Aerosolized Particle Reduction: A Novel Cadaveric Model and a Negative Airway Pressure Respirator (NAPR) System to Protect Health Care Workers From COVID‐19

Abstract

<jats:sec><jats:title>Objectives</jats:title><jats:p> This study aimed to identify escape of small-particle aerosols from a variety of masks using simulated breathing conditions. This study also aimed to evaluate the efficacy of a negative-pressure environment around the face in preventing the escape of small aerosolized particles. </jats:p></jats:sec><jats:sec><jats:title>Study Design</jats:title><jats:p> This study is an evaluation study with specific methodology described below. </jats:p></jats:sec><jats:sec><jats:title>Setting</jats:title><jats:p> This study was performed in our institution’s fresh tissue laboratory. </jats:p></jats:sec><jats:sec><jats:title>Subjects and Methods</jats:title><jats:p> A fixed cadaver head was placed in a controlled environment with a black background, and small-particle aerosols were created using joss incense sticks (mass-median aerosol diameter of 0.28 µ). Smoke was passed through the cadaver head, and images were taken with a high-resolution camera in a standardized manner. Digital image processing was used to calculate relative amounts of small-particle escape from a variety of masks, including a standard surgical mask, a modified Ambu mask, and our negative airway pressure respirator (NAPR). </jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p> Significant amounts of aerosolized particles escaped during the trials with no mask, a standard surgical mask, and the NAPR without suction. When suction was applied to the NAPR, creating a negative-pressure system, no particle escape was noted. </jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p> We present a new and effective method for the study of small-particle aerosols as a step toward better understanding the spread of these particles and the transmission of coronavirus disease 2019. We also present the concept of an NAPR to better protect health care workers from aerosols generated from the upper and lower airways. </jats:p></jats:sec>

Reducing Aerosolized Particles and Droplet Spread in Endoscopic Sinus Surgery during COVID‐19

“…In line with results from previous work by Khoury, 19 we demonstrated a significant emission of aerosolized particles without a mask. Table I summarizes the white pixel count for the final subtraction image in each scenario.…”

“…In the only other study to use smoke simulation of droplet nuclei, Khoury et al 19 used incense Joss sticks to generate aerosol particles of a diameter of 0.28 μm 26 . They also demonstrated that their Negative Airway Pressure Respirator (NAPR) was able to prevent aerosol escape.…”

“…The severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) responsible for the coronavirus disease 2019 (COVID- 19) was first reported in Wuhan, China, in December 2019 and has since spread globally in a few short months. 1 At the time of writing, it has claimed nearly 500,000 lives.…”

Innovations in otorhinolaryngology in the age of COVID‐19: A systematic literature review

“…They found that their negative airway respirator (NAPR), designed by drilling a small hole in the plastic bottom of a standard Ambu mask and inserting a suction tubing, allowed no particles to escape. 52 Dharmaraian et al 53 conducted similar studies in cadaver models to evaluate the efficacy of SPIWay® Endonasal sheaths in mitigating aerosol dispersion caused by endonasal drilling. These endonasal sheaths are typically used to reduce mucosal trauma during endoscopic procedures and to avoid contaminating scope lenses with surgical debris.…”

“… Negative pressure systems created from modified ambu masks (negative airway respirator or NAPR) or negative-pressure otolaryngology viral isolation drapes (NOVID). Khoury T, Lavergne P, Chitguppi C, et al 52 Preclinical evaluation of prototypes: proof-of-concept Level 4 (case-control simulation) Risk of Bias: Moderate (incense sticks used may not accurately reflect aerosol/smoke created in OR; difficult to quantitatively measure) NAPR consists of an Ambu mask with a small hole drilled into the front fitted with suction. Tested in the cadaver model only.…”