Motoyama E K, Hen J, Tamas L, Dolan T F
Am Rev Respir Dis. 1982 Nov;126(5):766-70. doi: 10.1164/arrd.1982.126.5.766.
In children with obstructive lung disease, the determination of functional resident capacity by the conventional helium dilution method [FRC(He)] often results in gross underestimations. This is due to exceptionally poor He mixing in children, which may be related to characteristics of the developing lung. We added a low level (2.5 cmH2O) of continuous positive pressure to the airway (CPAP) for 2 min beyond the end of conventional He rebreathing to evaluate its effect on gas mixing. The FRC was determined again from He concentration 1 min after CPAP was stopped. We recorded the results as an increase in measured FRC after CPAP (delta FRC) as percent of FRC(He). A total of 46 children (mean age: 13.5 yr) were studied, including those with normal lung function, those with central airway disease, and those with peripheral airway obstruction. With CPAP, delta FRC increased markedly in those with peripheral airway obstruction and was significantly correlated with volume of isoflow and the volume of trapped gas. Thus, the measurement of delta FRC is simple yet useful in detecting peripheral airway obstruction and air trapping.
在患有阻塞性肺病的儿童中，采用传统氦稀释法测定功能残气量[FRC(He)]常常会导致严重低估。这是因为儿童的氦气混合情况异常不佳，这可能与发育中的肺部特征有关。在传统氦气重复呼吸结束后，我们在气道上施加低水平（2.5 cmH₂O）的持续气道正压（CPAP）2分钟，以评估其对气体混合的影响。在停止CPAP 1分钟后，再次根据氦浓度测定FRC。我们将结果记录为CPAP后测量的FRC增加量（ΔFRC）占FRC(He)的百分比。总共研究了46名儿童（平均年龄：13.5岁），包括肺功能正常的儿童、患有中央气道疾病的儿童以及患有外周气道阻塞的儿童。使用CPAP时，外周气道阻塞患儿的ΔFRC显著增加，并且与等流量体积和滞留气体体积显著相关。因此，测量ΔFRC在检测外周气道阻塞和气体滞留方面简单而有用。
