Airflow and droplet spreading around oxygen masks: a simulation model for infection control research.

Background: Respiratory assist devices, such as oxygen masks, may enhance the potential to spread infectious aerosols from patients with respiratory infections.

Methods: A technique was developed to visualize exhaled aerosols during simulated patients' use of oxygen masks in a health care setting and tested using the simple, the nonrebreathing, and the Venturi oxygen masks. A smoke tracer was introduced into one of the lungs of the model to enable it to mix with the incoming oxygen and then to be further inhaled/exhaled by the model according to a variety of realistic respiratory settings (14, 24, and 30 breaths per minute, with tidal volumes of 500, 330, 235 mL, respectively) and oxygen supply flow rates (between 6 and 15 liters per minute).

Airflows around oxygen masks: A potential source of infection?

Patients with respiratory infections often require the use of supplemental oxygen via oxygen masks, which, in the hospital, may become sources of aerosolized infectious pathogens. To assess this risk, a human lung model (respiration rate, 12 breaths/min) was designed to test the potential for a simple oxygen mask at a common setting (4 L/min) to disperse potentially infectious exhaled air into the surrounding area. A laser sheet was used to illuminate the exhaled air from the mask, which contained fine tracer smoke particles.