Chuang Ming-Lung, Hsieh Benjamin Yung-Thing, Lin I-Feng
Division of Pulmonary Medicine and Department of Internal Medicine, Chung Shan Medical University Hospital, Taichung, Taiwan, 40201, Republic of China.
School of Medicine, Chung Shan Medical University, Taichung, Taiwan, 40201, Republic of China.
Int J Gen Med. 2021 Feb 3;14:169-177. doi: 10.2147/IJGM.S291555. eCollection 2021.
Measures of forced expired volume in one second % predicted (FEV%), residual volume to total lung capacity ratio (RV/TLC) and diffusing capacity for carbon monoxide measurements (DCO) are the standard lung function test for evaluating patients with chronic obstructive pulmonary disease (COPD). The dead space fraction (V/V) has been shown to be a robust marker of gas exchange abnormality. However, the use of V/V has gradually become less common. As V/V measured at rest (V/VR) has been successfully used in non-COPD conditions, it was hypothesized that in COPD the V/VR was more sensitive than the standard lung function test in correlation with clinical characteristics and gas exchange. This study aimed to test the hypothesis and to identify the variables relevant to V/VR.
A total of 46 male subjects with COPD were enrolled. Clinical characteristics included demographic data, oxygen-cost diagram (OCD), and image studies for pulmonary hypertension. The standard lung function was obtained. To calculate V/V, invasive arterial blood gas and pulmonary gas exchange (PGX) were measured. The variables relevant to V/VR were analyzed by multiple linear regression.
Compared to lung function, V/VR was more frequently and significantly related to smoking, carboxyhemoglobin level, pulmonary hypertension and PCO (all p <0.05) whereas FEV% was more related to lung function test, PO and OCD score. V/VR and FEV% were highly related to resting gas exchange but RV/TLC and DCO% were not. Cigarette consumption, the equivalent for CO output, arterial oxyhemoglobin saturation, and the product of tidal volume and inspiratory duty cycle were identified as the parameters relevant to V/VR with a power of 0.72.
Compared to lung function test, V/VR is more related to clinical characteristics and is a comprehensive marker of resting gas exchange. Further studies are warranted to provide a noninvasive measurement of V/VR.
MOST 106-2314-B-040-025 and CSH-2019-C-30.
一秒用力呼气容积占预计值百分比（FEV%）、残气量与肺总量比值（RV/TLC）以及一氧化碳弥散量测定（DCO）是评估慢性阻塞性肺疾病（COPD）患者的标准肺功能检查项目。死腔分数（V/V）已被证明是气体交换异常的可靠标志物。然而，V/V的应用已逐渐变得不那么常见。由于静息时测量的V/V（V/VR）已成功应用于非COPD情况，因此推测在COPD中，V/VR在与临床特征和气体交换的相关性方面比标准肺功能检查更敏感。本研究旨在验证这一假设并确定与V/VR相关的变量。
共纳入46名男性COPD患者。临床特征包括人口统计学数据、氧耗图（OCD）以及肺动脉高压的影像学检查。获取标准肺功能。为计算V/V，测量有创动脉血气和肺气体交换（PGX）。通过多元线性回归分析与V/VR相关的变量。
与肺功能相比，V/VR与吸烟、碳氧血红蛋白水平、肺动脉高压和PCO的相关性更频繁且更显著（均p<0.05），而FEV%与肺功能检查、PO和OCD评分的相关性更强。V/VR和FEV%与静息气体交换高度相关，但RV/TLC和DCO%则不然。香烟消耗量、相当于CO输出量、动脉血氧血红蛋白饱和度以及潮气量与吸气占空比的乘积被确定为与V/VR相关的参数，其效能为0.72。
与肺功能检查相比，V/VR与临床特征的相关性更强，是静息气体交换的综合标志物。有必要进一步研究以提供V/VR的无创测量方法。
MOST 106 - 2314 - B - 040 - 025和CSH - 2019 - C - 30。
