Maltais F, Simon M, Jobin J, Desmeules M, Sullivan M J, Bélanger M, Leblanc P
Centre de recherche, Institut de Cardiologie et de Pneumologie de Québec, Département de Médecine, Université Laval, Québec, Canada.
Med Sci Sports Exerc. 2001 Jun;33(6):916-22. doi: 10.1097/00005768-200106000-00010.
To quantify the effects of acute oxygen supplementation on lower limb blood flow (QLEG), O2 delivery (QO2LEG), and O2 uptake (VO2LEG) during exercise and to determine whether the metabolic capacity of the lower limb is exhausted at peak exercise during room air breathing in patients with COPD.
Oxygen (FIO2 = 0.75) and air were randomly administered to 14 patients with COPD (FEV1: 35 +/- 2% pred, mean +/- SEM) during two symptom-limited incremental cycle exercise tests. Before exercise, a cannula was installed in a radial artery and a thermodilution catheter inserted in the right femoral vein. At each exercise step, five-breath averages of respiratory rate, tidal volume, and ventilation (VE), dyspnea and leg fatigue scores, arterial and venous blood gases, and QLEG were obtained. From these measurements, VO2LEG was calculated.
Peak exercise capacity increased from 46 +/- 3 W in room air to 59 +/- 5 W when supplemental oxygen was used (P < 0.001). QLEG, QO2LEG, and VO2LEG were greater at peak exercise with O2 than with air (P < 0.05). During submaximal exercise, dyspnea score and VE were significantly reduced with O2 (P < 0.05), whereas QLEG, VO2LEG, and leg fatigue were similar under both experimental conditions. The improvement in peak exercise work rate correlated with the increase in peak QO2LEG (r = 0.66, P < 0.01), peak VO2LEG (r = 0.53, P < 0.05), and reduction in dyspnea at iso-exercise intensity (r = 0.56, P < 0.05).
The improvement in peak exercise capacity with oxygen supplementation could be explained by the reduction in dyspnea at submaximal exercise and the increases in QO2LEG and VO2LEG, which enabled the exercising muscles to perform more external work. These data indicate that the metabolic capacity of the lower limb muscles was not exhausted at peak exercise during room air breathing in these patients with COPD.
量化急性吸氧对运动期间下肢血流量（QLEG）、氧输送量（QO2LEG）和氧摄取量（VO2LEG）的影响，并确定慢性阻塞性肺疾病（COPD）患者在室内空气呼吸状态下进行运动至峰值时下肢的代谢能力是否已耗尽。
在两项症状限制递增式蹬车运动试验期间，对14例COPD患者（第1秒用力呼气容积[FEV1]：占预计值的35±2%，均值±标准误）随机给予氧气（吸入氧分数[FIO2]=0.75）和空气。运动前，在桡动脉置入套管，并在右股静脉插入热稀释导管。在每个运动阶段，获取呼吸频率、潮气量和通气量（VE）的五次呼吸平均值、呼吸困难和腿部疲劳评分、动脉和静脉血气以及QLEG。根据这些测量值计算VO2LEG。
峰值运动能力从室内空气呼吸时的46±3瓦增加到吸氧时的59±5瓦（P<0.001）。与呼吸空气相比，吸氧时峰值运动时的QLEG、QO2LEG和VO2LEG更高（P<0.05）。在次最大运动期间，吸氧时呼吸困难评分和VE显著降低（P<0.05），而在两种实验条件下QLEG、VO2LEG和腿部疲劳相似。峰值运动功率的改善与峰值QO2LEG的增加（r=0.66，P<0.01）、峰值VO2LEG的增加（r=0.53，P<0.05）以及等运动强度下呼吸困难的减轻（r=0.56，P<0.05）相关。
吸氧后峰值运动能力的提高可通过次最大运动时呼吸困难的减轻以及QO2LEG和VO2LEG的增加来解释，这使得运动肌肉能够完成更多的外部功。这些数据表明，在这些COPD患者室内空气呼吸状态下运动至峰值时，下肢肌肉的代谢能力并未耗尽。
