Influenza aerosols in UK hospitals during the H1N1 (2009) pandemic--the risk of aerosol generation during medical procedures

Spinal fusion is an aerosol generating procedure

BACKGROUND

Transmission of severe acute respiratory syndrome coronavirus 2 can occur during aerosol generating procedures. Several steps in spinal fusion may aerosolize blood but little data exists to quantify the risk this may confer upon surgeons. Aerosolized particles containing infectious coronavirus are typically 0.5-8.0 μm.

AIM

To measure the generation of aerosols during spinal fusion using a handheld optical particle sizer (OPS).

METHODS

We quantified airborne particle counts during five posterior spinal instrumentation and fusions (9/22/2020-10/15/2020) using an OPS near the surgical field. Data were analyzed by 3 particle size groups: 0.3-0.5 μm/m³, 1.0-5.0 μm/m³, and 10.0 μm/m³. We used hierarchical logistic regression to model the odds of a spike in aerosolized particle counts based on the step in progress. A spike was defined as a > 3 standard deviation increase from average baseline levels.

RESULTS

Upon univariate analysis, bovie (P < 0.0001), high speed pneumatic burring (P = 0.009), and ultrasonic bone scalpel (P = 0.002) were associated with increased 0.3-0.5 μm/m³ particle counts relative to baseline. Bovie (P < 0.0001) and burring (P < 0.0001) were also associated with increased 1-5 μm/m³ and 10 μm/m³ particle counts. Pedicle drilling was not associated with increased particle counts in any of the size ranges measured. Our logistic regression model demonstrated that bovie (OR = 10.2, P < 0.001), burring (OR = 10.9, P < 0.001), and bone scalpel (OR = 5.9, P < 0.001) had higher odds of a spike in 0.3-0.5 μm/m³ particle counts. Bovie (OR = 2.6, P < 0.001), burring (OR = 5.8, P < 0.001), and bone scalpel (OR = 4.3, P = 0.005) had higher odds of a spike in 1-5 μm/m³ particle counts. Bovie (OR = 0.3, P < 0.001) and drilling (OR = 0.2, P = 0.011) had significantly lower odds of a spike in 10 μm/m³ particle counts relative to baseline.

CONCLUSION

Several steps in spinal fusion are associated with increased airborne particle counts in the aerosol size range. Further research is warranted to determine if such particles have the potential to contain infectious viruses. Previous research has shown that electrocautery smoke may be an inhalation hazard for surgeons but here we show that usage of the bone scalpel and high-speed burr also have the potential to aerosolize blood.

Research Bronchoscopies in Critically Ill Research Participants: An Official American Thoracic Society Workshop Report

Bronchoscopy for research purposes is a valuable tool to understand lung-specific biology in human participants. Despite published reports and active research protocols using this procedure in critically ill patients, no recent document encapsulates the important safety considerations and downstream applications of this procedure in this setting. The objectives were to identify safe practices for patient selection and protection of hospital staff, provide recommendations for sample procurement to standardize studies, and give guidance on sample preparation for novel research technologies. Seventeen international experts in the management of critically ill patients, bronchoscopy in clinical and research settings, and experience in patient-oriented clinical or translational research convened for a workshop. Review of relevant literature, expert presentations, and discussion generated the findings presented herein. The committee concludes that research bronchoscopy with bronchoalveolar lavage in critically ill patients on mechanical ventilation is valuable and safe in appropriately selected patients. This report includes recommendations on standardization of this procedure and prioritizes the reporting of sample management to produce more reproducible results between laboratories. This document serves as a resource to the community of researchers who endeavor to include bronchoscopy as part of their research protocols and highlights key considerations for the inclusion and safety of research participants.

Current SARS-CoV-2 Protective Strategies for Healthcare Professionals

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for the Coronavirus disease 2019 (COVID-19). COVID-19 was first reported in China in December 2019. SARS-CoV-2 is highly contagious and spread primarily via an airborne route. Hand hygiene, surgical masks, vaccinations and boosters, air filtration, environmental sanitization, instrument sterilization, mouth rinses, and social distancing are essential infection control measures against the transmission of SARS-CoV-2. This paper aims to provide healthcare professionals with evidence-based protective strategies.

Re-evaluating our language when reducing risk of SARS-CoV-2 transmission to healthcare workers: Time to rethink the term, “aerosol-generating procedures”

The term, "aerosol-generating procedures” (AGPs), was proposed during the prior SARS-CoV-1 epidemic in order to maximise healthcare worker and patient protection. The concept of AGPs has since expanded to include routine therapeutic processes such as various modes of oxygen delivery and non-invasive ventilation modalities. Evidence gained during the SARS-CoV-2 pandemic has brought into question the concept of AGPs with regard to intubation, airway management, non-invasive ventilation and high flow nasal oxygen delivery. Although encounters where these procedures occur may still be associated with increased risk of infectious transmission, this is a function of the clinical context and not because the procedure itself is aerosol-generating.

What were the historical reasons for the resistance to recognizing airborne transmission during the COVID-19 pandemic?

The question of whether SARS-CoV-2 is mainly transmitted by droplets or aerosols has been highly controversial. We sought to explain this controversy through a historical analysis of transmission research in other diseases. For most of human history, the dominant paradigm was that many diseases were carried by the air, often over long distances and in a phantasmagorical way. This miasmatic paradigm was challenged in the mid to late 19th century with the rise of germ theory, and as diseases such as cholera, puerperal fever, and malaria were found to actually transmit in other ways. Motivated by his views on the importance of contact/droplet infection, and the resistance he encountered from the remaining influence of miasma theory, prominent public health official Charles Chapin in 1910 helped initiate a successful paradigm shift, deeming airborne transmission most unlikely. This new paradigm became dominant. However, the lack of understanding of aerosols led to systematic errors in the interpretation of research evidence on transmission pathways. For the next five decades, airborne transmission was considered of negligible or minor importance for all major respiratory diseases, until a demonstration of airborne transmission of tuberculosis (which had been mistakenly thought to be transmitted by droplets) in 1962. The contact/droplet paradigm remained dominant, and only a few diseases were widely accepted as airborne before COVID-19: those that were clearly transmitted to people not in the same room. The acceleration of interdisciplinary research inspired by the COVID-19 pandemic has shown that airborne transmission is a major mode of transmission for this disease, and is likely to be significant for many respiratory infectious diseases.

Prevention of droplet dispersal with 'e-mask': A new daily use endoscopic mask during bronchoscopy

BACKGROUND AND OBJECTIVE

Bronchoscopy is an airborne particle-generating procedure. However, few methods for safe bronchoscopy have been developed. To reduce airborne particles during bronchoscopy, we created an 'e-mask', which is a simple, disposable mask for patients. Our objective was to evaluate the e-mask's protective ability against airborne particles and to assess respiratory adverse events and complications.

METHODS

Patients with stage 2-4 chronic obstructive pulmonary disease were excluded. We performed visualization and quantifying experiments on airborne particles with and without the e-mask. We prospectively evaluated whether wearing the e-mask during bronchoscopy was associated with the incidence of patients requiring >5 L/min oxygen to maintain >90% oxygen saturation, and patients with >45 mm Hg end-tidal carbon dioxide (EtCO₂ ) elevation, in addition to complications, compared to historical controls.

RESULTS

In the visualization experiment, more than ten thousand times of airborne particles were generated without the e-mask than with the e-mask. The volume of airborne particles was significantly reduced with the e-mask, compared to that without the e-mask (p = 0.011). Multivariate logistic regression analysis revealed that wearing the e-mask had no significant effect on the incidence of patients requiring >5 L/min oxygen to maintain >90% oxygen saturation, (p = 0.959); however, wearing the e-mask was a significant factor in >45 mm Hg EtCO₂ elevation (p = 0.026). No significant differences in complications were observed between the e-mask and control groups (5.8% vs. 2.5%, p = 0.395).

CONCLUSION

Wearing the e-mask during bronchoscopy significantly reduced the generation of airborne particles during bronchoscopy without increasing complications.

Airborne SARS-CoV-2 in hospitals - effects of aerosol-generating procedures, HEPA-filtration units, patient viral load and physical distance

BACKGROUND

Transmission of covid-19 can occur through inhalation of fine droplets or aerosols containing infectious virus. The objective of this study was to identify situations, patient characteristics, environmental parameters and aerosol-generating procedures (AGPs) associated with airborne SARS-CoV-2 virus.

METHODS

Air samples were collected near hospitalised covid-19 patients and analysed by RT-qPCR. Results were related to distance to the patient, most recent patient diagnostic PCR Ct-value, room ventilation and ongoing potential AGP.

RESULTS

In total 310 air samples were collected, and of these 26 (8%) were positive. Of the 231 samples from patient rooms, 22 (10%) were positive for SARS-CoV-2. Positive air samples were associated with a low patient Ct-value (OR 5.0 for a Ct-value <25 vs >25, p=0.01, 95% confidence interval 1.18 to 29.5) and a shorter physical distance to the patient (OR 2.0 for every meter closer to the patient, p=0.05, CI 1.0 to 3.8). A mobile HEPA-filtration unit in the room decreased the proportion of positive samples (OR 0.3, p=0.02, CI 0.12 to 0.98). No association was observed between SARS-CoV-2 positive air samples and mechanical ventilation, high flow nasal cannula, nebulizer treatment or non-invasive ventilation. An association was found with positive expiratory pressure (PEP) training (p<0.01) and a trend towards association for airway manipulation, including bronchoscopies and in- and extubations.

CONCLUSIONS

Our results show that major risk factors for airborne SARS-CoV-2 include short physical distance, high patient viral load and poor room ventilation. AGPs, as traditionally defined, seem to be of secondary importance.

An exploration of the political, social, economic and cultural factors affecting how different global regions initially reacted to the COVID-19 pandemic

Responses to the early (February–July 2020) COVID-19 pandemic varied widely, globally. Reasons for this are multiple but likely relate to the healthcare and financial resources then available, and the degree of trust in, and economic support provided by, national governments. Cultural factors also affected how different populations reacted to the various pandemic restrictions, like masking, social distancing and self-isolation or self-quarantine. The degree of compliance with these measures depended on how much individuals valued their needs and liberties over those of their society. Thus, several themes may be relevant when comparing pandemic responses across different regions. East and Southeast Asian populations tended to be more collectivist and self-sacrificing, responding quickly to early signs of the pandemic and readily complied with most restrictions to control its spread. Australasian, Eastern European, Scandinavian, some Middle Eastern, African and South American countries also responded promptly by imposing restrictions of varying severity, due to concerns for their wider society, including for some, the fragility of their healthcare systems. Western European and North American countries, with well-resourced healthcare systems, initially reacted more slowly, partly in an effort to maintain their economies but also to delay imposing pandemic restrictions that limited the personal freedoms of their citizens.

Transmission of Respiratory Viral Diseases to Health Care Workers: COVID-19 as an Example

Health care workers (HCWs) can acquire infectious diseases, including coronavirus disease 2019 (COVID-19), from patients. Herein, COVID-19 is used with the source–pathway–receptor framework as an example to assess evidence for the role of aerosol transmission and indirect contact transmission of viral respiratory infectious diseases. Evidence for both routes is strong for COVID-19 and other respiratory viruses, but aerosol transmission is likely dominant for COVID-19. Key knowledge gaps about transmission processes and control strategies include the distribution of viable virus among respiratory aerosols of different sizes, the mechanisms and efficiency by which virus deposited on the facial mucous membrane moves to infection sites inside the body, and the performance of source controls such as face coverings and aerosol containment devices. To ensure that HCWs are adequately protected from infection, guidelines and regulations must be updated to reflect the evidence that respiratory viruses are transmitted via aerosols.

Expected final online publication date for the Annual Review of Public Health, Volume 43 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Evaluation of the aerosol generating potential of endoscopic dacryocystorhinostomy

PURPOSE

The COVID-19 pandemic gave rise to renewed concerns of the transmission risks posed by surgeries on sites of high viral colonization such as the nasopharynx. Endoscopic dacryocystorhinostomy (DCR) involves the creation of a new tear duct from the lacrimal sac to the nasal cavity. The purpose of this project is to determine if endoscopic DCR is an aerosol generating procedure (AGP).

METHODS

An optical particle sizer (OPS) was used to intraoperatively quantify aerosol concentrations during four cases of endoscopic DCR. The OPS sampled the air once every 60 seconds throughout the operations. The time of important operative steps were documented and correlated with OPS readings. Particle concentrations during each major surgical step were compared to baseline readings by the Mann Whitney U Test.

RESULTS

There were statistically significant increases in median particle concentrations during laryngeal mask airway intubations for both particles 0.3 to 5.0 μm and >5.0 μm (P < .001 and P = .023, respectively). Median particle concentrations during nasolacrimal duct probing, middle meatal debridement, drilling, balloon insertion, tube insertion, and Posisef insertion were not statistically different from baseline.

CONCLUSIONS

Endoscopic DCR in itself does not appear to be an AGP. It is, however, associated with other aerosol generating events such as laryngeal mask intubation, and thus requires appropriate personal protective equipment. Cautious interpretation of the results is encouraged given the limitations of OPS.

LEVEL OF EVIDENCE

4.

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.

Infection prevention measures in acute care settings based on severe acute respiratory syndrome coronavirus 2 transmission patterns and risk: a review

PURPOSE OF REVIEW

During the coronavirus disease 2019 pandemic, when facing extraordinary infection prevention challenges, acute care settings have balanced routine patient safety needs while minimizing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission risk to patients and healthcare personnel (HCP). Mitigation strategies in acute care settings are based on a combination of basic science, environmental, and epidemiologic evidence. Here, we review the literature on SARS-CoV-2 transmission, how it has shaped infection prevention interventions in acute care settings, and the results of such measures to reduce transmission.

RECENT FINDINGS

HCP adherence to transmission-based precautions in acute care settings, such as the use of personal protective equipment (PPE), is essential to mitigating SARS-CoV-2 spread. Although the SARS-CoV-2 virus has been isolated in nonrespiratory body sites, such exposure has not been shown to definitively cause transmission in humans. Epidemiologic evidence has demonstrated that implementation and adherence to infection prevention strategies reduces acute setting transmission.

SUMMARY

Given SARS-CoV-2 infection occurs primarily through respiratory transmission, preventing HCP acquisition requires fidelity to consistent PPE usage. Infection prevention strategies and implementation of transmission-based precautions have reduced spread and outbreaks. Epidemiologic studies of acute care outbreaks often include reports of PPE nonadherence and community exposure contributing to SARS-CoV-2 transmission within this setting.

Mechanistic theory predicts the effects of temperature and humidity on inactivation of SARS-CoV-2 and other enveloped viruses

Ambient temperature and humidity strongly affect inactivation rates of enveloped viruses, but a mechanistic, quantitative theory of these effects has been elusive. We measure the stability of SARS-CoV-2 on an inert surface at nine temperature and humidity conditions and develop a mechanistic model to explain and predict how temperature and humidity alter virus inactivation. We find SARS-CoV-2 survives longest at low temperatures and extreme relative humidities (RH); median estimated virus half-life is >24 hr at 10°C and 40% RH, but ∼1.5 hr at 27°C and 65% RH. Our mechanistic model uses fundamental chemistry to explain why inactivation rate increases with increased temperature and shows a U-shaped dependence on RH. The model accurately predicts existing measurements of five different human coronaviruses, suggesting that shared mechanisms may affect stability for many viruses. The results indicate scenarios of high transmission risk, point to mitigation strategies, and advance the mechanistic study of virus transmission.

Aerosol Generation During Laryngology Procedures in the Operating Room

OBJECTIVE

Severe acute respiratory syndrome coronavirus-2 spreads through respiratory fluids. We aim to quantify aerosolized particles during laryngology procedures to understand their potential for transmission of infectious aerosol-based diseases.

STUDY DESIGN

Prospective quantification of aerosol generation.

METHODS

Airborne particles (0.3-25 μm in diameter) were measured during live-patient laryngology surgeries using an optical particle counter positioned 60 cm from the oral cavity to the surgeon's left. Measurements taken during the procedures were compared to baseline concentrations recorded immediately before each procedure. Procedures included direct laryngoscopy with general endotracheal anesthesia (GETA), direct laryngoscopy with jet ventilation, and carbon dioxide (CO₂ ) laser use with or without jet ventilation, all utilizing intermittent suction.

RESULTS

Greater than 99% of measured particles were 0.3 to 1.0 μm in diameter. Compared to baseline, direct laryngoscopy was associated with a significant 6.71% increase in cumulative particles, primarily 0.3 to 1.0 μm particles (P < .0001). 1.0 to 25 μm particles significantly decreased (P < .001). Jet ventilation was not associated with a significant change in cumulative particles; when analyzing differential particle sizes, only 10 to 25 μm particles exhibited a significant increase compared to baseline (+42.40%, P = .002). Significant increases in cumulative particles were recorded during CO₂ laser use (+14.70%, P < .0001), specifically in 0.3 to 2.5 μm particles. Overall, there was no difference when comparing CO₂ laser use during jet ventilation versus GETA.

CONCLUSIONS

CO₂ laser use during laryngology surgery is associated with significant increases in airborne particles. Although direct laryngoscopy with GETA is associated with slight increases in particles, jet ventilation overall does not increase particle aerosolization.

LEVEL OF EVIDENCE

III Laryngoscope, 2021.

The use of pediatric flexible bronchoscopy in the COVID-19 pandemic era

On March 11, 2020, the World Health Organization (WHO) declared the pandemic because of a novel coronavirus, called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In January 2020, the first transmission to healthcare workers (HCWs) was described. SARS-CoV-2 is transmitted between people because of contact, droplets, and airborne. Airborne transmission is caused by aerosols that remain infectious when suspended in air over long distances and time. In the clinical setting, airborne transmission may occur during aerosol generating procedures like flexible bronchoscopy. To date, although the role of children in the transmission of SARS-CoV-2 is not clear the execution of bronchoscopy is associated with a considerably increased risk of SARS-CoV-2 transmission to HCWs. The aim of this overview is to summarize available recommendations and to apply them to pediatric bronchoscopy. We performed systematic literature searches using the MEDLINE (accessed via PubMed) and Scopus databases. We reviewed major recommendations and position statements published at the moment by the American Association for Bronchology and Interventional Pulmonology, WHO, European Center for Disease Prevention and Control and expert groups on the management of patients with COVID-19 to limit transmission among HCWs. To date there is a lack of recommendations for safe bronchoscopy during the pandemic period. The main indications concern adults and little has been said about children. We have summarized available recommendations and we have applied them to pediatric bronchoscopy.

SARS-Cov-2: The Relevance and Prevention of Aerosol Transmission

Coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2), has claimed many victims worldwide due to its high virulence and contagiousness. The person-to-person transmission of SARS-Cov-2 when in close contact is facilitated by respiratory droplets containing the virus particles, and by skin contact with contaminated surfaces. However, the large number of COVID-19 infections cannot be explained only by droplet deposition or contact contamination. It seems very plausible that aerosols are important in transmitting SARS-Cov-2. It has been demonstrated that SARS-CoV-2 remains viable in aerosols for hours, facilitating rapid distribution of the virus over great distances. Aerosols may, therefore, also be responsible for so-called super-spreader events. Indirect evidence points to a correlation between ventilation and the transmission and spread of SARS-Cov-2, supporting ventilation as an important factor in preventing airborne transmission. Further actions to avoid transmission of COVID-19 include social distancing, hygiene measures, and barrier measures, such as face-coverings. Professional masks offer better protection than cloth masks. These protection measures are especially relevant to health care workers, when performing endotracheal intubation, but the risk from non-invasive ventilation and nebulizing treatment seems to be moderate.

The COVID-19 Impact in Hospital Healthcare Workers: Development of an Occupational Health Risk Management Program

As with the SARS-CoV-1 outbreak in 2003–2004 and the MERS outbreak in 2012, there were early reports of frequent transmission to healthcare workers (HCW) in the SARS-CoV-2 pandemic. Our hospital center identified its first COVID-19 confirmed case on March 9, 2020, in a 6-day hospitalized patient. The first confirmed COVID-19 case in a HCW happened 3 days later, in a nurse with a probable epidemiological link related to the first confirmed patient. Our study's first objective is to describe and characterize the impact of the first 3 months of the SARS-CoV-2 pandemic on the Centro Hospitalar Universitário Lisboa Norte (CHULN). Our second objective is to report the performance of the CHULN Occupational Health Department (OHD) and the impact of the pandemic on CHULN HCW and its adaptation across national, regional, and institutional epidemiological evolution. Over the first 3 months, 2,152 HCW were screened (which represent 29.8% of the total HCW population), grouped in 100 separate identifiable clusters, each one ranging from 2 to 98 HCW. The most prevalent profession screened were nurses (n = 800; 37.2%) followed by doctors (n = 634; 29.5%). The main source of potential infection and cluster generating screening procedures was co-worker related (n = 1,216; 56.5%). A patient source or a combined patient co-worker source was only accountable for 559 (26%) and 43 (2%) of cases, respectively. Our preliminary results demonstrate a lower infection rate among HCW than the ones commonly found in the literature. The main source of infection seemed to be co-worker related rather than patient related. New preventive strategies would have to be implemented in order to control SARS-CoV-2 spread.

Aerosol Exposure During Surgical Tracheotomy in SARS-CoV-2 Positive Patients

INTRODUCTION

Since December 2019, the novel coronavirus SARS-CoV-2 has been spreading worldwide. Since the main route of infection with SARS-CoV-2 is probably via contact with virus-containing droplets of the exhaled air, any method of securing the airway is of extremely high risk for the health care professionals involved. We evaluated the aerosol exposure to the interventional team during a tracheotomy in a semiquantitative fashion. In addition, we present novel protective measures.

PATIENTS AND METHODS

To visualize the air movements occurring during a tracheotomy, we used a breathing simulator filled with artificial fog. Normal breathing and coughing were simulated under surgery. The speed of aerosol propagation and particle density in the direct visual field of the surgeon were evaluated.

RESULTS

Laminar air flow (LAF) in the OR reduced significantly the aerosol exposure during tracheostomy. Only 4.8 ± 3.4% of the aerosol was in contact with the surgeon. Without LAF, however, the aerosol density in the inspiratory area of the surgeon is 10 times higher (47.9 ± 10.8%, P < 0.01). Coughing through the opened trachea exposed the surgeon within 400 ms with 76.0 ± 8.0% of the aerosol-independent of the function of the LAF. Only when a blocked tube was inserted into the airway, no aerosol leakage could be detected.

DISCUSSION

Coughing and expiration during a surgical tracheotomy expose the surgical team considerably to airway aerosols. This is potentially associated with an increased risk for employees being infected by airborne-transmitted pathogens. Laminar airflow in an operating room leads to a significant reduction in the aerosol exposure of the surgeon and is therefore preferable to a bedside tracheotomy in terms of infection prevention. Ideal protection of medical staff is achieved when the procedure is performed under endotracheal intubation and muscle relaxation.

The effect of respiratory activity, non-invasive respiratory support and facemasks on aerosol generation and its relevance to COVID-19

Respirable aerosols (< 5 µm in diameter) present a high risk of SARS‐CoV‐2 transmission. Guidelines recommend using aerosol precautions during aerosol‐generating procedures, and droplet (> 5 µm) precautions at other times. However, emerging evidence indicates respiratory activities may be a more important source of aerosols than clinical procedures such as tracheal intubation. We aimed to measure the size, total number and volume of all human aerosols exhaled during respiratory activities and therapies. We used a novel chamber with an optical particle counter sampling at 100 l.min^‐1 to count and size‐fractionate close to all exhaled particles (0.5–25 µm). We compared emissions from ten healthy subjects during six respiratory activities (quiet breathing; talking; shouting; forced expiratory manoeuvres; exercise; and coughing) with three respiratory therapies (high‐flow nasal oxygen and single or dual circuit non‐invasive positive pressure ventilation). Activities were repeated while wearing facemasks. When compared with quiet breathing, exertional respiratory activities increased particle counts 34.6‐fold during talking and 370.8‐fold during coughing (p < 0.001). High‐flow nasal oxygen 60 at l.min^‐1 increased particle counts 2.3‐fold (p = 0.031) during quiet breathing. Single and dual circuit non‐invasive respiratory therapy at 25/10 cm.H₂O with quiet breathing increased counts by 2.6‐fold and 7.8‐fold, respectively (both p < 0.001). During exertional activities, respiratory therapies and facemasks reduced emissions compared with activities alone. Respiratory activities (including exertional breathing and coughing) which mimic respiratory patterns during illness generate substantially more aerosols than non‐invasive respiratory therapies, which conversely can reduce total emissions. We argue the risk of aerosol exposure is underappreciated and warrants widespread, targeted interventions.

Aerosol and Droplet Risk of Common Otolaryngology Clinic Procedures

OBJECTIVES

Define aerosol and droplet risks associated with routine otolaryngology clinic procedures during the COVID-19 era.

METHODS

Clinical procedures were simulated in cadaveric heads whose oral and nasal cavities were coated with fluorescent tracer (vitamin B2) and breathing was manually simulated through retrograde intubation. A cascade impactor placed adjacent to the nares collected generated particles with aerodynamic diameters ≤14.1 µm. The 3D printed models and syringes were used to simulate middle and external ear suctioning as well as open suctioning, respectively. Provider's personal protective equipment (PPE) and procedural field contamination were also recorded for all trials using vitamin B2 fluorescent tracer.

RESULTS

The positive controls of nebulized vitamin B2 produced aerosol particles ≤3.30 µm and endonasal drilling of a 3D model generated particles ≤14.1 µm. As compared with positive controls, aerosols and small droplets with aerodynamic diameter ≤14.1 µm were not detected during rigid nasal endoscopy, flexible fiberoptic laryngoscopy, and rigid nasal suction of cadavers with simulated breathing. There was minimal to no field contamination in all 3 scenarios. Middle and external ear suctioning and open container suctioning did not result in any detectable droplet contamination. The clinic suction unit contained all fluorescent material without surrounding environmental contamination.

CONCLUSION

While patients' coughing and sneezing may create a baseline risk for providers, this study demonstrates that nasal endoscopy, flexible laryngoscopy, and suctioning inherently do not pose an additional risk in terms of aerosol and small droplet generation. An overarching generalization cannot be made about endoscopy or suctioning being an aerosol generating procedure.

LEVEL OF EVIDENCE

3.

Bronchoscopy precautions and recommendations in the COVID-19 pandemic

As the airways of SARS-CoV-2 infected patients contain a high viral load, bronchoscopy is associated with increased risk of patient to health care worker transmission due to aerosolised viral particles and contamination of surfaces during bronchoscopy. Bronchoscopy is not appropriate for diagnosing SARS-CoV-2 infection and, as an aerosol generating procedure involving a significant risk of transmission, has a very limited role in the management of SARS-CoV-2 infected patients including children. During the SARS-CoV-2 pandemic rigid bronchoscopy should be avoided due to the increased risk of droplet spread. Flexible bronchoscopy should be performed first in SARS-CoV-2 positive individuals or in unknown cases, to determine if rigid bronchoscopy is indicated. When available single-use flexible bronchoscopes may be considered for use; devices are available with a range of diameters, and improved image quality and degrees of angulation. When rigid bronchoscopy is necessary, jet ventilation must be avoided and conventional ventilation be used to reduce the risk of aerosolisation. Adequate personal protection equipment is key, as is training of health care workers in correct donning and doffing. Modified full face masks are a practical and safe alternative to filtering facepieces for use in bronchoscopy. When anaesthetic and infection prevention control protocols are strictly adhered to, bronchoscopy can be performed in SARS-CoV-2 positive children.

Rewriting the playbook: infection prevention practices to mitigate nosocomial severe acute respiratory syndrome coronavirus 2 transmission

PURPOSE OF REVIEW

Given the limited evidence and experience with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), this novel pathogen has challenged the field of infection prevention. Despite uncertainty, infection prevention principles and experience with similar diseases have helped guide how to best protect providers and patients against disease acquisition.

RECENT FINDINGS

Guidance to date has relied on data from SARS-CoV-1 and MERS-CoV to guide practices on patient isolation and personal protective equipment (PPE) use. Although a face mask and eye protection are likely adequate for most clinical scenarios, published guidelines for PPE can be confusing and conflicting. Consensus for what constitutes a high-risk aerosol-generating procedure (AGP) is lacking, but most agree providers performing procedures such as bronchoscopy, intubation, and cardiopulmonary resuscitation would likely benefit from the use of an N95 respirator and eye protection.

SUMMARY

Needed research to elucidate the predominant SARS-CoV-2 mode of transmission is not likely to be completed in the immediate future. Recommendations for PPE to mitigate procedure-associated risk remain controversial. Nonetheless, implementation of existing measures based on basic infection prevention principles is likely to prevent transmission significantly.

Containment of procedure-associated aerosols by an extractor tent: effect on nebulized drug particle dispersal

Background

Several medical procedures involving the respiratory tract are considered as ‘aerosol-generating procedures’. Aerosols from these procedures may be inhaled by bystanders, and there are consequent concerns regarding the transmission of infection or, specific to nebulized therapy, secondary drug exposure.

Aim

To assess the efficacy of a proprietary high-efficiency-particulate-air-filtering extractor tent on reducing the aerosol dispersal of nebulized bronchodilator drugs.

Methods

The study was conducted in an unoccupied outpatient room at St. James's Hospital, Dublin, Ireland. A novel real-time, fluorescent particle counter, the Wideband Integrated Bioaerosol Sensor (WIBS), monitored room air continuously for 3 h. Baseline airborne particle count and count during nebulization of bronchodilator drug solutions were recorded.

Findings

Nebulization within the tent prevented any increase over background level. Nebulization directly into room air resulted in mean fluorescent particle counts of 4.75 x 10⁵/m³ and 4.21 x 10⁵/m³ for Ventolin and Ipramol, respectively, representing more than 400-fold increases over mean background level. More than 99.3% of drug particles were <2 μm in diameter and therefore small enough to enter the lower respiratory tract.

Conclusion

The extractor tent was completely effective for the prevention of airborne spread of drug particles of respirable size from nebulized therapy. This suggests that extractor tents of this type would be efficacious for the prevention of airborne infection from aerosol-generating procedures during the COVID-19 pandemic.

Percutaneous Tracheostomy in COVID Era: Time to Adapt and Improvise

Background

Percutaneous dilatation tracheostomy (PDT) is required in patients with novel coronavirus disease-2019 (COVID-19) with severe respiratory involvement, but the procedure needs modification to minimize the risk of aerosol exposure to caregivers.

Aim and objective

To share the experience of apnea approach of PDT in COVID patients. Also, to demonstrate the safety of the technique for healthcare workers (HCWs) and patients with respect to hemodynamic and oxygenation parameters. The incidence of adverse events and difficulties during the procedure were also recorded.

Materials and methods

According to this modified approach, percutaneous tracheostomy was performed with apnea technique during open tracheal steps (video attached) and the endotracheal tube was withdrawn to the level of cords under video-laryngoscopic guidance.

Study design

A retrospective data analysis of all the tracheostomy procedures (PDT) performed with the apnea technique during the COVID era (June–September) in non-COVID and COVID patients in intensive care units (ICUs).

Results

During these 4 months, 74 PDT procedures were performed in both COVID and non-COVID patients in the ICUs of our hospital. Out of these, PDT with apnea technique was performed in 45 patients (61%). This technique was successful in 44 patients (97.7%) with mean apnea time of 110 + 8.6 seconds. There was no significant (p < 0.05) change in mean arterial pressure and oxygen saturation of 15 COVID patients in pre-PDT and immediate post-PDT period. None of the six team members performing PDT had symptoms or tested positive for COVID-19.

Conclusion

PDT with apnea technique can be performed to minimize the risk of aerosol exposure and does not compromise the quality of care. It is safe both for the patient and HCWs.

How to cite this article

Paul G, Gautam PL, Sharma S, Sravani MV, Krishna MR. Percutaneous Tracheostomy in COVID Era: Time to Adapt and Improvise. Indian J Crit Care Med 2021;25(6):642–647.

SARS COV 2 positive healthcare workers in obstetrics and gynaecology- Save the saviour study

Context:

Health-care workers (HCWs), being the front-line warriors, have been at increased risk for COVID-19 throughout the pandemic. However, the current extent of SARS-CoV-2 transmission and associated risk factors is still unclear in low- and middle-income countries, like India, especially in the department of obstetrics and gynaecology, which propelled this study. Aims: (i) Frequency of infection among HCWs among OBGYN department and cycle threshold value (Ctv) of SARS-COV-2 on RT-PCR. (ii) Clinical presentation, assessment of risk factors, and its impact on HCWs. Settings and Design: This was a prospective study conducted at the Department of Obstetrics and Gynaecology, VMMC and Safdarjung Hospital, New Delhi for the duration of 6 months.

Methods and Material:

All SARS-CoV-2-positive HCWs in the department were interviewed verbatim after recovery, through a self-formulated, validated questionnaire, and answers recorded on pre-designed proforma. Statistical Analysis Used: Categorical variables were presented as number and percentage (%), whereas continuous variables as mean ± standard deviation (SD) and median values. Data were transferred on Microsoft Excel spreadsheet and analysed using SPSS v 27.0.

Results:

Amongst 727 HCWs working in the department, 350 RT-PCR tests were performed, and 110 tested positive (prevalence of 15.13%). Mean Ctv of RT-PCR was 28.03. Most HCWs were symptomatic (n = 94) with mild infection; working as nursing officers (40%). Majority of them acquired virus while working in non-COVID wards (76%). Noncompliance with IPC practices (40%) and lack of social distancing (34.5%) were key risk factors.

Conclusion:

Adept knowledge of the risk factors and IPC practices can aid in averting casualties due to SARS-COV-2 amongst the HCWs

Mechanistic theory predicts the effects of temperature and humidity on inactivation of SARS-CoV-2 and other enveloped viruses

Environmental conditions affect virus inactivation rate and transmission potential. Understanding those effects is critical for anticipating and mitigating epidemic spread. Ambient temperature and humidity strongly affect the inactivation rate of enveloped viruses, but a mechanistic, quantitative theory of those effects has been elusive. We measure the stability of the enveloped respiratory virus SARS-CoV-2 on an inert surface at nine temperature and humidity conditions and develop a mechanistic model to explain and predict how temperature and humidity alter virus inactivation. We find SARS-CoV-2 survives longest at low temperatures and extreme relative humidities; median estimated virus half-life is over 24 hours at 10 °C and 40 % RH, but approximately 1.5 hours at 27 °C and 65 % RH. Our mechanistic model uses simple chemistry to explain the increase in virus inactivation rate with increased temperature and the U-shaped dependence of inactivation rate on relative humidity. The model accurately predicts quantitative measurements from existing studies of five different human coronaviruses (including SARS-CoV-2), suggesting that shared mechanisms may determine environmental stability for many enveloped viruses. Our results indicate scenarios of particular transmission risk, point to pandemic mitigation strategies, and open new frontiers in the mechanistic study of virus transmission.

CSO (Canadian Society of Otolaryngology - Head & Neck Surgery) position paper on rhinologic and skull base surgery during the COVID-19 pandemic

Healthcare services in many countries have been partially or completely disrupted by the Coronavirus (COVID-19) pandemic since its onset in the end of 2019. Amongst the most impacted are the elective medical and surgical services in order to conserve resources to care for COVID-19 patients. As the number of infected patients decrease across Canada, elective surgeries are being restarted in a staged manner. Since Otolaryngologists - Head & Neck Surgeons manage surgical diseases of the upper aerodigestive tract where the highest viral load reside, it is imperative that these surgeries resume in a safe manner. The aim of this document is to compile the current best evidence available and provide expert consensus on the safe restart of rhinologic and skull base surgeries while discussing the pre-operative, intra-operative, and post-operative care and tips. Risk assessment, patient selection, case triage, and pre-operative COVID-19 testing will be analyzed and discussed. These guidelines will also consider the optimal use of personal protective equipment for specific cases, general and specific operative room precautions, and practical tips of intra-operative maneuvers to optimize patient and provider safety. Given that the literature surrounding COVID-19 is rapidly evolving, these recommendations will serve to start our specialty back into elective rhinologic surgeries over the next months and they may change as we learn more about this disease.

Care of the COVID-19 exposed complex newborn infant

As we confront COVID-19, the global public health emergency of our times, new knowledge is emerging that, combined with information from prior epidemics, can provide insights on how to manage this threat in specific patient populations. Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS), both caused by coronaviruses, caused serious respiratory illness in pregnant women that resulted in adverse perinatal outcomes. Thus far, COVID-19 appears to follow a mild course in the vast majority of pregnant women. A significant proportion of pregnant women appear to be asymptomatic carriers of SARS-CoV-2. However, there is limited information on how COVID-19 impacts the fetus and whether vertical transmission occurs. While these knowledge gaps are addressed, it is important to recognize the highly efficient transmission characteristics of SARS-C0V-2 and its potential for causing serious disease in vulnerable individuals, including health care workers. This review provides perspectives from a single center in New York City, the epicenter of the pandemic within the United States. It offers an overview of the preparations required for deliveries of newborns of mothers with COVID-19 and the management of neonates with particular emphasis on those born with complex issues.

Oropharyngeal hemorrhage in patients with COVID-19: A multi-institutional case series

Background

Patients with COVID-19 who are intubated and require mechanical ventilation have been observed to have oropharyngeal bleeding necessitating otolaryngology intervention.

Methods

We report five cases of oropharyngeal hemorrhage in COVID-19 patients on mechanical ventilation requiring evaluation by otolaryngologists at George Washington University Hospital (GWUH) and Boston Medical Center (BMC) from March to April 2020. Institutional Review Board at both institutions exempted this study from informed consent because there were no identifiable patient characteristics, photographs, or imaging studies included.

Results

All five patients were managed conservatively; four required packing with Kerlix gauze by an otolaryngologist. Two patients had the additional requirement of extracorporeal membrane oxygenation (ECMO) and associated anticoagulation. Three patients improved with oropharyngeal packing; two had persistent bleeding. Three patients expired. Endotracheal tubes were repositioned less frequently due to the COVID-19 pandemic.

Conclusions

Intubated patients with COVID-19 may have an increased risk of oropharyngeal hemorrhage. This may be due to anticoagulation, prolonged intubation, or decreased frequency of endotracheal tube repositioning. Otolaryngologists should wear appropriate PPE when managing this hemorrhagic complication.

COVID-19: What do we know?

•Evidence regarding the provision of orthodontic care during the COVID-19 pandemic is examined.

Recommendations for interventional pulmonology during COVID-19 outbreak: a consensus statement from the Portuguese Pulmonology Society

Coronavirus disease 2019 (COVID-19) is an emerging infectious disease caused by a novel SARS-CoV-2 pathogen. Its capacity for human-to-human transmission through respiratory droplets, coupled with a high-level of population mobility, has resulted in a rapid dissemination worldwide. Healthcare workers have been particularly exposed to the risk of infection and represent a significant proportion of COVID-19 cases in the worst affected regions of Europe. Like other open airway procedures or aerosol-generating procedures, bronchoscopy poses a significant risk of spreading contaminated droplets, and medical workers must adapt the procedures to ensure safety of both patients and staff. Several recommendation documents were published at the beginning of the pandemic, but as the situation evolves, our thoughts should not only focus on the present, but should also reflect on how we are going to deal with the presence of the virus in the community until there is a vaccine or specific treatment available. It is in this sense that this document aims to guide interventional pulmonology throughout this period, providing a set of recommendations on how to perform bronchoscopy or pleural procedures safely and efficiently.

A quantitative evaluation of aerosol generation during tracheal intubation and extubation

The potential aerosolised transmission of severe acute respiratory syndrome coronavirus‐2 is of global concern. Airborne precaution personal protective equipment and preventative measures are universally mandated for medical procedures deemed to be aerosol generating. The implementation of these measures is having a huge impact on healthcare provision. There is currently a lack of quantitative evidence on the number and size of airborne particles produced during aerosol‐generating procedures to inform risk assessments. To address this evidence gap, we conducted real‐time, high‐resolution environmental monitoring in ultraclean ventilation operating theatres during tracheal intubation and extubation sequences. Continuous sampling with an optical particle sizer allowed characterisation of aerosol generation within the zone between the patient and anaesthetist. Aerosol monitoring showed a very low background particle count (0.4 particles.l⁻¹) allowing resolution of transient increases in airborne particles associated with airway management. As a positive reference control, we quantitated the aerosol produced in the same setting by a volitional cough (average concentration, 732 (418) particles.l⁻¹, n = 38). Tracheal intubation including facemask ventilation produced very low quantities of aerosolised particles (average concentration, 1.4 (1.4) particles.l⁻¹, n = 14, p < 0.0001 vs. cough). Tracheal extubation, particularly when the patient coughed, produced a detectable aerosol (21 (18) l⁻¹, n = 10) which was 15‐fold greater than intubation (p = 0.0004) but 35‐fold less than a volitional cough (p < 0.0001). The study does not support the designation of elective tracheal intubation as an aerosol‐generating procedure. Extubation generates more detectable aerosol than intubation but falls below the current criterion for designation as a high‐risk aerosol‐generating procedure. These novel findings from real‐time aerosol detection in a routine healthcare setting provide a quantitative methodology for risk assessment that can be extended to other airway management techniques and clinical settings. They also indicate the need for reappraisal of what constitutes an aerosol‐generating procedure and the associated precautions for routine anaesthetic airway management.

Practical strategies to reduce nosocomial transmission to healthcare professionals providing respiratory care to patients with COVID-19

Coronavirus disease (COVID-19) is an emerging viral infection that is rapidly spreading across the globe. SARS-CoV-2 belongs to the same coronavirus class that caused respiratory illnesses such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). During the SARS and MERS outbreaks, many frontline healthcare workers were infected when performing high-risk aerosol-generating medical procedures as well as when providing basic patient care. Similarly, COVID-19 disease has been reported to infect healthcare workers at a rate of ~ 3% of cases treated in the USA. In this review, we conducted an extensive literature search to develop practical strategies that can be implemented when providing respiratory treatments to COVID-19 patients, with the aim to help prevent nosocomial transmission to the frontline workers.

An anaesthetic and intensive care perspective on infection control measures for the prevention of airborne transmission of SARS-CoV-2

Guidance regarding appropriate use of personal protective equipment in hospitals is in constant flux as research into SARS-COV-2 transmission continues to develop our understanding of the virus. The risk associated with procedures classed as 'aerosol generating' is under constant debate. Current guidance is largely based on pragmatic and cautious logic, as there is little scientific evidence of aerosolization and transmission of respiratory viruses associated with procedures. The physical properties of aerosol particles which may contain viable virus have implications for the safe use of personal protective equipment and infection control protocols. As elective work in the NHS is reinstated, it is important that the implications of the possibility of airborne transmission of the virus in hospitals are more widely understood. This will facilitate appropriate use of personal protective equipment and help direct further research into the true risks of aerosolization during these procedures to allow safe streamlining of services for staff and patients.

Minimising aerosol spread during endoscopic sinus and skull base surgery. Experimental model evaluation of the efficacy of the microscope drape method

BACKGROUND

Endoscopic sinus and anterior skull base surgery is considered particularly high risk for severe acute respiratory syndrome coronavirus-2 transmission in the operating theatre setting. In this context, the use of a microscope drape method is proposed, to minimise aerosol spread in the wider operating theatre environment.

METHODS

The efficacy of the method is assessed with a simulation model, using a CMI Concept Air Trace MK2 smoke generator for aerosol generation and a Fluke 985 air particle counter to measure air particles sized 0.3-10 μm in the operating theatre environment.

RESULTS

Aerosol spread was contained almost to baseline levels with the application of the drape barrier and the negative pressure created using suction within the drape.

CONCLUSION

The method is an efficient adjunct that could reduce the risk of aerosol shedding and viral transmission to the operating theatre team. It potentially allows faster operating theatre turnover and more liberal use of powered instruments during endonasal surgery.

Welche Schutzmaske schützt vor COVID-19? Was ist evidenzbasiert?

Die COVID-19-Pandemie hat sowohl in der Patientenversorgung als auch in der Öffentlichkeit zu Diskussionen geführt, mit welchen Schutzmasken man sich vor einer Ansteckung schützen kann. Ähnliche Diskussionen hatte es schon 2009/10 im Rahmen der damals weltweiten Ausbreitung einer neuen Variante des Influenzavirus A (H1N1) gegeben („Schweinegrippe“). Auffällig sind damals wie heute Unklarheiten und Verwirrungen in Bezug auf die Übertragungswege von Atemwegsinfektionen und über die sich daraus ableitenden Schutzmaßnahmen.

Severe acute respiratory syndrome coronavirus 2 infection risk during elective peri-operative care: a narrative review

The protection of healthcare workers from the risk of nosocomial severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection is a paramount concern. SARS‐CoV‐2 is likely to remain endemic and measures to protect healthcare workers against nosocomial infection will need to be maintained. This review aims to inform the assessment and management of the risk of SARS‐CoV‐2 transmission to healthcare workers involved in elective peri‐operative care. In the absence of data specifically related to the risk of SARS‐CoV‐2 transmission in the peri‐operative setting, we explore the evidence‐base that exists regarding modes of viral transmission, historical evidence for the risk associated with aerosol‐generating procedures and contemporaneous data from the COVID‐19 pandemic. We identify a significant lack of data regarding the risk of transmission in the management of elective surgical patients, highlighting the urgent need for further research.

Oxygen Therapy and Risk of Infection for Health Care Workers Caring for Patients With Viral Severe Acute Respiratory Infection: A Systematic Review and Meta-analysis

Study objective

To synthesize the evidence regarding the infection risk associated with different modalities of oxygen therapy used in treating patients with severe acute respiratory infection. Health care workers face significant risk of infection when treating patients with a viral severe acute respiratory infection. To ensure health care worker safety and limit nosocomial transmission of such infection, it is crucial to synthesize the evidence regarding the infection risk associated with different modalities of oxygen therapy used in treating patients with severe acute respiratory infection.

Methods

MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched from January 1, 2000, to April 1, 2020, for studies describing the risk of infection associated with the modalities of oxygen therapy used for patients with severe acute respiratory infection. The study selection, data extraction, and quality assessment were performed by independent reviewers. The primary outcome measure was the infection of health care workers with a severe acute respiratory infection. Random-effect models were used to synthesize the extracted data.

Results

Of 22,123 citations, 50 studies were eligible for qualitative synthesis and 16 for meta-analysis. Globally, the quality of the included studies provided a very low certainty of evidence. Being exposed or performing an intubation (odds ratio 6.48; 95% confidence interval 2.90 to 14.44), bag-valve-mask ventilation (odds ratio 2.70; 95% confidence interval 1.31 to 5.36), and noninvasive ventilation (odds ratio 3.96; 95% confidence interval 2.12 to 7.40) were associated with an increased risk of infection. All modalities of oxygen therapy generate air dispersion.

Conclusion

Most modalities of oxygen therapy are associated with an increased risk of infection and none have been demonstrated as safe. The lowest flow of oxygen should be used to maintain an adequate oxygen saturation for patients with severe acute respiratory infection, and manipulation of oxygen delivery equipment should be minimized.

Is Office Laryngoscopy an Aerosol-Generating Procedure?

Objectives/Hypothesis

The aims of this work were 1) to investigate whether office laryngoscopy is an aerosol‐generating procedure with an optical particle sizer (OPS) during clinical simulation on healthy volunteers, and 2) to critically discuss methods for assessment of aerosolizing potentials in invasive interventions.

Study Design

Prospective quantification of aerosol and droplet generation during clinical simulation of rigid and flexible laryngoscopy.

Methods

Two healthy volunteers were recruited to undergo both flexible and rigid laryngoscopy. An OPS was used to quantify aerosols and droplets generated for four positive controls relative to ambient particles (speech, breathing, /e/ phonation, and /æ/ phonation) and for five test interventions relative to breathing and phonation (flexible laryngoscopy, flexible laryngoscopy with humming, flexible laryngoscopy with /e/ phonation, rigid laryngoscopy, and rigid laryngoscopy with /æ/ phonation). Particle counts in mean diameter size range from 0.3 to >10 μm were measured with OPS placed at 12 cm from the subject's nose/mouth.

Results

None of the laryngoscopy interventions (n = 10 each) generated aerosols above that produced by breathing or phonation. Breathing (n = 40, 1–3 μm, P = .016) and /æ/ phonation (n = 10, 1–3 μm, P = .022; 3–5 μm. P = .083; >5 μm, P = .012) were statistically significant producers of aerosols and droplets. Neither speech nor /e/ phonation (n = 10 each) were associated with statistically significant aerosols and droplet generation.

Conclusions

Using OPS to detect droplets and aerosols, we found that office laryngoscopy is likely not an aerosol‐generating procedure. Despite its prior use in otolaryngological literature, an OPS has intrinsic limitations. Our study should be complemented with more sophisticated methods of droplet distribution measurement.

Level of Evidence

3 Laryngoscope, 130:2637–2642, 2020

Risk of SARS-CoV-2 transmission by aerosols, the rational use of masks, and protection of healthcare workers from COVID-19

OBJECTIVES

To determine the risk of SARS-CoV-2 transmission by aerosols, to provide evidence on the rational use of masks, and to discuss additional measures important for the protection of healthcare workers from COVID-19.

METHODS

Literature review and expert opinion.

SHORT CONCLUSION

SARS-CoV-2, the pathogen causing COVID-19, is considered to be transmitted via droplets rather than aerosols, but droplets with strong directional airflow support may spread further than 2 m. High rates of COVID-19 infections in healthcare-workers (HCWs) have been reported from several countries. Respirators such as filtering face piece (FFP) 2 masks were designed to protect HCWs, while surgical masks were originally intended to protect patients (e.g., during surgery). Nevertheless, high quality standard surgical masks (type II/IIR according to European Norm EN 14683) appear to be as effective as FFP2 masks in preventing droplet-associated viral infections of HCWs as reported from influenza or SARS. So far, no head-to-head trials with these masks have been published for COVID-19. Neither mask type completely prevents transmission, which may be due to inappropriate handling and alternative transmission pathways. Therefore, compliance with a bundle of infection control measures including thorough hand hygiene is key. During high-risk procedures, both droplets and aerosols may be produced, reason why respirators are indicated for these interventions.

Risk of SARS-CoV-2 transmission by aerosols, the rational use of masks, and protection of healthcare workers from COVID-19

OBJECTIVES

To determine the risk of SARS-CoV-2 transmission by aerosols, to provide evidence on the rational use of masks, and to discuss additional measures important for the protection of healthcare workers from COVID-19.

METHODS

Literature review and expert opinion.

SHORT CONCLUSION

SARS-CoV-2, the pathogen causing COVID-19, is considered to be transmitted via droplets rather than aerosols, but droplets with strong directional airflow support may spread further than 2 m. High rates of COVID-19 infections in healthcare-workers (HCWs) have been reported from several countries. Respirators such as filtering face piece (FFP) 2 masks were designed to protect HCWs, while surgical masks were originally intended to protect patients (e.g., during surgery). Nevertheless, high quality standard surgical masks (type II/IIR according to European Norm EN 14683) appear to be as effective as FFP2 masks in preventing droplet-associated viral infections of HCWs as reported from influenza or SARS. So far, no head-to-head trials with these masks have been published for COVID-19. Neither mask type completely prevents transmission, which may be due to inappropriate handling and alternative transmission pathways. Therefore, compliance with a bundle of infection control measures including thorough hand hygiene is key. During high-risk procedures, both droplets and aerosols may be produced, reason why respirators are indicated for these interventions.

Topographic aspects of airborne contamination caused by the use of dental handpieces in the operative environment

BACKGROUND

The use of dental handpieces produces aerosols containing microbial agents, bacteria, and viruses representing a high-risk situation for airborne cross infections. The aim of this study was to map and quantify the biological contamination of a dental operatory environment using a biological tracer.

METHODS

Streptococcus mutans suspension was infused into the mouth of a manikin, and an operator performed standardized dental procedures using an air turbine, a contra-angle handpiece, or an ultrasonic scaler. The presence of the tracer was measured at 90 sites on the dental unit and the surrounding surfaces of the operatory environment.

RESULTS

All tested instruments spread the tracer over the entire dental unit and the surrounding environment, including the walls and ceiling. The pattern and degree of contamination were related to the distance from the infection source. The maximum distance of tracer detection was 360 centimeters for air turbine, 300 cm for contra-angle handpiece, and 240 cm for ultrasonic scaler. No surface of the operative environment was free from the tracer after the use of the air turbine.

CONCLUSIONS

Attention should be paid to minimize or avoid the use of rotary and ultrasonic instruments when concerns for the airborne spreading of pandemic disease agents are present.

PRACTICAL IMPLICATIONS

This study supports the recommendations of dental associations to avoid treatments generating aerosols, especially during pandemic periods. Guidelines for the management of dental procedures involving aerosols, as well as methods for the modification of aerosols aimed to inactivate the infective agent, are urgently needed.

Position Paper for the State-of-the-Art Application of Respiratory Support in Patients with COVID-19

Against the background of the pandemic caused by infection with the SARS-CoV-2 virus, the German Respiratory Society has appointed experts to develop therapy strategies for COVID-19 patients with acute respiratory failure (ARF). Here we present key position statements including observations about the pathophysiology of (ARF). In terms of the pathophysiology of pulmonary infection with SARS-CoV-2, COVID-19 can be divided into 3 phases. Pulmonary damage in advanced COVID-19 often differs from the known changes in acute respiratory distress syndrome (ARDS). Two types (type L and type H) are differentiated, corresponding to early- and late-stage lung damage. This differentiation should be taken into consideration in the respiratory support of ARF. The assessment of the extent of ARF should be based on arterial or capillary blood gas analysis under room air conditions, and it needs to include the calculation of oxygen supply (measured from the variables of oxygen saturation, hemoglobin level, the corrected values of Hüfner's factor, and cardiac output). Aerosols can cause transmission of infectious, virus-laden particles. Open systems or vented systems can increase the release of respirable particles. Procedures in which the invasive ventilation system must be opened and endotracheal intubation carried out are associated with an increased risk of infection. Personal protective equipment (PPE) should have top priority because fear of contagion should not be a primary reason for intubation. Based on the current knowledge, inhalation therapy, nasal high-flow therapy (NHF), continuous positive airway pressure (CPAP), or noninvasive ventilation (NIV) can be performed without an increased risk of infection to staff if PPE is provided. A significant proportion of patients with ARF present with relevant hypoxemia, which often cannot be fully corrected, even with a high inspired oxygen fraction (FiO2) under NHF. In this situation, the oxygen therapy can be escalated to CPAP or NIV when the criteria for endotracheal intubation are not met. In ARF, NIV should be carried out in an intensive care unit or a comparable setting by experienced staff. Under CPAP/NIV, a patient can deteriorate rapidly. For this reason, continuous monitoring and readiness for intubation are to be ensured at all times. If the ARF progresses under CPAP/NIV, intubation should be implemented without delay in patients who do not have a "do not intubate" order.