Tissue PO2 measured in man by an implanted latex rubber tube.

A latex rubber tube easily permeable to O2 was implanted in a triceps muscle of six volunteers. Seven days later, PO2 in muscle tissue (PtO2) was measured repeatedly by filling the tube with saline. After a 2-minute equilibration, the saline was sampled in a glass capillary and its PO2 measured by polarographic technique. PaO2 and venous oxygen tension (PvO2) were measured simultaneously. Measurements were performed under four conditions: (1) air breathing, (2) breathing 100% O2, (3) breathing 14% O2, and (4) 50 Warm exercise. During (1) breathing air PaO2 was on an average 90 mmHg, PvO2 36 MMHg and PtO2 40 mmHg. During (2) PaO2 reached 570 mmHg in 2 min, PvO2 rose slightly and PtO2 increased to 80-90 mmHg in 30-40 min. During (3) PaO2 fell rapidly to 45 mmHg and PtO2 decreased from 40 to 30 mmHg in 8 min. During (4) PaO2 did not change, PvO2 decreased slightly and PtO2 fell to approximately 30 mmHg within 2-4 min. The interindividual scatter was of equal magnitude in tissue and blood. A PtO2 higher than PvO2 during oxygen breathing and less than PvO2 during hypoxia and physical exercise is explained by the existence of oxygen gradients in the extravascular space. The present technique proved to be simple despite a 1-week delay before measurements. There were no complications, and no discomfort was complained of. Thus, the latex rubber tube seems suitable for clinical use.