Preventing spread of aerosolized infectious particles during medical procedures: A lab-based analysis of an inexpensive plastic enclosure

Abstract

Severe viral respiratory diseases, such as SARS-CoV-2, are transmitted through aerosol particles produced by coughing, talking, and breathing. Medical procedures including tracheal intubation, extubation, dental work, and any procedure involving close contact with a patient's airways can increase exposure to infectious aerosol particles. This presents a significant risk for viral exposure of nearby healthcare workers during and following patient care. Previous studies have examined the effectiveness of plastic enclosures for trapping aerosol particles and protecting health-care workers. However, many of these enclosures are expensive or are burdensome for healthcare workers to work with. In this study, a low-cost plastic enclosure was designed to reduce aerosol spread and viral transmission during medical procedures, while also alleviating issues found in the design and use of other medical enclosures to contain aerosols. This enclosure is fabricated from clear polycarbonate for maximum visibility. A large single-side cutout provides health care providers with ease of access to the patient with a separate cutout for equipment access. A survey of medical providers in a local hospital network demonstrated their approval of the enclosure's ease of use and design. The enclosure with appropriate plastic covers reduced total escaped particle number concentrations (diameter > 0.01 μm) by over 93% at 8 cm away from all openings. Concentration decay experiments indicated that the enclosure without active suction should be left on the patient for 15-20 minutes following a tracheal manipulation to allow sufficient time for >90% of aerosol particles to settle upon interior surfaces. This decreases to 5 minutes when 30 LPM suction is applied. This enclosure is an inexpensive, easily implemented additional layer of protection that can be used to help contain infectious or otherwise potentially hazardous aerosol particles while providing access into the enclosure.

Fig 1. Design and dimensions of the enclosure: A schematic of the enclosure showing the three cutout openings.

One on the cephalad (provider) side to provide access for the healthcare worker’s hands, a second on the caudal (patient) side to allow room for the patient’s torso, and a third on the lateral side to enable ventilator and other tubing access. The provider access cutout is large to maximize mobility.

Fig 2. Effectiveness of different enclosure covering approaches and materials: Ratio of the maximum aerosol number concentration measured inside vs. measured outside the enclosure for particles larger than 0.1 micrometers when various types of one-layer of plastic covering with or without an added Steri-Drape layer were placed over the front and side holes in the enclosure.

Fig 3

Aerosol particle concentrations as a function of distance from enclosure: Outside particle concentration compared to inside particle number concentration as a function of distance for enclosure (A) without plastic coverings vs. (B) enclosure with dual coverings of furniture wrap and Steri-Drape.

Fig 4

Particle concentration decay in the enclosure as a function of time and suction: (A) Average decay rate curves for aerosol particle number concentrations within the enclosure following a particle generation event. The no cover condition kept the provider and ventilator access holes open. The 2-layer cover condition used the furniture wrap and Steri-Drape. Shaded region shows the standard deviation from 3 replicates. The black dashed line indicates 90% particle loss. (B) Comparison of average decay rates for aerosol particle concentration when suction is applied to the enclosure. All three conditions involve a dual-covered enclosure with furniture wrap and Steri-Drape. The patient side was covered for all experiments.