis' machine helps COPD patients avoid intubation

By Anne Harding

NEW YORK (Reuters Health) - A new "respiratory dialysis" device can non-invasively clear excess carbon dioxide from the blood of chronic obstructive pulmonary disease (COPD) patients in respiratory failure, new research shows.

Case reports and a small pilot study found COPD patients treated with the Hemolung RAS device were able to avoid mechanical ventilation, while others who were dependent on non-invasive or mechanical ventilation could be weaned from respiratory support after treatment.

European and Canadian authorities approved the Hemolung RAS device in February of this year, and Pittsburgh-based Alung Technologies is currently seeking an investigational device exemption from the U.S. Food and Drug Administration so it can begin conducting clinical trials in the U.S. in COPD patients. The FDA considers the Hemolung to be a Class 3 device, so pivotal trials must be performed before it can be approved. Australian authorities have approved limited use of the Hemolung RAS.

The device is not the only one of its kind; Hechingen, Germany-based Novalung GmgH has developed the Novalung iLA and iLA activve, and Salerno, Italy-based Hemodec has developed the Hemodec DECAPsmart.

To date, according to Dr. Laura Lund, Alung's director of scientific affairs, 45 patients have been treated with the device.

Chest reported the results of a pilot study of the device in March 2013. Seven COPD patients with "a high likelihood of requiring invasive ventilation" were able to avoid mechanical ventilation after use of the device; two patients who could not be weaned from non-invasive ventilation were weaned; and among 11 patients on invasive ventilation who had failed previous weaning attempts, three were able to get off mechanical ventilation, and three required less ventilatory support. Another patient died due to a retroperitoneal bleed after being catheterized.

The new devices are a far simpler, less invasive version of the ECMO (extracorporeal membrane oxygenation) machine, a cousin of the heart-lung bypass machine that removes carbon dioxide from the blood and adds oxygen. Treatment with the Hemolung involves inserting a 15.5 Fr venovenous cannula through the right femoral vein. The patient's blood is then passed through a machine that removes from 30% to 50% of metabolically produced carbon dioxide, according to Alung.

"It's most similar in operation to a dialysis machine, however the function is more like a mechanical ventilator," Dr. Lund explained. "Our device provides lung support separate from the lungs, in a way that is similar to dialysis."

As COPD worsens, patients begin to have acute exacerbations, and once one occurs they begin to happen more frequently, Dr. Lund added in an interview. Some patients respond to medication, while others require non-invasive ventilation support with a mask that helps them to breathe.

"That's typically enough to give them enough oxygen, but it's the removal of the carbon dioxide that becomes the problem," she said. Up to 26% of these patients will fail non-invasive treatment, and the Hemolung is intended to help these patients, Dr. Lund explained. Avoiding mechanical ventilation is the goal, she said, given the negative effects of intubation as well as the fact that many patients with COPD have difficulty being weaned from invasive ventilation.

Patients with acute respiratory distress syndrome (ARDS) are the other group of patients who can benefit from the device, Dr. Lund said. These patients require mechanical ventilation to survive. The safe ventilation mode used for these patients to reduce mortality allows carbon dioxide to build up in the blood, which can be removed by the Hemolung.

The device is typically used for three to 14 days, and is only intended to be used for patients with reversible conditions, Dr. Lund added.

SOURCE: http://bit.ly/IHYq0H

ASAIO Journal 2013;59:675-678.

http://bit.ly/1bNwrtz

Chest 2013;143:678-686

http://bit.ly/195SEki

Curr Respir Care Rep 2013;2:131-138.

(c) Copyright Thomson Reuters 2013. Click For Restrictions - http://about.reuters.com/fulllegal.asp