[Kinetics of the compensation of respiratory acidosis induced by experimental chronic hypercapnia in man (author's transl)].

Four groups of male volunteers have been exposed in a tight climatical chamber to PICO2 of 14, 21, 28 and 32 torr; exposure periods varied from two to 30 days, between two reference periods in normal air. The results deal with the evolution of arterial blood acid-base equilibrium and that of renal response in relation to PICO2. In all exposures, the carbon dioxide alveolar overload increases by several torr during the first 24 hours on account of attenuation of the initial hyperventilation. Kinetics of the respiratory acidosis compensation differs according to hypercapnia which is moderate (PICO2 of 14 and 21 torr) or relatively severe (PICO2 of 28 and 32 torr). The decrease in arterial pH lessens as early as the 24th hour at PICO2 28 and 32 torr, and only after two days at PICO2 14 and 21 torr. The renal response is characterized by a significant increase in aciduria during the first 24 hours at PICO2 28 and 32 torr; the changes are smaller and start latter at PICO2 14 torr.