Yasaka Y, Yamabe H, Yokoyama M
The First Department of Internal Medicine, Kobe University School of Medicine, Chuo-ku, Japan.
Int J Cardiol. 1997 Apr 18;59(2):149-56. doi: 10.1016/s0167-5273(96)02912-9.
Oxygen transport capacity is the most important determinant of maximum oxygen uptake (V(O2) max) in healthy subjects, however, its role is controversial in patients with chronic heart failure (CHF). The aim of this study was to clarify whether the oxygen transport capacity is an actual determinant of exercise capacity in CHF patients. Thirteen CHF patients underwent two maximum exercise tests, i.e., a graded protocol test and a fixed protocol test, measuring expiratory gases, leg blood flow (LBF), and arterial and venous blood gases. The workload of the fixed protocol was set to exceed the peak workload obtained by the graded protocol. Exercise with the fixed protocol caused significantly larger peak V(O2) compared to the graded protocol (813+/-194 to 971+/-203 ml/min, P<0.001). Peak LBF increased by 17%, while the peak leg arterio-venous oxygen difference increased by 5% from the graded protocol to the fixed protocol. The linear correlation between leg venous partial oxygen pressure and peak V(O2) was more clearly manifested in the fixed protocol (r=0.60, P<0.05) than in the graded protocol (r=0.47, NS). In conclusion, the exercise with graded protocol did not always conduct the upper limit of oxygen demand/supply relationship in CHF patients, whereas, the fixed protocol with a larger workload produced larger peak V(O2) and manifested the mechanism to limit V(O2) by oxygen transport capacity.
在健康受试者中，氧运输能力是最大摄氧量（V(O2) max）的最重要决定因素，然而，其在慢性心力衰竭（CHF）患者中的作用存在争议。本研究的目的是阐明氧运输能力是否是CHF患者运动能力的实际决定因素。13例CHF患者进行了两次最大运动试验，即分级方案试验和固定方案试验，测量呼出气、腿部血流（LBF）以及动脉和静脉血气。固定方案的工作量设定为超过分级方案获得的峰值工作量。与分级方案相比，固定方案运动导致的峰值V(O2)明显更大（813±194至971±203 ml/min，P<0.001）。从分级方案到固定方案，峰值LBF增加了17%，而腿部动静脉氧差峰值增加了5%。腿部静脉血氧分压与峰值V(O2)之间的线性相关性在固定方案中（r=0.60，P<0.05）比在分级方案中（r=0.47，无显著性差异）更明显。总之，分级方案运动并不总是能达到CHF患者氧需求/供应关系的上限，而工作量更大的固定方案产生了更大的峰值V(O2)，并揭示了氧运输能力限制V(O2)的机制。
