Aerosol Retention Characteristics of Barrier Devices.

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.

Quantifying the COVID19 infection risk due to droplet/aerosol inhalation.

The dose-response model has been widely used for quantifying the risk of infection of airborne diseases like COVID-19. The model has been used in the room-average analysis of infection risk and analysis using passive scalars as a proxy for aerosol transport. However, it has not been employed for risk estimation in numerical simulations of droplet dispersion. In this work, we develop a framework for the evaluation of the probability of infection in droplet dispersion simulations using the dose-response model. We introduce a version of the model that can incorporate the higher transmissibility of variant strains of SARS-CoV2 and the effect of vaccination in evaluating the probability of infection. Numerical simulations of droplet dispersion during speech are carried out to investigate the infection risk over space and time using the model. The advantage of droplet dispersion simulations for risk evaluation is demonstrated through the analysis of the effect of ambient wind, humidity on infection risk, and through a comparison with risk evaluation based on passive scalars as a proxy for aerosol transport.

Importance of the Precautionary Principle With Regard to the Risk of Exposure to Aerosols Containing Viral Loads of SARS-CoV-2 Present in Feces: In Perspective.

In COVID-19 infection, the emissions of droplets and aerosols produced by the respiratory tract of contaminated subjects may represent a high risk of spreading the SARS-COV-2 virus in the environment. Thus, studies have shown that there is, at least, another source of droplets and aerosols in which viral particles of SARS-COV-2 can be found. It happens after flushing of toilet to dispose of the stools of a patient who has contracted COVID-19. The presence of viral particles of SARS-COV-2 in the stool could be linked to the concentration of angiotensin-converting enzyme 2 (ACE2) found on the surface of intestinal cells. Therefore, there is a reason to wonder whether the emission of viral particles by activating a toilet flush could represent an important potential risk of contamination for health care workers. To investigate this hypothesis, we have correlated different studies on the production of droplets and aerosols as well as the presence of viral particles following flush of toilet. This pooling of these studies led to the following conclusion: the precautionary principle should be applied with regard to the potential risk represented by viral particles of SARV-COV-2 in the stool when flushing the toilet.

Aerosol release, distribution, and prevention during aerosol therapy: a simulated model for infection control.

Aerosol therapy is used to deliver medical therapeutics directly to the airways to treat respiratory conditions. A potential consequence of this form of treatment is the release of fugitive aerosols, both patient derived and medical, into the environment and the subsequent exposure of caregivers and bystanders to potential viral infections. This study examined the release of these fugitive aerosols during a standard aerosol therapy to a simulated adult patient. An aerosol holding chamber and mouthpiece were connected to a representative head model and breathing simulator. A combination of laser and Schlieren imaging was used to non-invasively visualize the release and dispersion of fugitive aerosol particles. Time-varying aerosol particle number concentrations and size distributions were measured with optical particle sizers at clinically relevant positions to the simulated patient. The influence of breathing pattern, normal and distressed, supplemental air flow, at 0.2 and 6 LPM, and the addition of a bacterial filter to the exhalation port of the mouthpiece were assessed. Images showed large quantities of fugitive aerosols emitted from the unfiltered mouthpiece. The images and particle counter data show that the addition of a bacterial filter limited the release of these fugitive aerosols, with the peak fugitive aerosol concentrations decreasing by 47.3-83.3%, depending on distance from the simulated patient. The addition of a bacterial filter to the mouthpiece significantly reduces the levels of fugitive aerosols emitted during a simulated aerosol therapy, p≤ .05, and would greatly aid in reducing healthcare worker and bystander exposure to potentially harmful fugitive aerosols.

COVID-19 transmission in surgical smoke during laparoscopy and open surgery: a systematic review.

AIM: To evaluate the risk of SARS-CoV-2 transmission in surgical smoke and aerosols during laparoscopy and open surgery. MATERIAL AND METHODS: A systematic review (PROSPERO ID: CRD42021268366) was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Articles were selected based on the title and abstract as well as the type of publication. Primary objectives of the study were to assess potential risk of contamination as well as comparing laparoscopic and open procedures in terms of danger of SARS-COV-2 transmission. RESULTS: Fifty-three articles were identified and included in the review. No case of SARS-CoV-2 transmission to operating room personnel during open or minimally invasive surgery was identified at the time the review was conducted. Furthermore, no significant difference was observed between smoke and aerosols generated from open surgery and those generated from minimally invasive surgery. CONCLUSION: COVID-19 transmission in surgical smoke and aerosols has yet to be observed. However, given the potential risk of viral transmission, caution should be exercised when performing surgery to ensure the safety of the operating room personnel. When clinically indicated and when protective measures can be implemented, minimally invasive surgery should be performed instead of open surgery to ensure optimal patient outcomes.

Aerosol generation through pars plana vitrectomy.

PURPOSE: To assess whether pars plana vitrectomy (PPV) is an aerosol-generating procedure (AGP) in an ex vivo experimental model. METHODS: In this ex vivo study on 10 porcine eyes, optical particle counter was used to measure particles ≤10 µm using cumulative mode in the six in-built channels: 0.3 µm, 0.5 µm, 1 µm, 2.5 µm, 5 µm and 10 µm aerosols during PPV. Two parts of the study were as follows: (1) to assess the pre-experimental baseline aerosol count in the theatre environment where there are dynamic changes in temperature and humidity and (2) to measure aerosol generation with 23-gauge and 25-gauge set-up. For each porcine eye, five measurements were taken for each consecutive step in the experiment including pre-PPV, during PPV, fluid-air exchange (FAX) and venting using a flute with 23-gauge set-up and a chimney with 25-gauge set-up. Therefore, a total of 200 measurements were recorded. RESULTS: With 23-gauge and 25-gauge PPV, there was no significant difference in aerosol generation in all six channels comparing pre-PPV versus PPV or pre-PPV versus FAX. Venting using flute with 23-gauge PPV showed significant reduction of aerosol ≤1 µm. Air venting using chimney with 25-gauge set-up showed no significant difference in aerosol of ≤1 µm. For cumulative aerosol counts of all particles measuring ≤5 µm, compared with pre-PPV, PPV or FAX, flute venting in 23-gauge set-up showed significant reduction unlike the same comparison for chimney venting in 25-gauge set-up. CONCLUSION: PPV and its associate steps do not generate aerosols ≤10 µm with 23-gauge and 25-gauge set-ups.

Are medical procedures that induce coughing or involve respiratory suctioning associated with increased generation of aerosols and risk of SARS-CoV-2 infection? A rapid systematic review.

BACKGROUND: The risk of transmission of SARS-CoV-2 from aerosols generated by medical procedures is a cause for concern. AIM: To evaluate the evidence for aerosol production and transmission of respiratory infection associated with procedures that involve airway suctioning or induce coughing/sneezing. METHODS: The review was informed by PRISMA guidelines. Searches were conducted in PubMed for studies published between January 1st, 2003 and October 6th, 2020. Included studies examined whether nasogastric tube insertion, lung function tests, nasendoscopy, dysphagia assessment, or suctioning for airway clearance result in aerosol generation or transmission of SARS-CoV-2, SARS-CoV, MERS, or influenza. Risk of bias assessment focused on robustness of measurement, control for confounding, and applicability to clinical practice. FINDINGS: Eighteen primary studies and two systematic reviews were included. Three epidemiological studies found no association between nasogastric tube insertion and acquisition of respiratory infections. One simulation study found low/very low production of aerosols associated with pulmonary lung function tests. Seven simulation studies of endoscopic sinus surgery suggested significant increases in aerosols but findings were inconsistent; two clinical studies found airborne particles associated with the use of microdebriders/drills. Some simulation studies did not use robust measures to detect particles and are difficult to equate to clinical conditions. CONCLUSION: There was an absence of evidence to suggest that the procedures included in the review were associated with an increased risk of transmission of respiratory infection. In order to better target precautions to mitigate risk, more research is required to determine the characteristics of medical procedures and patients that increase the risk of transmission of SARS-CoV-2.

Should chest compressions be considered an aerosol-generating procedure? A literature review in response to recent guidelines on personal protective equipment for patients with suspected COVID-19.

There is disagreement between international guidelines on the level of personal protective equipment (PPE) required for chest compressions for patients with suspected COVID-19. This discrepancy centres on whether they are considered to be an aerosol-generating procedure (AGP), thus requiring airborne protection to prevent transmission to healthcare workers (HCWs). The need to don higher-level PPE has to be weighed against the resulting delay to emergency treatment.We performed a literature search on this topic which found eight relevant studies. All were observational with low patient numbers and multiple confounding factors, but describe cases of acute respiratory infection transmission during chest compressions. One systematic review concluded that chest compressions were not an AGP. Two simulated studies (released as preprints) potentially demonstrate aerosol generation. Given that there is evidence for infection transmission during chest compressions, we conclude that a precautionary approach with appropriate PPE is necessary to protect HCW from contracting a potentially fatal infection.

Characteristics of pepper spray-related injuries reported to the National Electronic Injury Surveillance System during 2000-2020.

INTRODUCTION: Exposure to pepper spray may result in adverse dermal, ocular, and inhalation effects. Furthermore, pepper spray, including the more potent bear spray, was used by both law enforcement and protesters in 2020 in the protests related to racial justice and COVID-19 pandemic restrictions. The objective of this study was to characterize pepper spray-related injuries treated at United States (US) emergency departments (EDs). METHODS: Data were obtained from the National Electronic Injury Surveillance System, a database of consumer product-related injuries collected from approximately 100 US hospital EDs. Pepper spray-related injuries reported during 2000-2020 were identified by reviewing all records that included the letter groups "pep" or "bear" in the Narrative field and "spray" in the Narrative field or Product code 1619 in the Product_1, Product_2, or Product_3 fields. RESULTS: A total of 1112 pepper spray-related injuries were identified, resulting in a national estimate of 34,582 pepper spray-related injuries, of which 43.4% were reported during 2014-2020. Of the estimated exposures, the age distribution was 14.5% 0-5 years, 18.5% 6-12 years, 18.2% 13-19 years, 19.6% 20-29 years, 11.8% 30-39 years, 9.1% 40-49 years, and 8.3% 50 years or older; 55.9% of the patients were male. The exposure route was 52.0% ocular, 25.7% dermal, 13.6% inhalation, 2.9% ingestion/oral, and 14.1% unknown. CONCLUSIONS: Patients with pepper spray-related injuries tended to be older children and young adults, and the majority of patients were male. The route of exposure of most of the injuries was ocular.

Aerosol delivery systems for treating obstructive airway diseases during the SARS-CoV-2 pandemic.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes CoronaVirus Disease 2019 (COVID-19), has resulted in a worldwide pandemic and currently represents a major public health crisis. It has caused outbreaks of illness through person-to-person transmission of the virus mainly via close contacts, and droplets produced by an infected person's cough or sneeze. Aerosolised inhaled therapy is the mainstay for treating obstructive airway diseases at home and in healthcare settings, but there is heightened particular concern about the potential risk for transmission of SARS-CoV-2 in the form of aerosolised respiratory droplets during the nebulised treatment of patients with COVID-19. As a consequence of this concern, the use of hand-held inhalers, especially pressurised metered dose inhalers, has risen considerably as an alternative to nebulisers, and this switch has led to inadequate supplies of inhalers in some countries. However, there is no evidence supporting an increased risk of viral transmission during nebulisation in COVID-19 patients. Furthermore, some patients may be unable to adequately use their new device and may not benefit fully from the switch to treatment via hand-held inhalers. Thus, there is no compelling reason to alter aerosol delivery devices for patients with established nebuliser-based regimens. The purpose of this paper is to discuss the current evidence and understanding of the use of aerosolised inhaled therapies during the SARS-CoV-2 pandemic and to provide some guidance on the measures to be taken to minimise the risk of transmitting infection, if any, during aerosol therapies.

An in vitro visual study of fugitive aerosols released during aerosol therapy to an invasively ventilated simulated patient.

COVID-19 can cause serious respiratory complications resulting in the need for invasive ventilatory support and concurrent aerosol therapy. Aerosol therapy is considered a high risk procedure for the transmission of patient derived infectious aerosol droplets. Critical-care workers are considered to be at a high risk of inhaling such infectious droplets. The objective of this work was to use noninvasive optical methods to visualize the potential release of aerosol droplets during aerosol therapy in a model of an invasively ventilated adult patient. The noninvasive Schlieren imaging technique was used to visualize the movement of air and aerosol. Three different aerosol delivery devices: (i) a pressurized metered dose inhaler (pMDI), (ii) a compressed air driven jet nebulizer (JN), and (iii) a vibrating mesh nebulizer (VMN), were used to deliver an aerosolized therapeutic at two different positions: (i) on the inspiratory limb at the wye and (ii) on the patient side of the wye, between the wye and endotracheal tube, to a simulated intubated adult patient. Irrespective of position, there was a significant release of air and aerosol from the ventilator circuit during aerosol delivery with the pMDI and the compressed air driven JN. There was no such release when aerosol therapy was delivered with a closed-circuit VMN. Selection of aerosol delivery device is a major determining factor in the release of infectious patient derived bioaerosol from an invasively mechanically ventilated patient receiving aerosol therapy.

Aerosol generating procedures in trauma and orthopaedics in the era of the Covid-19 pandemic; What do we know?

PURPOSE: COVID-19 pandemic has created havoc all over the globe and spared no one regardless of status, gender, location and ethnicity. There were questions raised if trauma and orthopaedic (T&O) procedures actually generated aerosols? The need for a review of literature highlighting the nature and impact of aerosol generation within T&O surgery was noted. METHODS: A comprehensive online search was performed for all published articles in the English language, evaluating AGPs in T&O surgery and the relevant personal protection equipment used. RESULTS: The search strategy populated 43 studies. Six studies were identified as duplicates. The shortlisted 37 studies were screened and nine studies were included in the review. An additional four studies were included from the bibliography review. CONCLUSION: Most orthopaedic procedures are high-risk aerosol generating procedures (AGPs). Conventional surgical masks do not offer protection against high-risk AGPs. In the current era of COVID-19 pandemic, there is a significant risk to the transmission of infection to the theatre staff. For protection against airborne transmission, appropriate masks should be used. These need proper fitting and sizing to ensure full protection when used.

Airborne infection risk during open-air cardiopulmonary resuscitation.

AIM: Cardiopulmonary resuscitation (CPR) is an emergency procedure where interpersonal distance cannot be maintained. There are and will always be outbreaks of infection from airborne diseases. Our objective was to assess the potential risk of airborne virus transmission during CPR in open-air conditions. METHODS: We performed advanced high-fidelity three-dimensional modelling and simulations to predict airborne transmission during out-of-hospital hands-only CPR. The computational model considers complex fluid dynamics and heat transfer phenomena such as aerosol evaporation, breakup, coalescence, turbulence, and local interactions between the aerosol and the surrounding fluid. Furthermore, we incorporated the effects of the wind speed/direction, the air temperature and relative humidity on the transport of contaminated saliva particles emitted from a victim during a resuscitation process based on an Airborne Infection Risk (AIR) Index. RESULTS: The results reveal low-risk conditions that include wind direction and high relative humidity and temperature. High-risk situations include wind directed to the rescuer, low humidity and temperature. Combinations of other conditions have an intermediate AIR Index and risk for the rescue team. CONCLUSIONS: The fluid dynamics, simulation-based AIR Index provides a classification of the risk of contagion by victim's aerosol in the case of hands-only CPR considering environmental factors such as wind speed and direction, relative humidity and temperature. Therefore, we recommend that rescuers perform a quick assessment of their airborne infectious risk before starting CPR in the open air and positioning themselves to avoid wind directed to their faces.

Aerosol-generating behaviours in speech pathology clinical practice: A systematic literature review.

OBJECTIVE: To evaluate the evidence of aerosol generation across tasks involved in voice and speech assessment and intervention, to inform better management and to reduce transmission risk of such diseases as COVID-19 in healthcare settings and the wider community. DESIGN: Systematic literature review. DATA SOURCES AND ELIGIBILITY: Medline, Embase, Scopus, Web of Science, CINAHL, PubMed Central and grey literature through ProQuest, The Centre for Evidence-Based Medicine, COVID-Evidence and speech pathology national bodies were searched up until August 13th, 2020 for articles examining the aerosol-generating activities in clinical voice and speech assessment and intervention within speech pathology. RESULTS: Of the 8288 results found, 39 studies were included for data extraction and analysis. Included articles were classified into one of three categories: research studies, review articles or clinical guidelines. Data extraction followed appropriate protocols depending on the classification of each article (e.g. PRISMA for review articles). Articles were assessed for risk of bias and certainty of evidence using the GRADE system. Six behaviours were identified as aerosol generating. These were classified into three categories: vegetative acts (coughing, breathing), verbal communication activities of daily living (speaking, loud voicing), and performance-based tasks (singing, sustained phonation). Certainty of evidence ranged from very low to moderate with variation in research design and variables. CONCLUSIONS: This body of literature helped to both identify and categorise the aerosol-generating behaviours involved in speech pathology clinical practice and confirm the low level of evidence throughout the speech pathology literature pertaining to aerosol generation. As many aerosol-generating behaviours are common human behaviours, these findings can be applied across healthcare and community settings. SYSTEMATIC REVIEW REGISTRATION: Registration number CRD42020186902 with PROSPERO International Prospective Register for Systematic Reviews.

Learning to Interpret Pediatric Vocal Fold Mobility: A Laryngeal Ultrasound Training Module.

OBJECTIVES/HYPOTHESIS: Vocal fold movement impairment (VFMI) in infants and children is most commonly evaluated by flexible nasolaryngoscopy (FNL). FNL in this population can be challenging due to movement, floppy supraglottic structures, or secretions. Laryngeal ultrasound (LUS) may be an alternative, less invasive means of evaluating VFMI that also decreases aerosolization during the COVID-19 pandemic. The primary objective was to examine LUS interpretation proficiency for VFMI via an educational module. A secondary outcome was to determine whether quantitative measurements increase interpretation accuracy. STUDY DESIGN: Prospective cohort trial. METHODS: Medical students, residents, fellows, faculty, and staff were recruited to complete the module, composed of a 13-minute teaching video followed by 20 cases. Participants determined both qualitatively (subjective assessment) and then quantitatively (through protractor measurements of the vocal fold to arytenoid angle) whether there was normal versus impaired vocal fold mobility. RESULTS: Thirty participants completed the LUS training module, and about one-third were otolaryngology residents. On average, each participant correctly identified 18 cases. The mean rank percent correct for quantitative measurements was significantly higher than that of qualitative interpretations (P < .0001). Measurements significantly caused participants to change their answer correctly compared to incorrectly (P < .0001). As the module progressed, there was no significant trend of more correct interpretations (P = .30). The sensitivity was higher for quantitative interpretations (89.0% vs. 87.3%) but specificity remained unchanged (92.6%). CONCLUSION: Quantitative measurements may increase LUS interpretation accuracy. There was not a specific number of cases interpreted to achieve learning proficiency. LUS is an easily learned method to evaluate for VFMI across all training levels. LEVEL OF EVIDENCE: 3 (local cohort study nonrandomized) Laryngoscope, 131:2545-2549, 2021.