CHANGES IN HUMAN RESPIRATORY SENSATION INDUCED BY ACUTE HIGH-ALTITUDEHYPOXIA

RESPIRATORY sensation was studied in European lowlanders at an altitud e of 4382 m after a helicopter flight in order to investigate the acut e and prolonged effects of high altitude hypoxia. At rest the ability to detect four inspiratory resistive loads can be used to create a sen sitivity index P(A) without taking the response bias (B) into account, based on the Sensory Decision Theory. In 6 subjects respiratory sensi tivity increased significantly under acute and prolonged hypoxia after 3-4 days of high altitude exposure. The respiratory sensitivity incre ased with the hyperventilation and mouth pressure increase induced by hypoxia. Hypoxia might also have feedback effects on the peripheral an d central nervous integration of the respiratory sensation stimuli. On e subject suffering from acute mountain sickness showed a severe decre ase in his sensitivity index P(A) under hypoxic conditions, while the parameters of his cardiorespiratory function evolved in the same class ical way as the other subjects who adapted well to altitude hypoxia. T he increase in respiratory sensation may be the first necessary step i n altitude acclimatization and might serve as a useful marker of this adaptation.