Failure Rates During Reuse of Disposable N95 Masks in Clinical Practice in the Emergency Department

Abstract

Introduction The coronavirus 2019 pandemic caused a shortage of disposable N95 respirators, prompting healthcare entities to extend the use of these masks beyond their intended single-use manufacturer recommendation with a paucity of supporting research. Methods We performed a prospective cohort study of ED healthcare workers (HCW) (“subjects”) required to use respirators at an academic, Level I trauma center. Subjects had been previously fit tested and assigned an appropriately sized N95 mask per hospital protocol. Per study protocol, subjects were fit tested periodically throughout their shifts and on multiple shifts over the eight-week study period. Data points collected included the age of the mask, subjective assessment of mask seal quality, and fit test results. We analyzed the data using Fisher’s exact test, and calculated odds ratios (OR) to determine the failure rate of disposable N95 masks following reuse. Results A total of 130 HCWs underwent fit testing and 127 were included for analysis. Mask failure rate climbed after day 2 of use, with 33.3% of masks failing at day 3, 42.9% at day 4, and 50% at ≥ day 5. Categorizing the masks into those being used for two or fewer days vs those in use for three or more, failure was more common on day 3 of use or older compared to those in the first two days of use (41.8% vs 8.3%, P < 0.0001) with an OR of failure with an older mask of 7.9 (confidence interval [CI], 2.8–22.3). The healthcare workers’ assessment of poor seal was 33.3% sensitive (CI, 18.6–51.9) and 95.7% specific (CI, 88.8–98.6) for fit test failure. Conclusion Disposable N95 masks have significant failure rates following reuse in clinical practice. Healthcare personnel also performed poorly in assessing the integrity of the seal of their disposable respirators.

Filtration performance, fit test and side effects of respiratory personal protective equipment following decontamination: Observations for user safety and comfort

“…Other studies have been conducted in hospitals with extended use of FFRs (no decontamination) [ 22 , 40 – 44 ]. Similar to our study, these authors observed an increase in fit test failures with the number of times they were reused and/or hours of wear.…”

“…Therefore one can reasonably assume that hydrogen peroxide vapor can be used with several FFRs models that do not contain cellulose or valves since the latter were not tested. Studies on extensive use and reuse of disposable FFRs reported various fit test failure rates and recommended great care in seal checks before use [ 22 , 40 ]. Therefore, one can also reasonably assume that our conclusions about the lack of robustness of disposable Moldex series 1500 and 3M model 1870+ after repeated wearing and decontamination could apply to other FFRs models.…”

“…However, Levine and collaborators have demonstrated that 3M 1870+ FFRs (and possibly other folded FFR models) have significantly reduced fit test success with a second user [ 19 ]. Since health care workers have reported poor face seal integrity after FFR reuse [ 22 ], the decontamination of FFRs for multiple users must be conducted with extreme caution, preferably in low-risk areas, and be accompanied by regular thorough fit testing [ 41 , 43 ].…”

“…Several approaches have been proposed for the decontamination and reuse of N95 FFRs: microwave oven [4], ethylene oxide [4], light or UV light [4][5][6][7][8][9][10][11], methylene blue [11], dry heat [7,10,12], autoclave [13][14][15], bleach [4,10], and hydrogen peroxide [4,7,11,[16][17][18][19][20][21]. Bleach, ethylene oxide, and microwave oven has been shown to leave harmful residues or damage N95 FFRs [13,22], while autoclaving and dry heat has had contradictory results [7,10,[12][13][14][15]. This suggests that UV light, methylene blue and hydrogen peroxide are the most promising techniques [3,23].…”

Incidence of Fit Test Failure During N95 Respirator Reuse and Extended Use

“…[11][12][13] However, evidence of the safety of reuse practices in clinical settings is lacking, 14 as few prospective studies have been conducted to explicitly determine the incidence of fit failure during N95 reuse. [15][16][17] A pilot study conducted by some of us in 1 ED found that N95 reuse during increasing numbers of shifts was significantly associated with increased fit test failure. 15 These studies were limited, as single-center enrollment and cross-sectional designs did not permit definitive estimates of whether N95s could safely be reused.…”