Exhaled air and aerosolized droplet dispersion during application of a jet nebulizer.
BACKGROUND
As part of our influenza pandemic preparedness, we studied the dispersion distances of exhaled air and aerosolized droplets during application of a jet nebulizer to a human patient simulator (HPS) programmed at normal lung condition and different severities of lung injury.


METHODS
The experiments were conducted in a hospital isolation room with a pressure of - 5 Pa. Airflow was marked with intrapulmonary smoke. The jet nebulizer was driven by air at a constant flow rate of 6 L/min, with the mask reservoir filled with sterile water and attached to the HPS via a nebulizer mask. The exhaled leakage jet plume was revealed by a laser light sheet and images captured by high-definition video. Smoke concentration in the plume was estimated from the light scattered by smoke and droplet particles.


RESULTS
The maximum dispersion distance of smoke particles through the nebulizer side vent was 0.45 m lateral to the HPS at normal lung condition (oxygen consumption, 200 mL/min; lung compliance, 70 mL/cm H(2)O), but it increased to 0.54 m in mild lung injury (oxygen consumption, 300 mL/min; lung compliance, 35 mL/cm H(2)O), and beyond 0.8 m in severe lung injury (oxygen consumption, 500 mL/min; lung compliance, 10 mL/cm H(2)O). More extensive leakage through the side vents of the nebulizer mask was noted with more severe lung injury.


CONCLUSIONS
Health-care workers should take extra protective precaution within at least 0.8 m from patients with febrile respiratory illness of unknown etiology receiving treatment via a jet nebulizer even in an isolation room with negative pressure.
Hui
David S
DS
Department of Medicine and Therapeutics, The Chinese University of Hong Kong, The University of New South Wales, Australia. Electronic address: dschui@cuhk.edu.hk.
Chow
Benny K
BK
Center for Housing Innovations, Institute of Space and Earth Information Science, The Chinese University of Hong Kong, The University of New South Wales, Australia.
Chu
Leo C Y
LCY
Department of Anesthesia and Intensive Care, The Chinese University of Hong Kong, The University of New South Wales, Australia.
Ng
Susanna S
SS
Department of Medicine and Therapeutics, The Chinese University of Hong Kong, The University of New South Wales, Australia.
Hall
Stephen D
SD
School of Mechanical Engineering, The University of New South Wales, Australia.
Gin
Tony
T
Department of Anesthesia and Intensive Care, The Chinese University of Hong Kong, The University of New South Wales, Australia.
Chan
Matthew T V
MTV
Department of Anesthesia and Intensive Care, The Chinese University of Hong Kong, The University of New South Wales, Australia.
D000336:Aerosols; D000392:Air Movements; D045853:Exhalation; D006757:Hospital Units; D006801:Humans; D017758:Infectious Disease Transmission, Patient-to-Professional; D007251:Influenza, Human / Q000635:transmission; D008170:Lung Compliance; D055370:Lung Injury / Q000503:physiopathology / Q000628:therapy; D008348:Manikins; D008397:Masks; D009330:Nebulizers and Vaporizers; D010101:Oxygen Consumption; D012137:Respiratory System; D014691:Ventilation
D000336:Aerosols