Aerosol Retention Characteristics of Barrier Devices

Abstract

Background Disease severity in coronavirus disease 2019 (COVID-19) may be associated with inoculation dose. This has triggered interest in intubation barrier devices to block droplet exposure; however, aerosol protection with these devices is not known. This study hypothesized that barrier devices reduce aerosol outside of the barrier. Methods Aerosol containment in closed, semiclosed, semiopen, and open barrier devices was investigated: (1) “glove box” sealed with gloves and caudal drape, (2) “drape tent” with a drape placed over a frame, (3) “slit box” with armholes and caudal end covered by vinyl slit diaphragms, (4) original “aerosol box,” (5) collapsible “interlocking box,” (6) “simple drape” over the patient, and (7) “no barrier.” Containment was investigated by (1) vapor instillation at manikin’s right arm with video-assisted visual evaluation and (2) submicrometer ammonium sulfate aerosol particles ejected through the manikin’s mouth with ventilation and coughs. Samples were taken from standardized locations inside and around the barriers using a particle counter and a mass spectrometer. Aerosol evacuation from the devices was measured using standard hospital suction, a surgical smoke evacuator, and a Shop-Vac. Results Vapor experiments demonstrated leakage via arm holes and edges. Only closed and semiclosed devices and the aerosol box reduced aerosol particle counts (median [25th, 75th percentile]) at the operator’s mouth compared to no barrier (combined median 29 [−11, 56], n = 5 vs. 157 [151, 166], n = 5). The other barrier devices provided less reduction in particle counts (133 [128, 137], n = 5). Aerosol evacuation to baseline required 15 min with standard suction and the Shop-Vac and 5 min with a smoke evacuator. Conclusions Barrier devices may reduce exposure to droplets and aerosol. With meticulous tucking, the glove box and drape tent can retain aerosol during airway management. Devices that are not fully enclosed may direct aerosol toward the laryngoscopist. Aerosol evacuation reduces aerosol content inside fully enclosed devices. Barrier devices must be used in conjunction with body-worn personal protective equipment. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

Anesthesia care for coronavirus disease (COVID-19) patients: Results from a survey evaluating opinions of American Society of Anesthesiologists (ASA) members

“…A variety of barrier devices (e.g., cover box, or plastic tent) have been suggested to prevent aerosols and droplets from reaching the operator’s face 7 ; one third of respondents expressed being neutral and less than 50% seemed to agree/strongly agree with their use; although we do not know how many of respondents actually tried these devices, it is possible that most perceived the use of intubation boxes to be cumbersome in challenging cases, or that knowledge surrounding the fact that their manipulation may actually redirect aerosolized particles trapped under the shield had already emerged at the time of our survey. [8] , [9] , [10]…”

Aerosol Retention Barriers

“…3 Conversely, aerosol barrier devices may be useful during patient transport or while performing aerosol-generating procedures that require minimal access to the patient, such as nebulizer administration. The report of Fidler et al 5 aligns with the Food and Drug Administration's message and states that aerosol barrier devices are not a replacement for personal protective equipment. Further, they recommend that healthcare providers electing to use aerosol barriers should employ a mechanism to generate negative pressure within the enclosure.…”

“…In this issue of Anesthesiology, Fidler et al 5 conducted a simulation study of six barrier devices assessing the protection of the healthcare provider from aerosol and vapor spread during simulated intubation, extubation, and coughing. The investigators conducted experiments simulating aerosol and vapor spread during expiration and coughing, including quantitative and qualitative assessment of aerosol and vapor spread patterns.…”

“…An essential aspect of the work by Fidler et al 5 is the collaboration with bioaerosol scientists. The science of bioaerosols and their role in infection through inhalation and at times ingestion has drawn great interest among anesthesiologists and other healthcare professionals performing aerosol-generating medical procedures.…”

Size- and Time-Dependent Aerosol Removal from a Protective Box during Simulated Intubation and Extubation Procedures

“…Although adequate PPE can provide suitable protection, problems may arise, such as reduced dexterity and impaired visibility [4], which could be reflected in the number of errors in medical procedures. The spread of aerosols contaminated with SARS-CoV-2 can, in certain situations, also pose a problem such as during the intubation and extubation procedure when large quantities of aerosols are produced by the patient [5,6]. This increases the probability of an infection for the medical professionals attending the operation as well as the whole operation room, including all the equipment becoming contaminated.…”