Impact on aerosol generation during upper endoscopy of mouthpiece designed to reduce COVID-19 droplet spread: single-center randomized controlled trial

For nearly 2 years, the COVID-19 pandemic has continued to pose a major public health crisis. COVID-19 spreads through the generation of aerosols and droplets [1]. A growing number of studies have confirmed that esophagogastroduodenoscopy (EGD) is an aerosol-generating procedure [2] [3]. While numerous approaches to decreasing the amount of aerosol have been reported, most of them may reduce patient comfort and entail additional procedure time and personnel. During the pandemic, a droplet-shielding mouthpiece (B1 mouthpiece, MPC-ST; Fujifilm, Tokyo, Japan) was launched. This device is used similarly to the conventional mouthpiece but has a double sponge with slits incorporated into the mouthpiece orifice, and a transparent plastic drape shield ( [Fig. 1]).

Fig. 1 Droplet-reduction mouthpiece used during esophagogastroduodenoscopy (EGD).

To evaluate the efficacy of this modified mouthpiece, we performed a randomized study to quantify aerosol generation. Patients scheduled to undergo standard diagnostic EGDs or through-the-scope balloon dilation, and with negative findings from a polymerase chain reaction (PCR) test for COVID-19, were invited to participate. They were randomly assigned in a 1:1 ratio to receive a conventional or droplet-reduction mouthpiece.

Quantification of aerosols (of sizes 0.3, 0.5, 1.0, 3.0, 5.0, and 10 μm) was conducted using a particle counter (Lasair II Particle Counter; Particle Measuring Systems, Boulder, Colorado, United States). Measurements of particle counts occurred immediately before endoscope insertion and 1, 3, 5, and 10 minutes after insertion, if the endoscopy was not terminated, and also 1, 3, 5, 10, and 15 minutes after scope withdrawal. The mouthpiece was removed 2 minutes after completion of the procedure.

Aerosol particle counts (per cubic meter) were logarithmically transformed. Data are presented as mean ± SD and significance was set at P < 0.05. Chi-squared and unpaired t tests were used to compare baseline characteristics. A two-way mixed-model analysis was used to test for differences between mouthpiece types over time on number of aerosol particles of each size.

The study was approved by the Leuven University Hospitals Ethics Committee, Leuven, Belgium (S65197).

A total of 80 EGDs were included. There were no differences in baseline characteristics (Table  1s; available online in Supplementary material) and baseline particle counts (all sizes P = 1.00) of the two groups. During EGD, the use of a modified mouthpiece was associated with significantly lower counts in larger particle sizes 3.0, 5.0, and 10 µm (P = 0.03, P = 0.01, and P < 0.01, respectively), but not for smaller sizes 0.3, 0.5, and 1 µm (P = 0.41, P = 0.09, and P = 0.06, respectively) ( [Fig. 2], Table  2 s). After withdrawal of the endoscope, there were no differences in particle counts for each size over a 15-minute period (for ascending size order: P = 0.30, P = 0.25, P = 0.89, P = 0.65, P = 0.47; P = 0.29, respectively) (Fig. 1 s, Table  3 s).

Fig. 2 Aerosol counts for particles of different sizes (0.3, 0.5, 1.0, 3.0, 5.0, and 10.0 µm) during esophagogastroduodenoscopy in patients with conventional or with droplet-reduction (modified) mouthpieces. Particle numbers are presented on a logarithmic scale and as mean ± SD. The use of a modified mouthpiece significantly lowered the numbers of particles of size 3, 5, or 10 μm.

Our findings show that a commercially available mouthpiece, designed to reduce droplet generation during EGD, did not decrease particle counts for smaller sizes (0.3, 0.5, and 1.0 μm), but significantly lowered the numbers of particles of sizes 3, 5, and 10 μm particles during gastroscopy. This is consistent with the fact that larger particles are more easily blocked by personal protection equipment [4]. Accordingly, we believe that the modified mouthpiece helps to partially reduce the spread of particles (≥ 3.0 µm). However, it is does not avoid scattering of aerosols ≤ 1.0 µm. Appropriate personal protective equipment must still be worn to prevent aerosol transmission.

^* Joint first authors.

Publication History

Article published online:
24 November 2021

• References

• 1 Rabaan AA, Al-Ahmed SH, Al-Malkey MK. et al. Airborne transmission of SARS-CoV-2 is the dominant route of transmission: droplets and aerosols. Infez Med 2021; 29: 10-19
• 2 Sagami R, Nishikiori H, Sato T. et al. Aerosols produced by upper gastrointestinal endoscopy: a quantitative evaluation. Am J Gastroenterol 2021; 116: 202-205
• 3 Chan SM, Ma TW, Chong MK-C. et al. A proof of concept study: Esophagogastroduodenoscopy is an aerosol-generating procedure and continuous oral suction during the procedure reduces the amount of aerosol generated. Gastroenterology 2020; 159; 1949-1951
• 4 Dhand R, Li J. Coughs and sneezes: their role in transmission of respiratory viral infections, including SARS-CoV-2. Am J Respir Crit Care Med 2020; 202: 651-659