Aerosol protection using modified N95 respirator during upper gastrointestinal endoscopy: a randomized controlled trial

Background/Aims The coronavirus disease 2019 pandemic has affected the worldwide practice of upper gastrointestinal endoscopy. Here we designed a modified N95 respirator with a channel for endoscope insertion and evaluated its efficacy in upper gastrointestinal endoscopy. Methods Thirty patients scheduled for upper gastrointestinal endoscopy were randomized into the modified N95 (n=15) or control (n=15) group. The mask was placed on the patient after anesthesia administration and particles were counted every minute before (baseline) and during the procedure by a TSI AeroTrak particle counter (9306-04; TSI Inc.) and categorized by size (0.3, 0.5, 1, 3, 5, and 10 µm). Differences in particle counts between time points were recorded. Results During the procedure, the modified N95 group displayed significantly smaller overall particle sizes than the control group (median [interquartile range], 231 [54–385] vs. 579 [213–1,379]×103/m3; p=0.056). However, the intervention group had a significant decrease in 0.3-µm particles (68 [–25–185] vs. 242 [72–588]×103/m3; p=0.045). No adverse events occurred in either group. The device did not cause any inconvenience to the endoscopists or patients. Conclusions This modified N95 respirator reduced the number of particles, especially 0.3-µm particles, generated during upper gastrointestinal endoscopy.