Small Caliber Distal Cephalic Veins Undergo Significant Dilation under Anesthesia and Can Successfully Be Used for Arteriovenous Fistula Creation

Abstract

Successful arteriovenous fistula (AVF) maturation and use for dialysis is highly dependent on preoperative diameter. Small veins (<2mm) exhibit high failure rates and are typically avoided. This study investigates the effects of anesthesia on the distal cephalic vein diameter as compared to preoperative outpatient vein mapping for the purpose of hemodialysis access creation. One hundred eight consecutive procedures for dialysis access placement met inclusion criteria and were reviewed. All patients received preoperative venous mapping and postanesthesia ultrasound mapping (PAUS). All patients received either regional and/or general anesthesia. A multiple regression was conducted to determine predictors of venous dilatation. The independent variables included both demographical and operative-specific variables such as the type of anesthesia. Outcomes of fistula maturation (successful cannulation and dialysis) were analyzed. In this cohort, the mean preoperative vein diameter was 1.85mm and the mean PAUS diameter was 3.45mm, a 2.21× increase, with only 2 patient veins failing to increase in diameter. Smaller veins (<2mm) exhibited significantly more dilation than larger veins after anesthesia (2.73 vs. 1.47×, P<0.001). In the multiple regression analysis, smaller vein diameter was correlated with a significantly greater degree of dilation (P<0.001). The degree of venous dilation was not affected by patient demographic-specific factors or by the type of anesthesia (regional block versus general) in the multiple regression analysis. 6month follow-up data for fistula maturation was available for 75 of 108 patients. Small veins (<2mm) on preoperative ultrasound matured at a similar rate as larger veins (90% vs. 91.4%, P=0.833). Small caliber distal cephalic veins experience a significant degree of dilation under regional and general anesthesia and can successfully be used for AVF creation. Consideration should be made to perform a postanesthesia vein mapping for all patients undergoing access placement despite preoperative venous mapping results.