Importance of accurate identification of arterial perfusion in the lower limb using different non-invasive physiological tests

Abstract

Background: Although diagnostic and therapeutic decisions in patients with peripheral arterial disease are guided primarily by the history and physical examination, the use of noninvasive investigations has increased significantly in recent years, mainly as a result of technological advances in ultrasonography. Ultrasonic hand held doppler velocimeters are widely utilized by healthcare professionals for the assessment of lower limb arterial perfusion. However, a clinical assessment tool is only of value if the interpretation of the results is correct and repeatability has been clinically established. Ankle Brachial Pressure Index, TBIs, toe pressures and spectral waveforms at the ankle are all used to assess arterial perfusion especially in high risk populations. This chapter presents the findings of two studies conducted to compare the accuracy of different physiological tests used by various health care professionals for the identification of arterial perfusion in the foot and prediction of wound healing. Vascular testing included assessment of arterial spectral waveforms at the ankle, absolute toe pressures, Toe-Brachial Pressure Index (TBI), Ankle-Brachial Pressure Index (ABPI) and Pulsatiliy Index (PI). Outcomes: TBIs, toe pressures and spectral waveforms at the ankle are better predictors of arterial perfusion and the likelihood of wound healing and non-healing after minor amputation than ABPIs. ABPI alone is a poor indicator of tissue perfusion and the likelihood of healing of minor amputations and should not be relied on to determine the need for revascularization procedures in the high risk foot. The PI, being a continuous variable allows classification of patients on a scale, making it easier to diagnose severity of disease, thus resulting in a more accurate interpretation of the extent of disease. The advantage of PI over spectral waveforms is that it is a quantitative measure, rather than a subjective assessment of spectral waveforms thus ensuring no variability in user interpretation between waveforms especially in severely diseased arteries which can prove to be difficult to interpret correctly.