McAvoy Malia, Bui Ai-Tram N, Hansen Christopher, Plana Deborah, Said Jordan T, Yu Zizi, Yang Helen, Freake Jacob, Van Christopher, Krikorian David, Cramer Avilash, Smith Leanne, Jiang Liwei, Lee Karen J, Li Sara J, Beller Brandon, Huggins Kimberley, Short Michael P, Yu Sherry H, Mostaghimi Arash, Sorger Peter K, LeBoeuf Nicole R
Greater Boston Pandemic Fabrication Team (PanFab) c/o Harvard-MIT Center for Regulatory Science, Harvard Medical School, Boston, MA, USA.
Department of Neurosurgery, University of Washington, Seattle, WA, USA.
BMC Biomed Eng. 2021 Jun 7;3(1):10. doi: 10.1186/s42490-021-00055-7.
In response to supply shortages caused by 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 limited by degradation of fit. Possible substitutes, such as KN95 masks meeting Chinese standards, frequently fail fit testing even when new. The purpose of this study was to develop an inexpensive frame for damaged and poorly fitting masks using readily available materials and 3D printing.
An 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 = 45; average BMI = 25.4), underwent qualitative fit testing with and without mask frames wearing 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 to 94 % (depending on mask model). For individuals who underwent testing using respirators with broken or defective straps, 80-100 % (average 85 %) passed fit testing with mask frames. Among individuals who failed fit testing with a KN95, ~ 50 % passed testing by using a frame.
Our study suggests that 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. Use of frames made it possible for ~ 73 % of the test population to achieve a good fit based on qualitative and quantitative testing criteria, approaching the 85-90 % success rate observed for intact N95 masks. Frames therefore represent a simple and inexpensive way of expanding access to PPE and extending their useful life. 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, fit testing with user-specific masks and PanFab frames is required.
为应对新冠疫情导致的供应短缺，N95过滤式面罩呼吸器（FFR或“口罩”），这种在医疗环境中通常为一次性使用的设备，现在经常被长时间使用，并且在某些情况下根据“重复使用”和“延长使用”政策进行消毒处理。然而，N95口罩的可重复使用性受到贴合性下降的限制。可能的替代品，如符合中国标准的KN95口罩，即使是新的，也经常在贴合性测试中不合格。本研究的目的是使用现成材料和3D打印技术，为损坏且贴合性差的口罩开发一种低成本的框架。
一个迭代设计过程产生了一种口罩框架，它由两个3D打印的侧片、用户可按压在脸上的可锻金属丝连接件，以及绕头的弹性材料切段组成，用于将框架和口罩固定到位。志愿者（n = 45；平均BMI = 25.4）佩戴一种或多种符合美国N95或中国KN95标准的四种不同品牌FFR，在有和没有口罩框架的情况下进行定性贴合性测试。在没有框架的情况下，口罩通过定性贴合性测试的比例从48%到94%不等（取决于口罩型号）。对于使用肩带断裂或有缺陷的呼吸器进行测试的个体，80%-100%（平均85%）通过了使用口罩框架的贴合性测试。在使用KN95口罩贴合性测试失败的个体中，约50%通过使用框架通过了测试。
我们的研究表明，口罩框架可以作为断裂或有缺陷的绑带的替代品，从而延长N95和KN95口罩的使用寿命，且不会对贴合性产生不利影响。根据定性和定量测试标准，使用框架使约73%的测试人群能够实现良好的贴合，接近完整N95口罩观察到的85%-90%的成功率。因此，框架是一种简单且低成本的方式，可扩大个人防护装备的可及性并延长其使用寿命。对于对口罩框架感兴趣的临床医生和机构，我们提供了设计和规格，可自由使用或修改。为确保在临床环境中的充分性能，需要使用特定用户的口罩和PanFab框架进行贴合性测试。
