Colour Doppler ultrasound in dialysis access.

Abstract

The native arteriovenous fistula (AVF) at the wrist [1] is generally accepted as the vascular access of choice in haemodialysis patients due to its low complication and high patency rates [2]. However, with an increasing number of elderly patients and patients with co-morbid conditions such as vascular disease and diabetes mellitus in the haemodialysis population, the creation and maintenance of a patent and well-functioning AVF has become a real challenge to nephrologists and vascular surgeons [3]. The DOQI guidelines state that creation of a primary AVF is possible in only 50% of the patients [4]. Therefore, in the US, synthetic polytetrafluoroethylene (PTFE) grafts are still the predominant form of permanent vascular access [5,6], despite the well known poorer outcome compared to AVFs [4,6,7]. To further increase the use of native AVFs, especially in the co-morbid patient group, a thorough preoperative evaluation with colour Doppler ultrasound (CDU) and mapping of the arterial and venous vascular system allows the placement of an AVF in a higher proportion of patients [8,9] and to achieve a better cumulative patency rate of fistulas [10]. After creation of access, periodic monitoring is recommended, since early detection of access dysfunction and subsequent intervention may help to reduce the rate of access failure [11,12]. Although angiography has been considered as the gold standard for imaging of vascular access abnormalities, duplex ultrasound may be superior in some aspects since it provides information both on the morphology and on the function of vascular access. In addition, CDU offers the advantage of a non-invasive bedside procedure with lower costs and with no need for radiocontrast. The aim of this article is to provide an update on CDU and to give some new information on preoperative evaluation and routine monitoring.