Regional Anesthesia for Arteriovenous Fistula

To allow for chronic hemodialysis (HD), patients with end-stage renal disease (ESRD) require permanent vascular access in the form of either arteriovenous graft (AVG) or arteriovenous fistula (AVF). The latter option is the preferred form of vascular access given the lower rate of thrombosis, fewer interventions required, longer survival for vascular access and lower rate of infection as compared to AVG (1). Despite this, earlier reports have suggested that the initial failure rate of AVF approximates to 25% (2). A permanent vascular access is considered adequate when it has sufficient size (i.e. greater than 0.6 cm) for easy cannulation and a flow rate of approximately 600 mL/min for dialysis (1, 3). However, postoperative AVF blood flow may be compromised by arterial vasospasm and sympathetic activity from surgical manipulations (4, 5). Inadequate flow rate in the postoperative period can result in early thrombus formation at the fistula and, if left untreated, can lead to permanent loss of vascular access(6). Over the years, researchers have identified a number of patient and surgical factors that may influence the success and long-term survival of AVF, and recent evidence suggests that the choice of anesthetic techniques may play a significant role (7).

Vascular access surgery is usually conducted under either a) general anesthesia (GA), b) local anesthetics (LA) infiltrations with sedations, or c) regional anesthesia in the form of brachial plexus block (BPB). GA, while providing both anesthesia and analgesia, can present a challenge for maintaining intraoperative hemodynamic stability as patients with ESRD often have other significant comorbidities. LA infiltrations, though offering simplicity, does not provide motor blockade and patient movement can be a surgical challenge. LA requires multiple injections during the case. BPB thus presents as an attractive option as it provides both dense and prolonged sensory and motor blockade while avoiding the cardiopulmonary stress imposed by GA. Additionally, the sympathectomy associated with BPB has been shown to improve postoperative AVF blood flow through decreasing peripheral vascular resistance and increasing vasodilation and blood flow velocity (8-11). Similarly, stellate ganglion block (SGB), which offers sympathetic blockade without analgesic effect, has also been shown to augment postoperative AVF blood flow and average peak flow velocity and shorten maturation time when combined with LA infiltrations (5, 12).

Though it has been shown that regional anesthesia can affect a number of physiological parameters following AVF formation, it is not yet clear how fistula survival can be affected by the modification of these parameters. The investigators conducted a literature search in July 2013 using MEDLINE database. Two key words, one from List A and one from List B, were joined with the term "and" in all possible combinations for the literature search. Key words from List A included "arteriovenous fistula", "AVF", "vascular access", "dialysis", and "dialysis access". List B included "regional anesthesia", "brachial plexus block," "BPB", "brachial plexus", "stellate ganglion", "SGB", "sympathectomy", "supraclavicular", "infraclavicular", "axillary", and "interscalene". Search results were limited to English articles only. Abstracts were not included in the search results. To the investigators knowledge, no randomized trial has been conducted to directly compare the effect of axillary block (AB) against LA infiltration with or without SGB on AVF success in patients with ESRD. This will be the primary objective of the investigators study. To do so, the investigators intend to conduct a prospective randomized controlled trial at a tertiary vascular surgical center in Hamilton.