Transcutaneous oxygen pressure measurements in patients with intermittent claudication

Transcutaneous oxygen pressure (TcPO2) measurements were performed on 10 male patients with moderate-to-severe intermittent claudication. The TcPO2 electrode was attached to the dorsum of the foot. TcPO2 response to a standardized treadmill exercise test was evaluated, as was the reproducibility of TcPO2 measurements at rest and during exercise. Reproducibility was assessed using a similar exercise test within 2-5 days. Treadmill exercise induced a marked decrease in TcPO2 in all patients, from 9.3 +/- 0.9 to 2.8 +/- 2.0 kPa. Maximal walking distance was 280 +/- 127 m at the first treadmill test and 272 +/- 113 m at the second. Blood lactate and heart rates at rest and at end of exercise were also unchanged. TcPO2 at rest was highly reproducible, but considerable variation was found for measurements during and after exercise. This variation was most obvious for measurements during exercise and no direct or reproducible relation was found between ischaemic calf pain and TcPO2 values. Post-exercise measurements were slightly more reproducible and somewhat easier to assess. In contrast to standard TcPO2 measurements, total exercise-induced ischaemia expressed as area under the post-exercise TcPO2 curve was highly reproducible. In summary, our results with TcPO2 measurements in patients with intermittent claudication showed a marked exercise-induced decrease in all patients. However, the variation in TcPO2 values when the test was repeated after 2-5 days under stable clinical and circulatory conditions limits its application as a quantitative measure of lower-limb ischaemia. Thus, measurements of area under the TcPO2 curve might be preferred for this purpose.