MUSCLE-TISSUE OXYGEN PRESSURES IN HEALTHY-VOLUNTEERS DURING ACUTE EXPOSURE TO HYPOXIA

Tissue pO2 values (tibial anterior muscle), oxygen saturation, transcu taneous pO2, arterial pO2, and rheological parameters were measured in 10 young (mean age 26,9 +/- 0,9 years) as well as in 10 older (mean a ge 59,3 +/- 5,9 years) apparently healthy volunteers during acute expo sure to hypoxia according to a pressure altitude of approximately 8500 feet for 20 minutes. Hypoxia exposure was achieved by inspiration of an oxygen reduced gas mixture (116 mm Hg pO2). Average arterial pO2 an d oxygen saturation decreased significantly in the young but not in th e older volunteers. Tissue pO2 values showed a marked and significant decrease in both groups (23.9 mm Hg to 12.8 mm Hg in the young and 20. 8 mm Hg to 12.2 mm Hg in the older volunteers (medians)). Transcutaneo us pO2 values also decreased significantly in both groups. The studied hemorheological parameters did not change significantly. The data sho w, that even a short exposure to moderately elevated pressure altitude s leads to a marked decrease in tissue oxygen tensions in young as wel l as in older healthy persons.