Chemoreceptor sensitivity and maladaptation to high altitude in man.

Studies were carried out to find out the role of chemoreceptor sensitivity in the causation of maladaptation syndromes on acute exposure to altitude. The experiments were done in two phases. In phase I, the responses in chemoreceptor sensitivity were studied in altitude acclimatized subjects and compared with those who suffered from either High Altitude Pulmonary Oedema (HAPO) or Acute Mountain Sickness (AMS). In Phase II, a similar comparison was done in two groups of subjects, one representing normal sojourners at 3,500 m and the other being subjects who had just recovered from HAPO. The first phase was done at Delhi; and the second at an altitude of 3,500 m. Parameters of assessment were hypoxic sensitivity, carbon dioxide sensitivity, ventilation (VE), respiratory frequency (Rf), forced vital capacity (FVC), forced expiratory volume at the first second (FEV1), heart rate (HR), blood pressure (BP), and oral temperature (Tor). The results showed significantly lower sensitivity to both hypoxia and carbon dioxide in maladapted subjects, as compared to those who were acclimatized in both the categories suggesting thereby that reduced chemoreceptor sensitivity might be an initiating factor in the causation of maladaptation syndromes at altitude.