Individual Variation in Respiratory Response to Carbon Dioxide at Altitude

摘要

The extent of increase in ventilation due to inhalation of carbon dioxide at 15,000 feet is approximately equal to that obtained at sea level when carbon dioxide tensions are the same under the two conditions. Respiratory exchange at sea level while breathing 5 per cent carbon dioxide (36 mm. Hg. tension) was 2.25 times that while breathing air. At 15,000 feet, 9.25 per cent carbon dioxide (35 mm. Hg. tension) was required to obtain the same change in ventilation. Pronounced variability in response to carbon dioxide was noticed not only among different individuals but also in the same individual at different times both at sea level and at 15,000 feet simulated altitude. At 15,000 feet the subjective indications of anoxia were relieved slightly, though definitely, by carbon dioxide tensions of 27 mm. Hg. or more in the inspired air. Conclusions: The respiratory response of a group of subjects to carbon dioxide was the same at 15,000 feet pressure altitude as at sea level when the same tension of carbon dioxide in the inspired air was used in both cases. Therefore, the respiratory response to carbon dioxide at this altitude is not altered by anoxia. (Author)