Chemosensitivity in normal subjects, athletes, and patients with chronic airways obstruction

Abstract

Studies of CO2 and O2 sensitivity have been made using rebreathing methods in normal subjects, athletes, and patients with and without chronic airways obstruction. The rebreathing techniques enabled isoxic CO2 response curves and isocapnic O2 response curves to be constructed from many points obtained over a short time. There was little difference in response among the groups of normal subjects but the patients with lung disease had a flatter CO2 response curve and required lower levels of Po2 to stimulate ventilation. When ventilation was expressed as a fraction of the maximal voluntary ventilation, much of the difference between normal subjects and chest patients disappeared, suggesting that the reduced ventilatory response may be of mechanical origin. There remained some patients who were truly insensitive to one or both stimuli and they appeared to be those whose clinical condition was poorest. rebreathing techniques; isoxic CO2 sensitivity; isocapnic O2 sensitivity; relation to ventilatory capacity; insensitivity of some patients