The influence of extended exposure in artificial hypercapnic environments on the function of external respiration and gas exchange

: Effects of artificial hypercapnic atmosphere were studied in a series of ten 40-d experiments with participation of 42 volunteers aged from 20 to 61 years. Partial pressure of carbon dioxide was maintained at 27 +/- 2 mm Hg (3.4-3.8% CO2); partial pressure of oxygen was in the range of 122-136 mm Hg. Barometric pressure, air temperature and humidity had normal values. Results of the experiments were subjected to the variation analysis. Continuous breathing the gas mixture with specified PCO2 increased CO2 sensitivity of the breathing center in all age-groups both at rest and during exercise. The ventilatory reaction of subjects aged 41-61 grew to a less degree as compared to the subjects below 40. Medical selection of members for space crew to go to a distant voyage should take into consideration the parameters of oxygen demand and the volume of pulmonary ventilation per a time unit.