Abstract
Objectives To investigate the ability of a physical barrier to reduce
aerosol particle spread during a simulated aerosol generating procedure.
Design A simulated aerosol generating procedure. Setting Standard
hospital ward, St George’s Hospital, London. Participant One volunteer
participant - they were healthy, asymptomatic, and a non-smoker. Main
Outcome Measures 1. To compare the effect of the shield on particle
frequency (according to particle size) at different locations. 2. To
evaluate the length of time that particles remained within the shield,
both with and without an aspiration unit. Results Clinical
investigations using the shield demonstrated a twelve-fold decrease in
the number of particles detected at the position of the operating
surgeon when the shield was used (particle size 0.3μm; with shield 8662
versus 103800 without shield). Over a 7-minute period, there was a
reduction in the number of particles. At 7 minutes, the total number of
particles (size 0.3μm) measured within the shield was comparable to the
particle frequency at ambient levels (8752 within the shield compared
with 8592 within the ambient environment). The aspiration unit reduced
the number of particles detected within the shield over time. An average
of 9649 particles (similar to ambient level) sized 0.3μm were measured
under the shield after 2 minutes when the aspiration unit was used.
Conclusion The clinical simulation illustrates a significant decrease in
the number of particles detected at varying locations when the shield is
used. The shield, used with appropriate PPE, could help to minimise
exposure to aerosol-generated particles such as during tracheostomies on
patients with COVID-19.