Aerosol and droplet generation in upper and lower gastrointestinal endoscopy: whole procedure and event-based analysis

ABSTRACT Background and Aims Aerosol generating procedures have become an important healthcare issue due to the COVID-19 pandemic, as the SARS-CoV-2 virus can be transmitted via aerosols. We aimed to characterise aerosol and droplet generation in gastrointestinal endoscopy, where there is little evidence. Methods This prospective observational study included patients undergoing routine per-oral gastroscopy (POG, n=36), trans-nasal endoscopy (TNE, n=11) and lower gastrointestinal (LGI) endoscopy (n=48). Particle counters took measurements near the appropriate orifice (two models used, diameter ranges 0.3μm-25μm and 20μm-3000μm). Quantitative analysis was performed by recording specific events and subtracting the background particles. Results POG produced 1.96x the level of background particles (p<0.001) and TNE produced 2.00x (p<0.001) but a direct comparison shows POG produces 2.00x more particles than TNE. LGI procedures produce significant particle counts (p<0.001) with 2.4x greater production per procedure than POG but only 0.63x production per minute. Events significant relative to the room background particle count were: POG-throat spray (150.0x, p<0.001), oesophageal extubation (37.5x, p<0.001), coughing/gagging (25.8x, p<0.01); TNE-nasal spray (40.1x, p<0.001), nasal extubation (32.0x, p<0.01), coughing/gagging (20.0, p<0.01); LGI-rectal intubation (9.9x, p <0.05), rectal extubation (27.2x, p <0.01), application of abdominal pressure (9.6x, p <0.05), rectal insufflation/retroflexion (7.7x, p <0.01). These all produced particle counts larger than or comparable to volitional cough. Conclusion Gastrointestinal endoscopy performed via the mouth, nose or rectum all generates significant quantities of aerosols and droplets. As the infectivity of procedures is not established, we therefore suggest adequate PPE is used for all GI endoscopy where there is a high population prevalence of COVID-19. Avoiding throat and nasal spray would significantly reduce particles generated from UGI procedures.