McKay R T, Davies E
Department of Environmental Health, University of Cincinnati Medical Center, Ohio, USA.
Appl Occup Environ Hyg. 2000 Jun;15(6):479-84. doi: 10.1080/104732200301269.
This study was designed to evaluate and compare the ability of respirator wearers to detect qualitative respirator fit test agents (saccharin and Bitrex) when the respirators were modified to include fixed size leaks. In recent years the number of persons who require fit testing has increased, partly in response to the needs of health care workers with potential exposure to infectious bio-aerosols. Many health care providers have chosen qualitative respirator fit testing using saccharin and/or Bitrex for a variety of reasons, including (but not limited to) low initial equipment cost. Respirators were modified to include a mid-line sampling probe between the nose and mouth for quantitative fit testing with a TSI PortaCount. A second modification included the introduction of a shortened 14-gauge intravenous catheter at the bridge of the nose. The fixed leak was designed to produce fit factors < 100 when unplugged, with an average fit factor of 67 among 26 respirator wearers. A complete fit test was not performed, because one purpose of this study was to determine the ability of respirator wearers to detect a known fixed leak during a single normal breathing exercise, without introducing unknown and potentially variable size leaks. Sensitivity threshold screening included a placebo and requirement to correctly characterize the taste of the agent used. Quantitative fit factors without leaks ranged from 96 to > 20,000 and 22 to 160 with the leak present. Twenty four of 26 subjects had fit factors < 100 (92%) when fixed leaks were induced. All subjects correctly detected Bitrex with fixed leaks (sensitivity = 100%). Nine of 26 subjects (35%) were unable to detect saccharin in the presence of a known fixed leak even though the average fit factor for these subjects was 77. When the two subjects with fit factors > 100 were excluded, only 16 of 24 respirator wearers were able to detect saccharin with fixed leaks (sensitivity = 67%). There were several important aspects of our study design worth noting, including the introduction of a placebo during sensitivity threshold testing, limiting the subject response time to a single maneuver, using a higher concentration of Bitrex than commercially available, and requiring the subjects to correctly characterize the taste of the qualitative test agent. In conclusion, leak detection was correctly identified with Bitrex, but not saccharin.
本研究旨在评估和比较当呼吸器被改装以包含固定尺寸泄漏时，呼吸器佩戴者检测定性呼吸器适合性测试剂（糖精和倍他糖）的能力。近年来，需要进行适合性测试的人数有所增加，部分原因是为了满足可能接触传染性生物气溶胶的医护人员的需求。许多医疗保健提供者出于各种原因选择使用糖精和/或倍他糖进行定性呼吸器适合性测试，包括（但不限于）初始设备成本低。呼吸器被改装，在鼻子和嘴巴之间设置一个中线采样探头，以便使用TSI PortaCount进行定量适合性测试。第二项改装包括在鼻梁处引入一根缩短的14号静脉导管。固定泄漏的设计目的是在不拔除时产生小于100的适合因数，26名呼吸器佩戴者的平均适合因数为67。未进行完整的适合性测试，因为本研究的一个目的是确定呼吸器佩戴者在单次正常呼吸运动期间检测已知固定泄漏的能力，而不引入未知的且可能大小可变的泄漏。敏感性阈值筛查包括使用安慰剂以及要求正确辨别所使用测试剂的味道。无泄漏时的定量适合因数范围为96至大于20000，有泄漏时为22至160。26名受试者中有24名在诱导固定泄漏时适合因数小于100（92%）。所有受试者都能正确检测到有固定泄漏时的倍他糖（敏感性 = 100%）。26名受试者中有9名（35%）即使这些受试者的平均适合因数为77，在存在已知固定泄漏时也无法检测到糖精。当排除适合因数大于100的两名受试者后，24名呼吸器佩戴者中只有16名能够检测到有固定泄漏时的糖精（敏感性 = 67%）。我们的研究设计有几个重要方面值得注意，包括在敏感性阈值测试期间引入安慰剂、将受试者的反应时间限制为单次动作、使用比市售产品浓度更高的倍他糖，以及要求受试者正确辨别定性测试剂的味道。总之，使用倍他糖能正确识别泄漏，但使用糖精则不能。
