[Reaction of the human ventilatory apparatus to supplementary respiratory resistance upon inhalation of normo- and hypercapnic mixtures].

In 5 healthy young subjects, the intrathoracic pressure, pneumotachogram, and CO2 tension in exhaled air were recorded--under conditions of breathing with additional resistance (15 cm water/1/sec). While breathing with air, starting from the 1st respiratory cycle after switching on of the additional resistance, a respiratory regimen had been formed (decreased ventilation and increased respiratory activity) which did not alter during next 10 min. When breathing with hypercapnic mixture (4% CO2 in air), the respiratory regimen changed in two stages: a stepwise increase of respiratory activity and reducing of ventilation, and further gradual increase of these parameters. Increase in the respiratory activity was invariably followed by an increase in the CO2 alveolar tension. Role of chemo- and mechanoreceptors in formation of the ventilatory apparatus response to additional resistance against breathing, is discussed.