State University of Rio de Janeiro, Institute of Biology, Biomedical Instrumentation Laboratory, Rio de Janeiro/RJ, Brazil.
Clinics (Sao Paulo). 2011;66(12):2085-91. doi: 10.1590/s1807-59322011001200014.
Several studies have confirmed the high potential of the forced oscillation technique for the assessment of respiratory modifications related to chronic obstructive pulmonary disease. However, most of these studies did not employ within-breath analyses of the respiratory system. The aim of this study is to analyze respiratory impedance alterations in different phases of the respiratory cycle of chronic obstructive pulmonary disease patients and to evaluate their clinical use.
39 individuals were evaluated, including 20 controls and 19 individuals with chronic obstructive pulmonary disease who experienced severe airway obstruction. We evaluated the mean respiratory impedance (Zm) as well as values for inspiration (Zi) and expiration cycles (Ze), at the beginning of inspiration (Zbi) and expiration (Zbe). The peak-to-peak impedance (Zpp), and the impedance change (ΔZrs) were also analyzed. The clinical usefulness was evaluated by investigating the sensibility, specificity and the area under the receiver operating characteristic curve.
The respiratory impedance increased in individuals with chronic obstructive pulmonary disease in all of the studied parameters (Zm, Zi, Ze, Zbi, Zbe, ΔZrs and Zpp). These changes were inversely associated with spirometric parameters. Higher impedances were observed in the expiratory phase of individuals with chronic obstructive pulmonary disease. All of the studied parameters, except for ΔZrs (area under the receiver operating characteristic ,0.8), exhibited high accuracy for clinical use (area under the receiver operating characteristic >0.90; Sensibility ≥ 0.85; Sp ≥ 0.85).
The respiratory alterations in severe chronic obstructive pulmonary disease may be identified by the increase in respiratory system impedance, which is more evident in the expiratory phase. These results confirm the potential of within-breath analysis of respiratory impedance for the assessment of respiratory modifications related to chronic obstructive pulmonary disease.
多项研究证实，强迫振荡技术在评估与慢性阻塞性肺疾病相关的呼吸变化方面具有很大潜力。然而，这些研究大多没有进行呼吸周期内的呼吸系统分析。本研究旨在分析慢性阻塞性肺疾病患者呼吸周期不同阶段的呼吸阻抗变化，并评估其临床应用价值。
共评估 39 例个体，包括 20 例对照者和 19 例患有严重气道阻塞的慢性阻塞性肺疾病患者。我们评估了平均呼吸阻抗（Zm）以及吸气（Zi）和呼气（Ze）周期、吸气开始时（Zbi）和呼气结束时（Zbe）的各项值。还分析了峰值到峰值阻抗（Zpp）和阻抗变化（ΔZrs）。通过研究敏感性、特异性和接收者操作特征曲线下面积，评估临床实用性。
在所有研究参数中（Zm、Zi、Ze、Zbi、Zbe、ΔZrs 和 Zpp），慢性阻塞性肺疾病患者的呼吸阻抗均增加。这些变化与肺量计参数呈负相关。慢性阻塞性肺疾病患者呼气阶段的阻抗更高。除了ΔZrs（接收者操作特征曲线下面积，0.8）外，所有研究参数均具有较高的临床应用准确性（接收者操作特征曲线下面积＞0.90；敏感性≥0.85；特异性≥0.85）。
在严重慢性阻塞性肺疾病患者中，呼吸系统阻抗的增加可识别出呼吸变化，在呼气阶段更为明显。这些结果证实了在呼吸周期内分析呼吸阻抗以评估与慢性阻塞性肺疾病相关的呼吸变化的潜力。
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