RT Journal Article SR Electronic T1 Evaluation of heliox or oxygen breathing on improved quadriceps muscle oxygen delivery during exercise in COPD JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP p1533 VO 38 IS Suppl 55 A1 Vasilis Andrianopoulos A1 Zafeiris Louvaris A1 Eleni Kortianou A1 Helmut Habazettl A1 Spyros Zakynthinos A1 Peter D. Wagner A1 Ioannis Vogiatzis YR 2011 UL http://erj.ersjournals.com/content/38/Suppl_55/p1533.abstract AB Introduction: It is known that both normoxic heliox and pure oxygen breathing significantly increase locomotor O2 delivery during exercise in COPD. However, it remains unknown which of the two gases is the most beneficial in terms of enhancing exercise tolerance and locomotor muscle O2 availability.Methods: 12 COPD patients [FEV1=42±12%pred] performed 3 constant-load exercise tests at 75% of maximum work rate while breathing air, normoxic heliox or pure O2. We measured cardiac output (Fick method), haemodynamic responses, quadriceps muscle blood flow by near infrared spectroscopy with ICG dye and changes in quadriceps muscle deoxygenation ([HHb], an index of fractional O2extraction) at the transition from rest to exercise (on-kinetics).Results: Exercise endurance time was not significantly different between heliox and O2 [(mean±SEM) He: 637±46 vs O2: 670±43 vs Air: 394±35 s]. Peak cardiac output was significantly greater on heliox (He: 9.3±0.5 vs O2: 8.2±0.6 vs air: 8.9 l/min) but O2 caused a significant greater elevation of arterial oxygen content (He: 183±6 vs O2: 213±7 vs air: 180±5 ml/min). However, neither quadriceps muscle blood flow (He: 32±5 vs O2: 31±6 vs Air: 22±5 ml/min/100gr) nor quadriceps O2 delivery (He: 5.8±0.9 vs O2: 6.3±1.1 vs Air: 3.9±0.8 ml O2/min/100gr) were significantly different between heliox and O2. Mean response time of deoxygenated HHb on heliox (MRT=18.1±1.7s) and O2 (MRT=17.4±1.4s) were not significantly different but were both greater compared to air (MRT=13.8±1.3s) (P<0.05).Conclusion: Supplementation of heliox or O2 is equally beneficial in terms of enhancing exercise tolerance and locomotor muscle O2 availability during exercise in COPD.