Physician-Directed Duplex Augments Distal Arteriovenous Fistula Creation

Abstract

Best practice guidelines for arteriovenous access creation have emphasized selecting distal sites and autogenous tissue before using proximal sites and synthetic shunts. Preoperative vein mapping is a useful tool to evaluate the optimal access location. However, the vein size is often underestimated secondary to patient hydration, room temperature, and basal vascular tone. Infraclavicular brachial plexus blocks (BPBs) are routinely performed for anesthesia but also have known vasodilatory effects. Although many surgeons use both techniques, most do not repeat vein mapping after performance of the BPB to reevaluate the targets after BPB-mediated vasodilation. Therefore, we evaluated whether the role of physician-directed vein mapping after BPBs resulted in more favorable fistula creations. All patients who had undergone primary ipsilateral access creation with physician-directed post-BPB duplex ultrasound from 2017 to 2018 were evaluated. Vein mapping was reviewed for “theoretical access location” using the criterion of >25-mm vessels. Fistula priority was analogous to the current indications, with an order of preference given to wrist radiocephalic, forearm radiocephalic, brachiocephalic, and brachiobasilic, followed by a prosthetic graft. Forty-three patients met the inclusion criteria. Physician-directed vein mapping after initiation of a regional BPB resulted in creation of a more distal access than expected in 62.8% of the patients. In 34.9%, the access site was at the predicted level, with a more proximal graft used in 2.3%. Furthermore, no differences in the maturation rates between the access sites placed distally to the predicted sites compared with those placed at the predicted site (0.65 vs 0.63; P = .38). The overall revision rate for distal fistulas was 22.2%, of which 83.3% were revised to the theoretical location, and 17.7% had required a proximal revision or creation of a graft. Physician-directed ultrasound after BPB is able to identify larger targets for access creation compared with preoperative vein mapping. Of those fistulas created distally, no difference was found in the maturation rates compared with those created at the theoretical location from vein mapping.