What is the performance and impact of disposable and reusable respirators for healthcare workers in the context of COVID-19?

May 22, 2020

Chris Burton^1, Briana Coles^2, Anil Adisesh^3,4, Simon Smith⁵
Elaine Toomey^6, Xin Hui Chan^7, Lawrence Ross^8, Trisha Greenhalgh⁹

¹ Academic Unit of Primary Medical Care, University of Sheffield
² Diabetes Research Centre, University of Leicester, UK
³ Department of Medicine, Division of Occupational Medicine, University of Toronto
⁴Division of Occupational Medicine, St. Michael’s Hospital, Unity Health, Toronto
⁵ Chair, Canadian Standards Biological Aerosols Working Group
⁶ School of Allied Health, University of Limerick, Limerick, Ireland
 ⁷ Centre for Tropical Medicine and Global Health,
Nuffield Department of Medicine, University of Oxford
⁸ Department of Infectious Disease, Children’s Hospital of Los Angeles
⁹Nuffield Department of Primary Care Health Sciences, University of Oxford

VERDICT
This review looked at the performance of respirators (in terms of the protection they provide) and their impact (on wearers and clinical activities). We included disposable filtering facepiece respirator masks such as FFP3, N95 and P2 and reusable types such as elastomeric facepiece respirators and powered air-purifying respirators. We examined filtration standards for respirators and how they compare across different industries and 8 different international standards agencies. In a rapid systematic review, we summarised and assessed studies of different respirators’ impact on clinical practice. The main findings were:

1. Standards for respirator performance are industry-agnostic, so repurposing a respirator from another industry to healthcare is appropriate provided it meets the required standard.
2. Safe use of respirators requires proper fit testing and adherence to good practice.
3. Even with fit testing, some clinical procedures including chest compression may compromise fit with some respirators.
4. Wearing a respirator seems to have minimal impact on short-term clinical procedures such as endotracheal intubation.
5. All respirator types place a substantial burden on the user, with trade-offs between protection, comfort and communication.

A full-text paper has been submitted to an academic journal; link to preprint.

BACKGROUND
The global Covid-19 pandemic has increased demand worldwide for respirators to use in direct patient care. This includes both disposable devices (such as filtering facepiece respirators) and reusable ones (such as elastomeric and powered air-purifying respirators). Staff previously unfamiliar with these devices are now required or advised to use them. Shortages of supply have also led to consideration of “repurposing” respirators from other industries for healthcare use.

SEARCH STRATEGY
We performed a rapid database search of PubMed and Medline databases without date restrictions to identify relevant systematic reviews and primary research.  We framed the search using the SPiDER tool.

• Sample – healthcare workers or student healthcare workers
• Phenomenon of Interest – respirators: including disposable filtering facepiece and reusable (elastomeric filtering facepiece and powered air-purifying) types
• Design – wide range of designs including cross-sectional, cohort observation, simulation and interview or focus group
• Evaluation – either (a) test of respirator performance, or (b) test of clinician performance or adherence, or (c) self-reported comfort and impact, or (d) perceptions of use.
• Research types: quantitative, qualitative or mixed-method.

We defined performance in terms of effective filtration of inhaled air and impact in terms of the effects on healthcare workers’ work and comfort.

CRITICAL APPRAISAL CHECKLIST
We systematically extracted studies against a set of criteria which are described in the full paper. Two reviewers independently judged eligibility for inclusion.

SUMMARY OF FINDINGS

Review of standards
All the standards we found were applicable, but not specific, to healthcare. Therefore, a respirator (either disposable or reusable) may be used in a range of different settings, providing that the standards it meets are those applicable in the new setting. All standards documents are explicit that supplying a respirator is only one part of a respiratory protection programme and that ensuring adequate fit and safe use is essential.

Achieving satisfactory fit (10 studies)
Studies of disposable filtering facepiece respirator masks showed that (a) a standardised fit test involving detection of a chemical inside the mask is necessary to ensure that a model fits (b) about 10% of healthcare workers will need to try fitting with at least two different models to find one that provides adequate fit. One study measured the (substantial) impact of different types of facial hair on respirator fit.

Maintaining a satisfactory fit and protection (10 studies)
When carefully worn a well fitted filtering facepiece respirator can provide good protection for up to 8 hours. Some healthcare activities (particularly chest compression) reduce that fit. The clinical importance of this is not clear.

Interfering with clinical activities (10 studies)
Studies looked at interference with clinical activity of disposable respirator masks and reusable respirators (elastomeric facepiece and powered air-purifying types). Communication was more difficult, particularly with the reusable types, but ability to carry out procedures such as intubation was not.

User discomfort (10 studies)
All respirators bring a degree of discomfort and for around a quarter of users this is non-trivial. This includes facial warmth, breathing discomfort and headache.

Individual and organisational perceptions of use in healthcare (3 high-quality studies)
Respirator use represents a complex trade-off between protection and interference. Organisations need flexible policies which include provision of more than one filtering facepiece respirator model. Where hospitals provided reusable respirators a substantial proportion of healthcare workers preferred them over the simpler disposable filtering facepiece designs.

CONCLUSION
A wide range of respirator types and models can be used in patient care during the Covid-19 pandemic. Careful consideration of performance and impact of respirators is needed to maximise protection of healthcare workers and minimise disruption to the delivery of care.

Disclaimer: The views expressed in this commentary represent the views of the authors and not necessarily those of the host institution, the NHS, the NIHR, or the Department of Health and Social Care. The views are not a substitute for professional medical advice.