Forefoot transcutaneous oxygen tension at different leg positions in patients with peripheral vascular disease.

Transcutaneous oxygen tension (TcPo2) was measured on the forefoot of 150 limbs of 128 patients with different stages of peripheral vascular disease (PVD) and on 36 limbs of 18 healthy subjects in the sitting and supine position. The diagnostic value of TcPo2 measurements was tested and compared with indirect toe pressure measurements. TcPo2 measured in the supine position gives the best diagnostic discrimination between healthy controls and patients with PVD and between patients with different degrees of PVD. The median TcPo2 in patients with PVD and rest pain (severe PVD), patients with PVD without rest pain (moderate PVD) and control subjects was 12 mmHg (range 0-61), 50 mmHg (range 0-86), and 60 mmHg (range 35-78), respectively. In the supine position, 95% of the patients with severe PVD had TcPo2 values below 40 mmHg, as opposed to 28% of the patients with moderate PVD and 8% of the control subjects. TcPo2 below 40 mmHg measured on the forefoot in the supine position suggests severe ischaemia. The diagnostic value of TcPo2 measurement is comparable with that of toe systolic pressure measurement. As a diagnostic and quantitative non-invasive method of evaluating patients suspected of PVD, TcPo2 measurement is ideal as it is easy to perform, and does not cause discomfort.