Stewart R I
S Afr Med J. 1985 Jan 19;67(3):87-9.
Patients with chronic obstructive pulmonary disease (COPD) may incur exercise limitation by any one or combination of disturbances in breathing mechanics, oxygen transport, respiratory muscle metabolism or respiratory regulation and sensation. In spite of the increased ventilation demand/capacity ratio in these patients, the relationship between breathing mechanics, respiratory muscle fatigue, the adequacy of alveolar ventilation and the development of exertional dyspnoea is neither clearly defined nor predictable from data obtained with the patient at rest. The issue of oxygen transport during exercise has been complicated by confusion between arterial hypoxia and inadequate volume of oxygen transported to the tissues, which frequently may differ qualitatively and quantitatively. The cardiac output response to exercise in patients with COPD is therefore critical in determining oxygen transport. This response is also impossible to predict from resting lung mechanics, pulmonary arterial blood pressure, arterial oxygen tension or clinical disease profile. Without exercise testing, which includes measurement of all the variables mentioned, it is impossible to define clearly the cause of exercise-induced symptoms in patients with COPD. Exercise training with and without supplemental oxygen has been shown to improve exercise tolerance in these patients, but the precise mechanism of this improvement remains obscure.
慢性阻塞性肺疾病（COPD）患者可能会因呼吸力学、氧运输、呼吸肌代谢或呼吸调节与感觉方面的任何一种干扰或多种干扰的组合而出现运动受限。尽管这些患者的通气需求/能力比增加，但呼吸力学、呼吸肌疲劳、肺泡通气充足性与运动性呼吸困难的发生之间的关系既未明确界定，也无法根据患者静息时获得的数据进行预测。运动期间的氧运输问题因动脉低氧血症与输送到组织的氧量不足之间的混淆而变得复杂，这两者在质和量上常常有所不同。因此，COPD患者运动时的心输出量反应对于确定氧运输至关重要。这种反应也无法根据静息肺力学、肺动脉血压、动脉血氧张力或临床疾病特征进行预测。如果不进行包括上述所有变量测量的运动测试，就无法明确界定COPD患者运动诱发症状的原因。已证明，有或没有补充氧气的运动训练可提高这些患者的运动耐力，但这种改善的确切机制仍不清楚。
