J Korean Soc Emerg Med.  2021 Dec;32(6):601-610.

Simulation study: the development of a respiratory barrier enclosure with negative pressure and the analysis of its protective effect during intubation

• Jung YJ
• Sung KS
• Yu G
• Hong JY
• Chung HS

Abstract

Objective
Within the last 2 years, coronavirus disease 2019 has spread rapidly across several continents, with 100 million confirmed infected patients. Physical barrier enclosure, also called “aerosol-box,” is a solution for the shortage of protective devices and spaces. In this study, we examined the safety of the novel barrier enclosure.
Methods
We simulated droplets by nebulizing 1% glycerol+99% ethanol solution. Two experienced physicians performed intubation under two conditions, such as the isolator condition (applying isolator without negative condition) and the negative pressure condition (applying isolator with the negative condition). We compared two conditions with two control groups, including negative control (room air) and positive control (synthetizing droplet air). During the procedure, particles were counted for 30 seconds, and this was repeated 10 times. At each condition, depending on the result of the normality test (Shapiro-Wilk test), an independent t-test was used when normality was satisfied, and a Mann-Whitney U-test was used when normality was not satisfied.
Results
The total number of particles in the positive control was 308,788 (175,936-461,124). The total number of particles for both conditions was significantly less than the positive control. Total number of particles in the isolator condition was 30,952 (27,592-33,244, P=0.001) and that in the negative pressure condition was 27,890 (27,165-29,786, P=0.001).
Conclusion
The novel barrier significantly reduces synthetizing droplets exposure during intubation. Application of negative pressure through the isolator results in an additional decrease in particle exposure. Studies involving a larger population of operators and prolonged procedures are required.

Keyword

Aerosols; COVID-19; Infectious disease transmission; Intubation; Negative pressure; Patient isolation