Doppler Ultrasound in Vascular Access care: the pearls and pitfalls of flow volume measurement

Abstract

Vascular access (VA) care is a critical part of the management of end-stage renal disease. Optimal care is necessary to avoid underdialysis and VA loss, leading to increased morbidity, mortality, and health-care-associated costs. The cornerstone of VA surveillance is flow volume (Qa) measurement. One of the most common ways to quantify Qa in clinical practice is by using duplex ultrasound (DUS), which is based on the Doppler method. DUS is a cheap and non-invasive technology that allows direct Qa measurement and the simultaneous visualization of the VA morphology, which allows the diagnosis of underlying lesions. In addition, DUS has a similar precision to Ultrasound Dilution (UD) methods. On the other hand, DUS is an operator-dependent technique, has more potential measurement errors, is time-consuming, and also loses accuracy in higher Qa. This narrative review aims to discuss the theory and technical considerations behind DUS, as well as its advantages, disadvantages, and pitfalls. We also review the reliability of DUS measurement and its correlation with UD methods. Finally, we reflect on the role of DUS Qa measurements in arteriovenous fistula maturation and surveillance. Despite the overall quality of data regarding VA surveillance not being high, we believe that DUS will remain one of the most important tools at our disposal in every step of VA care.