Abstract
Alveolar carbon dioxide pressure-ventilation response curves were measured on 5-6 consecutive days by the rebreathing method of Campbell and his associates. The slopes of the response curves progressively increased until the third day and then leveled off. The ventilatory response evaluated by breath-by-breath recording after a single large breath of hypercapnic and/or hypoxic test gases also increased in the same manner when studied at the same time. This phenomenon was thought to be related to the altered neurogenic activity in the ventilatory control system. The slope of the response curve obtained by the conventional steady state method did not show the consistent increase observed with the rebreathing method.
