Schmalisch G, Wauer R R
Universitäts-Kinderklinik (Charité), Berlin.
Monatsschr Kinderheilkd. 1993 Sep;141(9):714-20.
Helium dilution or nitrogen washout techniques are commonly used to measure the functional residual capacity (FRC) in newborn babies. For both techniques equipment is available. Its clinical application, however, was difficult since there were no FRC reference ranges for the different weight groups of newborn infants; reference studies are very time consuming and cause several technical and ethical problems.
Statistical methods were used to evaluate several results from the literature and to exclude significantly differing data of some authors. Measured values of FRC were related to body weight, and the percentiles of FRC/kg were estimated by the smoothed cumulative distribution function of the pooled data.
No significant differences were found between the results of helium dilution and nitrogen washout techniques. The distribution of 178 results showed a significant skewedness (x5% = 18.3 ml/kg; x50% = 27.5 ml/kg x95% = 42.8 ml/kg), which could also be seen in the percentile curves calculated approximately, assuming a linear development of functional residual capacity with body weight.
Percentile curves describe best the development and interindividual variability of FRC in newborn babies as our evaluation could show. We conclude that the nonparametric estimation of percentiles is more adequate for the description than the use of simple regression models.
氦稀释法或氮洗出法常用于测量新生儿的功能残气量（FRC）。这两种技术都有相应设备。然而，由于缺乏不同体重组新生儿的FRC参考范围，其临床应用存在困难；参考研究非常耗时，且会引发一些技术和伦理问题。
运用统计方法评估文献中的多个结果，并排除部分作者差异显著的数据。将FRC测量值与体重相关联，通过合并数据的平滑累积分布函数估算FRC/kg的百分位数。
氦稀释法和氮洗出法的结果之间未发现显著差异。178个结果的分布显示出明显的偏态（第5百分位数 = 18.3 ml/kg；第50百分位数 = 27.5 ml/kg；第95百分位数 = 42.8 ml/kg），在假设功能残气量随体重呈线性发展而大致计算出的百分位数曲线中也能看出这种偏态。
如我们的评估所示，百分位数曲线能最好地描述新生儿FRC的发育情况和个体间差异。我们得出结论，与使用简单回归模型相比，百分位数的非参数估计更适合用于描述。
