Aerosol generation during airway management
Throughout the SARS-CoV-2 pandemic, a clear message has been given that healthcare workers (HCWs) performing airway management are at risk of viral infection from contact, droplet and aerosol spread. Hence, optimising staff safety using appropriate PPE has been given the highest priority by leading authorities, including the Intensive Care Medicine- Anaesthesia Covid-19 Hub [1, 2]. Evidence, however, for an increased risk to airway managers is by no means conclusive [3]. More recently, there has been debate regarding the extent of aerosol generation during airway management and whether the risk of airborne transmission is significant.
The risk of SARS-CoV-2 transmission from patients to airway managers and those working alongside them, and the development of subsequent Covid-19 is unclear. There are no studies that conclude that the risk of infection transmission to airway managers is significant. The intubateCOVID study reported an association between involvement in intubation and subsequent symptoms of COVID-19, but did not show causation [4].
The controversy about aerosol generation during airway management has been highlighted by two papers recently published in Anaesthesia which provide contrasting evidence. In Brown et al.’s study, the authors conclude that tracheal intubation is not an aerosol generating procedure (AGP) and that tracheal extubation, although generating more aerosol, also falls below the currently recognised level for designation as a high-risk AGP [5]. The authors conclude by proposing the need to re-evaluate what constitutes an AGP and what PPE is required as a result. In Dhillon et al.’s study, the authors report significant aerosolisation of small particles during airway management in clinical settings, suggesting the risk to airway managers was genuine [6].
These papers, which have significant methodological differences, offer conflicting, perhaps confusing conclusions and have generated considerable debate. Studies of in-hospital SARS-CoV-2 infection and seroconversion amongst healthcare workers have generally identified anaesthetists and intensivists to be at low risk compared to other specialties, but the reason for this is difficult to confirm and is likely multifactorial [7, 8]. At this stage, it would be premature to assume this is solely due to tracheal intubation not being an AGP. Effective PPE, as well as other infection preventative measures, may be equally relevant.
Some might feel it is time to dispense with aerosol-protective PPE during tracheal intubation and perhaps even extubation and other interventions. There may be concerns regarding PPE availability; it can be unpleasant to wear and possibly impairs technical and non-technical performance during airway management. However, the precautionary principle should be adhered to and while there is uncertainty HCW safety should be prioritised. Public Health bodies from England, Scotland, Wales and Northern Ireland and NERVTAG may update their guidance in the light of the evolving evidence base, but until then, our recommendation is to maintain current standards of protection against aerosol transmission during airway management.
McGuire B, Cook T, El-Boghdadly K, McNarry A, Higgs A, Ahmad I, Patel A.
Difficult Airway Society, November 2020
References
- ICM Anaesthesia Covid-19 Hub.
https://icmanaesthesiacovid-19.org/ppe-guidance - Cook TM, El-Boghdadly K, McGuire B, McNarry AF, Patel A, Higgs A. Consensus guidelines for managing the airway in patients with COVID-19: Guidelines from the Difficult Airway Society, the Association of Anaesthetists the Intensive Care Society, the Faculty of Intensive Care Medicine and the Royal College of Anaesthetists. Anaesthesia 2020; 75: 785-99.
- Cook TM. Risk to health from COVID-19 for anaesthetists and intensivists – a narrative review. Anaesthesia 2020.
https://doi.org/10.1111/anae.15220 - El-Boghdadly K, Wong DJN, Owen R et al. Risks to healthcare workers following tracheal intubation of patients with COVID‐19: a prospective international multicentre cohort study. Anaesthesia 2020.
https://doi.org/10.1111/anae.15170 - Brown J, Gregson FKA, Shrimpton A, Cook TM, Bdzek BR, Reid JP, Pickering AE. A quantitative evaluation of aerosol generation during intubation and extubation. Anaesthesia 2020.
https://doi.org/10.1111/anae.15292 - Dhillon, Rowin WA, Humphries RS et al. Aerosolisation during tracheal intubation and extubation in an operating theatre setting. Anaesthesia 2020.
https://doi.org/10.1111/anae.15301 - Shields A, Faustini SE, Perez-Toledo et al. SARS-CoV-2 seroprevalence and asymptomatic viral carriage in healthcare workers: a cross-sectional study. Thorax 2020. doi: 10.1136/thoraxjnl-2020-215414
- Eyre DW, Lumley SF, O'Donnell D et al. Differential occupational risks to healthcare workers from SARS-CoV-2 observed during a prospective observational study. eLife 2020 Aug 21; 9: e60675.
