Vein distensibility is superior to vein diameter for predicting unassisted maturation of arteriovenous fistulae.

ABSTRACT

BACKGROUND: A mature arteriovenous fistula (AVF) is the preferred hemodialysis access owing to its durability and lower risk of complications. Various factors have been implicated as predictors for maturation, including vein diameter and access type. Vein distensibility, which refers to the ability of the vein to dilate in response to changes in blood flow and pressure, has been proposed as a potential predictor for maturation, but its utility remains poorly studied. METHODS: This is a single-institution retrospective study of AVFs performed under regional anesthesia. Vein distensibility was defined as the absolute and relative difference in target vein diameter (TVD) between the preoperative ultrasound vein mapping performed with tourniquet and a repeat ultrasound examination after a regional block before AVF creation and without a tourniquet. RESULTS: There were 46 patients who underwent first-time AVF surgery and had distensibility captured in a prospectively maintained database. The mean initial preoperative TVD was 2.7 mm and after the block 3.4 mm. The unassisted maturation rate for the entire cohort was 76%. In patients with an absolute change of TVD of <0.5 mm (Δ<0.5), the unassisted maturation rate was 63% (12/19), even though 95% of the group had a preoperative TVD of >3 mm. In those with ≥0.5 mm, the unassisted maturation rate was 85% (23/27; P = .08), even though the preoperative vein map TVD was 2.3 mm and 75% had a vein map TVD of <3 mm. For radiocephalic AVFs (n = 26), the unassisted maturation rate was 75% for Δ<0.5 vs 94% for Δ≥0.5 (P = .16), despite a preoperative vein map TVD of >3 mm in 92% vs 75%, respectively. The receiver operatring characteristic area under the curve for unassisted maturation with a Δ≥0.5 mm was 0.68 (P = .26). CONCLUSIONS: Quality in dialysis access surgery requires optimizing the unassisted maturation rate. A physiological measure that accounts for the dynamic process of maturation may be more informative than anatomic measurements alone. The results shown here demonstrate that vein distensibility may be a better predictor than absolute vein diameter on standard vein mapping ultrasound examinations.