COVID-19 in the Clinic: Human Testing of an Aerosol Containment Mask for Endoscopic Clinic Procedures

Abstract

Objective: To create an aerosol containment mask (ACM) for common otolaryngologic endoscopic procedures that also provides nanoparticle-level protection to patients.

Study design: Prospective feasibility study .

Setting: In-person testing with a novel ACM.

Methods: The mask was designed in Solidworks and 3D printed. Measurements were made on 10 healthy volunteers who wore the ACM while reading the Rainbow Passage repeatedly and performing a forced cough or sneeze at 5-second intervals over 1 minute with an endoscope in place.

Results: There was a large variation in the number of aerosol particles generated among the volunteers. Only the sneeze task showed a significant increase compared with normal breathing in the 0.3-µm particle size when compared with a 1-tailed t test (P = .013). Both the 0.5-µm and 2.5-µm particle sizes showed significant increases for all tasks, while the 2 largest particle sizes, 5 and 10 µm, showed no significant increase (both P < .01). With the suction off, 3 of 30 events (2 sneeze events and 1 cough event) had increases in particle counts, both inside and outside the mask. With the suction on, 2 of 30 events had an increase in particle counts outside the mask without a corresponding increase in particle counts inside the mask. Therefore, these fluctuations in particle counts were determined to be due to random fluctuation in room particle levels.

Conclusion: ACM will accommodate rigid and flexible endoscopes plus instruments and may prevent the leakage of patient-generated aerosols, thus avoiding contamination of the room and protecting health care workers from airborne contagions.

Level of evidence: 2.

Keywords: COVID-19; Rainbow Passage; aerosol production; cough; endoscopy; laryngoscopy; nasal endoscopy; negative-pressure mask; sneeze; virus.

Figure 1.

Mask testing setup in a human volunteer. (a) Mask design. (b) Setup for human volunteer. (c) Human volunteer undergoing rigid endoscopy.

Figure 2.

Box plots of cumulative particle counts at sensor 1 measured over 1 minute in human volunteers wearing the aerosol containment mask with no suction. Abbreviations: C, cough; N, normal breathing; R, Rainbow; S, sneeze.

Figure 3.

The 0.3-µm particle counts for a representative healthy volunteer for normal breathing, Rainbow Passage, coughing, and sneezing. Inside aerosol containment mask (sensor 1) and outside (sensor 2).

Figure 4.

Particle count as a function of time for 2 volunteers. Sensor 1 is inside the mask. Sensor 2 is outside the mask. The leaks are marked by (↔) on both sensor plots.