Knihtilä Hanna, Kotaniemi-Syrjänen Anne, Pelkonen Anna S, Kalliola Satu, Mäkelä Mika J, Malmberg Leo Pekka
Pediatric Unit of the Department of Allergy, Skin and Allergy Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
Pediatr Pulmonol. 2017 Oct;52(10):1260-1267. doi: 10.1002/ppul.23794. Epub 2017 Aug 18.
The impulse oscillometry (IOS) indices absolute and relative difference between respiratory resistance at 5 and 20 Hz (R5-20 and R5-20%, respectively) and the area under the reactance curve (AX) are postulated to reflect small airway function. Data on their cutoff values to evaluate bronchodilator responsiveness (BDR) or between-visit changes after interventions are limited in young children.
We evaluated the BDR of 103 healthy children aged 2-7 years, who received either salbutamol (n = 84) or placebo (n = 19) in order to determine cutoff values for BDR of R5-20, R5-20%, and AX. We then determined the repeatability within and between two IOS measurements 7-14 days apart in young children aged 4-8 years with asthmatic symptoms (n = 43), including cutoff values for significant between-visit changes.
The investigated IOS parameters showed marked BDR (fifth percentile cutoff of 75-110% of the baseline value) in healthy children, whereas no significant changes were seen after inhalation of placebo. The agreement within the triplicate IOS measurement was excellent (ICC > 0.80), and the agreement of results between visits was good (ICC > 0.60). A change in R5-20, R5-20%, and AX of 0.65, 1.08, and 0.84 z-scores, respectively, would exceed 95% confidence intervals for between-visit variability.
We introduce cutoff values for BDR of R5-20, R5-20%, and AX, and their repeatability indices and cutoff limits for significant between-visit changes. These IOS parameters may show greater variability than the conventional IOS indices during follow-up, but the between-visit agreement remains good, providing potentially useful endpoints for monitoring lung function in young children.
脉冲振荡法（IOS）指标，即5赫兹和20赫兹时呼吸阻力的绝对值和相对差值（分别为R5-20和R5-20%）以及电抗曲线下面积（AX），被认为可反映小气道功能。关于其用于评估幼儿支气管扩张剂反应性（BDR）或干预后随访期间变化的临界值的数据有限。
我们评估了103名2至7岁健康儿童的BDR，这些儿童接受了沙丁胺醇（n = 84）或安慰剂（n = 19）治疗，以确定R5-20、R5-20%和AX的BDR临界值。然后我们确定了4至8岁有哮喘症状儿童（n = 43）在间隔7至14天的两次IOS测量中，测量值在测量内和测量间的重复性，包括随访期间有显著变化的临界值。
在健康儿童中，所研究的IOS参数显示出明显的BDR（第五百分位数临界值为基线值的75%-110%），而吸入安慰剂后未见显著变化。IOS重复测量三次之间的一致性极佳（组内相关系数>0.80），随访间结果的一致性良好（组内相关系数>0.60）。R5-20、R5-20%和AX分别变化0.65、1.08和0.84个z分数，将超过随访间变异性的95%置信区间。
我们引入了R5-20、R5-20%和AX的BDR临界值，以及它们的重复性指标和随访间有显著变化的临界限值。这些IOS参数在随访期间可能比传统IOS指标显示出更大的变异性，但随访间的一致性仍然良好，为监测幼儿肺功能提供了潜在有用的终点指标。
