Muscle tissue PO2 during moderate altitude exposure in patients with peripheral arterial occlusive disease

In 10 patients with peripheral arterial occlusive disease (intermittent claudication) and in 10 healthy volunteers serving as controls, muscle tissue pO2, transcutaneous pO2, arterial pO2 and rheological parameters were measured before and during breathing (for 20 min) of an oxygen reduced gas mixture simulating an altitude of about 8500 feet (2600 m, approximately 116 mm Hg pO2). Oxygen pressure values were determined by means of a polarographic method according to Ehrly and Schroeder using atraumatic micro-pt-needle electrodes.

Tissue oxygen tension in the tibialis anterior muscle of patients with peripheral arterial occlusive disease decreased significantly from 6.5 mm Hg to 2.4 mm Hg (medians). The pooled histograms were markedly shifted to hypoxic values. The controls showed a decrease from 20.8 to 12.2 mm Hg and a strong shift to the left. Transcutaneous pO2 measured in the diseased leg decreased from 53.4 +/- 11.6 to 36.1 +/- 9.3 mm Hg (controls 57.1 +/- 9.9 to 39.7 +/- 8.9 mm Hg), arterial pO2 decreased from 80.2 +/- 15.1 to 60.0 +/- 10.4 mm Hg (controls: 86.5 +/- 16.0 to 64.7 +/- 13.6 mm Hg) and pulsoximetrically determined O2-saturation from 95.0 +/- 2.5 to 90.0 +/- 5.5% (controls: 96.1 +/- 2 to 92.0 +/- 4.2%).

Exposure of patients with intermittent claudication to moderate altitude led to a marked decrease of tissue pO2 values in the diseased legs without any evidence of clinical worsening, especially no rest pain. It may be discussed if rest pain in ischaemic legs is due to low pO2-values or to disturbed microcirculatory perfusion.