Factors associated with access blood flow in native vessel arteriovenous fistulae

Hirsch, David J.; Chan, Christopher T.; Marryatt, Joanne; Mossop, Paula; Wile, Colleen; Jindal, Kailash

doi:10.1093/ndt/gfh406

Cited by 26 publications

(20 citation statements)

References 18 publications

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“…These parameters were not recorded in the present study. Despite this omission, we can confirm that the found factors are related to decreased Qa [50] . To what extent demographics and cardiovascular risk factors are specifically related to decreased Qa remains to be investigated in a study including both CO and blood pressure.…”

Section: Limitationssupporting

confidence: 51%

Access Blood Flow and the Risk of Complications in Mature Forearm and Upper Arm Arteriovenous Fistulas

Huijbregts

Bots

Wittens³

et al. 2009

Blood Purif

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Background/Aims: Optimization of vascular access use in the ‘fistula first’ era requires comprehension of its clinical behavior. Little is known about mature arteriovenous fistula (AVF) performance and the role of fistula location. Widely used access flow (Qa) was used to analyze complication risks and functionality after first hemodialysis use. Methods: 178 Mature AVFs were analyzed. Complication was defined as permanent failure or ≥1 intervention. Factors associated with complications and mean Qa were determined using Cox proportional-hazards and linear regression models. Results: Baseline Qa was significantly lower in complicated versus uncomplicated forearm and upper arm AVFs. In complicated forearm AVFs, preoperative arterial diameter was smaller while the risk of complications was graded per 100 ml/min baseline Qa increase. Diabetics had an increased risk of upper arm AVF complications. In uncomplicated forearm AVFs, diabetes was related to lower mean Qa, and BMI to higher Qa. Conclusions: In mature AVFs, baseline Qa depends on fistula location and is related to the risk of complications in a graded manner.

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Section: Limitationssupporting

confidence: 51%

Access Blood Flow and the Risk of Complications in Mature Forearm and Upper Arm Arteriovenous Fistulas

Huijbregts

Bots

Wittens³

et al. 2009

Blood Purif

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“…This study confirms the clinical observation that MAP has a large effect on Q and underscores the importance of avoiding hypotension in preventing thrombosis. It often has been proposed that Q should be normalized for MAP (Q/MAP) or systolic pressure so as to offset the effect of hemodynamic changes on Q (31)(32)(33). This adjustment assumes that a change in MAP causes a proportionally equal change in Q.…”

Section: Discussionmentioning

confidence: 99%

Influence of Luminal Diameters on Flow Surveillance of Hemodialysis Grafts

White

Ram

Jones

et al. 2006

Clinical Journal of the American Society of Nephrology

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Randomized controlled trials have not shown that surveillance of graft blood flow (Q) prolongs graft life. Because luminal diameters affect flow resistance, this study examined whether the influence of diameters on Q can explain the limitations of surveillance. Inflow artery and outflow vein diameters were determined from duplex ultrasound studies of 94 patients. These diameters were applied to a mathematical model for determination of how they affect the relation between Q and stenosis. Also determined was the correlation between Q (by ultrasound dilution) and diameters, stenosis, and mean arterial pressure in 88 patients. Artery and vein diameters varied widely between patients, but arteries generally were narrower than veins. The model predicts that the relation between Q and stenosis is sigmoid: as stenosis progresses, Q initially remains unchanged but then rapidly decreases. A narrower artery increases flow resistance, causing a longer delay followed by a more rapid reduction in Q. In a multiple regression analysis of data from patients, Q correlated with artery and vein diameters, sum of largest stenoses from each circuit segment, and mean arterial pressure (R ‫؍‬ 0.689, P < 0.001). This study helps to explain why Q surveillance predicts thrombosis in some patients but not others. Luminal diameters control the relation between Q and stenosis, and these diameters vary widely. During progressive stenosis, the delay and then rapid reduction in Q may impair recognition of low Q before thrombosis occurs. Surveillance outcomes might be improved by taking frequent measurements so that there is no delay in discovering that Q has decreased.

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“…It has been shown, however, that the site of stenosis varies according to the type of AVF, the most common location being the juxta-anastomotic region in the case of forearm radiocephalic AVFs, and the outflow region for upper-arm brachiocephalic and brachiobasilic AVFs (2)(3)(4)(5). It has also been reported that the access blood flow rate (Qa), a measurement widely accepted as a means for detecting access dysfunction, also varies according to the site of the AVF, being lower in the more distal accesses than in the more proximal accesses (6,7). Some researchers have found that the Qa threshold indicative of stenosis is lower in the wrist than in mid-forearm AVFs (6), and others have suggested that the Qa threshold warranting imaging and intervention should depend on access site, a Qa limit of 400 ml/min being acceptable in the forearm as opposed to 600 ml/min in the upper arm AVFs (8).…”

Section: Introductionmentioning

confidence: 99%

Bedside Screening for Fistula Stenosis Should Be Tailored to the Site of the Arteriovenous Anastomosis

Tessitore¹,

Bedogna²,

Lipari³

et al. 2011

Clinical Journal of the American Society of Nephrology

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SummaryBackground and objectives Given different sites of stenosis and access blood flow rates (Qa), the criteria for diagnosing fistula stenosis might vary according to anastomotic site. To test this, we analyzed the database of a prospective blinded study seeking an optimal bedside screening program for fistula stenosis.Design, setting, participants, & measurements Several methods used during dialysis (physical examination [PE], dynamic and derived static venous pressure [VAPR], dialysis blood pump flow/arterial pressure ratio, and Qa measurement) to diagnose angiographically-proven Ͼ50% stenosis were assessed in an unselected population of hemodialysis patients with mature fistulae (43 at the wrist [distal fistulae], 76 at midforearm or the elbow [proximal fistulae]).Results Prevalence of inflow stenosis was uninfluenced by anastomotic site, whereas outflow stenoses were more prevalent in proximal fistulae. The best test for inflow stenosis was Qa Ͻ650 ml/min in distal fistulae and a combination of a positive PE and Qa Ͻ900 ml/m in proximal fistulae. In proximal fistulae, PE and VAPR Ͼ0.5 were both equally highly diagnostic of outflow stenosis. Tailoring choice of test to site of the anastomosis may also contain the screening-associated workload, by reducing the need to perform PE and measure VAPR, compared with a screening approach regardless of the access location. ConclusionsOur study shows that an effective bedside screening program with Ն85% accuracy for fistula stenosis can be tailored to the site of the anastomosis, Qa being the tool of choice for the wrist, and PE alone or combined with Qa and VAPR measurements for more proximally-located accesses.

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Factors associated with access blood flow in native vessel arteriovenous fistulae

Cited by 26 publications

References 18 publications

Access Blood Flow and the Risk of Complications in Mature Forearm and Upper Arm Arteriovenous Fistulas

Access Blood Flow and the Risk of Complications in Mature Forearm and Upper Arm Arteriovenous Fistulas

Influence of Luminal Diameters on Flow Surveillance of Hemodialysis Grafts

Bedside Screening for Fistula Stenosis Should Be Tailored to the Site of the Arteriovenous Anastomosis

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