Transcutaneous oxygen pressure measurements (tcpO2) at ankle during exercise in arterial claudication

Abstract

Aim: Although a time consuming technique, tcpO2 provides complementary information as compared to other tests. Simultaneous recording of systemic and peripheral oxygen pressure changes with exercise could be interesting to confirm that local hypoxemia is of arterial origin, but accuracy versus gold standard arteriography and objectively determined cut-off points to be used in arterial claudication at the ankle are not reported.

Experimental design: retrospective plus prospective study.

Setting: institutional practice, ambulatory care.

Patients: 100 patients suffering stage 2 claudication (group A) were retrospectively studied to objectively define cut-off points derived from tcpO2 recordings to be used in exercise testing. Then, applicability and reproducibility of these cut-off points were analysed prospectively in another 50 patients (group B).

Intervention: tcpO2 was measured on both calves and with a chest reference electrode. Arteriography on each side was quoted positive for a diameter stenosis superior to 75% or occlusion on the aorto-popliteal axis or of all-3-calf arteries.

Results: The best performance was obtained with tcpO2 changes from rest at the calf normalised to eventual chest changes (DROP) during or following the treadmill test. Optimal cut-off point determined through ROC curve analysis for DROP was -15 mmHg in group A. Applying this cut-off point in group B provided a 86/84% sensitivity/specificity and showed excellent reproducibility.

Conclusions: TcpO2 measurement on the calf during exercise could be useful in a selected population of patients with claudication of questionable vascular origin and/or when other non-invasive investigations cannot be performed.