TY - JOUR T1 - The Relationship Between Skeletal Muscle Oxygenation and Systemic Oxygen Uptake During Exercise in Subjects With COPD: A Preliminary Study JF - Respiratory Care SP - 1602 LP - 1610 DO - 10.4187/respcare.01602 VL - 57 IS - 10 AU - Kazuyuki Tabira AU - Jun Horie AU - Hiromasa Fujii AU - Toshio Aida AU - Ken-ichi Ito AU - Takahiko Fukumoto AU - Hidetaka Imagita AU - Hideki Ishihara Y1 - 2012/10/01 UR - http://rc.rcjournal.com/content/57/10/1602.abstract N2 - BACKGROUND: Muscle oxygenation correlates with systemic oxygen uptake (V̇O2) in normal subjects; however, whether this relationship exists in COPD patients remains unclear. The purpose of this study was to investigate the influence of skeletal muscle oxygenation on V̇O2 during exercise in patients with COPD. METHODS: Eight subjects performed an incremental cycle ergometer exercise test. We measured ventilation and pulmonary gas exchange with a metabolic measurement system. We also continuously monitored SpO2, and measured tissue oxygen saturation (StO2) in the vastus lateralis with continuous-wave near-infrared spectroscopy. We calculated the muscle oxygen extraction rate (MOER) based on SpO2 and StO2. In addition, we calculated Pearson correlation coefficients to examine the relationships between the V̇O2 obtained during exercise testing and the mean values of SpO2, StO2, heart rate (HR), and MOER for each 30-second interval of the tests. Finally, we analyzed the relationships between the peak V̇O2 and the slopes of HR/V̇O2, SpO2/V̇O2, StO2/V̇O2, and MOER/V̇O2. RESULTS: With the increasing exercise intensity, many subjects showed a gradual decrease in StO2 and SpO2, but a gradual increase in HR and MOER. V̇O2 was negatively correlated with StO2 and SpO2, and was positively correlated with HR and MOER. However, peak V̇O2 was not correlated with any of the slopes. CONCLUSIONS: V̇O2 is highly influenced by oxygen utilization in exercising muscles, as well as by blood oxygenation levels and cardiac function. However, the impact of skeletal muscle utilization during exercise on peak V̇O2 varied greatly among the subjects. ER -