Obliteration index: A simple non-invasive tool for the assessment of peripheral vascular disease in chronic kidney disease

摘要

Background: Peripheral artery disease (PAD) represents a major complication in chronic kidney disease (CKD) patients, but its early diagnosis is still problematic. Traditionally, ankle-arm blood pressure index (API) determined by means of a simple hand-held unidimensional Doppler device has been used for noninvasive diagnosis of PAD, with a cutoff value of 0.9. However, in CKD patients, vascular disease includes not only atherosclerosis but also arteriosclerosis with high calcification score. There, the API method often fails. Development of the method: Based on complex examination of Doppler signals recorded at 4 main arteries of both lower extremities (a. femoralis, a. poplitea, a. dorsalis pedis, a. tibialis posterior) and their semiquantitative assessment, we introduced the Obliteration Index (OI) as a novel and simple tool allowing semiquantitative assessment of PAD in CKD patients: the signal from each artery is assessed in a 6-grade scale, with each grade represented by 5 points. The sum of points allocated to all arteries constitutes the final OI value, ranging from 0 (normal finding) up to 240 (most severe PAD). Verification of the method: Comparison of the OI method with the conventional API examined in over 100 renal patients revealed superior OI sensitivity in detection of PAD in the early stage and low-grade vessel infliction where the API still remains within the normal range. OI can also be evaluated even when API is not measurable. Very good correspondence was found between the OI and angiography. Conclusions: The OI method has now been introduced into routine use in the authors' department. Based on over 1,500 OI evaluations performed so far, it can be recommended as a simple, noninvasive, bedside tool for diagnosis of early as well as advanced PAD.