The Future of Ankle-Brachial Index (ABI) measurement

Peripheral artery disease (PAD) might be an insidious condition with growing prevalence and few, if any, symptoms, but it can be quickly and easily diagnosed with modern diagnostic devices. The main obstacle to achieving this goal is the sporadic use of said devices and their slow adoption in healthcare facilities.

Characterising PAD (frequently also referred to as lower-extremity artery disease or LEAD) as a disease with few symptoms or which is even largely asymptomatic is fairly appropriate as only 10% of patients have typical symptoms (i.e. intermittent claudication), while as much as 40% are entirely asymptomatic [2]. The rest of them, on the other hand, may have symptoms (atypical leg pain) that could be attributed to other medical conditions, evading proper and timely diagnosis [1].

Even in developed countries, this goes hand in hand with the prevalent lack of awareness among the general public and in some cases even relatively low physician’s awareness of PAD diagnosis [2, 3, 4, 5]. Those two factors, combined with the lack of or sporadic use of modern diagnostic tools, contribute to the growing silent epidemic of PAD (in addition to greater prevalence of risk factors).

There are a number of diagnostic methods appropriate for diagnosing PAD, but some are more appropriate for general practices than others (i.e. angiography, which is the most accurate and reliable method, but often prohibitively expensive and unsuitable for preventive screening of patients). Far more appropriate is assessment on the basis of the Ankle-Brachial (pressure) Index (ABPI or ABI) that can be measured in two similar, yet vastly distinct ways.

Another option is, likewise, physical examination, complemented by a comprehensive questionnaire (assessment of risk factors and possible symptoms), but its accuracy and reliability are greatly predicated on the examiner’s skill and (in)experience [6]. But even the most skilled examiner is no match for virtually any modern diagnostic method.

The ABI, on the other hand, is the best of both worlds, as it requires relatively (in comparison with angiography) inexpensive equipment and can be performed by healthcare professionals other than cardiologists. Until fairly recently, most ABI measurements were performed using a Doppler probe and a sphygmomanometer—this method, while accurate and reliable, can also yield false positives if the examiner has little practical experience [7]. Additionally, the whole examination procedure usually takes up to 30 minutes.

Diagnostic devices that work on the oscillometric-plethysmographic principle are a far superior choice as they are completely automatic (eliminating user error) and can perform the ABI assessment in 1 minute, lending themselves to preventive screening of a large number of patients (in general practice setting) [8]. There is, however, still room for improvement and an entirely new class of diagnostic devices, which aim to address the biggest elephant in the room in modern preventive healthcare—effective communication between healthcare professionals—is slowly making its way into the mainstream.

When second opinion matters

Modern diagnostic devices enable physicians to accurately assess the patient’s PAD status on the basis of an ABI measurement and help them determine the severity of the disease, but may be of limited help in borderline or special cases. For example: a patient’s ABI score was calculated to be just above the low cut-off value for confirmed diagnosis of PAD (this is usually 0.91) and the examiner is unsure whether the patient should be referred to a specialist, requires additional diagnostic tests or should be simply classified as not at risk (the worst option), making the ABI score just a footnote in their medical record. If the examiner is not the patient’s personal physician, who should have at least cursory knowledge of their patient’s medical history, they may overlook (risk) factors that would change the initial classification.

The risk factors for PAD are numerous and include smoking, diabetes, age, weight, hyperlipidaemia, hypertension, previous diagnosis of coronary artery disease (CAD) and/or myocardial infarction (MI) and cerebrovascular issues, diagnosis of chronic kidney disease (CKD), family history of the disease and even diagnosis of chronic obstructive pulmonary disease (COPD) [9-24]. Some of them are self-evident to the examiner, like age and weight, while the vast majority of others are not. If only there were a way to have the patient’s medical records always at hand.

The MESI mTABLET offers just that and much more. It’s a fully customisable, portable diagnostic device that among, other features, an integrated electric health record (EHR) management system called MESI mRECORDS, supplemented by apps available in the MESI mSTORE.

The MESI mTABLET enables fast and easy execution of a variety of diagnostic procedures (with appropriate wireless diagnostic modules), including ABI, and automatic saving of results in the patient’s EHR.

The examiner consequently has everything at hand to decide on the next course of action, including sharing the results with other healthcare professionals (including those that are not users of the mTABLET, but have access to a PC, mobile phone or tablet).

Alternatively, the patient could have severely low ABI, indicating advanced stage PAD, which can quickly progress into arterial insufficiency ulcers (ischaemic wounds) and continue to (in the absence of effective treatment) critical limb ischaemia (CLI). Upon completion of the examination, the examiner can nearly instantly forward the results to a cardiologist for a second opinion. A very low ABI score combined with possible comorbid conditions, like CAD or diabetes (as noted in the patient’s EHR) will likely result in additional diagnostic tests or start of the treatment. The ABI might also be on the other end of the spectrum, i.e. abnormally high. A quick look at the EHR would probably reveal a previous diabetes diagnosis and the possibility of incompressible arteries (highly prevalent in diabetics and the cause of diagnostically unusable ABI score) and the need for a Toe-Brachial Index (TBI) assessment (using the combination of the mTABLET with the TBI diagnostic module) [25, 26, 27].

Another typical situation where the sharing of ABI score and other data is of great use is in wound care. The examiner can forward the ABI results to a wound care specialist who will instantly know what kind of wounds they are dealing with. They can also share the patient’s EHR with a cardiologist in cases when the ABI indicates the presence of wounds with mixed aetiology and needs a second opinion since arterial and venous leg ulcers require vastly different treatments.

Modern diagnostic tools for ABI assessment with integrated support for electronic health records offer unprecedented versatility in facilitating collaboration between healthcare professionals through data sharing and contribute to greater time and cost efficiency of treatments and better outcomes for the patients.