Impulse oscillometry in acute and stable asthmatic children: a comparison with spirometry

<i>Objective</i>: Lung function tests have attracted interest for the diagnosis and follow-up of childhood asthma in recent years. For patients who cannot perform forced expiratory maneuvers, impulse oscillometry (IOS), performed during spontaneous breathing, may be an alternative tool. <i>Methods</i>: Thirty-five acute, 107 stable asthmatic and 103 healthy children who presented to our clinic performed IOS followed by spirometry before and after salbutamol inhalation. The mean baseline and reversibility of IOS and spirometry parameters were compared between the groups. Correlation analyses were undertaken within the asthmatics, and the healthy controls separately. To distinguish the three groups, the sensitivity and specificity of baseline and reversibility values of IOS and spirometry were computed. When spirometry was taken as the gold standard, the discriminating performance of IOS to detect the airway obstruction and reversibility was investigated. <i>Results</i>: The mean absolute values of Zrs, R5, R5−R20, X5, X10, X15, Fres, AX, and all spirometric parameters, and the mean reversibility values of R5, R10, Fres, AX and forced expiratory volume in one second were different between the groups and the highest area under curve values to discriminate the groups was obtained from area of reactance (AX) and ΔAX. Zrs, all resistance (including R5−R20) and reactance parameters, Fres and AX were correlated with at least one spirometric parameter. Spirometric reversibility was detected by ≤−22.34 and ≤−39.05 cut-off values of ΔR5 and ΔAX, respectively. <i>Conclusions</i>: IOS has shown a highly significant association with spirometric indices and reversibility testing. It may be a substitute for spirometry in children who fail to perform forced expiratory maneuvers.

### 研究目的（Objective）：近年来，肺功能检测在儿童哮喘的诊断与随访中受到广泛关注。对于无法完成用力呼气动作的患者，自发呼吸状态下开展的脉冲振荡肺功能检测（impulse oscillometry, IOS）或可作为替代检测工具。
### 研究方法：就诊于本门诊的35例急性哮喘患儿、107例稳定期哮喘患儿及103例健康儿童参与本研究，所有受试者均先行接受IOS检测，随后在沙丁胺醇吸入前后分别完成肺量计检测（spirometry）。研究对各组IOS与肺量计参数的基线均值及可逆性指标开展组间比较；分别在哮喘患儿群体与健康对照组内进行相关性分析；为区分上述三组人群，计算IOS及肺量计检测的基线值与可逆性指标的灵敏度与特异度；以肺量计检测为金标准，探究IOS在识别气道阻塞及可逆性改变中的鉴别效能。
### 研究结果：各组间Zrs、R5、R5−R20、X5、X10、X15、Fres、AX以及所有肺量计参数的平均绝对值，与R5、R10、Fres、AX及一秒用力呼气容积的平均可逆性值均存在显著差异；其中，电抗面积（AX）与ΔAX的曲线下面积最高，可实现最优的组间区分效能。Zrs、所有阻力参数（含R5−R20）与电抗参数、Fres及AX均与至少一项肺量计参数存在相关性。通过ΔR5≤−22.34与ΔAX≤−39.05的截断值，可分别检测出肺量计可逆性改变。
### 研究结论：IOS检测结果与肺量计指标及可逆性检测结果存在高度显著的相关性，对于无法完成用力呼气动作的儿童，IOS或可作为肺量计检测的替代手段。