[Doppler echo in evaluating arteriovenous fistulae for dialysis]

US-Doppler has recently gained attention as a noninvasive method for the functional evaluation of arteriovenous fistulas (FAV). Twenty patients with well-functioning FAV were studied, and the results compared with those from a control group of 10 healthy subjects. Time average velocity (TAV) was calculated as hemodialysis parameter, together with telesystolic (Vts) and telediastolic (Vtd) velocities, absolute (F) and normalized (FN) fluxes to the area unit (cm2 1) and resistance index (IR). All of them proved to be statistically significant indexes of FAV functionality. Doppler has thus proved to be a valuable means both to calculate FAV capacity in a patient and to establish FAV functionality. Four parameters are recommended: FN greater than 2000 ml/min/cm2; IR less than 0.05; TAV greater than 50 cm/s: and Vtd greater than 35 cm/s.