[Activation of external respiration and level of alveolar PCO2 in pilots in flight]

The paper discusses the emergence of spontaneous hypocapnia in real aircraft flights. The flying personnel were taken under study. The hypocapnic state was diagnosed on the basis of the CO2 concentration in the alveolar air measured by a special device. In flight the CO2 concentration in the alveolar air decreased insignificantly (by 5 min Hg on the average). In emergency situations the external respiration was activated to a greater extent. It is suggested that the alveolar Pco2 level is indicative of the emotional stress.