• Paolo Perella, Mohammad Tabarra, Ertan Hataysal, Amir Pournasr, and Ian Renfrew.
• Department of Anaesthesia & Perioperative Medicine, Royal London Hospital, Barts Health NHS Trust, London, UK. Electronic address: paolo.perella1@nhs.net.
• Br J Anaesth. 2021 Feb 1; 126 (2): 544-549.

BackgroundHazardous 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 (CFD) modelling to optimise the performance of a custom-designed shield.MethodsWe modelled airflow patterns and trajectories of particles (size range 1-500 μm) emitted during a typical cough using CFD (ANSYS Fluent software, Canonsburg, PA, USA), 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.ResultsUse 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 (40-160 L 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.ConclusionCFD 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, pragmatic clinical trials, or both.Copyright © 2020 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.

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