EFFECT OF CHF O2 TRANSPORT & UPTAKE KINETICS DURING REST TO WORK TRANSITION

充血性心力衰竭患者的运动耐量有限。据信，导致运动耐力下降的一个因素是氧气输送到活跃肌肉的减弱。在以前的报告中，外周血流量测量被用作氧气运输的指标，但对于CHF是否改变外周血流调节存在分歧。在其他因素中，这种不确定性可能是由于不同类型的CHF患者的携氧能力的差异。较低的载氧能力可能会导致增强的流动响应，以尝试优化氧气输送。然而，似乎很明显的是，从正常血流反应中增加氧气提取不能补偿导致肌肉糖酵解早期激活的情况。一个关键因素可能是运动开始时氧气运输增加的速度(即氧运输动力学)。众所周知，对运动开始的缓慢适应会减缓氧摄取发生的速度(即输送速度可能限制氧气摄取的速度)，从而增加运动开始时产生的缺氧量，导致乳酸和氢离子的提前和加速释放。这些代谢物被认为在疲劳的发展过程中起着重要作用。本研究的目的是研究慢性心力衰竭对握力训练从静息过渡到稳定状态时血流量增加速度的影响。第二个目标是研究血流动力学减慢对肌肉新陈代谢的影响。第三个目标是评估前臂水肿在血流和氧气摄取时间进程中的作用。我们认为，CHF与运动开始时氧气转运增加的速度减慢有关。血流反应减慢可能是由于血管扩张减慢和肢体浮肿。

Patients suffering from CHF are limited in their exercise tolerance. One factor leading to the reduced exercise tolerance is believed to involve attenuated oxygen transport to active muscle. In previous reports, peripheral blood flow measures have been used as an index of oxygen transport but there is a disagreement as to whether or not CHF alters the peripheral regulation of blood flow. Among other factors, this uncertainty may be due to differences in oxygen carrying capacity in heterogeneous groups of CHF patients. Lower oxygen carryinmg capacity may result in augmented flow responses in an attempt to optimize oxygen delivery. However, it seems clear that an augmented oxygen extraction from a normal flow response cannot compensate leading to an early activation of muscle glycolosis. A critical factor may be the rate at which oxygen transport increases at the onset of exercise (i.e. oxygen transport kinetics) It is known that a slowed adaption to the onset of exercise can slow the rate at which oxygen uptake occurs (i.e. the rate of delivery may limit the rate of oxygen uptake) thereby increasing the oxygen deficit incurred at the exercise onset, leading to an early and accelerated release of lactate and hydorgen ion. These metabolites are believed to be instrumental in the development of fatigue. The objectives of this study are to investigate the effect of CHF on the rate of increase in blood flow during the transition from rest to steady state handgrip exercise. A second objective is to examine the consequent effect of slowed blood flow kinetics on muscle metabolism. A third objective is to asses the role of forearm edema in the blood flow and oxygen uptake time course. We believe that CHF is associated with a slowed rate of increase in oxygen transport at the onset of exercise. The slower blood flow response may be due to slowed vasodilation and to limb edema.