Pierce R J, Brown D J, Holmes M, Cumming G, Denison D M
Thorax. 1979 Dec;34(6):726-34. doi: 10.1136/thx.34.6.726.
The cross-sectional shapes of the chest and its contained structures have been assessed in post-mortem anatomical sections and from computerised tomographic scans in living subjects. These shapes are described by simple equations that can be used to increase the accuracy of measuring lung volumes from chest radiographs. Radiographic estimates of total lung capacity, using the equations, were compared with plethysmographic and single-breath helium dilution measurements in 35 normal subjects. The postures commonly used for taking chest radiographs were found, on average, to decrease total lung capacity (TLC) and to increase residual volume by about 200 ml when compared with the sitting positions used for the other two measurements (studies made in 18 of the subjects). After correction for this effect, the radiographic estimates of TLC, which measure the displacement volume of the lung, exceeded the plethysmographic estimates of contained gas volume by a mean of 720 ml, which was taken as the volume of tissue, blood, and water in the lungs. The single-breath dilution estimates of TLC fell short of the plethysmographic values by a mean of 480 ml, taken as the volume of contained gas that was inaccessible to helium in 10 seconds. The tomographic studies suggested that the radiographic technique of measuring lung displacement volumes has an accuracy of +/- 210 ml. The method is rapid and simple to use and has intra- and inter-observer variabilities of less than 1% and less than 5% respectively.
已在尸检解剖切片以及活体受试者的计算机断层扫描中评估了胸部及其所含结构的横截面形状。这些形状由简单的方程式描述，可用于提高从胸部X光片测量肺容积的准确性。使用这些方程式对35名正常受试者的肺总量进行X光片估计，并与体积描记法和单次呼吸氦稀释测量结果进行比较。结果发现，与用于其他两项测量的坐姿（对18名受试者进行的研究）相比，通常用于拍摄胸部X光片的姿势平均会使肺总量（TLC）降低，并使残气量增加约200毫升。校正此效应后，测量肺移位容积的TLC的X光片估计值比体积描记法估计的所含气体容积平均高出720毫升，这被视为肺中组织、血液和水的容积。TLC的单次呼吸稀释估计值比体积描记法值平均低480毫升，这被视为10秒内氦无法进入的所含气体容积。断层扫描研究表明，测量肺移位容积的X光片技术的准确度为±210毫升。该方法快速且易于使用，观察者内和观察者间的变异性分别小于1%和小于5%。
