Novel Assessment (BlueDop) Device for Detection of Lower Limb Arterial Disease: A Prospective Comparative Study.

According to National Institute of Clinical Excellence guidelines, the ankle-brachial pressure index coupled with a full clinical evaluation has been the mainstay of detecting peripheral arterial disease on its suspicion. However, this technique is not free of its own limitations in calcified arteries, ulcerative and diabetic patients. We introduce a new, novel, and effective assessment device (BlueDop) with a minimal learning curve that could overcome such barriers and serve as a valid replacement in perihospital settings.

Volume blood flow, static pressure ratio and venous conductance in native arterio-venous fistulae: three surveillance methods compared.

PURPOSE: Dialysis venous pressure monitoring has been widely recommended as a surveillance method but has not been shown to improve access outcomes in randomised controlled trials. The method has been impaired by the need to either turn off the blood pump or to derive the static venous pressure from the venous pressure measured with the dialysis pump running. We have developed a unique algorithm which converts Doppler-shifted spectral information derived from unscaled pulsatile blood flow waveforms into an estimate of mean blood pressure (MBP) at the point of ultrasound insonation. METHODS: We have devised the unique expression shown here: MBP = MAP/(1 + Pff/Vff) where MAP is the mean arterial pressure, Pff = (systolic - diastolic)/MAP measured on the contralateral arm and Vff = spectral maximum - minimum/mean. Venous conductance (VC) can be measured by combining this pressure data with Duplex ultrasound blood flow data. A new device BlueDop™ has been used to illustrate the potential clinical value of non-invasive static pressure ratio (SPRn) in a monitoring role. Duplex and BlueDop™ technology were tested in an arterio-venous fistula (AVF) study in which VC, Q and SPRn were compared. Thresholds used for detection of ≥60% venous stenosis were VC <10 mL min-1 mm Hg-1, Q <500 mL min-1, SPRn >0.56. RESULTS: The following accuracy was achieved: VC = 96%, Q = 92%, SPRn = 76% with similar accuracy in predicting premature thrombosis. CONCLUSIONS: A new algorithm has been described and its in vivo accuracy in estimating mean 'pressure from flow' has been confirmed. Two new variables and a new dedicated instrument BlueDop™ have been demonstrated in clinical use.

Ankle brachial pressure index (ABPI): An update for practitioners.

Peripheral vascular disease affects some 12%-14% of the general population, and the majority of people with the disease are asymptomatic. The ankle brachial pressure index (ABPI) test is widely used by a diverse range of practitioners (in the community and hospital setting) in order to screen asymptomatic patients, diagnose patients with clinical symptoms, and to monitor patients who have had radiological or surgical intervention. This paper explains the theoretical basis of the ABPI test, as well as the relevance of the common modifications of the test. It explores the background to the quoted normal ranges for the ABPI test. It reviews the large body of literature that has developed on the association between ABPI and cardiovascular risk, as well as ABPI as a predictor for cardiovascular morbidity and mortality, highlighting the evidence that can inform practice. The review looks critically at the limitations of the ABPI test, providing practitioners with an evidence-based update on the importance and challenges of standardizing ABPI methodology. This paper highlights the influence of the key technical aspects of the ABPI test that all practitioners need to consider in order to be able to make more reliable and informed management decisions based on ABPI findings.