Comparison of responses to CO2 under the conditions of natural respiration and controlled artificial pulmonary ventilation

The relationship between the sensation of lack of air caused by the addition of carbon dioxide to inhaled air and minute pulmonary ventilation was studied in eight healthy male volunteers. Under the conditions of both natural respiration and controlled artificial ventilation of the lungs, ventilation increased in proportion to the increase in the partial pressure of CO₂ in the end-tidal exhaled air. The individual differences in the ventilation responses to CO₂ under the conditions of controlled ventilation and natural ventilation are regarded as a property of voluntary control.