THE VALUE OF NONINVASIVE TECHNIQUES FOR THE ASSESSMENT OF CRITICAL LIMB ISCHEMIA

Objective: The European Consensus Document (ECD) defines critical isch aemia (CI) according to clinical (Fontaine) and blood pressure paramet ers. However, clinical symptoms may be non-specific and CI may exist w ithout severely reduced blood pressures. This study prospectively inve stigated the additive value of transcutaneous oxygen tension (pO(2)) a nd toe blood pressure measurements to assess the presence of CI. Metho ds: Forty-nine patients with 65 legs clinically classified as Fontaine Stages III (n = 23) and IV (n = 26) were studied. Ankle and toe systo lic blood pressures anti pO(2) were measured to assess the presence of CI (cut-off values mere 50, 30 and 30 mmHg, respectively). The surgeo n was blinded for the toe pressure and pO(2) results. The treatment re ceived within 1 month after presentation was recorded as being either conservative or invasive (vascular surgery or PTA). Results: An ankle pressure of less than or equal to 50 mmHg classified only 17% of the l egs as having CI. By adding toe pressure and pO(2), significantly more legs (63%; p<0.0001) were classified as CI, of which 68% received inv asive therapy. Forty-nine percent of the legs with an ankle pressure > 50 mmHg were treated invasively, whereas only 32% of the legs classifi ed as not having CI by means of toe pressure and pO(2) underwent invas ive therapy. If the need for invasive treatment is used as the ''gold standard'' for the presence of CI, 54% of the legs would accurately be classified on the basis of the ankle blood pressure. The combination of toe pressure and pO(2) would have yielded 71% and the ECD criteria 72% accurately classified legs. The odds ratio for invasive therapy gi ven a pO(2) or toe pressure above the cut-off value ions 14. Conclusio n: Ankle blood pressure measurements have limited diagnostic value. Ad ding toe and/or oxygen pressures enhances the detection of CI requirin g invasive therapy.