Aerosol containment device design considerations and performance evaluation metrics.

BACKGROUND: Spurred by the Coronavirus infectious disease 2019 pandemic, aerosol containment devices (ACDs) were developed to capture infectious respiratory aerosols generated by patients at their source. Prior reviews indicated that such devices had low evidence of effectiveness, but did not address how ACDs should be evaluated, how well they should perform, nor have clearly defined performance standards. Towards developing design criteria for ACDs, two questions were posed: 1) What characteristics have guided the design of ACDs? 2) How have these characteristics been evaluated? METHODS: A scoping review was performed consistent with PRISMA guidelines. Data were extracted with respect to general study information, intended use of the device, device design characteristics and evaluation. RESULTS: Fifty-four articles were included. Evaluation was most commonly performed with respect to device aerosol containment (n = 31, 61%), with only 5 (9%), 3 (6%) and 8 (15%) formally assessing providing experience, patient experience and procedure impact, respectively. Nearly all of the studies that explored provider experience and procedure impact studied intubation. Few studies provided a priori performance criteria for any evaluation metric, or referenced any external guidelines by which to bench mark performance. CONCLUSION: With respect to aerosol containment, ACDs should reduce exposure among HCP with the device compared with the absence of the device, and provide ≥90% reduction in respirable aerosols, equivalent in performance to N95 filtering facepiece respirators, if the goal is to reduce reliance on personal protective equipment. The ACD should not increase awkward or uncomfortable postures, or adversely impact biomechanics of the procedure itself as this could have implications for procedure outcomes. A variety of standardized instruments exist to assess the experience of patients and healthcare personnel. Integration of ACDs into routine clinical practice requires rigorous studies of aerosol containment and the user experience.

The effect of using personal protective equipment and aerosol box in the emergency department on the intubation times.

Background: Endotracheal intubation is a procedure commonly performed in the emergency department (ED). Endotracheal intubation poses a risk of exposure to infectious aerosol droplets. Aim: The present study aims to test the effect of using an aerosol box (AB) and personal protective equipment (PPE) on the intubation time while performing endotracheal intubation manikin. Subjects and Methods: The study participants (11 emergency specialists, 11 emergency physicians, and 11 general practitioners) performed endotracheal intubation on a training manikin in three different airway simulations. Simulation 1 had neither PPE nor AB, simulation 2 had PPE, and simulation 3 had both PPE and AB. The intubation times, the number of intubation attempts, and the discomfort caused by the AB were recorded. Results: There was no significant difference in the number of intubation attempts between the physicians according to their position and airway simulations (p > 0.05). There was a significant difference at all time points except for the time to endotracheal tube cuff inflation in three different airway simulations using PPE and an AB (p < 0.05). The median intubation times were longer using PPE and an AB. Conclusion: The use of PPE and an AB significantly increases the total intubation time.

Prevention of submicron aerosolized particle dispersion: evaluation of an aerosol box using a pediatric simulation model.

Background and Aim: The SplashGuard CG (SG) is a barrier enclosure developed to protect healthcare workers from SARS-CoV-2 transmission during aerosol-generating procedures. Our objective was to evaluate the protection provided by the SG against aerosolized particles (AP), using a pediatric simulation model of spontaneous ventilation (SV) and noninvasive ventilation (NIV). Methods: An aerosol generator was connected to the airways of a pediatric high-fidelity manikin with a breathing simulator. AP concentrations were measured both in SV and NIV in the following conditions: with and without SG, inside and outside the SG, with and without suction applied to the device. Results: In the SV simulated setting, AP peaks were lower with SG: 0.1 × 105 particles/L compared to without: 1.6 × 105, only when the ports were closed and suction applied. In the NIV simulated setting, AP peaks outside the SG were lower than without SG (20.5 × 105 particles/L), whatever the situation, without suction (14.4 × 105particles/L), with suction and ports open or closed: 10.3 and 0.7 × 105 particles/L. In SV and NIV simulated settings, the AP peaks measured within the SG were much higher than the AP peaks measured without SG, even when suction was applied to the device. Conclusions: The SG seems to decrease peak AP exposure in the 2 ventilation contexts, but only with closed port and suction in SV. However, high concentrations of AP remain inside even with suction and SG should be used cautiously.

Evaluation of the conventional and modified aerosol boxes during tracheal intubation in normal and difficult airways: a randomized, crossover, manikin simulation study.

The aim of this study was to evaluate conventional and modified aerosol boxes in terms of intubation time, first-pass intubation success, and mouth-to-mouth distance between the laryngoscopist and patient during tracheal intubation in simulated patients with normal and difficult airways. Sixteen anesthesiologists performed tracheal intubations with direct laryngoscope or three different videolaryngoscopes (McGRATH MAC videolaryngoscope, C-MAC videolaryngoscope, and Pentax-AWS) without an aerosol box or with a conventional or a modified aerosol boxes in simulated manikins with normal and difficult airways. Intubation time, first-pass intubation success, and mouth-to-mouth distance during tracheal intubation were recorded. Compared to no aerosol box, the use of a conventional aerosol box significantly increased intubation time in both normal and difficult airways (Bonferroni-corrected P-value (Pcorrected) = 0.005 and Pcorrected = 0.003, respectively). Intubation time was significantly shorter with the modified aerosol box than with the conventional one for both normal and difficult airways (Pcorrected = 0.003 and Pcorrected = 0.011, respectively). However, no significant differences were found in intubation time between no aerosol box and the modified aerosol box for normal and difficult airways (Pcorrected = 0.336 and Pcorrected = 0.112, respectively). The use of conventional or modified aerosol boxes significantly extended the mouth-to-mouth distances compared to not using an aerosol box during tracheal intubation with each laryngoscope (all Pcorrected < 0.05), and the distances were not different between the conventional and modified boxes in normal and difficult airways. The use of modified aerosol box did not increase intubation time and could help maintain a distance from the simulated patients with normal and difficult airways.

Aerosol boxes decrease aerosol exposure only in depressurized rooms during aerosol-generating procedures in a simulation study.

PURPOSE: The aim of this study was to compare aerosol exposure with or without an aerosol box in a pressurized/depressurized room during aerosol-generating procedures using an experimental model. METHODS: Cake flour (aerosol model) was expelled from an advanced life support training mannequin. The primary outcome measure was the number of 0.3-10 µm-sized particles at three locations corresponding to the physician, medical staff, and environmental aerosol exposure levels. The aerosol dispersion was visualized using a high-resolution video. The number of expelled particles was measured after artificial coughing during simulated tracheal intubation and extubation in four situations, with or without an aerosol box in a pressurized or depressurized room (≤ 2.5 Pa). RESULTS: The particles arising from tracheal intubation at the three positions in the four groups differed significantly in size (p < 0.05). The sizes of particles arising from extubation at the physicians' and medical staff's faces in the four groups differed significantly in size (p < 0.05). Post hoc analysis showed that the counts of all particles at the three positions were significantly lower in the depressurized room with an aerosol box than in the pressurized room without an aerosol box during tracheal intubation (p < 0.05 at three positions) and extubation (p < 0.05) at the physician's and medical staff's positions). Visual assessments supported these results. CONCLUSION: The aerosol box decreased the exposure of the aerosol to the physician, medical staff, and environment during aerosol-generating procedures in the depressurized room only.

Barrier enclosure use during aerosol-generating medical procedures: A scoping review.

INTRODUCTION: Barrier enclosure devices were introduced to protect against infectious disease transmission during aerosol generating medical procedures (AGMP). Recent discussion in the medical community has led to new designs and adoption despite limited evidence. A scoping review was conducted to characterize devices being used and their performance. METHODS: We conducted a scoping review of formal databases (MEDLINE, Embase, Cochrane Database of Systematic Reviews, CENTRAL, Scopus), grey literature, and hand-searched relevant journals. Forward and reverse citation searching was completed on included articles. Article/full-text screening and data extraction was performed by two independent reviewers. Studies were categorized by publication type, device category, intended medical use, and outcomes (efficacy - ability to contain particles; efficiency - time to complete AGMP; and usability - user experience). RESULTS: Searches identified 6489 studies and 123 met criteria for inclusion (k = 0.81 title/abstract, k = 0.77 full-text). Most articles were published in 2020 (98%, n = 120) as letters/commentaries (58%, n = 71). Box systems represented 42% (n = 52) of systems described, while plastic sheet systems accounted for 54% (n = 66). The majority were used for airway management (67%, n = 83). Only half of articles described outcome measures (54%, n = 67); 82% (n = 55) reporting efficacy, 39% (n = 26) on usability, and 15% (n = 10) on efficiency. Efficacy of devices in containing aerosols was limited and frequently dependent on use of suction devices. CONCLUSIONS: While use of various barrier enclosure devices has become widespread during this pandemic, objective data of efficacy, efficiency, and usability is limited. Further controlled studies are required before adoption into routine clinical practice.

Comparison of the Efficiency and Usability of Aerosol Box and Intubation Tent on Intubation of a Manikin Using Personal Protective Equipment: A Randomized Crossover Study.

BACKGROUND: The aerosol box and intubation tent are improvised barrier-enclosure devices developed during the novel coronavirus pandemic to protect health care workers from aerosol transmission. OBJECTIVE: Using time to intubation as a crude proxy, we aimed to compare the efficiency and usability of the aerosol box and intubation tent in a simulated manikin. METHODS: This was a single-center, randomized, crossover manikin study involving 28 participants (9 anesthetists, 16 emergency physicians, and 3 intensivists). Each participant performed rapid sequence intubations in a random sequence of three different scenarios: 1) no device use; 2) aerosol box; 3) intubation tent. We compared the time to intubation between different scenarios. RESULTS: The median total intubation time with no device use, aerosol box, and intubation tent were 23.7 s (interquartile range [IQR] 19.4-28.4 s), 30.9 s (IQR 24.1-52.5 s), and 26.0 s (IQR 22.1-30.8 s), respectively. Post hoc analysis showed a significantly longer intubation time using the aerosol box compared with no device use (p < 0.001) and compared with the intubation tent (p < 0.001). The difference between the intubation tent and no device use was not significant. The first-pass intubation success rate did not differ between the groups. Only aerosol box use had resulted in breaches of personal protective equipment. Participants considered intubation with the intubation tent more favorable than the aerosol box. CONCLUSIONS: The intubation tent seems to have a better barrier-enclosure design than the aerosol box, with a reasonable balance between efficiency and usability. Further evaluation of its efficacy in preventing aerosol dispersal and in human studies are warranted prior to recommendation of widespread adoption.

An overview of COVID-19 aerosol box for preventing droplet and aerosol contaminations in healthcare providers performing airway intubation.

The COVID-19 is caused by the SARS-CoV-2, which is extremely infectious. Numerous virologist suggestions and guidelines advised using P2/N95 masks, gloves, goggles, face-shields, and frocks or gowns as routine specific protective tools during airway management to protect healthcare personnel from infection (PPE). However, numerous imitation research has indicated that conventional PPE cannot adequately protect healthcare personnel. Since then, numerous firms and healthcare professionals have created their personal reformed devices 'aerosol containment devices' (ACD). Their usage has expanded throughout the world without being properly evaluated for usefulness, efficacy, or safety. The practice of 'ACD' has been shown to make tracheal intubation (TI) more problematic in several simulated tests. Furthermore, the device should limit the transmission of droplets from a patient; however, it might put healthcare personnel at danger of being exposed to greater levels of viral aerosols. Consequently, the existing state of information suggests that 'ACD' deprived of a vacuum mechanism can simply protect healthcare personnel against viral transmission to a limited extent. We search various databases for the literature with keywords 'COVID-19,' 'aerosol box,' 'aerosol contaminations,' and 'droplet contaminations.' The current review focused on the aerosol box from various perspectives, including their mechanism, optimum time of use, the spread of aerosol control, current gaps, and future perspective for bridging those gaps.

Aerosol containment device for airway management of patients with COVID-19: a narrative review.

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), is highly contagious. To protect healthcare workers from infection during airway management, some expert recommendations and guidelines recommended wearing P2/N95 masks, goggles or glasses, glove, face-shields, and gowns as standard personal protective equipment (PPE). Nevertheless, several simulation studies have suggested that the standard PPE may not fully protect healthcare workers. Dr. Hsien Yung Lai introduced an acrylic box ("aerosol box") as a part of PPE during airway management. Since then, several companies and healthcare workers have made their own modified devices ("aerosol containment device"), and the use of such a device has spread worldwide, without being formally assessed for its effectiveness, efficacy and safety. Several simulation studies have indicated that "aerosol containment device" would make tracheal intubation more difficult. In addition, the device would prevent the spread of droplets from a patient, but may increase the risk of healthcare workers being exposed to a higher concentration of viral aerosols. Therefore, the current state of knowledge indicates that an "aerosol containment device" without vacuum mechanism has only limited efficacy in protecting healthcare workers from viral transmission.

Aerosol boxes and barrier enclosures for airway management in COVID-19 patients: a scoping review and narrative synthesis.

Exposure of healthcare providers to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a significant safety concern during the coronavirus disease 2019 (COVID-19) pandemic, requiring contact/droplet/airborne precautions. Because of global shortages, limited availability of personal protective equipment (PPE) has motivated the development of barrier-enclosure systems, such as aerosol boxes, plastic drapes, and similar protective systems. We examined the available evidence and scientific publications about barrier-enclosure systems for airway management in suspected/confirmed COVID-19 patients. MEDLINE/Embase/Google Scholar databases (from December 1, 2019 to May 27, 2020) were searched for all articles on barrier enclosures for airway management in COVID-19, including references and websites. All sources were reviewed by a panel of experts using a Delphi method with a modified nominal group technique. Fifty-two articles were reviewed for their results and level of evidence regarding barrier device feasibility, advantages, protection against droplets and aerosols, effectiveness, safety, ergonomics, and cleaning/disposal. The majority of analysed papers were expert opinions, small case series, technical descriptions, small-sample simulation studies, and pre-print proofs. The use of barrier-enclosure devices adds to the complexity of airway procedures with potential adverse consequences, especially during airway emergencies. Concerns include limitations on the ability to perform airway interventions and the aid that can be delivered by an assistant, patient injuries, compromise of PPE integrity, lack of evidence for added protection of healthcare providers (including secondary aerosolisation upon barrier removal), and lack of cleaning standards. Enclosure barriers for airway management are no substitute for adequate PPE, and their use should be avoided until adequate validation studies can be reported.

Measurement of airborne particle exposure during simulated tracheal intubation using various proposed aerosol containment devices during the COVID-19 pandemic.

The COVID-19 pandemic has led to the production of novel devices intended to protect airway managers during the aerosol-generating procedure of tracheal intubation. Using an in-situ simulation model, we evaluated laryngoscopist exposure of airborne particles sized 0.3 - 5.0 microns using five aerosol containment devices (aerosol box; sealed box with and without suction; vertical drape; and horizontal drape) compared with no aerosol containment device. Nebulised saline was used as the aerosol-generating model for 300 s, at which point, the devices were removed to assess particle spread. Primary outcome was the quantity and size of airborne particles measured at the level of the laryngoscopist's head at 30, 60, 120 and 300 s, as well as 360 s (60 s after device removal). Airborne particles sizes of 0.3, 0.5, 1.0, 2.5 and 5.0 microns were quantified using an electronic airborne particle counter. Compared with no device use, the sealed intubation box with suction resulted in a decrease in 0.3, 0.5, 1.0 and 2.5 micron, but not 5.0 micron, particle exposure over all time-periods (p = 0.003 for all time periods). Compared with no device use, the aerosol box showed an increase in 1.0, 2.5 and 5.0 micron airborne particle exposure at 300 s (p = 0.002, 0.008, 0.002, respectively). Compared with no device use, neither horizontal nor vertical drapes showed any difference in any particle size exposure at any time. Finally, when the patient coughed, use of the aerosol box resulted in a marked increase in airborne particle exposure compared with other devices or no device use. In conclusion, novel devices intended to protect the laryngoscopist require objective testing to ensure they are fit for purpose and do not result in increased airborne particle exposure.

The aerosol box for intubation in coronavirus disease 2019 patients: an in-situ simulation crossover study.

The coronavirus disease 2019 pandemic has led to the manufacturing of novel devices to protect clinicians from the risk of transmission, including the aerosol box for use during tracheal intubation. We evaluated the impact of two aerosol boxes (an early-generation box and a latest-generation box) on intubations in patients with severe coronavirus disease 2019 with an in-situ simulation crossover study. The simulated process complied with the Safe Airway Society coronavirus disease 2019 airway management guidelines. The primary outcome was intubation time; secondary outcomes included first-pass success and breaches to personal protective equipment. All intubations were performed by specialist (consultant) anaesthetists and video recorded. Twelve anaesthetists performed 36 intubations. Intubation time with no aerosol box was significantly shorter than with the early-generation box (median (IQR [range]) 42.9 (32.9-46.9 [30.9-57.6])s vs. 82.1 (45.1-98.3 [30.8-180.0])s p = 0.002) and the latest-generation box (52.4 (43.1-70.3 [35.7-169.2])s, p = 0.008). No intubations without a box took more than 1 min, whereas 14 (58%) intubations with a box took over 1 min and 4 (17%) took over 2 min (including one failure). Without an aerosol box, all anaesthetists obtained first-pass success. With the early-generation and latest-generation boxes, 9 (75%) and 10 (83%) participants obtained first-pass success, respectively. One breach of personal protective equipment occurred using the early-generation box and seven breaches occurred using the latest-generation box. Aerosol boxes may increase intubation times and therefore expose patients to the risk of hypoxia. They may cause damage to conventional personal protective equipment and therefore place clinicians at risk of infection. Further research is required before these devices can be considered safe for clinical use.

Effect of an aerosol box on tracheal intubation difficulty.

The aim of this study was to determine the effect of an aerosol box on tracheal intubation difficulty. Eighteen experienced anesthetists intubated the trachea of a manikin with a normal airway 6 times using a direct laryngoscope, a McGRATH™ MAC videolaryngoscope, or an airway scope AWS-S200NK videolaryngoscope with or without an aerosol box. Although the aerosol box prolonged the time to successful intubation and decreased the percentage of glottic opening (POGO) score when using a direct laryngoscope, the statistically significant differences were clinically irrelevant. When a McGRATH™ MAC and an AWS-S200NK were used, the times to successful intubation and POGO scores were comparable with and without the aerosol box. When using any of the laryngoscopes, there were no statistically significant differences in the Cormack-Lehane grade and peak force to maxillary incisors with and without the aerosol box. In summary, the effect of an aerosol box on tracheal intubation difficulty is not clinically relevant when an experienced anesthetist intubates the trachea in a normal airway condition.

The aerosol box.

Despite being scientifically unproven, aerosol boxes have quickly risen in popularity during the COVID-19 pandemic. They have been created in various shapes and sizes, as well as materials across the world. Aerosol boxes offer a transparent barrier between the patient and the healthcare personnel, during intubation and may prove to be useful when prescribed protection equipment such as masks and eyewear are unavailable. In this article, we undertake a brief overview of aerosol boxes in current practice.

Using the Multicomponent Aerosol FORmation Model (MAFOR) to Determine Improved VOC Emission Factors in Ship Plumes.

International shipping's particulate matter primary emissions have a share in global anthropogenic emissions of between 3% and 4%. Ship emissions of volatile organic compounds (VOCs) can play an important role in the formation of fine particulate matter. Using an aerosol box model for the near-plume scale, this study investigated how the changing VOC emission factor (EF) for ship engines impacts the formation of secondary PM2.5 in ship exhaust plumes that were detected during a measurement campaign. The agreement between measured and modeled particle number size distribution was improved by adjusting VOC emissions, in particular of intermediate-, low-, and extremely low-volatility compounds. The scaling of the VOC emission factor showed that the initial emission factor, based on literature data, had to be multiplied by 3.6 for all VOCs. Information obtained from the box model was integrated into a regional-scale chemistry transport model (CTM) to study the influence of changed VOC ship emissions over the Mediterranean Sea. The regional-scale CTM run with adjusted ship emissions indicated a change in PM2.5 of up to 5% at the main shipping routes and harbor cities in summer. Nevertheless, overall changes due to a change in the VOC EF were rather small, indicating that the size of grid cells in CTMs leads to a fast dilution.

Development and demonstration of the protective efficacy of a convertible respiratory barrier enclosure: a simulation study.

OBJECTIVE: The efficacy of previously developed respiratory barrier enclosures to limit healthcare workers' exposure to aerosols from COVID-19 patients remains unclear; in addition, the design of these devices is unsuitable for transportation or other emergency procedures. Therefore, we developed a novel negative pressure respiratory isolator to improve protection from patient-generated aerosols and evaluated its protective effect in conversion to systemic isolator. METHODS: This in vitro study simulated droplets by nebulizing 1% glycerol + 99% ethanol solution. We performed cardiopulmonary resuscitation (CPR) and converted a respiratory barrier enclosure into a systemic isolator with a respiratory barrier as well as a respiratory barrier with negative pressure generator (NPG), which were compared with control and room air. During the procedure, particles were counted for 30 seconds and the count was repeated 10 times. RESULTS: During CPR, the total number of particles in the respiratory barrier with NPG (280,529; interquartile range [IQR], 205,263-359,195; P=0.970) was similar to that in the control (308,789; IQR, 175,056-473,276). Using NPG with a respiratory barrier reduced the number of particles to 27,524 (IQR, 26,703- 28,905; P=0.001). Particle number during conversion of the respiratory barrier into a systemic isolator was also lower than in the control (25,845; IQR, 19,391- 29,772; P=0.001). CONCLUSION: The novel isolator was converted to a systemic isolator without air leakage. The aerosol-blocking effect of the isolator was quantified using a particle counter during CPR. Further studies comparing the barrier effect of isolators within various pressure differentials are warranted.

Does the aerosol box accommodate the double-lumen tube intubation?

The aerosol box was widely used to shield healthcare providers from exposure to COVID-19 during single-lumen intubation procedures. However, it has not previously been evaluated for its use in double-lumen tube intubations. This report presents the case of a 25-year-old COVID-19-positive male with a fever who required an emergency thoracotomy for a mediastinal abscess. During the rapid-sequence induction of general anesthesia, an attempt to use the aerosol box for double-lumen tube intubation was made. The attempt faced unique challenges due to the aerosol box's restrictive dimensions and the double-lumen tube's physical characteristics, such as length and flexibility, resulting in an unsuccessful first attempt. Consequently, the aerosol box was removed, and a successful intubation was achieved without it. Postoperatively, the patient remained intubated, was transferred to the intensive care unit, and was extubated on the second postoperative day, followed by intensive care unit discharge. This experience suggests that the standard aerosol box size (50 cm wide, 40 cm deep, and 50 cm tall) may not be suitable for double-lumen tube intubations. This highlights the importance of assessing the feasibility of each aerosol box before its clinical use in such procedures.

Performance of Aerosol Boxes for Endotracheal Intubation during the COVID-19 Pandemic with Systematic Review.

Introduction: In the backdrop of the COVID-19 pandemic, endotracheal intubation using an aerosol box (AB) became the norm in the emergency department (ED) and the intensive care unit. We compared two models of AB with different dimensions to compare and identify a device that helps in reducing viral exposure without compromising successful airway management. Methods: We conducted this prospective observational study for 7 months (October 20-April 21) on 143 patients presenting with an acute airway compromise to the ED. All intubations were performed using one of the two models available. The primary outcome was time taken for intubation (TTI). Results: The overall median time taken to intubate using any AB was 63 (interquartile range [IQR]: 46.2-87.7) s with an 81.9% first-pass success (FPS) rate. TTI for AB I was 67 (IQR: 53-106) s with a 76.3% FPS rate, while TTI for AB II was 57 (IQR: 44-75) s with an 85.9% FPS rate. TTI was much shorter without the use of an AB (34: IQR: 24-53 s) with a 92% FPS rate. Intubations done by emergency physicians with more than 2 years of experience were faster in both with or without AB when compared to intubations done by physicians with <2 years of experience. Conclusion: The use of an AB is associated with a longer TTI when compared to intubations done without an AB. TTI was relatively shorter when more experienced emergency physicians performed intubation. FPS rates were low with intubations done using AB.