Eect of haemodynamic variables on surgically created arteriovenous fistula flow (original) (raw)
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Patterns of blood flow as a predictor of maturation of arteriovenous fistula for haemodialysis
The journal of vascular access
A palpable "thrill" is traditionally associated with success following arteriovenous fistula (AVF) surgery. A thrill typically characterizes turbulent flow and this is a paradox as turbulence is a driver of neointimal hyperplasia. Spiral laminar flow (SLF) has been described as normal and protective pattern of flow in native arteries and is associated with superior patency in bypass grafts that generate it. The aim of this study was to define the pattern of flow within AVFs immediately post-operatively and at follow-up to assess maturation. Doppler ultrasound was used immediately post-operatively and at follow-up (6 weeks). Blood flow was assessed as SLF or non-SLF. Two blinded qualified observers analysed the images. Patients were followed up for 6 months. Maturation was statistically analysed against the type of flow. Sequential patients having AVF surgery (n=56) were assessed: 46 (82%) patients had a thrill, 3 patients had no flow and 7 patients had pulsatile flow witho...
Determinants of native arteriovenous fistula blood flow
Nephrology, 2004
Background: Determinants of native arteriovenous fistula (AVF) placement have been well studied. Little is known on whether these factors impact on subsequent blood flow (Qa) in the mature AVF. Methods: Arteriovenous fistula Qa and cardiac index (CI) were determined by ultrasound dilution. Multiple linear regression was used to assess independent predictors of AVF Qa. Results: Of the 148 patients available for the analysis, 68% were male, with 61% using a radiocephalic AVF. Aetiology of renal disease was: 38% glomerulonephritis (GN), 22% diabetes mellitus (DM), 9% hypertension/ischaemic (HTN) and 31% other. Thirty per cent had coronary artery disease (CAD), 10% cerebrovascular disease and 11% peripheral vascular disease (PVD). Median (iqr) Qa was 1185 mL/min (790-1650) and CI was 3.15 L/min per 1.73 m 2 (2.60-3.93). On univariable analysis, log CI (0.98, P < 0.001), age -0.1 per 10 years, P = 0.002), access position (upper vs lower 0.26, P = 0.003, PVD ( -0.35, P = 0.015), CAD ( -0.25, P = 0.008), and primary renal disease (DM vs GN, -0.35, P = 0.003, HTN vs GN, -0.34, P = 0.04) were associated with Qa. On multivariable analysis, CI (0.84, P < 0.001), access position (upper vs lower, 0.17, P = 0.018) and primary renal disease (DM vs GN, -0.26, P = 0.005, and HTN vs GN, -0.26, P = 0.038) remained significant predictors of AVF Qa. Conclusion: Once established, CI, AVF position and primary renal disease (hypertension/ ischaemic and diabetes) are the major determinants of AVF Qa while female gender, CAD, PVD and body mass index were not significant determinants of Qa in this cohort. KEY WORDS: access blood flow, cardiac output, haemodialysis, native fistula.
Factors associated with early failure of arteriovenous fistulae for haemodialysis access
European Journal of Vascular and Endovascular Surgery, 1996
The radiocephalic arteriovenous fistula remains the method of choice for haemodialysis access. In order to assess their suitability for fistula formation, the radial arteries and cephalic veins were examined preoperatively by ultrasound colour flow scanner in conjunction with a pulse-generated run-off system. Intraoperative blood flow was measured after construction of the fistulae. Post-operative follow-up was performed at various intervals to monitor the development of the fistulae. Radial artery and cephalic vein diameter less than 1.6 mm was associated with early fistula failure. The intraoperative fistula blood flow did not correlate with the outcome of the operation probably due to vessel spasm from manipulation. However, blood flow velocities measured non-invasively 1 day after the operation were significantly lower in fistulae that failed early compared with those that were adequate for haemodialysis. Most of the increase in fistula diameter and blood flow occur within the first 2 weeks of surgery.
Simulated hemodynamic comparison of arteriovenous fistulas
Journal of Vascular Surgery, 1987
The hemodynamic consequences of six current types of surgically constructed arteriovenous fistulas (AVFs) in the human arm are studied with the use of the model of a stationary electric resistance circuit. Variations in arterial and venous resistances and in anastomosis techniques are considered. With this model all possible AVFs can be compared in terms of risk (loss of distal perfusion pressure) and benefit (volume of fistula flow). According to our model the most efficient type of fistula is the end-to-end AVF at the wrist. In patients with abnormally high resistance of the arm arteries this fistula is inadequate for efficient hemodialysis treatment. To reduce the incidence of finger ischemia in more proximal AVFs our model indicates that the arterial anastomosis should be as proximal as possible and/or hemodynamicaUy nonsmooth (i.e., side-to-side).
J Vasc Access ( 2012; 3): 271-278 13 -271 REVIEW positive diastolic flow, in contrast to the negative diastolic phase in the arterial system. This, in turn, leads to high flow rates according to Poiseuille's law, Q = ΔPπR 4 /8μL, where: ΔP = Pressure drop, Q = Flow rate, L = Length, μ = Viscosity, R = Radius, with consequent high wall shear stress values, τ=ΔP R/2 L.
Clinical Kidney Journal, 2016
Background: Satisfactory vascular access flow (Qa) of an arteriovenous fistula (AVF) is necessary for haemodialysis (HD) adequacy. The aim of the present study was to further our understanding of haemodynamic modifications of the cardiovascular system of HD patients associated with an AVF. The main objective was to calculate using real data in what way an AVF influences the load of the left ventricle (LLV). Methods: All HD patients treated in our dialysis unit and bearing an AVF were enrolled into the present observational crosssectional study. Fifty-six patients bore a lower arm AVF and 30 an upper arm AVF. Qa and cardiac output (CO) were measured by means of the ultrasound dilution Transonic Hemodialysis Monitor HD02. Mean arterial pressure (MAP) was calculated; total peripheral vascular resistance (TPVR) was calculated as MAP/CO; resistance of AVF (AR) and systemic vascular resistance (SVR) are connected in parallel and were respectively calculated as AR = MAP/Qa and SVR = MAP/(CO − Qa). LLV was calculated on the principle of a simple physical model: LLV (watt) = TPVR•CO 2. The latter was computationally divided into the part spent to run Qa through the AVF (LLV AVF) and that part ensuring the flow (CO − Qa) through the vascular system. The data from the 86 AVFs were analysed by categorizing them into lower and upper arm AVFs.
Improving arteriovenous fistula rate: Effect on hemodialysis quality
Hemodialysis International, 2014
Vascular access (VA) is the lifeline for patients with end-stage renal disease on regular hemodialysis (HD). Tunneled catheters have been associated with increased risk of luminal thrombosis, infection, hospitalization, and high cost. Our aims were to follow the "Fistula First Initiative," avoid or reduce the rate of catheter insertion, improve the rate of arteriovenous fistula (AVF) use, and study the effect of increased AVF use on quality of dialysis and patient's outcome. A VA program has been established in collaboration with an enthusiastic and professional vascular surgery team to manage 358 patients who have been on regular HD treatment for a period ranging from 1 to 252 months. The mean ± standard deviation age of patients was 52 ± 15 years with 62% male patients. Over a period of 2 years, 408 procedures were performed. These include 293 AVFs and 56 arteriovenous grafts (AVGs). Other procedures include 39 permanent catheter insertions, 8 AVF aneurysmectomy, removal of 6 AVGs, embolectomy of 4 AVGs, excision of 1 AVG lymphocele, and ligation of 1 AVF. This program resulted in significant increase in AVF rate from 35% to 82%; reduction in catheter rate from 62% to 10.9%; infection rate down from 6.6% to 0.6%; VA clotting down from 5.1% to 1.0%; and increase in average blood flow rate from 214 ± 32 to 298 ± 37 mL/min (P < 0.01). These results have been associated with improved average single pool Kt/V from 0.88 ± 0.19 to 1.28 ± 0.2 (P < 0.01); increased hemoglobin from 9.2 ± 1.2 to 10.9 ± 0.9 g/dL (P < 0.01); improved serum albumin from 3.2 ± 0.5 to 3.7 ± 0.4 g/dL (P < 0.05); reduction in administered erythropoietin dose by 19%; and significant drop in hospitalization rate from 6.1% to 3.8%. These results confirm the great benefits of AVF on quality of HD and patient outcome, and clearly affirm that AVF should always be considered first.
A-V Fistula Blood Flow and Complications: A One Year Survey
Journal of Medicine, 2014
Background: Worldwide haemodialysis(HD) is the mostly used method of renal replacement therapy. Arteriovenous fistula use is on rise due to Fistula First Initiative due to least complications of fistulae than catheters.But they are also subjected to many complications. Thereby appropriate surveillance of the fistulae is important. Objectives: To measure the blood flow as well as fistula related complications in study population. Materials and Methods: This was a cross sectional study, conducted in the department of Nephrology, Dhaka Medical College Hospital during September 2010 to December 2011.Total 118 subjects were included in the study. Besides visualization technique colour Doppler ultrasonogram of fistula and echocardiography were performed for each patients. Results: Most of the patients had adequate fistula flow. Aneurysm was most common complication. Many subjects were suffered from primary and secondary fistula failure. Conclusion: Arterio-Venous fistula is subjected to many complications and appropriate surveillance should be launched to detect complications and to prevent fistula failure.