Division of Respiratory Medicine, Department of Internal Medicine, Shiga University of Medical Science, Shiga, Japan.
Health Administration Center, Shiga University of Medical Science, Shiga, Japan.
Int J Chron Obstruct Pulmon Dis. 2019 Dec 20;14:2971-2977. doi: 10.2147/COPD.S224902. eCollection 2019.
The forced oscillation technique (FOT) is a non-invasive method to measure respiratory impedance, the respiratory resistance (Rrs) and reactance (Xrs). The disease probability measure (DPM) is a useful computed tomography (CT) imaging variable for the assessment of gas trapping and emphysema in patients with chronic obstructive pulmonary disease (COPD) using pairs of inspiratory and expiratory CT images. We aimed to develop FOT-based phenotypes and determine whether the phenotypes and their imaging characteristics could facilitate the understanding of COPD pathophysiology.
FOT and spirometry were examined in 164 COPD patients and 22 non-COPD smokers. COPD patients were divided into four FOT-based phenotypes (NL, normal group; RD, resistance-dominant group; XD, reactance-dominant group; and MIX, mixed group) based on the 3rd quartile values of R5 (Rrs at 5Hz) and X5 (Xrs at 5Hz) in the non-COPD group. The emphysematous lesions and the airway lesions were quantitatively assessed in CT images by low attenuation volume and the square root of the wall area of a hypothetical airway with an internal perimeter of 10 mm (√Aaw at Pi10), respectively. DPM imaging analysis was also performed in 131 COPD patients. We investigated the differences in COPD parameters between the FOT-based phenotypes.
√Aaw at Pi10 were significantly higher in the RD, XD, and MIX groups than in the NL group. The XD group showed lower pulmonary function and higher dyspnea scores than the RD group. No significant changes in DPM values were observed between the RD and the NL groups. The gas-trapping area was significantly higher in the XD group than in the NL group. The MIX group showed the highest dyspnea score, most emphysematous lesions, and the lowest forced expiratory volume in 1 s % predicted value.
The FOT-based phenotyping may be useful to assess pathophysiological changes of COPD with CT assessments.
强迫振荡技术（FOT）是一种测量呼吸阻抗的非侵入性方法，可测量呼吸阻力（Rrs）和电抗（Xrs）。疾病概率测量（DPM）是一种有用的计算断层扫描（CT）成像变量，可用于评估慢性阻塞性肺疾病（COPD）患者吸气和呼气 CT 图像对气体捕获和肺气肿的评估。我们旨在开发基于 FOT 的表型，并确定这些表型及其影像学特征是否有助于理解 COPD 病理生理学。
对 164 例 COPD 患者和 22 例非 COPD 吸烟者进行了 FOT 和肺量测定。根据非 COPD 组中 R5（Rrs 在 5Hz 时）和 X5（Xrs 在 5Hz 时）的第 3 四分位数值，将 COPD 患者分为 4 种基于 FOT 的表型（NL、正常组；RD、阻力主导型组；XD、电抗主导型组；和 MIX，混合组）。通过低衰减体积和假想气道壁面积的平方根（以 10mm 内周长表示的 √Aaw at Pi10）对 CT 图像中的肺气肿病变和气道病变进行定量评估。还对 131 例 COPD 患者进行了 DPM 成像分析。我们研究了 FOT 表型之间 COPD 参数的差异。
RD、XD 和 MIX 组的 √Aaw at Pi10 明显高于 NL 组。XD 组的肺功能较低，呼吸困难评分较高。RD 组和 NL 组之间 DPM 值没有明显变化。XD 组的气体捕获面积明显高于 NL 组。MIX 组的呼吸困难评分最高，肺气肿病变最严重，1 秒用力呼气量（FEV1）%预计值最低。
基于 FOT 的表型分析可能有助于结合 CT 评估来评估 COPD 的病理生理学变化。
