Oxygen tension of peripheral tissue

Abstract

Changes in oxygen tension of living tissues in situ can be estimated by means of a small platinum electrode in a suitable electrical circuit. Many such studies have been made in normal human extremities, in which during cutaneous vasodilatation the cutaneous oxygen tension closely approaches that of arterial blood. In cutaneous vasoconstriction and with arterial occlusion the oxygen tension of the skin is reduced, sometimes to a small fraction of that in normal vasodilated skin. In ischemic extremities cutaneous oxygen tension can be increased by environmental oxygen, by inhaled oxygen and by various physical measures and drugs that increase the cutaneous circulation. There is some evidence that cutaneous oxygen tension can be made to change without concomitant changes in blood flow, perhaps because of changes in oxygen utilization or in the rate of delivery of oxygen through the capillary wall. Fewer studies have been made on oxygen tension of muscle: these have been of resting skeletal muscle. In normal man oxygen tension of muscle rises when oxygen is inhaled and decreases with arterial arrest by a pressure cuff. Changes in oxygen tension of muscle with positional changes have also been demonstrated. The several drugs studied produced no measurable change in oxygen tension of human muscle. In the dog epinephrine appears to increase the oxygen tension of muscle. Oxygen tension tends to reflect blood flow but the method measures the resultant of oxygen delivered through capillaries and utilized by the tissue rather than the total blood flow alone. More measurements, perhaps especially those of muscle, are needed in studies of the complex disorders incident to peripheral vascular disease.