Aerosolised fluorescein can quantify FFP mask faceseal leakage: a cost-effective adaptation to the existing point of care fit test.
Clin Med (Lond)
; 21(3): e263-e268, 2021 05.
Article
in English
| MEDLINE | ID: covidwho-1518788
ABSTRACT
BACKGROUND:
A qualitative fit test using bitter-tasting aerosols is the commonest way to determine filtering face-piece (FFP) mask leakage. This taste test is subjective and biased by placebo. We propose a cheap, quantitative modification of the taste test by measuring the amount of fluorescein stained filter paper behind the mask using image analysis.METHODS:
A bitter-tasting fluorescein solution was aerosolised during mask fit tests, with filter paper placed on masks' inner surfaces. Participants reported whether they could taste bitterness to determine taste test 'pass' or 'fail' results. Filter paper photographs were digitally analysed to quantify total fluorescence (TF).RESULTS:
Fifty-six healthcare professionals were fit tested; 32 (57%) 'passed' the taste test. TF between the taste test 'pass' and 'fail' groups was significantly different (p<0.001). A cut-off (TF = 5.0 × 106 units) was determined at precision (78%) and recall (84%), resulting in 5/56 participants (9%) reclassified from 'pass' to 'fail' by the fluorescein test. Seven out of 56 (12%) reclassified from 'fail' to 'pass'.CONCLUSION:
Fluorescein is detectable and sensitive at identifying FFP mask leaks. These low-cost adaptations can enhance exiting fit testing to determine 'pass' and 'fail' groups, protecting those who 'passed' the taste test but have high fluorescein leak, and reassuring those who 'failed' the taste test despite having little fluorescein leak.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Respiratory Protective Devices
/
Occupational Exposure
Type of study:
Experimental Studies
/
Qualitative research
/
Randomized controlled trials
Limits:
Humans
Language:
English
Journal:
Clin Med (Lond)
Year:
2021
Document Type:
Article
Affiliation country:
CLINMED.2020-0982
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