Hong Kong Med J 2014;20(Suppl 4):S9-13
Aerosol dispersion during various respiratory therapies: a risk assessment model of nosocomial infection to health care workers
DSC Hui, MTV Chan, B Chow
Department of Medicine and Therapeutics, The Chinese University of Hong Kong
1. Substantial exposure to exhaled air occurs within 1 m from patients receiving non-invasive positive pressure ventilation, even in an isolation room with negative pressure, with far more extensive leakage and room contamination via the Image 3 facemask that requires connection to the whisper swivel exhalation port, especially at higher inspiratory pressures.
2. For non-invasive ventilation, it is advisable to choose facemasks with predictable exhaled air directions and distances through the exhalation port without addition of the whisper swivel device.
3. To avoid wider distribution of exhaled air and substantial room contamination during non- invasive ventilation, high inspiratory pressures should not be used.
4. The maximum exhaled air distances during application of jet nebuliser and oxygen via nasal cannula, Venturi mask, and the non-rebreathing mask were about 0.8 m, 0.42 m, 0.4 m, and <0.1 m, respectively.
5. More extensive exhaled air dispersion and room contamination occurs during application of a jet nebuliser to patients with more severe lung injury. Use of alternative methods to deliver bronchodilators (eg meter-dose inhaler via an aerochamber or a spacer) is advised.