Minimising exposure to droplet and aerosolised pathogens: a computational fluid dynamics study

Abstract

Background Hazardous pathogens are spread in either droplets or aerosols produced during aerosol generating procedures (AGP). Adjuncts minimising exposure of healthcare workers to hazardous pathogens released during AGP may be beneficial. We used state-of-the-art Computational Fluid Dynamics modelling to optimise the performance of a custom-designed shield. Methods We modelled airflow patterns and trajectories of particles (size range 1−500µm) emitted during a typical cough using Computational Fluid Dynamics (ANSYS Fluent software), in the presence and absence of a protective shield enclosing the head of a patient. We modelled the effect of different shield designs, suction tube position, and suction flow rate on particle escape from the shield. Results Use of the shield prevented escape of 99.1−100% of particles, which were either trapped on the shield walls (16−21%) or extracted via suction (79−82%). At most, 0.9% particles remained floating inside the shield. Suction flow rates (40−160L min-1) had no effect on the final location of particles in a closed system. Particle removal from within the shield was optimal when a suction catheter was placed vertically next to the head of the patient. Addition of multiple openings in the shield reduced the purging performance from 99% at 160 L min-1 to 67% at 40 L min-1. Conclusion Computational fluid dynamics modelling provides information to guide optimisation of the efficient removal of hazardous pathogens released during AGP from a custom-designed shield. These data are essential to establish before clinical use and/or pragmatic clinical trials.

Barrier enclosure use during aerosol-generating medical procedures: A scoping review

“…Box designs were often similar to the original design in Canelli et al [ 7 ], which is a transparent 4-sided structure with two open faces: an inferior face bound by the stretcher and a caudal face pointed towards the foot of the bed. Common modifications included change in the number or size of ports (i.e., for operators and/or tools) [ [8] , [9] , [10] , [11] , [12] ], increased device size for improved operator ergonomics and/or patient body habitus [ [13] , [14] , [15] ], built-in gloves and/or port coverings [ 11 , 12 , 16 , 17 ], addition of a plastic drape or covering on the caudal face [ [18] , [19] , [20] ], a sloped top panel for improved visibility [ 15 , 18 , 21 ] and the use of a negative suction system [ [22] , [23] , [24] ].…”

“…Two studies (2%, n = 2/83) used a device in pediatric laryngoscopy and bronchoscopy [ 54 , 55 ]. Nine studies (7%) discussed these devices for general AGMPs [ 22 , 25 , 32 , 46 , [56] , [57] , [58] , [59] , [60] ] and 9 (7%) for endoscopic procedures. [ 10 , 11 , 43 , 45 , [61] , [62] , [63] , [64] ]…”

Size- and Time-Dependent Aerosol Removal from a Protective Box during Simulated Intubation and Extubation Procedures

“…Only a sufficient negative airflow ensures that there is no leakage of particles through the armholes. As each barrier enclosure device is different, a sufficient negative airflow can only be determined through an experiment and supported by calculations [22]. Our experiments show that concentrations of all measured particle sizes decrease within the same time frame.…”

On COVID-19-safety ranking of seats in intercontinental commercial aircrafts: A preliminary multiphysics computational perspective

“…One option is to permanently remove less suited seats, while the other is to seat passengers only on the better positioned seats. A few recent studies (Adwibowo 2020;Garbey et al 2020;Perella et al 2020;Vuorinen 2020;Li et al 2020) have tried to numerically model the indoor spread of COVID-19 viral particles using CFD. A couple of studies (Li et al 2016;Bhatia and De Santis 2020) have explicitly studied the transport of pollutants inside aircraft cabins.…”