Optimisation of the non-invasive assessment of critical limb ischaemia requiring invasive treatment

Objective: to assess the optimal cut-off values of toe blood pressure (TBP) and transcutaneous oxygen pressure (TcpO(2)) in the supine and sitting pos itions, in order to accurately detect the presence of severe leg ischaemia requiring invasive treatment. Methods: in 49 consecutive patients (65 legs) with severe ischaemia accordi ng to clinical symptoms of Fontaine III or IV and a lowered ankle blood pre ssure, TBP and TcpO(2) were measured in the supine and sitting positions. T reatment within 6 weeks after the diagnosis was classified as either conser vative or invasive (revascularisation or amputation). Results: of the 65 legs, 38 (58%) required invasive treatment. The mean ank le pressure for this group was 70 mmHg. The optimal cut-off value for TBP w as 38 mmHg and for TcpO(2) 35 mmHg. A TBP of less than or equal to 30 mmHg and a TcpO(2) less than or equal to 25 mmHg while supine, showed likelihood ratios (LR) of 7.0 and 3.3, respectively, and when combined an LR of 12.4. Measurements in the sitting position did not enhance diagnostic power. Conclusions: the need for invasive therapy in patients with severe leg isch aemia might be predicted by measuring TBP and TcpO(2), using the above-ment ioned cut-off values.