Background: Vascular access guidelines recommend routine screening for the timely detection of stenosis using noninvasive methods, including clinical assessment (monitoring) and device-based surveillance relying on access blood flow (Qa) and static intra-access pressure (sVPR, static venous pressure ratio) measurements and duplex ultrasound (DU).
Methods: We reviewed the literature to see how monitoring compares with surveillance in terms of compliance with the World Health Organization's criteria for screening tests.
Results: The fundamental element of monitoring, physical examination (PE), has a fair-to-good performance in detecting stenosis in both fistulas and grafts, similar to the Qa criteria recommended in the guidelines. In fistulas, the "or" combination of a positive PE with a Qa <900 mL/min or sVPR >0.5 is more sensitive in detecting stenosis (in up to 98% of cases), making it as good as DU. In grafts, PE performed significantly less well in diagnosing stenosis than sVPR or DU.In randomized controlled trials on fistulas, Qa surveillance enables a significant halving of the risk of thrombosis and access loss by comparison with monitoring alone when Qa criteria highly sensitive to stenosis are considered. In grafts, neither Qa nor DU nor sVPR is able to reduce thrombosis or access loss rates by comparison with monitoring alone.
Conclusions: Our analysis indicates that regular monitoring should be the backbone of any vascular access stenosis screening program (possibly associated with Qa and sVPR surveillance for fistulas), and PE should be part of every teaching program for caregivers involved in hemodialysis.