Protection levels of N95-level respirator substitutes proposed during the COVID-19 pandemic: safety concerns and quantitative evaluation procedures.

OBJECTIVE: The COVID-19 pandemic has precipitated widespread shortages of filtering facepiece respirators (FFRs) and the creation and sharing of proposed substitutes (novel designs, repurposed materials) with limited testing against regulatory standards. We aimed to categorically test the efficacy and fit of potential N95 respirator substitutes using protocols that can be replicated in university laboratories. SETTING: Academic medical centre with occupational health-supervised fit testing along with laboratory studies. PARTICIPANTS: Seven adult volunteers who passed quantitative fit testing for small-sized (n=2) and regular-sized (n=5) commercial N95 respirators. METHODS: Five open-source potential N95 respirator substitutes were evaluated and compared with commercial National Institute for Occupational Safety and Health (NIOSH)-approved N95 respirators as controls. Fit testing using the 7-minute standardised Occupational Safety and Health Administration fit test was performed. In addition, protocols that can be performed in university laboratories for materials testing (filtration efficiency, air resistance and fluid resistance) were developed to evaluate alternate filtration materials. RESULTS: Among five open-source, improvised substitutes evaluated in this study, only one (which included a commercial elastomeric mask and commercial HEPA filter) passed a standard quantitative fit test. The four alternative materials evaluated for filtration efficiency (67%-89%) failed to meet the 95% threshold at a face velocity (7.6 cm/s) equivalent to that of a NIOSH particle filtration test for the control N95 FFR. In addition, for all but one material, the small surface area of two 3D-printed substitutes resulted in air resistance that was above the maximum in the NIOSH standard. CONCLUSIONS: Testing protocols such as those described here are essential to evaluate proposed improvised respiratory protection substitutes, and our testing platform could be replicated by teams with similar cross-disciplinary research capacity. Healthcare professionals should be cautious of claims associated with improvised respirators when suggested as FFR substitutes.

Patient-defined duration of benefit from juvederm (hyaluronic acid) used in injection laryngoplasty.

OBJECTIVES/HYPOTHESIS: Injection laryngoplasty has become valuable in treating laryngologic disorders including vocal cord atrophy, paralysis, and paresis. Although materials such as carboxymethylcellulose and calcium hydroxylapatite are Food and Drug Administration (FDA) approved, they are not without limitations. Juvederm (hyaluronic acid) is an alternative treatment that is not FDA approved. Although studies have examined Juvederm's longevity in cutaneous injections, there are limited data examining durability of Juvederm used in laryngoplasty. We aimed to determine the longevity and effectiveness of Juvederm used in injection laryngoplasty. STUDY DESIGN: Retrospective cohort study. METHODS: Subjects who underwent injection laryngoplasty using Juvederm were reviewed. Longevity was defined as the time between injection and the date that a patient first noted subjective deterioration of their voice. All subjects were subsequently followed using videostroboscopy to evaluate for Juvederm resorption. Longevity was analyzed using a Kaplan-Meier survival model, and effectiveness of laryngoplasty was determined using the Voice-Related Quality of Life index scores and analyzed using a Wilcoxon signed ranks test. RESULTS: Fifty-nine subjects met inclusion criteria and underwent Juvederm injection laryngoplasty. Kaplan-Meier survival analysis revealed a mean longevity of 10.6 months (95% confidence interval: 9.1-12.0 months). Wilcoxon signed ranks analysis of the pre- and postinjection Voice Related Quality of Life (VRQOL) scores revealed improvement, with a mean preinjection VRQOL of 49.2 (standard deviation [SD] = 25.8) and mean postinjection VRQOL of 68.2 (SD = 27.5) (P < .001). CONCLUSIONS: Injection laryngoplasty using Juvederm is an effective treatment for vocal cord atrophy, paralysis, and paresis. Knowledge of the patient-defined duration of benefit following laryngoplasty using Juvederm plays an important role in counseling patients as well as in the planning of future interventions. LEVEL OF EVIDENCE: 4 Laryngoscope, 129:2744-2747, 2019.

Hearing Loss After Activation of Hearing Preservation Cochlear Implants Might Be Related to Afferent Cochlear Innervation Injury.

OBJECTIVE: Characterize hearing loss (HL) after hearing preservation cochlear implantation and determine the association between high charge electrical stimulation (ES) and late loss of acoustic hearing. METHODS: A retrospective cohort analysis of all hearing preservation implantees at our center (n = 42) assayed HL as a function of maximum charge. We analyzed serial audiometry from 85 patients enrolled in the multicenter Hybrid S8 trial to detail the hearing loss greater than 1 month after implantation. Cochleotypic explant cultures were used to assess susceptibility to high levels of ES. RESULTS: Early HL after implantation tends to be mild and averages 12.2 dB. After activation of the Hybrid S8 device, 17 (20%) of 85 patients experienced acceleration of HL. Compared with the majority of patients who did not lose significant hearing after activation, these patients experienced more severe HL at 1 year. Five patients implanted at our center experienced acceleration of HL after high charge exposure. In patients implanted at our center, high charge was associated with late HL (Pearson 0.366, p = 0.016). In rat cochleotypic explants, high voltage ES damaged afferent nerve fibers, reflected by blebbing and a 50% reduction in the number of fibers innervating the organ of Corti. In contrast, hair cells displayed only minor differences in cell number and morphology. CONCLUSIONS: Based on clinical and in vitro data, we theorize that the combination of acoustic amplification and ES in the setting of intact hair cells and neural architecture may contribute, in part, to cochlear toxicity, perhaps by damaging the afferent innervation.