Airborne transmission of severe acute respiratory syndrome coronavirus-2 to healthcare workers: a narrative review.

Healthcare workers are at risk of infection during the severe acute respiratory syndrome coronavirus-2 pandemic. International guidance suggests direct droplet transmission is likely and airborne transmission occurs only with aerosol-generating procedures. Recommendations determining infection control measures to ensure healthcare worker safety follow these presumptions. Three mechanisms have been described for the production of smaller sized respiratory particles ('aerosols') that, if inhaled, can deposit in the distal airways. These include: laryngeal activity such as talking and coughing; high velocity gas flow; and cyclical opening and closure of terminal airways. Sneezing and coughing are effective aerosol generators, but all forms of expiration produce particles across a range of sizes. The 5-μm diameter threshold used to differentiate droplet from airborne is an over-simplification of multiple complex, poorly understood biological and physical variables. The evidence defining aerosol-generating procedures comes largely from low-quality case and cohort studies where the exact mode of transmission is unknown as aerosol production was never quantified. We propose that transmission is associated with time in proximity to severe acute respiratory syndrome coronavirus-1 patients with respiratory symptoms, rather than the procedures per se. There is no proven relation between any aerosol-generating procedure with airborne viral content with the exception of bronchoscopy and suctioning. The mechanism for severe acute respiratory syndrome coronavirus-2 transmission is unknown but the evidence suggestive of airborne spread is growing. We speculate that infected patients who cough, have high work of breathing, increased closing capacity and altered respiratory tract lining fluid will be significant producers of pathogenic aerosols. We suggest several aerosol-generating procedures may in fact result in less pathogen aerosolisation than a dyspnoeic and coughing patient. Healthcare workers should appraise the current evidence regarding transmission and apply this to the local infection prevalence. Measures to mitigate airborne transmission should be employed at times of risk. However, the mechanisms and risk factors for transmission are largely unconfirmed. Whilst awaiting robust evidence, a precautionary approach should be considered to assure healthcare worker safety.

Wilson NM ，Norton A ，Young FP ，Collins DW ... -  《-》

[Respiratory and Facial Protection: Current Perspectives in the Context of the COVID-19 Pandemic].

Peres D ，Boléo-Tomé JP ，Santos G 《Acta Medica Portuguesa》

Guidance for otolaryngology health care workers performing aerosol generating medical procedures during the COVID-19 pandemic.

Lammers MJW ，Lea J ，Westerberg BD 《Journal of Otolaryngology-Head & Neck Surgery》

Operative team checklist for aerosol generating procedures to minimise exposure of healthcare workers to SARS-CoV-2.

In many countries around the world, the COVID-19 pandemic has resulted in health services being diverted to manage patients with the condition. There are situations however that still require the undertaking of aerosol generating procedures (AGP) with potentially high exposure of healthcare workers to SARS-CoV-2 transmission through droplet, contact and possibly airborne routes. The objective of this paper is to explore a structured way for the operative team to approach AGP to reduce aerosolisation of secretions, decrease open airway time and minimise staff exposure. The authors (otolaryngologists, anaesthetists and nursing staff) created a unified operative team checklist based on collation of national and international specialty society statements, local state government recommendations, hospital policies and literature review. Simulation was undertaken and the checklist was refined after performing AGP on patients with unknown (presumed positive) COVID-19 status. An 8 step operative team checklist is provided describing details for the immediate pre-operative, intra-operative and post-operative journey of the patient to encourage healthcare workers to reflect upon and modify usual practice during AGP to mitigate exposure to SARS-CoV-2. The example of paediatric laryngo-bronchoscopy for diagnostic purposes or retrieval of an inhaled airway foreign body is used to illustrate the steps however the checklist structure is modifiable for other AGP and adaptable for local needs. At a time of overwhelming and changing information and recommendations, an operative team checklist may provide some structure to healthcare workers undertaking AGP to reduce anxiety, maintain focus, prompt consideration of alternatives and potentially reduce risk.

Soma M ，Jacobson I ，Brewer J ，Blondin A ，Davidson G ，Singham S ... -  《-》

Aerosol-generating otolaryngology procedures and the need for enhanced PPE during the COVID-19 pandemic: a literature review.

Mick P ，Murphy R 《Journal of Otolaryngology-Head & Neck Surgery》