Arteriovenous Fistula Maturation The specialist's experience

he Dialysis Outcome Quality Initiative (DOQI) guidelines revised in 2000 recommend place- ment of native arteriovenous fistulae rather than synthetic grafts for dialysis in all patients in which this is feasible, with the goal of increasing the frequency of initial placement of fistulae to 50% for those patients new to dialysis.1 Native fistulae are pre- ferred because they have an increased primary patency at 3 to 4 years compared with synthetic bridge grafts.2 After placement, a fistula must mature before it can be used. Therefore, it was also recommended that the fis- tula should be placed in patients with renal insufficien- cy before they require dialysis, allowing 3 to 4 months for fistula maturation, so that the fistula can be used immediately when needed for hemodialysis access. The team that developed the DOQI guidelines recognized that many fistulae fail to mature, and we note that in their guidelines their ultimate goal is to have success- fully functioning fistulae placement in just 40% of patients.1 This is where interventionists come in. Although fistulae can mature in 3 to 4 months, the average fistula requires 6 to 9 months to mature before it can routinely tolerate catheterization with 15-gauge needles during hemodialysis. Fistula maturation typically has occurred when the diameter of the fistula is at least 4 mm to 5 mm in diameter, and it has a flow rate of at least 500 mL/min.2 Nevertheless, in our experience, the vein caliber may need to be between 6 mm to 7 mm in diameter or greater, before the average technologist or nurse at a dialysis center can reliably perform repeated cannulation of the fistula, without infiltrating or damag- ing it. Fistulae fail to mature in at least 20% of patients. Although fistulae can be placed successfully in adults older than 65 years, maturation failure is almost twice that of younger patients.3 Typically, fistulae are placed in the upper extremities, after vein mapping using ultrasound or venography to determine if the veins are suitable, and after a careful peripheral vascular evaluation of the arteries. The DOQI 2000 guidelines recommend that surgeons join the radi-