FRIDAY, Oct. 9 (HealthDay News) -- Health-care workers, take note: Hospital patients using positive pressure ventilation masks to help them breathe may be spreading germs every time they exhale, a new study finds.

The masks can leak exhaled air up to one meter from patients receiving treatments, spreading contagious respiratory illness within a hospital, researchers say. This may be of particular concern if the patient has the highly contagious H1N1 swine flu.

"Health-care workers should take adequate respiratory precautions -- wearing N95 masks and personal protective equipment -- when providing noninvasive ventilatory support to patients with pneumonia of unknown etiology complicated by respiratory failure, including patients with pandemic H1N1 influenza," said lead researcher Dr. David S. Hui, from the department of medicine and therapeutics at the Chinese University of Hong Kong.

The report is published in the October issue of Chest.

For the study, Hui's team measured air leakage from two commonly used positive pressure ventilation masks, the Respironics ComfortFull 2 mask and the Image3 mask. The test was done on a patient simulator, which mimicked a patient with lung injury.

These masks fit over the patient's nose and mouth and provide a continuous flow of air at a steady pressure to help the patient breathe. They are used for patients with heart failure, chronic obstructive pulmonary disease (COPD), asthma and sleep apnea in addition to pneumonia.

With both models and using negative pressure, the researchers found substantial exposure to exhaled air occurs within one meter of patients receiving non-invasive ventilation in an isolation room. But far more leakage and room contamination occurred from the Image 3 mask, especially at higher pressures, Hui said.

Hui said the study results argue for avoiding the use of high pressure, which will lead to more exhaled air dispersion, and "exhalation devices, which will lead to widespread exhaled air dispersion."

Dr. Roland Schein, professor of medicine in the division of pulmonary, critical care and sleep medicine at the University of Miami Leonard M. Miller School of Medicine, said it is well-known that these masks can spread contagious germs.

"The concern has always been with open systems and highly infectious pathogens. People within a certain range are at risk and need to take precautions to reduce those risks," Schein said.

This study has defined how far those germs can spread, he added.

Health-care workers caring for patients using these masks should take precautions, including face masks and protective clothing, Schein said. This is especially important now with "the concerns about H1N1 and other respiratory pathogens," he said.

SOURCES: David S. Hui, M.D., department of medicine and therapeutics, the Chinese University of Hong Kong; Roland Schein, M.D., professor, division of pulmonary, critical care and sleep medicine, University of Miami Leonard M. Miller School of Medicine; October 2009 Chest

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