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

Abstract

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.

Keywords: Aerosols; COVID-19; Endoscopy; Gastroscopy; N95 respirators.

Fig. 1.

Illustration of a modified N95 respirator. A standard N95 respirator (3M Aura 1870+ model) was modified as shown. In proportion to the 9.9-mm outer diameter of the gastroscope (GIF-HQ190; Olympus), two intersecting 10.4-mm linear holes were created and fitted to the diameter of the scope. Illustrated by the author.

Fig. 2.

TSI AeroTrak (9306-04) handheld particle counter (TSI Inc.).

Fig. 3.

Endoscopic unit setup. The TSI AeroTrak (9306-04; TSI Inc.) handheld particle counter was placed 1 m apart from patient at the same side as the endoscopist, without any blockages, and the endoscope was inserted through the modified N95 respirator. Illustrated by the author.