Mazurek H K, Marchal F, Derelle J, Hatahet R, Moneret-Vautrin D, Monin P
Laboratoire d'Exploration Fonctionnelles Pédiatriques, Hôpital d'Enfants Service de Médecine D, Centre Hospitalier Universitaire de Nancy, France.
Chest. 1995 Apr;107(4):996-1002. doi: 10.1378/chest.107.4.996.
Flow in the upper airway wall induces significant error in estimating respiratory impedance by the standard forced oscillation technique in subjects with airway obstruction and may be minimized by oscillating pressure around the subject's head (head generator technique). The aim of this study was to determine whether the latter improves the power of forced oscillations in detecting airway response to bronchodilators in children. Seventy-five children with airway obstruction were studied (ages 5.5 to 15 years old). Fifty-three had asthma and 22, cystic fibrosis. A bronchodilator was administered, and the percent changes in respiratory resistance at 10 Hz (Rrs10), 20 Hz (Rrs20), respiratory compliance (Crs), and resonant frequency (fn) with standard and head generator were compared with the corresponding change in FEV1. The response was positive in 38 (delta % FEV1 > or = 15%) and negative in 37 patients. Data on Rrs10, Crs, and fn could not be obtained in 7, 8, and 4 subjects, respectively, for technical reasons. The delta % Rrs20 was not different between head and standard generator in nonresponders (mean +/- SEM: -19.0 +/- 4.5, vs -11.8 +/- 3.1%), but significantly larger with head than standard generator in responders (-54.1 +/- 3.0 vs -26.5 +/- 2.4%; p < 0.001). The optimal decision level determined by Receiver Operation Characteristic analysis showed that, compared with the standard method, the head generator improved the specificity of Rrs20 (78 vs 65%) with no change in sensitivity (76% for both). Resonant frequency had larger sensitivity with standard than with head generator (91 vs 53%) but slightly lower specificity (70 vs 78%). Finally, delta %Crs was more specific (72 vs 67%) and more sensitive (68 vs 52%) with standard than with head generator. The overall incidence of false results was lower with the head generator than with the standard generator for resistance and lower with the standard generator than with the head generator for fn and compliance. Thus, the head generator improves the diagnostic power of the forced oscillation resistance in establishing the reversibility of airway obstruction, but parameters derived from the reactance may have better diagnostic value with the standard method.
在上气道壁中的气流，会导致采用标准强迫振荡技术估计气道阻塞患者的呼吸阻抗时产生显著误差，而通过在受试者头部周围振荡压力（头部发生器技术），这种误差可能会降至最低。本研究的目的是确定后者是否能提高强迫振荡检测儿童气道对支气管扩张剂反应的能力。对75名气道阻塞儿童（年龄5.5至15岁）进行了研究。其中53名患有哮喘，22名患有囊性纤维化。给予支气管扩张剂后，比较了采用标准方法和头部发生器方法时，10赫兹（Rrs10）、20赫兹（Rrs20）处的呼吸阻力、呼吸顺应性（Crs）以及共振频率（fn）的百分比变化与第一秒用力呼气容积（FEV1）相应变化之间的关系。38名患者反应为阳性（Δ%FEV1≥15%），37名患者反应为阴性。由于技术原因，分别有7、8和4名受试者无法获得Rrs10、Crs和fn的数据。在无反应者中，头部发生器和标准发生器的Δ%Rrs20无差异（平均值±标准误：-19.0±4.5，对比-11.8±3.1%），但在有反应者中，头部发生器的Δ%Rrs20显著大于标准发生器（-54.1±3.0对比-26.5±2.4%；p<0.001）。受试者工作特征分析确定的最佳决策水平表明，与标准方法相比，头部发生器提高了Rrs20的特异性（78%对比65%），而敏感性没有变化（两者均为76%）。共振频率采用标准方法时的敏感性高于头部发生器（91%对比53%），但特异性略低（70%对比78%）。最后，对于Crs，标准方法的特异性（72%对比67%）和敏感性（68%对比52%）均高于头部发生器。对于阻力，头部发生器产生的假结果总体发生率低于标准发生器；对于fn和顺应性，标准发生器产生的假结果总体发生率低于头部发生器。因此，头部发生器提高了强迫振荡阻力在确定气道阻塞可逆性方面的诊断能力，但电抗衍生参数采用标准方法时可能具有更好的诊断价值。
