Ankle Brachial Pressure Index: An update for the vascular specialist and general practitioner

Abstract

Objectives Ankle brachial pressure index (ABPI) is an invaluable tool for assessing the severity of peripheral arterial disease. In addition, it can be used as an independent marker of cardiovascular risk, with a predictive ability similar to the Framingham criteria. Identification of an abnormal ABPI should therefore trigger aggressive cardiac risk factor modulation for a patient. Unfortunately, the significance of abnormal ABPIs is poorly understood within the general medical community. This is compounded by the influence of various comorbidities on accurate measurement of ABPI, potentially leading to a wide variability in readings that need to be considered before interpretation in these patient populations. We aim to address these issues by revealing several common misunderstandings and pitfalls in ABPI measurement, describing accurate methodology, and highlighting patient cohorts in whom additional or alternative approaches may be required. Methods We present a narrative review of the role of ABPI in both the community and hospital setting. We have performed a literature review, exploring the validity and reproducibility of methodology for obtaining ABPI, alongside the utility of ABPI in different clinical scenarios. Results The measurement of ABPI is often performed incorrectly. Common pitfalls include inadequate patient preparation, failure to obtain the blood pressure from the correct lower limb artery in patients with tibial disease, failure to account for differences in brachial blood pressure between the arms, inappropriately chosen equipment and patient factors such as highly calcified arteries. Standardisation of methodology greatly improves reliability of the test. Exercise ABPI can identify significant peripheral arterial disease in patients with normal resting ABPI. In addition to its role in peripheral arterial disease, ABPI measurement has a role in assessing venous ulcers, entrapment syndromes and injured extremities; conversely, it has a more limited utility in the diabetic population. Conclusions A thorough understanding of the correct technique and associated limitations of ABPI measurement is essential in accurately generating and interpreting the data it provides. With this knowledge, the ABPI is an invaluable tool to help manage patients with peripheral arterial disease. Perhaps more importantly, ABPI can be used to identify and risk stratify patients with asymptomatic peripheral arterial disease, itself a major indicator of significant underlying cardiovascular disease. With the emergence of best medical therapy, targeted pharmacotherapy and lifestyle changes can reduce the risk of major cardiovascular events in high-risk patients by approximately 30%, particularly in diabetic patients. Therefore, the utility of ABPI transgresses vascular surgery, with an essential role in general practice and public health.