Rate of change of alveolar carbon dioxide and the control of ventilation during exercise.
The relationship between rate of change of alveolar PCO2 (delta PA, CO2/delta te), CO2 output (VCO2) and ventilation (VE) has been determined following a rapid increase in exercise intensity, to test the hypothesis that VE is related to VCO2 by a feed-forward control system responding to delta PA, CO2/delta te. There was a close relationship between delta PA, CO2/delta te and VCO2 (delta PA, CO2/delta te = 3.2 VCO2 + 0.85), but delta PA, CO2/delta te increased more rapidly than VCO2. Increases in mean inspiratory flow, an index of inspiratory drive, were more closely related to changes in delta PA, CO2/delta te than to changes in VCO2. Increases in VE during transient and steady-state conditions may be described by the equation: VE = 6.76 delta PA, CO2/delta te -3.50, a relationship which is consistent with a feed-forward control system.
D002245:Carbon Dioxide / Q000502:physiology*; D006801:Humans; D008297:Male; D010100:Oxygen / Q000502:physiology; D005082:Physical Exertion; D011650:Pulmonary Alveoli / Q000502:physiology*; D012123:Pulmonary Ventilation; D012119:Respiration; D013990:Tidal Volume; D013997:Time Factors
D002245:Carbon Dioxide; D010100:Oxygen