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Expanding The Possibilities For Avf Creation With Brachial Plexus Block
Alex Murrant-Johnson1, Joann Lohr, MD
2, Chase Hoffman, MD
2, Brayden Reince, MD
2, Jillian Smith, MD
2, Wesley Gray
2.
1University of South Carolina School of Medicine- Columbia, COLUMBIA, SC, USA,
2Dorn VA, COLUMBIA, SC, USA.
OBJECTIVES: Vessel diameter is a key determinant of successful maturation of Arteriovenous Fistula (AVF). Without a vessel of adequate diameter, surgeons must use less efficacious alternatives to AVF. Vessel diameters are determined during a vein mapping appointment prior to operation. However, vein mapping is done immediately prior to operation start (intra-operatively), after brachial plexus block (BPB) placement. Consistently, intraoperative measurements are larger than the diameters measured in the pre-op appointment. This observation has been previously described and reported on, however, the extent of dilation has not been quantified and described in detail. This study aims to provide specific metrics on the nature of these effects so they can be more strategically applied to clinical scenarios. If the measurement of a vein that was deemed unusable in pre-op mapping is now large enough to use intra-op, then that vein may be considered for use.
METHODS: Data was retrospectively collected from 22 patients receiving AVF. Vein diameters were recorded during a preoperative vein mapping appointment, then again perioperatively after BPB. Sonography was used to determine vessel size in both settings. Data from fistula operation notes and vein mapping appointments were reviewed and vessel diameters before and after BPB were compared. Vein measurements were standardized by equally spaced zones of reference: Zone 1- midline/vena cava, Zone 3- acromion, Zone 5- antecubital, Zone 8- wrist.
RESULTS: Vessel diameters measured after BPB were on average 104% larger than before BPB. Additionally, there is an inverse correlation (R=-0.76) between vessel size and the increase in diameter after BPB. Vessels less than 2mm (n=29) had a 184% average increase while vessels greater than 2mm (n=41) had a 46% average increase. There appears to be no correlation between % change and upper extremity zone of reference. One patient’s brachial plexus block was not effective, and their vein diameters were smaller intraoperatively.
CONCLUSIONS: This study suggests that pre-operative vein mapping measurements can be significantly augmented after BPB, thus increasing the availability of vessels previously deemed unusable by pre-op appointment vein mapping. Further investigation is needed to determine the long-term efficacy/maturation rate when using these newly available veins.
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