Noninvasive Positive-Pressure Ventilation

Abstract

Substantial exposure to exhaled air occurs within a 0.5-m radius of patients receiving NPPV. Medical wards should be designed with an architectural aerodynamics approach and knowledge of air/particle dispersion from common mechanical ventilatory techniques.

Exhaled air dispersion during bag-mask ventilation and sputum suctioning - Implications for infection control

“…Moreover, water content in the respiratory droplets may be evaporated and hence produce small droplet nuclei that are suspended in air. Nevertheless, the smoke particles used in this study mark the continuous air phase, and therefore our data indicated the anticipated "upper limits" of droplet dispersion [10][11][12][13][14][15][16]21 .…”

“…Our research team of investigators, consisting of a respiratory physician, an anesthesiologist/intensivist, and an aerodynamic architect that have jointly conducted and published a series of infection control experiments on a HPS (HPS 6.1, CAE Healthcare, Sarasota, FL) to display exhaled air dispersion quantitatively using a laser visualization technique during application of common respiratory therapies in different hospital ventilation settings [10][11][12][13][14][15][16] . In this study, we characterized the pattern of dispersion of potentially infected aerosols during two commonly performed procedures during resuscitation.…”

“…The arbitrary threshold allows us to eliminate background contamination and provides a clear and distinctive contour for defining the boundary of dispersion. Using this method, exhaled air was shown to disperse by 0.8 and 1.0 m after application of jet nebulizer and non-invasive ventilation, respectively 11,13,14 . These data are remarkably consistent with the dispersion of 1.0 m, measured by droplet counts, in patients with influenza and chronic lung diseases receiving the same respiratory therapies 23 .…”

“…Smoke particles of <1 μm in diameter, produced by a M-6000 smoke generator (N19, DS Electronics, Sydney, Australia) was used to highlight exhaled airflow as previously described [10][11][12][13][14][15][16]21,24 . A 6 FG catheter was inserted into the right main bronchus of the HPS to deliver smoke particles.…”

“…After mixing with alveolar gas, smoke particles were exhaled through the normal airway passage. Leakage jet plume were then illuminated by a green (532 nm wavelength) laser light-sheet using a continuous pulse, diode-pumped solid state laser generator (OEM UGH-800 mW, Lambdapro Technologies, China) [10][11][12][13][14][15][16]21 . Assuming the intensity of the laser and the size or shape of the smoke particles remained constant during examination 24 , the intensity of light scattered by the smoke particles indicated the exhaled air smoke concentration.…”