Tissue oxygen tension in normal and ischaemic human skin

Tissue oxygen tension has been measured in the skin of the lower limbs in ten normal subjects and in six patients with peripheral vascular disease. Measurements of oxygen tension breathing air, PO2(air) and breathing oxygen for 4 min, PO2(O2:4) were assessed in the thigh, below knee and foot levels of all subjects. In normal subjects PO2(air) and PO2(O2:4) values were (+/- SD) 4.9 +/- 0.8 kPa (37.2 +/- 6.1 mmHg) and 14.8 +/- 2.2 kPa (111 +/- 16.3 mmHg) respectively with no significant difference at any level. In ischaemic subjects PO2 (air) values were significantly reduced at the foot level but PO2(O2:4) values were significantly reduced at both below knee and foot levels. Our results suggest that the rise in oxygen tension following a change from air to oxygen breathing may be a better indicator of local blood flow conditions than a measure of the tissue oxygen tension by itself.