Impulse oscillometry (IOS) for detection of exercise induced bronchoconstriction in children with asthma ages 6–15 years

To determine the discriminatory value of various impulse oscillometry (IOS) parameters, and to find the cutoff value of the appropriate parameter for identifying exercise-induced bronchoconstriction (EIB) in children with asthma. This cross-sectional study was conducted in India from October 2016 to March 2018 in children with asthma who were 6–15 years of age. One hundred and five children were enrolled and subjected to pre-exercise IOS and spirometry followed by free running treadmill test as an exercise challenge. All children could achieve minute ventilation >17.5–21 times of FEV1 during the exercise challenge test. Then, IOS and spirometry were performed at 10 ± 2, 20 ± 2, and 30 ± 2 min post-exercise challenge. EIB was defined as reduction of FEV1 ≥10% within 30 min of exercise. For purposes of analysis, the children were grouped into two categories: “EIB Present” or “EIB Absent”. The prevalence of EIB in our study was 20.95% (n = 22). ΔR5max percentage within 30 min post-exercise (AUC 0.74; 95% CI: 0.64, 0.84) had the best discriminating capacity among all IOS parameters for identifying EIB. A cutoff value of 14.1% increase in R5 within 30 min post-exercise was obtained for detection of EIB (sensitivity—95.45%, specificity—50.6%, PPV—33.87% and NPV—97.67%). A percentage change in R5 with a cutoff value of 14.1% increase post-exercise had the best discriminatory capacity among all IOS parameters for detection of EIB in children with asthma. However, low positive predictive value (PPV) with high negative predictive value (NPV) made this cutoff value more apt to rule out EIB.

为明确各类脉冲振荡肺功能检测（impulse oscillometry, IOS）参数的判别价值，并筛选可用于识别哮喘儿童运动诱发性支气管收缩（exercise-induced bronchoconstriction, EIB）的适宜参数截断值，本研究于2016年10月至2018年3月在印度开展，纳入对象为6~15岁的哮喘患儿。
本研究为横断面研究，共纳入105名哮喘儿童，所有受试者均接受运动前IOS检测与肺量计检测，随后进行自由平板运动试验作为运动激发试验。所有受试者在运动激发试验期间的分钟通气量均达到17.5~21倍一秒用力呼气容积（FEV1）。
运动激发试验结束后，分别于10±2、20±2、30±2分钟时重复开展IOS检测与肺量计检测。本研究将EIB定义为运动后30分钟内FEV1下降幅度≥10%，并按分析需求将受试者分为"EIB阳性"与"EIB阴性"两组。
本研究中EIB的患病率为20.95%（n = 22）。在所有IOS参数中，运动后30分钟内最大R5（ΔR5max）百分比变化的判别效能最优，其受试者工作特征曲线下面积（AUC）为0.74，95%置信区间（CI）为0.64~0.84。以运动后30分钟内R5升高14.1%作为截断值检测EIB，其灵敏度为95.45%，特异度为50.6%，阳性预测值（PPV）为33.87%，阴性预测值（NPV）为97.67%。
相较于其他IOS参数，运动后R5百分比变化以14.1%升高作为截断值时，对哮喘儿童EIB的判别效能最佳。但该截断值的阳性预测值较低、阴性预测值较高，因此更适用于排除EIB诊断。