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

Perella, P.; Tabarra, M.; Hataysal, E.; Pournasr, A.; Renfrew, I.

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 1-500{micro}m) 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.