Schmidt Anne, Yammine Sophie, Proietti Elena, Frey Urs, Latzin Philipp, Riedel Thomas, Singer Florian
Department of Pediatrics, University Hospital of Bern, Bern, Switzerland.
University Children's Hospital of Basel, Basel, Switzerland.
Pediatr Pulmonol. 2015 Jun;50(6):607-14. doi: 10.1002/ppul.23010. Epub 2014 Feb 25.
The new ATS/ERS consensus report recommends in vitro validation of multiple-breath inert gas washout (MBW) equipment based on a lung model with simulated physiologic conditions. We aimed to assess accuracy of two MBW setups for infants and young children using this model, and to compare functional residual capacity (FRC) from helium MBW (FRC(MBW)) with FRC from plethysmography (FRC(pleth)) in vivo.
The MBW setups were based on ultrasonic flow meter technology. Sulfur hexafluoride and helium were used as tracer gases. We measured FRC in vitro for specific model settings with and without carbon dioxide and calculated differences of measured to generated FRC. For in vivo evaluation, difference between FRC(MBW) and FRC(pleth) was calculated in 20 healthy children, median age 6.1 years. Coefficient of variation (CV) was calculated per FRC.
In the infant model (51 runs, FRC 80-300 ml), mean (SD) relative difference between generated and measured FRCs was 0.7 (4.7) %, median CV was 4.4% for measured FRCs. In the young child model, one setting (8 runs, FRC 400 ml) showed a relative difference of up to 13%. For the remaining FRCs (42 runs, FRC 600-1,400 ml), mean (SD) relative difference was -2.0 (3.4) %; median CV was 1.4% for measured FRCs. In vivo FRC(pleth) exceeded FRC(MBW) values by 37% on average.
Both setups measure lung volumes in the intended age group reliably and reproducibly. Characteristics of different techniques should be considered when measuring lung volumes in vivo.
美国胸科学会/欧洲呼吸学会新的共识报告建议基于具有模拟生理条件的肺模型对多呼吸惰性气体冲洗（MBW）设备进行体外验证。我们旨在使用该模型评估两种针对婴幼儿的MBW设置的准确性，并在体内比较氦气MBW测得的功能残气量（FRC）（FRC(MBW)）与体积描记法测得的FRC（FRC(pleth)）。
MBW设置基于超声波流量计技术。六氟化硫和氦气用作示踪气体。我们在有和没有二氧化碳的特定模型设置下体外测量FRC，并计算测得的FRC与生成的FRC之间的差异。对于体内评估，计算了20名健康儿童（中位年龄6.1岁）的FRC(MBW)与FRC(pleth)之间的差异。每个FRC计算变异系数（CV）。
在婴儿模型中（51次运行，FRC为80 - 300毫升），生成的FRC与测得的FRC之间的平均（标准差）相对差异为0.7（4.7）%，测得的FRC的中位CV为4.4%。在幼儿模型中，一种设置（8次运行，FRC为400毫升）显示相对差异高达13%。对于其余的FRC（42次运行，FRC为600 - 1400毫升），平均（标准差）相对差异为 - 2.0（3.4）%；测得的FRC的中位CV为1.4%。在体内，FRC(pleth)平均比FRC(MBW)值高37%。
两种设置都能可靠且可重复地测量目标年龄组的肺容积。在体内测量肺容积时应考虑不同技术的特点。
