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Effects of increased respiratory rate on cortical oxygenated hemoglobin during low-intensity exercise
Keiichi Oyanagi1, Atsuhiro Tsubaki2
1Department of Rehabilitation, Kobe City Medical Center General Hospital, Kobe, Japan.
Abstract:
This study aimed to examine whether the end-tidal partial pressure of CO2 (PEtCO2) affects the concentration of oxygenated hemoglobin (O2Hb) measured by near-infrared spectroscopy (NIRS). Participants were examined under the conditions of normal and increased ventilation. We measured O2Hb, mean blood pressure, skin blood flow, PEtCO2, respiratory rate, and minute volume at 30 % of the maximum oxygen uptake during exercise. ΔO2Hb and PEtCO2 during exercise were lower in the increased ventilation than in the normal ventilation condition. Pearson's product-moment correlation analysis showed a significant positive correlation between ΔO2Hb and ΔMAP, ΔSBF, and PEtCO2. Correlation coefficients were 0.249 (p < 0.001) for ΔMAP, 0.343 (p < 0.001) for ΔSBF, and 0.315 (p < 0.001) for PEtCO2. In conclusion, we identified increased ventilation during bicycle ergometer exercise as a significant factor associated with significantly low PEtCO2 and ΔO2Hb.
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