Respiratory Investigation Unit, Department of Medicine, Queen’s University, Kingston, Ontario, Canada.
Am J Respir Crit Care Med. 2011 Dec 15;184(12):1367-73. doi: 10.1164/rccm.201106-1128OC. Epub 2011 Sep 1.
Patients with chronic obstructive pulmonary disease (COPD) primarily describe their exertional dyspnea using descriptors alluding to increased effort or work of breathing and unsatisfied inspiration or inspiratory difficulty.
The purpose of this study was to examine the impact of changes in dynamic respiratory mechanics during incremental (INCR) and high-intensity constant work-rate (CWR) cycle exercise on the evolution of dyspnea intensity and its major qualitative dimensions in patients with moderate-to-severe COPD.
Sixteen subjects with COPD performed symptom-limited INCR and CWR cycle exercise tests. Measurements included dyspnea intensity and qualitative descriptors, breathing pattern, operating lung volumes, and esophageal pressure (Pes).
During both exercise tests, there was an inflection in the relation between tidal volume (Vt) and ventilation. This inflection occurred significantly earlier in time during CWR versus INCR exercise but at a similar ventilation, Vt, and tidal Pes swing. Beyond this inflection, there was no further change in Vt despite a continued increase in ventilation and tidal Pes. During both tests, "work and effort" was the dominant dyspnea descriptor selected up to the inflection point, whereas after this point dyspnea intensity and the selection frequency of "unsatisfied inspiration" rose sharply.
Regardless of the exercise test protocol, the inflection (or plateau) in the Vt response marked the point where dyspnea intensity rose abruptly and there was a transition in the dominant qualitative descriptor choice from "work and effort" to "unsatisfied inspiration." Intensity and quality of dyspnea evolve separately and are strongly influenced by mechanical constraints on Vt expansion during exercise in COPD.
慢性阻塞性肺疾病（COPD）患者主要用暗示呼吸做功增加或呼吸费力以及吸气未满足或吸气困难的描述词来描述运动性呼吸困难。
本研究旨在探讨递增（INCR）和高强度恒功（CWR）运动期间动态呼吸力学变化对中重度 COPD 患者呼吸困难强度及其主要定性维度演变的影响。
16 例 COPD 患者进行了症状限制递增和高强度恒功循环运动试验。测量包括呼吸困难强度和定性描述、呼吸模式、肺容积和食管压力（Pes）。
在两项运动试验中，潮气量（Vt）和通气之间的关系都出现了拐点。与 INCR 运动相比，CWR 运动中拐点出现得更早，但在相同的通气、Vt 和潮 Pes 摆动时出现拐点。超过拐点后，尽管通气和潮 Pes 继续增加，但 Vt 不再发生变化。在两项试验中，“工作和努力”是直到拐点之前选择的主要呼吸困难描述词，而在此之后，呼吸困难强度和“吸气未满足”的选择频率急剧上升。
无论运动试验方案如何，Vt 反应的拐点（或平台）标志着呼吸困难强度突然上升以及主导定性描述词从“工作和努力”向“吸气未满足”转变的转折点。呼吸困难的强度和质量是分开演变的，并且在 COPD 患者的运动中受到 Vt 扩张的机械限制的强烈影响。
