Speeding up ABPI measurements

The detection of peripheral arterial disease (PAD) can offer a reliable marker of future vascular disease, such as congestive heart disease (CHD) and stroke.1 Detection of PAD is also important when treating diabetic foot disease, as vascular insufficiency is potentially treatable. The most common cause of PAD is atherosclerosis, which is a build up of plaque in arteries that causes the vessels to harden and narrow. The National Institute for Health and Clinical Excellence (NICE) guidelines recommend palpation of pedal pulses for PAD detection. However, clinically, this is known to be inadequate.2 In cases of diabetic patients with foot ulceration, the Second European Consensus Document recommends additional, non-invasive vascular assessments, which include the Ankle Brachial Pressure Index (ABPI).3 European guidelines on bandaging also state that an ABPI should be undertaken before applying compression therapy, to identify the presence and extent of arterial disease. Compression therapy is contraindicated in patients with an ABPI of <0.8 unless the patient is carefully monitored or reduced compression is used. An ABPI of <0.5 indicates severe arterial disease and an urgent vascular referral is required.4

A proven technique

The ABPI is a proven technique that has been used for 20 years to assess for the presence of PAD. It allows clinicians to identify the disease and its severity, offering assistance in guiding a suitable treatment approach. Dr Jane Lewis, clinical specialist and research podiatrist at Cardiff and Vale UHB Podiatry Department, explains more: “As a podiatrist, checking out the peripheral arterial disease status of the limbs, particularly in diabetic patients, is very important. Part of our clinical assessment would be to undertake an ABPI measurement. However, the current process is very time consuming as you have to rest the patient for between 15-20 minutes before you can begin the procedure, to ensure there is equilibrium between the upper and lower limbs. It is also very much up to the clinical skills of the person undertaking the procedure as to the accuracy of the results.” The method that Dr Lewis refers to is the traditionally used handheld Doppler. “With the Doppler you have to manually inflate and deflate the cuff. You use a handheld probe with coupling gel and have to ensure contact with the blood vessel is maintained as the cuff is inflated and deflated.” The blood pressure cuff is inflated proximal to the artery until the pulse in the artery ceases. The cuff is then slowly deflated. The pressure in the cuff at the moment that the pulse is re-detected through the Doppler indicates the systolic pressure of that artery. The procedure then has to be repeated on all of the limbs to find the systolic pressure for each limb. A manual calculation is then required to work out the ABPI at the end of the process. In total this can take around 30 minutes, often more. “You need to be able to audibily hear the pulse. If this is weak it can take some time to locate it and to hear it. Only then can you inflate the cuff. You need to be able to hear the sounds from the returning flow, as the cuff is deflated. This is not the easiest thing to achieve,” explains Dr Lewis. One of the recommendations of Dr Lewis’s PhD, which she completed in 2006, relating to the risk assessment of diabetic foot disease, was that more work needed to be done on lower limb arterial investigation. “The Doppler method is cumbersome and time consuming, but it is all that we have,” said Dr Lewis, which was why she was happy to be involved in the study to test an alternative solution, developed by Huntleigh Healthcare. The Dopplex Ability has been developed to offer an automated solution to taking ABPI measurements. “It takes the technical complexity out of the testing procedure, and offers better continuity of results. The results are more reliable, and it allows anyone to conduct the test, as the skill element has been removed. It is also a very repeatable test and removes the element of clinician variability,” said Dr Lewis. The system produces a time and date stamped printout of all results, including systolic pressure, ABPIs and Pulse Volume waveforms.