a Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Queen's University & Kingston General Hospital , Kingston , ON , Canada.
COPD. 2019 Apr;16(2):174-181. doi: 10.1080/15412555.2019.1631776. Epub 2019 Jul 5.
Combining measurements of impaired lung mechanics (inspiratory constraints) with an index of increased respiratory stimuli to metabolic demand (poor ventilatory efficiency) might enhance the ability of cardiopulmonary exercise testing (CPET) in exposing a mechanistic role for ventilation on exertional dyspnea in COPD. In addition to the standard approach to suggest ventilatory limitation to exercise - a low breathing reserve (1-(peak ventilation (V̇E)/maximal voluntary ventilation × 100 < 20%) - we assessed the presence of critical inspiratory constraints (end-inspiratory lung volume (EILV)/total lung capacity (TLC) ≥ 0.9) and ventilatory inefficiency (V̇E/CO output (V̇CO) nadir > 34) in 288 patients with mild to very severe COPD (FEV ranging from 18 to 121% predicted). We found that ∼50% of the patients with preserved breathing reserve developed critical inspiratory constraints. A low breathing reserve was weakly related to a lower peak O uptake (V̇O) and/or a higher dyspnea burden; for instance, patients with low breathing reserve but without critical inspiratory constraints had similar dyspnea and peak V̇O than those with preserved breathing reserve ( > 0.05). In contrast, critical inspiratory constraints and ventilatory inefficiency were strongly associated with a negative outcome (likelihood ratio = 42.3 and 47.7, respectively; < 0.001). A multiple logistic regression analysis revealed that only EILV/TLC ≥ 0.9 and V̇E/V̇CO nadir >34 predicted a severely reduced peak V̇O due to a high dyspnea burden ( < 0.001). Measurements of dynamic mechanical constraints and ventilatory inefficiency during incremental CPET are key to determine the impact of COPD on dyspnea and exercise tolerance across the spectrum of disease severity.
将肺力学受损（吸气受限）的测量与呼吸刺激对代谢需求的指数（通气效率差）相结合，可能会增强心肺运动测试（CPET）在揭示 COPD 运动性呼吸困难的通气机制作用的能力。除了建议运动时通气受限的标准方法（呼吸储备低-1-（峰值通气量（VE）/最大自主通气量×100<20%）-我们还评估了 288 例轻度至重度 COPD 患者（FEV 从 18%到 121%预测值）中存在临界吸气受限（吸气末肺容积（EILV）/总肺容量（TLC）≥0.9）和通气效率低下（VE/CO 输出（V̇CO）最低点>34）。我们发现，约 50%的呼吸储备正常的患者出现了临界吸气受限。低呼吸储备与较低的峰值 O 摄取量（V̇O）和/或较高的呼吸困难负担呈弱相关；例如，呼吸储备低但无临界吸气受限的患者与呼吸储备正常的患者具有相似的呼吸困难和峰值 V̇O（>0.05）。相比之下，临界吸气受限和通气效率低下与不良结局密切相关（比值比分别为 42.3 和 47.7；均<0.001）。多因素逻辑回归分析显示，只有 EILV/TLC≥0.9 和 V̇E/V̇CO 最低点>34 可预测因高呼吸困难负担而导致的峰值 V̇O 严重降低（<0.001）。递增 CPET 期间动态力学限制和通气效率低下的测量是确定 COPD 在疾病严重程度谱上对呼吸困难和运动耐量的影响的关键。
