Cardiodynamic Factors Affecting Hyperpnea during Steady-State Exercise in Man

抄録

In order to know the role of cardiodynamic factors for exercise hyperpnea, ventilation and several cardiorespiratory variables were measured simultaneously in human subjects during exercise. Cardiac output (Q) and mixed venous CO₂ content (CvCO₂) were determined by a rebreathing method. The correlation coefficients (r) for the relationships between minute expiratory ventilation (VE) and each of end-tidal CO₂ tension (PETCO₂), Q, CvCO₂, CO₂ flow into the lung (QCO₂, the product of Q and CvCO₂), oxygen consumption (VO2), and CO₂ output (V_CO2) were determined during the steady-state exercise up to 90W. The correlation was highly significant (r=0.84-0.99, p<0.001) in each case except for PETCO₂ (r=0.13, N.S.). The highest correlation was observed in the VE-V_CO2 relationship. It was assume that V_CO2 released from the pulmonary capillaries into the alveoli is the most likely stimulus leading to exercise hyperpnea. Arterial CO₂ oscillation may be regarded as a potential linkage between V_CO2 and VE.