Air filtration mitigates aerosol levels both during and after endoscopy procedures. Issue 1 (17th April 2023) - Phillips, Frank
Abstract: Objectives: Upper gastrointestinal endoscopies are aerosol‐generating procedures, increasing the risk of spreading airborne pathogens. We aim to quantify the mitigation of airborne particles via improved ventilation, specifically laminar flow theatres and portable high‐efficiency particulate air (HEPA) filters, during and after upper gastrointestinal endoscopies. Methods: This observational study included patients undergoing routine upper gastrointestinal endoscopy in a standard endoscopy room with 15–17 air changes per hour, a standard endoscopy room with a portable HEPA filtration unit, and a laminar flow theatre with 300 air changes per hour. A particle counter (diameter range 0.3 μm‐25 μm) took measurements 10 cm from the mouth. Three analyses were performed: whole procedure particle counts, event‐based counts, and air clearance estimation using post‐procedure counts. Results: Compared to a standard endoscopy room, for whole procedures we observe a 28.5x reduction in particle counts in laminar flow ( p < 0.001) but no significant effect of HEPA filtration ( p = 0.50). For event analysis, we observe for lateral flow theatres reduction in particles >5 μm for oral extubation (12.2x, p < 0.01), reduction in particles <5 μm for coughing/gagging (6.9x, p < 0.05), and reduction for all sizes in anesthetic throat spray (8.4x, p < 0.01) but no significant effect of HEPA filtration. However, we find that in the fallow period between procedures HEPA filtration reduces particle clearance times by 40%. Conclusions: Laminar flow theatres are highly effective at dispersing aerosols immediately after production and should be considered for high‐risk cases where patients are actively infectious or the supply of personal protective equipment is limited. Portable HEPA filers can safely reduce the fallow time between procedures by 40%.