Chinn D J, Naruse Y, Cotes J E
Thorax. 1986 Feb;41(2):133-7. doi: 10.1136/thx.41.2.133.
Fifty lung function laboratories in England and Wales analysed test gas mixtures of carbon monoxide and helium. Most of them also analysed mixtures of oxygen and carbon dioxide in nitrogen. The percentage accuracy of the results was within 1% of the expected value in only 14% of determinations of carbon monoxide concentration, 28% for carbon dioxide, 37% for helium, and 48% for oxygen. The accuracy of ratios of two concentrations of helium and carbon monoxide was better than that of the individual gas samples. Overall the variation in results between laboratories was wide, the coefficient of variation ranging from about 3% for analysis of helium to 9% for carbon dioxide. This variation affected the values calculated for carbon monoxide transfer factor, where 20% were in error by more than 5%, and for the calculated value of the respiratory exchange ratio, where the interlaboratory coefficient of variation was about 10%. Errors in analysis were due to unsatisfactory calibration of analysers; five oxygen analysers had large zero errors; five carbon monoxide analysers and one helium analyser had notably curvilinear calibration curves. Insufficient information was obtained to ascertain the nature of the errors in analysis of carbon dioxide. Given the improvements in instrumentation, these results are evidence for deterioration in analytical standards in lung function laboratories from the standards of 20 years ago.
英格兰和威尔士的50个肺功能实验室分析了一氧化碳和氦气的测试气体混合物。其中大多数实验室还分析了氮气中的氧气和二氧化碳混合物。在一氧化碳浓度测定中，只有14%的结果百分比准确度在预期值的1%以内；二氧化碳为28%，氦气为37%，氧气为48%。氦气和一氧化碳两种浓度比值的准确度优于单个气体样本。总体而言，各实验室之间的结果差异很大，变异系数从氦气分析的约3%到二氧化碳分析的9%不等。这种差异影响了一氧化碳转移因子的计算值，其中20%的误差超过5%，以及呼吸交换率的计算值，实验室间变异系数约为10%。分析误差是由于分析仪校准不令人满意；五台氧气分析仪存在较大的零点误差；五台一氧化碳分析仪和一台氦气分析仪有明显的曲线校准曲线。没有获得足够的信息来确定二氧化碳分析误差的性质。鉴于仪器的改进，这些结果证明肺功能实验室的分析标准与20年前相比有所下降。
