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

CHF患者的运动耐量有限。 导致运动耐量降低的一个因素被认为涉及到活动肌肉的氧运输减弱。 在以前的报告中，外周血流量的措施已被用作氧运输的指标，但有一个分歧是否CHF改变外周调节血流。 在其他因素中，这种不确定性可能是由于异质性CHF患者组的携氧能力差异所致。 较低的携氧能力可导致增大的流量响应，以试图优化氧气输送。然而，似乎清楚的是，从正常流量响应中增加的氧提取不能补偿，导致肌肉糖酵解的早期激活。 一个关键因素可能是运动开始时氧运输增加的速率（即氧转运动力学）已知对运动开始的缓慢适应可减慢氧摄取发生的速率（即输送速率可能限制氧摄取速率）从而增加在运动开始时引起的氧缺乏，导致乳酸盐和氢离子的早期和加速释放。 这些代谢物被认为有助于疲劳的发展。本研究的目的是调查CHF对从休息到稳态握力运动过渡期间血流量增加率的影响。 第二个目的是检查血流动力学减慢对肌肉代谢的影响。 第三个目的是评估前臂水肿在血流和氧摄取时间过程中的作用。 我们认为，CHF与运动开始时氧转运增加速率减慢有关。 较慢的血流反应可能是由于血管舒张减慢和肢体水肿。

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.