Abstract
Objectives: Diffuse enlargements of arteriovenous dialysis fistulas customarily attributed to either excessive arterial inflow or central outflow stenosis. The relationship between volume status and clinically enlarged (arteriovenous) fistula (CEF) formation in end-stage renal disease (ESRD) patients is not well understood.Methods: We assessed the pre-dialysis bioimpedance spectroscopy-measured percentage of overhydration (OH%) in 13 prevalent dialysis patients with CEF development and negative angiography and compared the results with those of 52 control dialysis patients (CONTR). All patients were prevalent ESRD patients receiving thrice-weekly maintenance hemodiafiltration at an academic outpatient dialysis unit.Results: 10/13 CEF patients had OH% ≥15% as compared to 20/52 control patients (Chi square p: .02). The degree of OH% was 20.2 ± 7.4% among the CEF vs. 14.4 ± 7.1% in the control group (Student’s t-test p: .01), representing 4.2 ± 3.2 vs. 2.8 ± 1.6 L of excess fluid pre-dialysis (p: .03). Patients with CEF development took an average of 1.7 ± 1.4 vs. 0.8 ± 0.8 (p: .002) antihypertensive medications compared to the CONTR patients, yet their blood pressure was higher: 156/91 vs. 141/78 mmHg (systolic/diastolic p: .03<.0001). We found no difference in fistula vintage, body mass index, age, diabetes status, or diuretic use. The odds ratio of having a CEF in patients with ≥15% OH status was 5.3 (95% CI: 1.3–21.7; p: .01), the Number Needed to Harm with overhydration was 4.Conclusions: There is an association between bioimpedance spectroscopy-measured overhydrated clinical state and the presence of CEF; either as an increased volume capacitance or as a potential cause.
Highlights
Introduction and backgroundFor decades, arterio-venous fistulas (AVFs) have been deemed the primary and desired dialysis access for hemodialysis [1], with the successful creation and maintenance of AVFs remaining Achilles’ heel of hemodialysis
We have previously described the measurement method [16]; it shall be added that we measured the patients’ fluid compartments by positioning them flat on their backs and placing two conductive electrodes on their hands and ankles on the same side at the same time. We measured their total body water (TBW), extracellular water (ECW), intracellular water (ICW), and overhydration (OH) levels in liters and acquired the percentage (OH%) of the excess fluid that is greater than the anticipated ECW
While our working definition of clinically enlarged (arteriovenous) fistula (CEF) in our study was not harmonized to the diagnosis of ultrasonography-defined megafistula with high overall flow nor did we perform the NicoladoniBranham maneuver, our study entertains yet another striking possibility contributing to enlargement of arteriovenous accesses; the one of chronic salt-water overload
Summary
Arterio-venous fistulas (AVFs) have been deemed the primary and desired dialysis access for hemodialysis [1], with the successful creation and maintenance of AVFs remaining Achilles’ heel of hemodialysis. Failure of arteriovenous dialysis access occurs at a rate of about 17.5% [4] to 23% [5] and the overall one-year primary patency rate is about 60%. Albeit much less common mechanism of hemodialysis access failure is the development of fistulas with excessively high flow and large diameters, known as megafistulas [6], most commonly originating from the brachio-cephalic location. Established risk factors for megafistulas are wide arterio-venous anastomoses with large blood flow rates or a relative narrowing of the draining vein in the venous circulation. Megafistula formation is most commonly recognized by an excessive blood flow and clinically confirmed by the Nicoladoni-Branham maneuver. The suggested criteria include an increased blood flow greater than 2.2 L/min, increased cardiac output and index, increased (>20%) cardio-pulmonary recirculation and hypertrophied feeding artery [6,7]
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