Portex Respiratory Unit, UCL Institute of Child Health and Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK.
Pediatr Pulmonol. 2013 Apr;48(4):370-80. doi: 10.1002/ppul.22656. Epub 2012 Sep 4.
With increasing use of infant pulmonary function tests (IPFTs) in both clinical and research studies, appropriate interpretation of results is essential.
To investigate the potential bias associated with "normalising" IPF by expressing results as a ratio of body size and to develop reference ranges for tidal breathing parameters, passive respiratory mechanics (compliance [Crs] and resistance [Rrs]) and plethysmographic functional residual capacity (FRCp ) for white infants during the first 2 years of life.
IPFTs were measured using the Jaeger BabyBody system and standardized protocols. Reference equations, adjusted for body size, age, and sex where appropriate, were created using multilevel modeling.
The ratio of lung function to body length changes markedly with growth, thereby precluding its use for any outcome. While the ratio of tidal volume and Crs to body weight remained relatively constant with growth, this was not the case for FRCp . Even in healthy infants, a strong inverse relationship was observed between lung function/body weight and weight z-score which could distort interpretation of results in growth-restricted infants with lung disease, such as cystic fibrosis. Reference equations were derived from 153 healthy white infants on 232 test occasions (median age 35.5 weeks [range: 2.6-104.7]). Crown-heel length was the strongest predictor of IPF.
When reporting IPF, use of size-corrected ratios should be discouraged, with interpretation instead based on appropriate reference equations. The current equations are applicable to white infants and young children up to 2 years of age, studied using the same commercially available equipment. The extent to which these equations are applicable to infants and young children of other ethnic backgrounds or who are tested with different equipment needs to be established.
随着婴儿肺功能测试（IPFT）在临床和研究中的应用越来越广泛，正确解读测试结果至关重要。
研究通过将测试结果表示为身体大小的比值来“标准化” IPFT 可能存在的偏差，并为白人婴儿在生命的头 2 年的潮气呼吸参数、被动呼吸力学（顺应性[Crs]和阻力[Rrs]）和体描仪功能残气容量（FRCp）建立参考范围。
使用 Jaeger BabyBody 系统和标准化方案进行 IPFT 测量。使用多层次模型创建适当地调整了身体大小、年龄和性别的参考方程。
肺功能与身长的比值随生长而显著变化，因此不能用于任何结果。虽然潮气量和 Crs 与体重的比值随生长而保持相对稳定，但 FRCp 并非如此。即使在健康婴儿中，也观察到肺功能/体重与体重 z 分数之间存在强烈的负相关关系，这可能会扭曲对患有肺部疾病（如囊性纤维化）的生长受限婴儿的结果解读。参考方程来自 153 名健康白人婴儿在 232 次测试中的数据（中位数年龄 35.5 周[范围：2.6-104.7]）。头-脚长是 IPFT 的最强预测因子。
在报告 IPFT 时，应避免使用大小校正比值，而应根据适当的参考方程进行解释。目前的方程适用于使用相同商业可用设备研究的 2 岁以下的白人婴儿和幼儿。这些方程在多大程度上适用于其他族裔背景的婴儿和幼儿，或者适用于使用不同设备进行测试的婴儿和幼儿，尚需进一步研究。
