Clinical characterization of respiratory droplet production during common airway procedures using high-speed imaging

Abstract

<jats:p>Background: During the COVID-19 pandemic, a significant number of healthcare workers have been infected with SARS-CoV-2. However, there remains little knowledge regarding droplet dissemination during airway management procedures in real life settings. Methods: 12 different airway management procedures were investigated during routine clinical care. A high-speed video camera (1000 frames/second) was for imaging. Quantitative droplet characteristics as size, distance traveled, and velocity were computed. Results: Droplets were detected in 8/12 procedures. The droplet trajectories could be divided into two distinctive patterns (type 1/2). Type 1 represented a ballistic trajectory with higher speed droplets whereas type 2 represented a random trajectory of slower particles that persisted longer in air. Speaking and coughing lead to a larger amount of droplets than non-invasive ventilation therapy. The use of tracheal cannula filters reduced the amount of droplets. Conclusions: Respiratory droplet patterns generated during airway management procedures follow two distinctive trajectories based on the influence of aerodynamic forces. Speaking and coughing produce more droplets than non-invasive ventilation therapy confirming these behaviors as exposure risks. Even large droplets may exhibit patterns resembling the fluid dynamics smaller airborne aerosols that follow the airflow convectively and may place the healthcare provider at risk.</jats:p>

Risk of Transmitting Coronavirus Disease 2019 During Nebulizer Treatment: A Systematic Review

“…One was included. (44) In addition, we reviewed LitCOVID and found no additional studies. We reviewed the collection of 474 articles on COVID-19 within the Chinese Medical Journal Network, screened 4 articles at full text, and included none.…”

“…A second experimental study, identified through a preprint server, sought to characterize the pattern of droplet dispersion with human participants of unknown clinical status receiving selected common airway management procedures during routine care, one of which was nebulization. (44) Droplet patterns were captured by a high-speed camera of illuminated droplets against a black background. They found no evidence of droplet dispersion during nebulization, though they noted that fine aerosols were detected but not quantified due to ''abundance.…”

Simulation of aerosol dispersion during medical examinations

“…The realistic coughing velocity profile of Gupta et al [46] is scaled to the maximum total velocity of 26.4 m s taken from the experiments of Müller et al [15], see Fig. 2.…”

“…Other authors distinguish between liquid particles suspended in the air that remain in the air for a short time due to ballistic trajectories (droplets) and particles that float and remain in the air for a longer time (aerosol particles). In this study, based on previous results of our group (clinical characterization), we will use the second definition based on ballistic and hovering behavior of respiratory particles [15]. Filtering mechanisms in the upper airways effectively seems to remove the majority of particles larger than 5 µm from the air stream already in the nose/mouth/throat [12].…”