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COVID-19: minimising contaminated aerosol spreading during CPAP treatment
  1. Snorri Donaldsson1,2,
  2. Lars Naver2,3,
  3. Baldvin Jonsson1,2,
  4. Thomas Drevhammar1,4
  1. 1 Department of Women's and Children's Health, Karolinska Institute, Stockholm, Sweden
  2. 2 Department of Neonatology, Karolinska University Hospital, Stockholm, Sweden
  3. 3 CLINTEC, Karolinska Institute, Stockholm, Sweden
  4. 4 Department of Anesthesiology, Östersunds sjukhus, Ostersund, Sweden
  1. Correspondence to Dr Snorri Donaldsson, Department of Women's and Children's Health, Karolinska Institute, Stockholm 171 77, Sweden; snorri.donaldsson{at}


Background The COVID-19 pandemic has raised concern for healthcare workers getting infected via aerosol from non-invasive respiratory support of infants. Attaching filters that remove viral particles in air from the expiratory limb of continuous positive airway pressure (CPAP) devices should theoretically decrease the risk. However, adding filters to the expiratory limb could add to expiratory resistance and thereby increase the imposed work of breathing (WOB).

Objective To evaluate the effects on imposed WOB when attaching filters to the expiratory limb of CPAP devices.

Methods Two filters were tested on three CPAP systems at two levels of CPAP in a mechanical lung model. Main outcome was imposed WOB.

Results There was a minor increase in imposed WOB when attaching the filters. The differences between the two filters were small.

Conclusion To minimise contaminated aerosol generation during CPAP treatment, filters can be attached to expiratory tubing with only a minimal increase in imposed WOB in a non-humidified environment. Care has to be taken to avoid filter obstruction and replace filters as recommended.

  • neonatology
  • virology
  • technology

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  • Contributors SD study design, data interpretation and writing of manuscript. LN and BJ manuscript writing, construction and review. TD study design, data interpretation, data collection, data and statistical analysis and writing of manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information. All data relevant to the study are included in the article.