A Comparison of Preoperative and Intraoperative Vein Mapping Sizes for Arteriovenous Fistula Creation

Abstract

Preoperative duplex ultrasound mapping (DUM) of the veins and arteries of the upper extremities is widely accepted to optimize creation of arteriovenous fistulas for long-term hemodialysis access. Vein diameter is an independent predictor for fistula maturation. A diameter of 2.5 mm has been established as the minimum vein size predictive of fistula success. Based on the preoperative vein size an operative plan is typically established. This study compares the size of veins measured by DUM preoperatively with that obtained after an anesthetic to determine if the anesthetic results in increases in vein diameter and thus changes the operative plan (conversion from graft to fistula, or to a fistula more distal in the upper extremity). A second goal was to determine if a change in plan resulted in a matured access. Sixty-eight patients were enrolled (July 2013-December 2014). Preoperative DUM were completed in an accredited vascular laboratory. Intraoperative vein mapping and surgery were performed by two board certified vascular surgeons. Intraoperative measurements were performed after an anesthetic (regional or general) at the same levels as preoperative mapping. Access success was determined at routine follow-up appointments. Significance testing was two sided with a significance level of 5%. Sixty-eight patients were analyzed. Average age was 57.7 years (range, 16-83 years). There were 47 men (69%) and 21 women (31%). Sixty-five had a regional anesthetic with a supra- or infraclavicular block; three patients had a general anesthetic. The Table shows that two areas, the intraoperative mid forearm and distal forearm cephalic veins, were significantly larger than the preoperative measurements. Other areas measured were generally larger than the preoperative DUM but not significant (Table). Thirty-eight of 68 patients (56% of study group) had the preoperative surgical plan altered based on the repeat intraoperative DUM. Of this group 4 were lost to follow-up or underwent transplantation. Of the remaining 34 patients with an intraoperative plan change, 19 (56%) had a more distal fistula created or were converted from a graft to a fistula that matured and was used for dialysis. In three of the 34 patients (9%), the intraoperative DUM findings prompted the alteration to a more proximal fistula or conversion to a graft that was successfully used for dialysis. Overall, in 22 of the 34 cases (65%) where the plan was changed resulted in an access that was used for dialysis. The use of an intraoperative duplex after an anesthetic resulted in a significant dilation of the forearm cephalic veins and a change in the preoperative plan in 56% of patients in this study. This suggests that intraoperative DUM is a valuable tool to increase the use of veins that would normally not be used based on their preoperative size, and in over one-half will result in a functioning access.TableVein sizesZonePre-op cephalic in mm (SE)Intra-op cephalic in mm (SE)Delta (SE)P valueProximal arm2.62 (0.20)2.95 (0.31)0.33 (0.29)NSMid-arm2.81 (0.20)3.25 (0.30)0.44 (0.26)NSAntecubital fossa3.29 (0.20)3.17 (0.30)−0.12 (0.30)NSProximal forearm2.28 (0.15)2.51 (0.23)0.27 (0.22)NSMid-forearm1.18 (0.16)2.14 (0.22)0.96 (0.19)a<.001Distal forearm (wrist)1.74 (0.14)2.23 (0.20)0.50 (0.16)a.04NS, Not significant; SE, standard error.aSignificant. Open table in a new tab