Oxygen Affinity and Acid-Base Status of Human Blood during Exposure to Hypoxia and Carbon Monoxide

Abstract

In eight subjects exposed to hypoxia at high altitude the oxyhemoglobin dissociation curve was shifted to the right, the half saturation oxygen tension at pH 7.40 being changed from 26.7 to 30.2 mm Hg on the average. The decreased affinity of hemoglobin for oxygen appeared within 12 hours after exposure to hypoxia. The shift was confirmed in short exposure experiments using simulated high altitude in a low pressure chamber. At prolonged carbon monoxide exposure the expected shift of the oxygen dissociation curve to the left occurred, but no adaptive changes were found. The physiological implication of these differences are discussed. It is suggested that the rapid shift to the right at high altitude may be a physiological regulation.

Key-words:

• Hypoxia
• carbon monoxide
• high altitude
• hemoglobin
• oxygen
• adaptation