Plasma Catecholamines and Stress Assessment in Men Exposed to Moderate Altitudes

摘要

Plasma norepinephrine (NE), epineprine (E), and venous oxygen content, P02, PC02, and pH were measured in six resting males before, during, and after exposures to hypobaric hypoxia in a hypobaric chamber. Cardiopulmonary parameters were monitored during the exposures and a subjective survey of psychological stress and acute mountain sickness (AMS) symptoms was carried out. Each subject was acutely exposed to four separate pressure altitudes; 5,000 ft (632 torr), 8,500 ft (553 torr), 12,500 ft (474 torr), and 17,000 ft (395 torr), for one hour. Resting venous blood gas values did not indicate a hypoxic response at 5,000 or 8,500 ft, but hypoxemia, tachycardia, and hyperventilation were detected at 12,500 and 17,000 ft. Plasma E showed no significant changes while plasma NE increased due to altitude only during the 17,000 ft exposure. Psychological stress could not be determined from the survey data at any altitude, but AMS symptoms were experienced during the 12,500 and 17,000 ft exposures. Changes in plasma NE did not correlate with the degree of AMS experienced. A correlation between plasma NE and venous oxygen content seen during the 5,000 and 8,500 ft exposures but not during the 12,500 or 17,000 ft exposures. It was concluded that while the 12,500 and 17,000 exposures elicited cardiopulmonary compensatory changes and AMS symptoms, only exposure to 17,000 ft elicited a sympathetic response. (Author)