Development, manufacturing, and preliminary validation of a reusable half-face respirator during the COVID-19 pandemic.

INTRODUCTION: The COVID-19 pandemic has led to widespread shortages of N95 respirators and other personal protective equipment (PPE). An effective, reusable, locally-manufactured respirator can mitigate this problem. We describe the development, manufacture, and preliminary testing of an open-hardware-licensed device, the "simple silicone mask" (SSM). METHODS: A multidisciplinary team developed a reusable silicone half facepiece respirator over 9 prototype iterations. The manufacturing process consisted of 3D printing and silicone casting. Prototypes were assessed for comfort and breathability. Filtration was assessed by user seal checks and quantitative fit-testing according to CSA Z94.4-18. RESULTS: The respirator originally included a cartridge for holding filter material; this was modified to connect to standard heat-moisture exchange (HME) filters (N95 or greater) after the cartridge showed poor filtration performance due to flow acceleration around the filter edges, which was exacerbated by high filter resistance. All 8 HME-based iterations provided an adequate seal by user seal checks and achieved a pass rate of 87.5% (N = 8) on quantitative testing, with all failures occurring in the first iteration. The overall median fit-factor was 1662 (100 = pass). Estimated unit cost for a production run of 1000 using distributed manufacturing techniques is CAD $15 in materials and 20 minutes of labor. CONCLUSION: Small-scale manufacturing of an effective, reusable N95 respirator during a pandemic is feasible and cost-effective. Required quantities of reusables are more predictable and less vulnerable to supply chain disruption than disposables. With further evaluation, such devices may be an alternative to disposable respirators during public health emergencies. The respirator described above is an investigational device and requires further evaluation and regulatory requirements before clinical deployment. The authors and affiliates do not endorse the use of this device at present.

Subject validation of reusable N95 stop-gap filtering facepiece respirators in COVID-19 pandemic.

INTRODUCTION: The COVID-19 pandemic has unveiled widespread shortages of personal protective equipment including N95 respirators. Several centers are developing reusable stop-gap respirators as alternatives to disposable N95 respirators during public health emergencies, using techniques such as 3D-printing, silicone moulding and plastic extrusion. Effective sealing of the mask, combined with respiratory filters should achieve 95% or greater filtration of particles less than 1um. Quantitative fit-testing (QNFT) data from these stop-gap devices has not been published to date. Our team developed one such device, the "SSM", and evaluated it using QNFT. METHODS: Device prototypes were iteratively evaluated for comfort, breathability and communication, by team members wearing them for 15-30min. The fit and seal were assessed by positive and negative pressure user seal checks. The final design was then formally tested by QNFT, according to CSA standard Z94.4-18 in 40 volunteer healthcare providers. An overall fit-factor >100 is the passing threshold. Volunteers were also tested by QNFT on disposable N95 masks which had passed qualitative fit testing (QLFT) by institutional Occupational Health and Safety Department. RESULTS: The SSM scored 3.5/5 and 4/5 for comfort and breathability. The median overall harmonic mean fit-factors of disposable N95 and SSM were 137.9 and 6316.7 respectively. SSM scored significantly higher than disposable respirators in fit-test runs and overall fit-factors (p <0.0001). Overall passing rates in disposable and SSM respirators on QNFT were 65% and 100%. During dynamic runs, passing rates in disposable and SSM respirators were 68.1% and 99.4%; harmonic means were 73.7 and 1643. CONCLUSIONS: We present the design and validation of a reusable N95 stop-gap filtering facepiece respirator that can match existent commercial respirators. This sets a precedence for adoption of novel stop-gap N95 respirators in emergency situations.

Population analysis of predictors of difficult intubation with direct laryngoscopy in pediatric patients with and without thyroid disease.

PURPOSE: There are no data on the prevalence and predictors of difficult intubation (DI) in pediatric patients with thyroid disease. This study (1) assesses the prevalence of DI in patients with thyroid disease undergoing elective operations, (2) identifies other predictors of DI in children, and (3) evaluates the effect of DI on postoperative care and length-of-stay. METHODS: A single-center retrospective cohort analysis of procedures in patients assigned with an ICD-9 code for thyroid disease between June 2012 and February 2016. A comparative group was created which comprised of patients without thyroid disease receiving orthopedic or urologic surgeries to determine differences in DI prevalence. Univariate analyses compared demographics and intubation details between groups, and logistic regression identified independent variables associated with DI. Patients with and without DI were compared based on procedure duration, PACU-LOS, and escalation-of-care. RESULTS: DI prevalence was greater in the thyroid group (4.9%, 51/1046) compared to the non-thyroid group (2.6%, 33/1289) (OR 1.95, 95% CI 1.25-3.05; p = 0.003). DI was associated with younger age, higher American Society of Anesthesiologists (ASA) class, and smaller body habitus (p < 0.001 for all comparisons). Congenital hypothyroidism (OR 2.49, 95% CI 1.44-4.32; p = 0.002)) and acquired hypothyroidism (OR 2.20, 95% CI 1.42-3.41; p < 0.001) were seen in a greater proportion of DI patients. After adjustment for demographic confounders, age and ASA class were independently associated with DI (p < 0.05), while hypothyroidism did not reach statistical significance (p = 0.077). Direct laryngoscopy (DL) was most frequently used as the successful subsequent maneuver in securing the airway in DI patients. A longer PACU length-of-stay was seen after procedures with DI (p < 0.001). CONCLUSION: Elective pediatric surgical patients with thyroid-related diagnoses at our institution had a higher prevalence of DI than those without thyroid disease, but this finding could not be isolated to thyroid pathology. Repeat DL achieves successful intubation in the majority of DI patients. DI patients often require longer recovery times due to prolonged cardiopulmonary monitoring.