Assessing the Physiological Relevance of Cough Simulators for Respiratory Droplet Dispersion

Abstract

Various breathing and cough simulators have been used to model respiratory droplet dispersion and viral droplets, in particular for SARS-CoV-2 modeling. However, limited data are available comparing these cough simulations to physiological breathing and coughing. In this study, three different cough simulators (Teleflex Mucosal Atomization Device Nasal (MAD Nasal), a spray gun, and GloGermTM MIST) that have been used in the literature were studied to assess their physiologic relevance. Droplet size, velocity, dispersion, and force generated by the simulators were measured. Droplet size was measured with scanning electron microscopy (SEM). Slow-motion videography was used to 3D reconstruct and measure the velocity of each simulated cough. A force-sensitive resistor was used to measure the force of each simulated cough. The average size of droplets from each cough simulator was 176 to 220 µm. MAD Nasal, the spray gun, and GloGermTM MIST traveled 0.38 m, 0.89 m, and 1.62 m respectively. The average velocities for the MAD Nasal, spray gun, and GloGermTM MIST were 1.57 m/s, 2.60 m/s, and 9.27 m/s respectively, and all yielded a force of <0.5 Newtons. GloGermTM MIST and the spray gun most closely resemble physiological coughs and breathing respectively. In conclusion, none of the simulators tested accurately modeled all physiologic characteristics (droplet size, 3-D dispersion velocity, and force) of a cough, while there were various strengths and weaknesses of each method. One should take this into account when performing simulations with these devices.

KN95 and N95 Respirators Retain Filtration Efficiency despite a Loss of Dipole Charge during Decontamination

“… 3 When an infected person coughs, sneezes, or speaks, the virus is excreted and dissolved droplets (>5 to 10 μm) or aerosols (≤5 μm) that can remain and travel in the air. 4 , 5 …”

“…3 When an infected person coughs, sneezes, or speaks, the virus is excreted and dissolved droplets (>5 to 10 μm) or aerosols (≤5 μm) that can remain and travel in the air. 4,5 N95 respirators have been used to protect wearers against such viral aerosols and droplets. They have at least 95% filtration efficiency for NaCl particles sized 0.1−0.3 μm with even higher filtration efficiency at higher particle size (approximately 99.5% or higher for 0.75 μm particles).…”

The effectiveness of the Safety in Interventional Radiology (SIR) Shield in reducing droplet transmission and its effect on image quality and radiation dose

“… 6 Our human fluorescent droplet visualisation model allows for direct visual confirmation that the large droplets can be retained within the confines of the box reducing risk to operators on splash exposure of infectious droplets. While there have been many studies on cough and sneezing simulation for droplet spread especially in the context of COVID-19, 7–9 as far as we are aware, this is the first time that droplet spread from coughing has been assessed from supine position. This is more physiologically representative of the working conditions of the interventional radiology theatre, where the greatest risk is likely to be from the patient coughing directly beside the operator during aerosol generating procedures.…”

What We Are Learning from COVID-19 for Respiratory Protection: Contemporary and Emerging Issues

“…In other research, droplet and aerosol generation is simulated using devices such as spray guns to study the transport of aqueous particles [ 124 , 125 ]. As these types of simulations are easier to replicate and repeat in different environments, they can be used to further explore the influence of environmental conditions on particle transmission.…”