3D Printed frames to enable reuse and improve the fit of N95 and KN95 respirators

BackgroundIn response to supply shortages during the COVID-19 pandemic, N95 filtering facepiece respirators (FFRs or "masks"), which are typically single-use devices in healthcare settings, are routinely being used for prolonged periods and in some cases decontaminated under "reuse" and "extended use" policies. However, the reusability of N95 masks is often limited by degradation or breakage of elastic head bands and issues with mask fit after repeated use. The purpose of this study was to develop a frame for N95 masks, using readily available materials and 3D printing, which could replace defective or broken bands and improve fit. ResultsAn iterative design process yielded a mask frame consisting of two 3D-printed side pieces, malleable wire links that users press against their face, and cut lengths of elastic material that go around the head to hold the frame and mask in place. Volunteers (n= 41; average BMI= 25.5), of whom 31 were women, underwent qualitative fit with and without mask frames and one or more of four different brands of FFRs conforming to US N95 or Chinese KN95 standards. Masks passed qualitative fit testing in the absence of a frame at rates varying from 48 - 92% (depending on mask model and tester). For individuals for whom a mask passed testing, 75-100% (average = 86%) also passed testing with a frame holding the mask in place. Among users for whom a mask failed in initial fit testing, 41% passed using a frame. Success varied with mask model and across individuals. ConclusionsThe use of mask frames can prolong the lifespan of N95 and KN95 masks by serving as a substitute for broken or defective bands without adversely affecting fit. Frames also have the potential to improve fit for some individuals who cannot fit existing masks. Frames therefore represent a simple and inexpensive way of extending the life and utility of PPE in short supply. For clinicians and institutions interested in mask frames, designs and specifications are provided without restriction for use or modification. To ensure adequate performance in clinical settings, qualitative fit testing with user-specific masks and frames is required.

Clinical analysis of tympanosclerosis: characteristics and treatment / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To explore the clinical characteristics, diagnosis and surgical management of tympanosclerosis.@*METHOD@#The data of 73 patients who underwent surgery for tympanosclerosis were retrospectively analyzed with respects to the clinical characteristics, diagnosis and management.@*RESULT@#Seventy-three patients with tympanosclerosis (involving 73 ears) , including 17 patients with sclerosis of tympanic membrane (type I), 23 patients with fixed Malleus-incus complex (type II), 8 (type III) with fixed stapes, and 25 (type IV) with extensive typannosclerosis. Sclerosis was seen most frequently in the malleus, incus and attic, followed by the tympanic membrane, incudomalleolar joint and other regions. Audiometry was performed for all the patients 1 weeks before and 1 year( the least) after operation, which were (51.70 ± 14.93)dB HL and (36.24 ± 11.58) dB HL respectively, with success rate 83% (61/73).@*CONCLUSION@#Most of the patients suffer from conductive hearing loss. Teatment of the sclerosis around stapes is a key point. Acording to the sites of lesion and hearing level, hearing structures should be reconstructed by the rules of tympanoplasty and stapes surgery.

The Application of the Three Dimension Reconstruction with Multi-slice Helical CT in Acetabular Fractures / 实用放射学杂志

Objective To assess the clinial application of 3D reconstruction with MSCT for acetabular fractures.Methods Volume scanning was performed in 20 patients with acetabular fractures,all data sets were transferred to workstation.Reconstruction were done with more thinner slices.Results Acetabular frature 3D images went all the way with the results of surgery in 17 cases.Conclusion MSCT 3D images can compare beauty with gross specimen,which could be propitious to the subtype of acetabulum fracture and have an advantage in the application.