Exhalation From Ventilation Masks May Pose Infection Risk

Study recommends precautions for health care workers around pneumonia patients
By Jeff Muise
HealthDay Reporter

MONDAY, Oct. 12 (HealthDay News) -- Leakage of exhaled air from the face masks used for noninvasive positive-pressure ventilation (NPPV) in patients with pneumonia poses a risk of infection for health care workers, according to a study in the Oct. 1 issue of Chest.

David S. Hui, M.D., of the Chinese University of Hong Kong, and colleagues studied the potential for the spread of airborne microbes in exhaled air from patients undergoing NPPV. Using a human patient respiration simulator, the researchers applied inspiratory positive airway pressure, gradually increasing from 10 to 18 cm H2O, while keeping expiratory pressure constant at 4 cm H2O. Mask leakage was marked by smoke visualized using laser light, and the exhaled smoke plume concentration was estimated by the degree to which light was scattered. The ComfortFull 2 and the Image 3 masks from Respironics were evaluated.

The researchers note that both masks permitted leakage of exhaled air. The dispersion of exhaled air from the ComfortFull 2 mask extended from 0.65 to 0.85 m along the median sagittal plane of the simulated patient. The Image 3 mask dispersed up to 0.95 m along the median sagittal plane, with the concentration increasing as ventilation pressure increased.

"Health care workers should take adequate precautions when providing NPPV support to patients with pneumonia of unknown etiology complicated by respiratory failure," the authors write.

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