School of Public Health & Community Medicine, The University of New South Wales, Sydney, NSW, Australia.
Crit Care Med. 2010 Feb;38(2):657-67. doi: 10.1097/ccm.0b013e3181b9e8b3.
The successful management of an influenza pandemic will be reliant on the expertise of healthcare workers at high risk for occupationally acquired influenza. Recommended infection control measures for healthcare workers include surgical masks to protect against droplet-spread respiratory transmissible infections and N95 masks to protect against aerosol-spread infections. A literature review was undertaken for evidence of superior protective value of N95 masks or surgical masks for healthcare workers against influenza and extraneous factors influencing conferred protection.
Four scientific search engines using 12 search sequences identified 21 mask studies in healthcare settings for the prevention of transmission of respiratory syncytial virus, Bordetella pertussis, and severe acute respiratory syndrome. Each was critically assessed in accordance with Australian National Health Medical Research Council guidelines. An additional 25 laboratory-based publications were also reviewed.
All studies reviewed used medium or lower level evidence study design. In the majority of studies, important confounders included the unrecognized impact of concurrent bundling of other infection control measures, mask compliance, contamination from improper doffing of masks, and ocular inoculation. Only three studies directly compared the protective value of surgical masks with N95 masks. The majority of laboratory studies identified both mask types as having a range of filtration efficiency, yet N95 masks afford superior protection against particles of a similar size to influenza.
World Health Organization guidelines recommend surgical masks for all patient care with the exception of N95 masks for aerosol generating procedures. Because of the paucity of high-quality studies in the healthcare setting, the advocacy of mask types is not entirely evidence-based. Evidence from laboratory studies of potential airborne spread of influenza from shedding patients indicate that guidelines related to the current 1-meter respiratory zone may need to be extended to a larger respiratory zone and include protection from ocular inoculation.
成功管理流感大流行将依赖于高风险职业性获得流感的医护人员的专业知识。建议医护人员采取的感染控制措施包括外科口罩，以防止飞沫传播的呼吸道传染性感染，以及 N95 口罩，以防止气溶胶传播的感染。进行了文献回顾，以寻找 N95 口罩或外科口罩对医护人员预防流感和影响所赋予保护的外来因素的保护价值的证据。
使用 12 个搜索序列的四个科学搜索引擎确定了 21 项在医疗保健环境中预防呼吸道合胞病毒、百日咳博德特氏菌和严重急性呼吸系统综合征传播的口罩研究。根据澳大利亚国家卫生医疗研究委员会的指南对每一项进行了严格评估。还审查了另外 25 项基于实验室的出版物。
所有审查的研究都使用了中等或较低水平的证据研究设计。在大多数研究中，重要的混杂因素包括其他感染控制措施同时实施的未被认识到的影响、口罩的合规性、口罩脱除不当造成的污染以及眼部接种。只有三项研究直接比较了外科口罩与 N95 口罩的保护价值。大多数实验室研究都确定了这两种口罩类型都具有一系列过滤效率，但 N95 口罩对类似大小的颗粒提供了更好的保护。
世界卫生组织指南建议在进行所有患者护理时使用外科口罩，但在产生气溶胶的程序中除外使用 N95 口罩。由于在医疗保健环境中缺乏高质量的研究，对口罩类型的倡导并非完全基于证据。关于从脱落患者传播的流感的潜在空气传播的实验室研究表明，与当前 1 米呼吸区相关的指南可能需要扩展到更大的呼吸区，并包括对眼部接种的保护。
