Cincinnati VAMC, Cincinnati, OH, USA.
Lung. 2013 Apr;191(2):177-82. doi: 10.1007/s00408-012-9443-3. Epub 2013 Jan 3.
Dynamic hyperinflation (DH) causes exercise limitation and exertional dyspnea in patients with chronic obstructive pulmonary disease (COPD). Exertional desaturation (ED) also occurs commonly in COPD but neither routine physiologic parameters nor imaging predict ED accurately. In this study we evaluated the relationship between DH and ED during 6-min walk testing (6MWT).
We measured ED and DH in patients with stable COPD. SpO2 was measured by continuous pulse oximetry during 6MWT. ED was defined as a decline in SpO2 (ΔSpO2) ≥4 %. DH was determined by measuring inspiratory capacity (IC) before and after the 6MWT using a handheld spirometer. DH was defined as ΔIC >0.0 L. We correlated DH and ED with clinical and pulmonary physiologic variables by regression analysis, χ (2), and receiver operator curve (ROC) analysis.
Thirty males [age = 65 ± 9.4 years, FEV1 % predicted = 48 ± 14 %, and DLCO % predicted = 50 ± 21 % (mean ± SD)] were studied. ΔSpO2 correlated with ΔIC (r = 0.49, p = 0.005) and age (r = 0.39, p = 0.03) by univariate analysis; however, only ΔIC correlated on multivariate regression analysis (p = 0.01). ΔSpO2 did not correlate with FEV1, FVC, FEF25-75, RV, DLCO % predicted, BMI, smoking, BORG score, or distance covered in 6MWT. DH strongly correlated with ED (p = 0.001). On ROC analysis, DH had an area under the curve of 0.92 for the presence of ED (sensitivity = 90 %; specificity = 77 %, p < 0.001).
Routine pulmonary function test results and clinical variables did not correlate with ED in patients with stable COPD. Dynamic hyperinflation strongly correlates with exertional desaturation and could be a reason for this desaturation.
动态过度充气（DH）导致慢性阻塞性肺疾病（COPD）患者运动受限和运动性呼吸困难。运动性低氧血症（ED）在 COPD 中也很常见，但常规生理参数或影像学均不能准确预测 ED。本研究旨在评估 6 分钟步行试验（6MWT）期间 DH 与 ED 的关系。
我们测量了稳定期 COPD 患者的 ED 和 DH。6MWT 期间通过连续脉搏血氧仪测量 SpO2。ED 定义为 SpO2 下降（ΔSpO2）≥4%。DH 通过使用手持式肺活量计在 6MWT 前后测量吸气量（IC）来确定。DH 定义为ΔIC>0.0 L。通过回归分析、χ2 和受试者工作特征曲线（ROC）分析，将 DH 和 ED 与临床和肺生理变量相关联。
共 30 名男性[年龄=65±9.4 岁，FEV1%预计值=48±14%，DLCO%预计值=50±21%（平均值±标准差）]进行了研究。ΔSpO2 与ΔIC（r=0.49，p=0.005）和年龄（r=0.39，p=0.03）呈正相关，但仅在多元回归分析中与ΔIC 相关（p=0.01）。ΔSpO2 与 FEV1、FVC、FEF25-75、RV、DLCO%预计值、BMI、吸烟、BORG 评分或 6MWT 覆盖距离均不相关。DH 与 ED 高度相关（p=0.001）。在 ROC 分析中，DH 对 ED 的存在的曲线下面积为 0.92（敏感性=90%；特异性=77%，p<0.001）。
稳定期 COPD 患者的常规肺功能检查结果和临床变量与 ED 不相关。DH 与运动性低氧血症密切相关，可能是导致低氧血症的原因。
