Does using liquid nitrogen to treat skin cancer aerosolize coronavirus in an infected patient?Posted on by
Guidelines do not include liquid nitrogen as an aerosol generating procedure. There is no empiric evidence about whether liquid nitrogen can aerosolize viruses, but there is a study that suggests that liquid nitrogen generates and influences aerosol mist particles in the vicinity of the surface of a container of liquid nitrogen.
Liquid nitrogen (LN2) therapy is not listed as an aerosol generating procedure by Ottawa Hospital guidelines or Vancouver Coastal Health (1, 2). Being omitted from these lists does not necessarily mean that the procedure is without risks. There is no empiric evidence about whether LN2 could aerosolize COVID-19 (or any virus), but the following information outlines what we do know about LN2 and aerosolization.
The novel coronavirus that causes COVID-19 is approximately 60-140 nm in diameter (3).
III. Liquid Nitrogen and Aerosol Mist Particles
- Aerosol mist particles of sizes 1, 3, and 5 µm are generated in surrounding environments of the surface of a container of LN2 (4).
- The concentration of aerosol mist particles of various sizes was strongly affected by liquid nitrogen up to a distance of 20 cm from the liquid nitrogen surface, whereas they returned to their ordinary levels at distances greater than 30 cm from the liquid nitrogen surface (4).
- Smaller particles (0.3 and 0.5 µm) decreased in concentration in the vicinity of LN2. Investigators suggested this was because smaller particles joined together into larger particles as a result of the liquid nitrogen (4). The novel coronavirus is much smaller than any particle size tested.
- This study focussed on aerosols from the surface of a container of LN2 and it is unclear how this form of LN2 would differ from the aerosol spray typically used in medical treatments.
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- Cascella M, Rajnik M, Cuomo A, Dulebohn SC, Raffaela Di Napoli. Features, Evaluation and Treatment Coronavirus (COVID-19) [Internet]. Nih.gov. StatPearls Publishing; 2020 [cited 2020 May 12]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554776/
- Infection Control Manual\Resource Manuals\Acute IPAC BEST PRACTICES GUIDELINE Aerosol Generating Medical Procedures [Internet]. [cited 2020 May 12]. Available from: http://ipac.vch.ca/Documents/Acute%20Resource%20manual/Aerosol%20Generating%20Medical%20Procedures.pdf
- Updated IPAC Recommendations for Use of Personal Protective Equipment for Care of Individuals with Suspect or Confirmed COVID-19 Key Findings [Internet]. 2020. Available from: https://www.publichealthontario.ca/-/media/documents/ncov/updated-ipac-measures-covid-19.pdf?la=en
- Lee BU. Cryogenic Aerosol Generation: Airborne Mist Particles Surrounding Liquid Nitrogen. International Journal of Environmental Research and Public Health [Internet]. 2020 Feb 7 [cited 2020 May 12];17(3):1071. Available from: https://www.mdpi.com/1660-4601/17/3/1071
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