Access blood flow as a predictor of early failures of native arteriovenous fistulas in hemodialysis patients

Early access flow rate predicts vascular access patency-related intervention in the first year: A retrospective cohort study

INTRODUCTION

Arteriovenous fistulas and grafts are lifelines for most hemodialysis patients, and a low access flow rate often requires patency-related intervention, such as angioplasty or thrombectomy, to prevent access failure. We examined whether early access flow rate, measured after initial fistula/graft cannulation, predicts vascular access patency-related intervention within 1 year.

METHODS

This was a single-center retrospective cohort study. Among 172 patients undergoing surgical creation of a fistula/graft, 52 (30.2%) had documented access flow rates measurement by the Transonic™ ultrasound dilution technique, performed within an average of 48 days from initial access cannulation. The need for a patency-related intervention, defined as undergoing a fistulogram, angioplasty, thrombectomy, or surgical revision, was ascertained within 1 year. A receiver-operating characteristic curve (ROC) was generated to evaluate the diagnostic performance of first and average access flow rates for predicting patency-related intervention within 1 year.

FINDINGS

Twenty-eight (53.8%) of the 52 study subjects required a patency-related intervention within 1 year. Their characteristics were not significantly different from those who did not require patency-related interventions. However, first access flow rates were significantly lower in patients requiring patency-related intervention compared to those who did not (898 vs. 1471 mL/min; p = 0.003), as were average access flow rates (841 vs. 1506 mL/min; p < 0.001). The ROC analyses revealed that first access flow rates and average access flow rates predicted the need for patency-related intervention within 1 year, with an area under-the-ROC curve of 0.743 (95% confidence interval [CI] 0.608, 0.877) and 0.775 (95% CI 0.648, 0.903), respectively, demonstrating acceptable discrimination.

DISCUSSION

In adults undergoing hemodialysis, early access flow rate measurement can predict patency-related intervention within 1 year after initial vascular access cannulation. Additional studies are required to confirm these findings and identify optimal access flow rate cut-off values to predict vascular accesses at higher risk of stenosis.

Fully no-touch technique without inflating the cephalic vein increase the patency rate of arteriovenous fistulas

INTRODUCTION

One of the most important problems for patients undergoing hemodialysis due to chronic renal failure is the need for a long-lasting vascular access. The patency of vascular access is affected by many factors. Factors related to surgery are also among these factors. No-touch techniques theoretically and practically prevent endothelial damage due to minimal contact on vascular structures. It is a well-known fact that surgeries performed with these methods also increase long-term survival.

METHODS

Patients who underwent distal radiocephalic arteriovenous fistula (AVF) surgery for the first time between 2017 and 2021 were included in our study. The groups, whose cephalic veins were inflated conventionally and not inflated, were compared in a prospective randomized manner.

RESULTS

There was a significant difference between both groups in terms of failure and patency rates, which is one of the study endpoints (p = 0.012). The fact that the patency period is long, and the failure rate is low stands out as the superiority of the fully no-touch technique in AVF surgery. On the other hand, no significant difference was observed in terms of failure to maturation and fistula maturation time.

CONCLUSIONS

Fully no-touch technique in AVF surgery should be considered primarily in suitable patients due to its long patency time and low failure rate.

Assessment of Duplex ultrasound carried out by the vascular surgeon after locoregional anesthesia for preferred arteriovenous fistula access

OBJECTIVES

Preoperative vascular mapping by duplex ultrasound is required in construction of an arteriovenous fistula for hemodialysis (AVF). Due to venous vasospasm in cool temperatures and variability of the dialysis patient's blood volume, the conditions for performing this examination may be less than ideal. However, local regional anesthesia (LRA) resulting in vasodilation of the limb, can allow the use of veins considered to be of insufficient caliber during preoperative ultrasound mapping. The aim of this study was to assess the functionality of AVF when duplex ultrasound is performed by the surgeon following LRA. These results were compared with those from the preceding year, during which preoperative duplex ultrasound had been performed without LRA by vascular specialists, (Clinical Trial registration number: NCT04978155).

MATERIALS AND METHODS

This is a prospective study of all the patients having received AVF after systematic immediate preoperative ultrasound (US) under LRA (US-LRA group) in 2020. The initial surgical programming based on the Silva criteria was reported by a vascular medicine specialist. The change of AVF strategy following US-LRA was reported together with AVF usability and patency and compared to the results of the control group, in which AVF had been performed in 2019 without US-LRA.

RESULTS

Ninety patients were included in the US-LRA group and 93 in the control group. Modified surgical planning was observed in 38% of cases (35/90) in the US-LRA group including more distal AVF in 28% of patients (26/90) and alternative target vein in 6.6% (6/90). AVF usability at 6 weeks was 80% (72/90) in the US-LRA group and 51.6% (48/93) in the control group (p<.001). Median follow-up was 12 months [IQR:9-15] in the US-LRA group and 13 months [IQR:9-18] in the control group. Primary patency at 6, 12, 18 months was significantly better in the US-LRA group (73.6% vs. 57.4%, 54.4% vs. 40.2%, 31.3% vs. 28.2%, respectively, p<.001). Assisted patency and secondary patency were comparable in the two groups.

CONCLUSION

This study showed the benefit of having the surgeon perform US-LRA before starting the procedure, thereby allowing for more distal AVF, better usability and patency.

Brief overview of surgical aspect of autologous arterio-venous fistula for dialysis access

Patients with the end-stage renal disease require renal replacement therapy in renal transplant, peritoneal dialysis, and intermittent hemodialysis. Hemodialysis remains the primary modality for renal replacement therapy. Excellent vascular access is a mainstay for performing hemodialysis. Here we present a brief review of the various surgical aspects of AV fistula creation. Preoperative physical examination and judicious use of the imaging modalities to define the artery and venous mapping provide a good outcome of the fistula formation. Surgical creation of RC-AVF is preferred for the end-stage renal disease patient. The end-to-side anastomosis between the radial artery and cephalic vein has shown very good results.

Point-of-care ultrasound for assessing arteriovenous fistula maturity in outpatient hemodialysis

BACKGROUND

Point-of-care ultrasound in end-stage renal disease is on the rise. Presently the decision to cannulate an arteriovenous fistula is based on its duration since surgery and physical exam. This study examines the effects of point-of-care ultrasound on decreasing the time to arteriovenous fistula cannulation, time spent with a central venous catheter, and the complications and infections that arise.

METHODS

Prospective point-of-care ultrasound patients were recruited between January 2015 and January 2018, while retrospective data (non-point-of-care ultrasound) were collected via chart review from patients who had fistula creation between November 2011 and May 2014. Patients had point-of-care ultrasound within 3 weeks after arteriovenous fistula creation and were followed for 1 year. Arteriovenous fistula cannulation was initiated when the following parameters were met: diameter > 6 mm (with no depreciable narrowing of more than 20% throughout), depth < 6 mm, and length > 6 cm. Demographic data, as well as time to cannulation and central venous catheter removal, number of infections, complications, and interventions were compared between point-of-care ultrasound and non-point-of-care ultrasound groups using unpaired t-test, chi-square, and Fisher exact test statistical analysis.

RESULTS

A total of 37 patients with new arteriovenous fistulas were followed by point-of-care ultrasound compared to 29 non-point-of-care ultrasound patients. Point-of-care ultrasound patients had earlier cannulations (35.5 vs 63.3 days, p < 0.05), shorter central venous catheter duration (68.2 vs 98.3 days, p < 0.05), and less infections (12 vs 19) without differences in complication compared to the non-point-of-care ultrasound.

CONCLUSION

Point-of-care ultrasound facilitates early and safe arteriovenous fistula cannulation leading to a reduction in central venous catheter time and risk of infection. Point-of-care ultrasound may also aid in earlier identification of complications and difficult cannulations.

Molecular Targets for Improving Arteriovenous Fistula Maturation and Patency

The increasing prevalence of chronic and end-stage renal disease creates an increased need for reliable vascular access, and although arteriovenous fistulae (AVF) are the preferred mode of hemodialysis access, 60% fail to mature and only 50% remain patent at one year. Fistulae mature by diameter expansion and wall thickening; this outward remodeling of the venous wall in the fistula environment relies on a delicate balance of extracellular matrix (ECM) remodeling, inflammation, growth factor secretion, and cell adhesion molecule upregulation in the venous wall. AVF failure occurs via two distinct mechanisms with early failure secondary to lack of outward remodeling, that is insufficient diameter expansion or wall thickening, whereas late failure occurs with excessive wall thickening due to neointimal hyperplasia (NIH) and insufficient diameter expansion in a previously functional fistula. In recent years, the molecular basis of AVF maturation and failure are becoming understood in order to develop potential therapeutic targets to aide maturation and prevent access loss. Erythropoietin-producing hepatocellular carcinoma (Eph) receptors, along with their ligands, ephrins, determine vascular identity and are critical for vascular remodeling in the embryo. Manipulation of Eph receptor signaling in adults, as well as downstream pathways, is a potential treatment strategy to improve the rates of AVF maturation and patency. This review examines our current understanding of molecular changes occurring following fistula creation, factors predictive of fistula success, and potential areas of intervention to decrease AVF failure.

Effect of Hydraulic Expansion on Arteriovenous Fistula of Hemodialysis Patients

BACKGROUND

Chronic kidney disease has become a serious public health problem in China. Our study is to explore effect of hydraulic expansion on arteriovenous fistula (AVF) of hemodialysis patients.

METHODS

A total of 190 patients with end-stage renal disease (ESRD) were randomly divided into hydraulic expansion group (n = 117) and conventional surgery group (n = 73). Age, sex, the cause of ESRD, height, weight, body mass index (BMI), blood pressure, and diameter of artery and vein from ultrasonography before surgery from patients were recorded. Doppler ultrasonography of vessel was performed with a 12-MHz scanning probe for vascular measurements. The time of first cannulation was recorded. Primary and secondary patency rates were compared between the two groups.

RESULTS

The mean arterial pressure for this cohort of patients was around 98.12 mm Hg. The mean diameters of artery and vein ready for anastomoses measured by ultrasonography before surgery were 1.96 and 2.04 mm, respectively. Age, weight, BMI, sex ratio, the cause of renal failure, history of catheter insertion, mean arterial pressure, frequency of hemodialysis, blood flow of hemodialysis, and the mode of anastomoses of AVF in conventional surgery group were similar to hydraulic expansion group. There were no differences in stroke volume of radius arterial and venous pressure before dilation between the two groups. The stroke volume of radius artery increased significantly after hydraulic expansion than before dilation and control group. The primary patency rates of AVF in patients with hydraulic expansion were higher significantly than conventional surgery group. The secondary patency rates in conventional surgery group were not different from hydraulic expansion group.

CONCLUSION

Hydraulic expansion showed no difference from conventional surgery in complication after operation, and could decrease the time reliance on catheters and the risk of catheter-related infection, thrombosis, and decrease the related medical care costs.

Prediction of Arteriovenous Fistula Clinical Maturation from Postoperative Ultrasound Measurements: Findings from the Hemodialysis Fistula Maturation Study

BACKGROUND

The utility of early postoperative ultrasound measurements in predicting arteriovenous fistula (AVF) clinical maturation is uncertain.

METHODS

We investigated the relationships of ultrasound parameters with AVF clinical maturation in newly created AVF, measured at 1 day and 2 and 6 weeks, in 602 participants of a multicenter, observational cohort study. A backward elimination algorithm identified ultrasound measurements that independently predicted unassisted and overall AVF maturation. Candidate variables included AVF blood flow, diameter, and depth, upper arm arterial diameter, presence of stenosis, presence of accessory veins, seven case-mix factors (age, sex, black race, AVF location, diabetes, dialysis status, and body mass index), and clinical center. We evaluated the accuracy of the resulting models for clinical prediction.

RESULTS

At each ultrasound measurement time, AVF blood flow, diameter, and depth each predicted in a statistically significant manner both unassisted and overall clinical maturation. Moreover, neither the remaining ultrasound parameters nor case-mix factors were associated with clinical AVF maturation after accounting for blood flow, diameter, and depth, although maturation probabilities differed among clinical centers before and after accounting for these parameters. The crossvalidated area under the receiver operating characteristic curve for models constructed using these three ultrasound parameters was 0.69, 0.74, and 0.79 at 1 day and 2 and 6 weeks, respectively, for unassisted AVF clinical maturation and 0.69, 0.71, and 0.76, respectively, for overall AVF maturation.

CONCLUSIONS

AVF blood flow, diameter, and depth moderately predicted unassisted and overall AVF clinical maturation. The other factors considered did not further improve AVF maturation prediction.

Native Arterio-Venous Fistula for Hemodialysis: What to Expect Early after Creation?

Native arterio-venous fistulas (AVFs) are preferred for hemodialysis vascular access over synthetic grafts and long-term catheters. However, prevalence rates of native AVFs are variable around the world and have increased only slightly in United States since the DOQI guidelines. To increase rates of native AVFs, pre-operative vascular mapping by ultrasound has been found of major help for appropriate selection of the vessels. The minimal desirable lumen diameter of the artery should be > 2 mm and > 2.5 to 3 mm for the vein at the anatomosis. Early failure can be reduced to less than 10% when the feeding artery is > 2 mm, even in diabetics. If sizes of the vessels are smaller than those targets at the wrist, moving to the upper arm should be considered. The interval between creation and first cannulation varies from 2 weeks to 4 months. There might not be much advantage to wait for more than 4 weeks; however, in large dialysis units, observing a delay of 4 to 6 weeks may be worthwhile to avoid initial problems such as infiltrations and lacerations. Access flow monitoring is essential since it is a reliable predictor of vascular access dysfunction, reducing associated morbidity and costs. Early monitoring of recently created native AVFs has shown that the increase in intra-access blood flow occurs very soon after construction and becomes maximal after a few weeks. A recent prospective study involving all new native AVFs monitored by ultrasound-dilution between weeks 6 and 10 after creation, and every 3 to 6 weeks over 4 months, showed no statistically significant difference in access blood flow between the initial and final measurements (respective values of 1132 ± 681 and 1097 ± 644 ml/min). Access flow was higher in males, and in brachio-cephalic compared to radio-cephalic AVFs. Over the long-term, AVFs are associated with longer patency and lower complication rates, and efforts should be directed at further increasing their prevalence.

Early Failure Rates of Arterovenous Fistulas for Hemodialysis: Evaluation of Six-Year Activity

Maintenance and complications of vascular access (VA) for hemodialysis (HD) represent the leading cause of morbidity and health care cost among end stage renal disease population.

To define the reasons for the use of a particular VA at the beginning of replacement treatment, we prospectively evaluated the early failure rate and survival of arterovenous fistula (AVF) in 183 patients. These patients had high prevalence of cardiovascular risk factors and co-morbid conditions, and began HD in our renal unit from the 1st of January 1995. As a part of this study the present analysis focuses on potential predictors of early failure of the first AVF (within the first 7 days after the operation).

Overall, 279 AVF were prepared: 193 at the wrist and 86 at the upper arm, including 11 prosthetic grafts; 150 patients (82%) were given a distal AVF in the first operation. Our conservative policy resulted in a relatively high prevalence of native AVF in use among our prevalent HD patients (84.3%).

Early failure of the first VA was 10.4%. Multivariate analysis showed that this event was neither significantly associated with all traditional risk factors and co-morbids tested, nor with the operating surgeon.

We conclude that in this prospectively studied cohort, the high rate of native AVF created in order to preserve the vascular bed, though associated with a high early failure rate unaffected by traditional cardiovascular risk factors, resulted in a low proportion of permanent catheters and arterovenous grafts in use among prevalent HD patients.

Is Brachial Artery Blood Flow Measured by Sonography During Early Postoperative Periods Predictive of Arteriovenous Fistula Failure in Hemodialysis Patients?

OBJECTIVES

The aim of our study was to determine a brachial artery blood flow level measured by sonography during early postoperative periods that is predictive of arteriovenous fistula failure in hemodialysis patients.

METHODS

Doppler sonography was used to estimate the blood flow in the brachial artery of 103 patients at 1 and 14 days after arteriovenous fistula creation. The performance of brachial artery blood flow during early postoperative periods for predicting fistula failure was evaluated, and optimal cutoff values were determined.

RESULTS

During a 6-month follow-up, 85 fistulas were classified as mature, and 18 were classified as failures. The reproducibility of blood flow measurements in the brachial artery was good (intraclass correlation coefficient, 0.912). The blood flow in the failure group was significantly lower than that in the mature group at both 1 and 14 days after fistula creation (P < .05). During the first 2 postoperative weeks, the blood flow increased by 40.7% in the failure group versus 78.3% in the mature group. The areas under the receiver operating characteristic curves of brachial artery blood flow for predicting failure were 0.77 (95% confidence interval, 0.66-0.87; optimal cutoff value, 310 mL/min)at 1 day and 0.91 (95% confidence interval, 0.83-0.99; 413 mL/min) at 14 days after fistula creation.

CONCLUSIONS

Brachial artery blood flow measured by sonography during early postoperative periods may be predictive of forearm fistula failure. Blood flow of less than 310 mL/min at 1 day and 413 mL/min at 14 days after fistula creation may indicate a risk of failure to mature.

Prospective Evaluation of Factors Associated with Early Failure of Arteriovenous Fistulae in Hemodialysis Patients

Recent guidelines have recommended performing native arteriovenous fistulae (AVF) in hemodialysis patients rather than synthetic grafts whenever possible. However, early failure of AVF may reach up to 50%. The purpose of this study was to assess the factors associated with early failure of such procedures in hemodialysis patients.

A prospective study was performed on all patients with end-stage renal disease who had an AVF between June 2003 and March 2005. Data including patient characteristics and the type of AVF were recorded. The internal diameter of the vein and artery and intraoperative blood flow were measured. Patients were followed up for 3 months.

One hundred twenty-six AVF were included in this study. Early failure was in 14 (9%) patients. The internal diameter of the vein and artery and intraoperative blood flow were significantly lower in the failure group than in the patent group. The failure rate was not significantly related to other parameters.

Our data showed that intraoperative blood flow is a reliable parameter that determines the early failure of an AVF. Careful selection of the vein and the artery may reduce the rate of failure.

Interventions for Failed Wrist Fistulae: Is it Worthwhile?

A well-functioning forearm fistula is considered as the most suitable access for dialysis. It is easy to construct, has the fewest number of complications and lasts for a long time. Many patients fail to enjoy this benefit due to the high rates of thrombosis and the failure to mature associated with this procedure. Attempts to salvage failed and failing fistula suggest that there is a group of patients where interventions can help provide this benefit. This article provides a brief review of current experience using surgical and interventional techniques to salvage failing forearm fistulae. It attempts to classify modes of presentation of access failure and different modalities used to salvage them. It also suggests an algorithm that can be used to identify patients who may benefit from these interventions and a guide to make the decisions related to selection of a treatment modality. Successful salvage of a failing forearm fistula provides the patient with an opportunity to enjoy all the benefits of this access.

First-week postoperative flow measurements are highly predictive of primary patency of radiocephalic arteriovenous fistulas

PURPOSE

This study was conducted to determine whether volume flow rate at the first postoperative visit could predict early failure of radiocephalic arteriovenous fistulas (RCAVFs).

METHODS

We retrospectively studied the records of 264 patients who received a RCAVF between 2007 and 2013 at our centers. Data collected included patient demographics, medical history, arterial and venous mapping, and volume flow rate intraoperatively after fistula creation but before closing the surgical incision. An intraoperative flow rate &gt;100 mL/minute was targeted. We measured volume flow at the first postoperative visit 1 week after surgery and thereafter as needed.

RESULTS

Intraoperative flow was not a significant predictor of primary patency (p = 0.44) but flow at the first postoperative visit was a statistically significant predictor of fistula primary patency (p = 0.002). No fistula with a blood flow &lt;200 mL/minute at the 1-week postoperative visit reached maturity without receiving a maturation procedure. The hazard ratio for the first follow-up flow (mL/min) was 0.9973 (95% CI 0.9956, 0 .9989), indicating that for every 100 mL increase in blood flow the primary patency increases by 10%.

CONCLUSIONS

Flow rate at the 1-week postoperative visit was the most important predictor of RCAVF patency. Thus, it should be possible to identify patients who would benefit from early intervention or closer follow-up as soon as the first postoperative visit. This should help reduce the use of bridging hemodialysis catheters and minimize the risks of catheter dependency.

Color Doppler ultrasound and arteriovenous fistulas for hemodialysis

Native arteriovenous fistula (AVF) is the vascular access of choice for hemodialysis patients. Compared with grafts and central venous catheters, AVFs last longer and are associated with fewer complications. The widespread use of the Doppler ultrasound (DUS) has increased the number of patients who are eligible for AVF by facilitating the identification of vessels that are suitable for fistula construction (preoperative vascular mapping). DUS can also extend native AVF survival by improving the early detection of complications (post-operative surveillance). It is the only imaging modality that furnishes both morphological and functional data on the native vascular access, and it is also the only imaging tool that can be used directly by the surgeon, an indisputable advantage. This review examines the numerous roles played by DUS in the construction and postoperative follow-up of AVFs, including preoperative vascular mapping, AVF maturation, and surveillance.

Hemodynamic Shear Stress and Endothelial Dysfunction in Hemodialysis Access

Surgically-created blood conduits used for chronic hemodialysis, including native arteriovenous fistulas (AVFs) and synthetic AV grafts (AVGs), are the lifeline for kidney failure patients. Unfortunately, each has its own limitations: AVFs often fail to mature to become useful for dialysis and AVGs often fail due to stenosis as a result of neointimal hyperplasia, which preferentially forms at the graft-venous anastomosis. No clinical therapies are currently available to significantly promote AVF maturation or prevent neointimal hyperplasia in AVGs. Central to devising strategies to solve these problems is a complete mechanistic understanding of the pathophysiological processes. The pathology of arteriovenous access problems is likely multi-factorial. This review focuses on the roles of fluid-wall shear stress (WSS) and endothelial cells (ECs). In arteriovenous access, shunting of arterial blood flow directly into the vein drastically alters the hemodynamics in the vein. These hemodynamic changes are likely major contributors to non-maturation of an AVF vein and/or formation of neointimal hyperplasia at the venous anastomosis of an AVG. ECs separate blood from other vascular wall cells and also influence the phenotype of these other cells. In arteriovenous access, the responses of ECs to aberrant WSS may subsequently lead to AVF non-maturation and/or AVG stenosis. This review provides an overview of the methods for characterizing blood flow and calculating WSS in arteriovenous access and discusses EC responses to arteriovenous hemodynamics. This review also discusses the role of WSS in the pathology of arteriovenous access, as well as confounding factors that modulate the impact of WSS.

Accuracy of Early Postoperative Clinical and Ultrasound Examination of Arteriovenous Fistulae to Predict Dialysis Use

Aim

The aim of this article is to assess the accuracy of early clinical and ultrasound (US) examination in terms of predicting arteriovenous fistula (AVF) dialysis use.

Methods

Physical and US examination of patent AVF was performed 4 weeks after fistula creation. AVF dialysis use was defined as subsequent use of an AVF for at least six consecutive dialysis sessions with two needles and a blood flow of more than 200 mL/min.

Results

Of 119 AVF patent at 4 weeks, 26 (22%) failed. Clinical examination was 96% sensitive for predicting successful dialysis, but only 21% specific for failure. Vein diameter above 5 mm and an arterial end-diastolic velocity above 110 cm/s were the best US predictors for dialysis use. Vein diameter was slightly better than arterial velocity in terms of predicting maturity (sensitivity: 83% vs 67%, specificity: 68% vs 65%). All assessments predicted AVF maturity (positive predictive value: clinical = 81%, US diameter = 90%, US velocity = 87%) much better than AVF failure (negative predictive value: clinical = 63%, US diameter = 53%, US velocity = 37%).

Conclusion

One month after surgery, a new AVF with a thrill or a vein diameter >5 mm is likely to be used for dialysis. An AVF not meeting these criteria has an increased risk of failure and further investigations may be required.

Arterio venous fistula experience at a tertiary care hospital in Pakistan

OBJECTIVE

To evaluate the two year patency rate of functioning arteriovenous fistula.

METHODOLOGY

This prospective case series study was conducted at Department of Urology, Jinnah Postgraduate Medical Centre, Karachi, from 1(st) January 2009 to 31(st) December, 2010. Patients were chosen for CBRC arteriovenous fistula at wrist and patients undergoing other types of vascular access or secondary fistula formation were excluded.

RESULTS

One hundred and eighty two patients underwent arteriovenous fistula formation. The mean ± SD age was 63 ± 13 years and there were 102 (56%) males and 80 (44%) females. 12.6% fistulae failed within first month without dialysis. The primary patency rate was 66.5% at three months and 57.7% at six months. Failing arteriovenous fistula was managed by new arteriovenous fistula in our series. 28.6% patients had redo arteriovenous fistula. This study demonstrated a poor outcome for fistulas in diabetic patients. Fifteen out of 23 (65.2%) who failed primarily were diabetics and out of these diabetics 13 (86.7%) failed in first three months. Infection and burst fistulae were found in nine (4.9%), pseudo aneurysm in 3.2%, fever 4.9%, peri-operative failure 0.55% and burst fistulae 3.2%.

CONCLUSIONS

One-third of radiocephalic fistulas fail within two years. The outcome is worse for women and diabetic patients. This information may be useful in assessing and counseling patients with end-stage renal failure. Arteriovenous fistula is the better and ideal choice for haemodialysis. A Radiocephalic fistula in forearm seems to have better results as comparison to cubital fossa arteriovenous fistula. End to side anastomosis results are better than side to side anastomosis.

Effect of intradialytic change in blood pressure and ultrafiltration volume on the variation in access flow measured by ultrasound dilution

BACKGROUND

Prospective access flow measurement is the preferred method for vascular access surveillance in hemodialysis (HD) patients. We studied the effect of intradialytic change in blood pressure and ultrafiltration volume on the variation in access flow measured by ultrasound dilution.

METHODS

Access flow was measured 30 minutes, 120 minutes, and 240 minutes after the start of HD by ultrasound dilution in 30 patients during 89 HD sessions and evaluated for variation.

RESULTS

The mean age of the 30 patients was 62±11 years: 19 were male. The accesses comprised 16 fistulae and 14 grafts. The mean access flow over all sessions decreased by 6.1% over time (1265±568 mL/min after 30 minutes, 1260±599 mL/min after 120 minutes, and 1197±576 mL/min after 240 minutes, P<0.01 by repeated measures ANOVA). In addition, a≥5% decrease in mean arterial pressure during HD significantly reduced access flow (P=0.014). However, no other variable (ultrafiltration volume, sex, age, presence of diabetes, type or location of access, body surface area, hemoglobin, serum albumin level) interacted significantly with the effect of time on access flow. Furthermore, mean arterial pressure did not correlate with ultrafiltration volume.

CONCLUSION

We conclude that the variation in access flow during HD is relatively small. Decreased blood pressure is a risk factor for variation in access flow measured by ultrasound dilution. In most patients whose blood pressures are stable during HD, the access flow can be measured at any time during the HD treatment.

Subclavian vein angioplasty during arteriovenous fistula surgery: case report and literature review

Patients with chronic kidney disease stage 5 are generally treated by hemodialysis, preferentially performed via an arteriovenous fistula (AVF). We report the case of a 58-year-old male patient with diabetes mellitus, hypertension and end-stage renal disease in whom hemodialysis was conducted via a long-term catheter. His medical record described numerous central venous cannulations and several AVF creations. The patient developed subclinical subclavian stenosis that required creation of a new vascular access route. The purpose of this case report is to describe treatment of subclavian vein stenosis during AVF creation.

Duplex sonography in the planning and evaluation of arteriovenous fistulae for haemodialysis

This paper describes how to perform duplex sonography in the planning and evaluation of arteriovenous fistulae in haemodialysis patients, discusses its roles in these settings, and presents a review of commonly encountered complications.

Early vascular access blood flow as a predictor of long-term vascular access patency in incident hemodialysis patients

The long-term clinical benefits of vascular access blood flow (VABF) measurements in hemodialysis (HD) patients have been controversial. We evaluated whether early VABF may predict long-term vascular access (VA) patency in incident HD patients. We enrolled 57 patients, of whom 27 were starting HD with arteriovenous fistulas (AVFs) and 30 with arteriovenous grafts (AVGs). The patients' VABF was measured monthly with the ultrasound dilution technique over the course of the first six months after the VA operation. During the 20.4-month observational period, a total of 40 VA events in 23 patients were documented. The new VA events included 13 cases of stenosis and 10 thrombotic events. The lowest quartile of average early VABF was related to the new VA events. After adjusting for covariates such as gender, age, hypertension, diabetes, VA type, hemoglobin levels, body mass index, parathyroid hormone, and calcium-phosphorus product levels, the hazard ratio of VABF (defined as <853 mL/min in AVF or <830 mL/min in AVG) to incident VA was 3.077 (95% confidence interval, 1.127-8.395; P=0.028). There were no significant relationships between early VABF parameters and VA thrombosis. It is concluded that early VABF may predict long-term VA patency, particularly VA stenosis.

Small dose contrast venography as venous mapping in predialysis patients

PURPOSE

This study was designed to evaluate radiocontrast-induced nephrotoxicity (RIN), and the image quality and findings of venography using small doses of radiocontrast as a venous mapping method in pre-dialysis patients.

METHODS

Twenty-eight patients with stage 4 and 5 chronic kidney disease underwent arm venography with 10-15 ml of dilute contrast medium. Image quality, venographic findings and glomerular filtration rate (GFR) before and after the procedure were evaluated.

RESULTS

Mean GFR was 19.3+/-5.8 ml/min/1.73 m2 (7-30 ml/min/1.73 m2). Image quality of venography in the forearm and upper arm veins was good in all patients. Central veins were visualized well in 26 (92.8%) patients. Eight (28.5%) patients showed cephalic veins inadequate for creation of radiocephalic arteriovenous fistula (AVF) because of occlusion or small diameter veins. There was no significant difference in GFR between the pre- and post-study (19.3+/-5.8 vs. 19.2+/-6.2 ml/min/1.73 m2, p=0.693). RIN developed (GFR: 17 to 13 ml/min/1.73 m2) in only one patient but without sequelae, and the GFR completely recovered to baseline level 7 days after the study.

CONCLUSION

Small dose venography is safe and effective for venous mapping in pre-dialysis patients.

Polymorphism in the promoter region of the klotho gene (G-395A) is associated with early dysfunction in vascular access in hemodialysis patients

BACKGROUND/AIMS

Vascular access dysfunction is an important cause of morbidity and mortality in hemodialysis (HD) patients. Recent studies have shown that a klotho gene mutation is related to endothelial dysfunction, thrombosis, and arteriosclerosis, which are regarded as causes of vascular access dysfunction. We investigated the relationship between the klotho G-395A polymorphism and early dysfunction in vascular access in HD patients.

METHODS

Patients who underwent vascular access operations between 1999 and 2002 were enrolled (n=126). Genotyping was performed by allelic discrimination using a 5'-nuclease polymerase chain reaction assay. Clinical data that could be relevant to access dysfunction were obtained from medical records. Early dysfunction of vascular access was defined as the need for any angioplastic or surgical intervention to correct or replace a poorly or nonfunctioning vascular access within 1 year and at least 8 weeks after initial access placement.

RESULTS

Of the 126 patients, the genotype frequency of G-395A was 72.2% for GG (n=91), 24.6% for GA (n=31), and 3.2% for AA (n=4), and the frequency of minor allele was 0.155. Clinical data were similar between the two groups, divided according to the status of the A allele. Early dysfunction occurred in 34 (27.0%) of patients, but it occurred at a significantly higher rate in A allele carriers (45.7%, 16/35) than in noncarriers (19.8%, 18/91; p=0.003).

CONCLUSIONS

Our results suggest that the klotho G-395A polymorphism could be a risk factor for early dysfunction of vascular access in HD patients.

Comparison of hemodialysis blood access flow rates using online measurement of conductivity dialysance and ultrasound dilution

BACKGROUND

Routine access flow (AF) surveillance is recommended by the Kidney Disease Outcomes Quality Initiative as one of several components for an arteriovenous vascular access maintenance program. A reliable, but affordable, measurement tool is needed for outpatient hemodialysis facilities.

STUDY DESIGN

Diagnostic test study.

SETTING & PARTICIPANTS

50 adult patients with 27 grafts and 23 fistulas from a single center who consented to sequential AF measurements, all performed within the first 90 minutes of the hemodialysis treatment.

INDEX TEST

AF measured by using online conductivity dialysance (OLC-AF).

REFERENCE TEST

AF measured by using ultrasound dilution (UD-AF).

RESULTS

Mean UD-AF was 1,086 +/- 629 mL/min, and mean OLC-AF was 951 +/- 575 mL/min, with a mean difference of 135 +/- 229 mL/min. OLC-AF correlated significantly with UD-AF (0.93; P < 0.0001), becoming tighter for flows less than 1,000 mL/min (0.95; P < 0.0001). The coefficient of variation for sequential measurement by using UD was 6.4%, and for OLC, 11.5%, with the difference becoming insignificant (7.6% versus 8.8%; P = 0.5) for flows less than 1,000 mL/min. The average of 2 sequential UD-AF measurements correlated tightly with that of OLC-AF (0.99; P < 0.0001).

LIMITATIONS

Tests were performed by 2 highly trained coordinators in a single clinic with a small sample size, and clinical outcomes were not evaluated.

CONCLUSION

The OLC method is a reasonable alternative to UD for flow surveillance of arteriovenous hemodialysis accesses and provides an option for widespread implementation of a vascular access surveillance program. Additional studies are needed to determine whether routine use impacts on clinical outcomes.

Ultrasonographic maturation of native arteriovenous fistulae: a follow-up study

BACKGROUND/AIMS

Ideal time needed for arteriovenous fistula (AVF) maturation is still controversial. In this study, we aimed to investigate the natural course of AVF maturation and also investigated the factors affecting AVF maturation.

METHODS

We studied 31 (21M/10F, mean age 55.8 +/- 16.2) chronic renal failure patients. We evaluated the patients with color Doppler ultrasound examination before the fistula operation, at the first day, and at the first, second, third, and sixth months. Radial artery (RA) diameter, flow velocity, flow, resistance index, fistula vein diameter, flow velocity, and flow were measured.

RESULTS

Patency rates at the first post-operative day and the sixth month were 87.1% and 67.1%, respectively. Cephalic vein flow was 451.2 +/- 248.6 mL/min at the first month and 528.6 +/- 316.5 mL/min at the sixth month. Baseline RA diameter was lower in failing fistulas than that of patent fistulas. Failing fistulas were more common in women.

CONCLUSION

Blood flow was enough for hemodialysis at the end of the first month. However, fistula maturation had continued until the end of the study; women and patients with low RA diameter are particularly prone to fistula failure. Therefore, especially in these patients, AVF must be created at least three or four months before the predicted hemodialysis initiation time.

Blood flow volume changes in the maturing arteriovenous access for hemodialysis

In our center, we start hemodialysis using arteriovenous accesses empirically 1 mo after surgery in nearly all patients, when the vein diameter reaches 5 mm and blood flow is assumed to be adequate. We measured blood flow and vessel diameter in the maturing autogenous and prosthetic access to determine if this approach can be justified by quantitative physiological parameters. Of 66 consecutive autogenous and prosthetic arteriovenous accesses created over 3 mo in 2004, 62 were prospectively examined by duplex ultrasonography preoperatively, immediately after surgery in the recovery room, at 10 d postoperatively and 1 mo after surgery before first cannulation. In the 20 forearm accesses, the immediate postoperative mean blood flow was 549 +/- 189 mL/min, 885 +/- 227 mL/min at 10 d and 934 +/- 260 mL/min at 1 mo. In the 22 upper-arm accesses, the immediate postoperative mean access blood flow was 858 +/- 292 mL/min, 1060 +/- 326 mL/min at 10 d and 1116 +/- 427 mL/min at 1 mo. In 20 prosthetic accesses, near maximal flow was attained immediately after surgery (990 +/- 256 mL/min). Most of the increased flow in autogenous accesses occurred early in the maturation process. This suggests that 1 mo is adequate for autogenous access maturation before use for hemodialysis. The process of access maturation appears to be less relevant in prosthetic accesses, where blood flow is high from the day of surgery and tissue incorporation is, therefore, more important.

Pre-operative Radial Arterial Diameter Predicts Early Failure of Arteriovenous Fistula (AVF) for Haemodialysis

INTRODUCTION

Long term patency of arteriovenous fistula (AVF) is relevant to the management of end stage renal failure (ESRF) patients on haemodialysis (HD). We evaluated the role of routine radial arterial duplex for imaging radial artery before AVF formation to investigate the relationaship between radial artery internal diameter (ID) and AVF patency.

METHODS

21 patients with ESRF were examined by duplex sonography before AVF formation, 1 day, 1 week, 4 week and 12 weeks post AVF formation. For assessment of AVF patency, patients were divided into 2 groups. Group-1, 11 patients with radial artery ID <1.5mm and Group-2, 10 patients with radial artery ID >1.5mm. Measurement of radial artery blood inflow rate was calculated from mean blood flow velocity and vessel diameter. All AVFs were constructed on the forearm using autologous veins.

RESULTS

In Group-1, 5 patients (45%) showed immediate thrombosis of AVF graft. All patients in group-2 had patent AVF at 12 weeks. Pre-AVF formation radial artery blood inflow rate between two groups was not significantly different (p=0.06). Radial artery blood inflow rate was consistently and significantly higher in group-2 at all later time points with p value of <0.01 (Mann Whitney test).

CONCLUSION

There was a high failure rate of AVF with radial artery ID of <1.5mm. In the presence of small radial arteries primary access AVF in the upper arm should be considered.

Maintenance and salvage of arteriovenous fistulas

PURPOSE

To describe the number and type of percutaneous interventions required to promote maturation and maintain patency of hemodialysis fistulas.

MATERIALS AND METHODS

One hundred fifty-four hemodialysis fistulas were created in 146 patients by a single surgeon between August 2001 and March 2005. There were 88 male patients (60%), and the median age of the group was 66 years. The records of all percutaneous procedures performed on these patients were retrospectively reviewed. The medical records from the hemodialysis treatment centers were also reviewed to assess fistula patency during the follow-up period.

RESULTS

Of the initial 154 fistulas created, 112 (73%) were successfully used for hemodialysis. One hundred thirteen procedures were performed to promote maturation of 65 fistulas (1.7 procedures per fistula), including 66 venous angioplasty procedures, 16 arterial angioplasty procedures, ligation of 21 venous side branches, five thrombectomy procedures, three banding procedures, and two other procedures. Only 48 of these nonmaturing fistulas (74%) became functional. Sixty-three mature fistulas required 209 procedures (3.3 procedures per fistula, 1.75 procedures per access-year) to maintain vascular access patency. These included 174 venous angioplasty procedures, 18 arterial angioplasty procedures, 14 thrombectomy procedures, ligation of three venous side branches, and two stent placement procedures. The mean follow-up period for all 154 fistulas was 317 days (range, 12-1,138 days). Primary patency rates at 90, 180, and 360 days were 71%, 69%, and 64%, respectively, and secondary patency rates were 73%, 72%, and 68%, respectively.

CONCLUSIONS

Percutaneous procedures can promote maturation and maintain patency of arteriovenous fistulas. However, despite numerous procedures to promote maturation, only 74% of nonmaturing fistulas became functional.

The impact of intima-media thickness of radial artery on early failure of radiocephalic arteriovenous fistula in hemodialysis patients

This study was performed to investigate the impact of intima-media thickness (IMT) of radial artery on early failure of radiocephalic arteriovenous fistula (AVF) in hemodialysis (HD) patients. Ninety uremic patients undergoing radiocephalic AVF operation were included in this study. During the operation, 10-mm long partial arterial walls were removed with elliptical form for microscopic analysis. Specimens were stained with trichrome and examined by a pathologist blinded to the clinical data. And then AVF patency was followed up for 1 yr after the operation. Of the total 90 patients, 31 patients (34%) had AVF failure within 1 yr after the operation. Mean IMT was thicker in failed group (n=31) than in patent group (n=59) (486+/-130 micrometer vs. 398+/-130 micrometer, p=0.004). The AVF patency rate within 1 yr after the operation was lower in patients with IMT > or = 500 micrometer (n=26) than in patients with IMT <500 micrometer (n=64) (p=0.017). Age was an independent risk factor of IMT. Diabetes mellitus tended to be independent risk factor but not statistically significant. Our data suggest that increased radial artery IMT is closely associated with early failure of radiocephalic AVF in HD patients.

Ultrasonographic measurement of intima-media thickness of radial artery in pre-dialysis uraemic patients: comparison with histological examination

BACKGROUND

Increased intima-media thickness (IMT) of the radial artery is associated with early failure of radiocephalic arteriovenous fistula (AVF) in haemodialysis patients. Therefore, non-invasive measurements of radial artery IMT before AVF operations are very important in predicting AVF patency. This study was designed to evaluate the accuracy of high-resolution ultrasonography in measuring radial artery IMT in pre-dialysis uraemic patients.

METHODS

This study enrolled 43 pre-dialysis uraemic patients awaiting radiocephalic AVF operations for the first time. In this study, 17 age- and sex-matched uncomplicated hypertensive patients and 15 healthy subjects were included as a control. We measured the internal diameter (ID) and IMT of the radial artery using high-resolution ultrasonography on the wrists of uraemic patients as well as the control group before the AVF operation. We obtained specimens of the radial artery during the AVF operation and directly measured the IMT by histological examination.

RESULTS

The radial artery IMT of the uraemic patients (0.41 +/- 0.09 mm) was significantly thicker, compared to both those of the hypertensive (0.33 +/- 0.05 mm, P < 0.001) and the healthy patients (0.25 +/- 0.04 mm, P = 0.002). In contrast, the radial artery ID in the uraemic patients (1.85 +/- 0.48 mm) was smaller than both that of the hypertensive patients (2.08 +/- 0.31 mm, P = 0.023) and the healthy persons (2.34 +/- 0.37 mm, P = 0.001). Radial artery IMT had a negative correlation with radial artery ID in a total of 73 subjects (r = -0.290, P = 0.012). The value of the radial arterial IMT measured by sonographic examination correlated significantly with that by histological examination in 43 uraemic patients (r = 0.786, P < 0.001) and it correlated significantly with early AVF failure (r = 0.358, P = 0.027).

CONCLUSION

Our data suggest that high-resolution ultrasonography is an effective tool in measuring radial artery IMT in uraemic patients before AVF operation.

Effect of surgical banding of a high-flow fistula on access flow and cardiac output: Intraoperative and long-term measurements

Creation of either a natural arteriovenous graft or a fistula as a vascular access to support long-term hemodialysis can lead to "high-output" cardiac failure. The authors describe a patient who underwent surgical banding of an upper arm arteriovenous fistula. Access flow and cardiac output were measured not only pre- and postoperatively but also intraoperatively using a modified Swan Ganz catheter, originally developed to measure access flows during radiologic procedures. Banding resulted in a significant decrease in access flow and cardiac output, which was sustained for up to 1 year postoperatively.

Colour Doppler ultrasound assessment of well-functioning mature arteriovenous fistulas for haemodialysis access

BACKGROUND

A well-functioning mature arteriovenous fistula is essential for the maintenance of haemodialysis in patients with chronic renal failure. The Brescia-Cimino arteriovenous fistula has the best survival characteristics and low rate of complications. The most common reason of fistula failure is thrombosis caused by stenosis. Colour Doppler ultrasonography has proven to be effective in the assessment of anatomical vascular features. The majority of studies were done in patients with clinically presumed arteriovenous fistula complications. However, only limited data are available about the well-functioning mature arteriovenous fistulas. The purpose of the present study was to evaluate completely asymptomatic, mature arteriovenous fistulas with colour Doppler ultrasound.

MATERIALS AND METHODS

From July 2001 to April 2003, we examined 139 patients with the end-stage renal disease. They were in the range of 19-79 years of age (mean, 46.7 years). The study included only the patients who met the following criteria: (1) no difficulties with haemodialysis (as reported by nurses); (2) normal venous diastolic blood pressure (<150 mmHg) at monthly evaluation; (3) normal urea clearance x time/urea volume of distribution; (4) blood cells count, plasma electrolytes, and liver function at monthly evaluation. The mean fistula age was 26 months (S.D.=21.9). The mean time of dialysis therapy was 49 months. Thirty-eight percent patients had primary fistulas, 23%--secondary, 11%--third and 11%--fourth, 4%--fifth, 5%--sixth, and 8% patients had more than sixth.

RESULTS

There was no correlation between: (1) patient's age and fistula age; (2) patient's age and number of fistulas in one patient; (3) fistula age and number of fistulas in one patient; (4) localization of fistula and fistula age. There was a strong correlation between dialysis therapy period and number of fistulas in one patient. The mean flow volume was 1204.1 ml/min (S.D.=554). It was significantly higher in the fistulas with aneurysms, calcifications and tortuous vessels and lower in those with stenosis. There was no correlation between the flow volume or presence of stenosis and fistula age. Stenosis was detected in 64% fistulas. Fifty-seven percent of stenoses were located in the anastomotic region, 22% stenoses were in vein junction, 19% were at one or both ends of aneurysm, and 2% in the remaining region of the efferent vein. Perivascular colour artefacts were present at the 94% fistulas with stenosis. Chronic venous occlusion with collateral veins was detected in 6% of fistulas. The aneurysms were observed in 54% fistulas. The mean diameter of aneurysms was 12.4 mm. Ninety-six percent of aneurysms were located at puncture sites. Ten patients had a small thrombus in an aneurysm and at puncture sites.

CONCLUSIONS

We conclude that there was a high level of abnormalities present in well-functioning mature arteriovenous fistulas. However, these abnormalities were not sufficient to affect the functioning of the dialysis fistula.

Resistive Index Measurement of Native Hemodialysis Arteriovenous Fistula Feeding Artery as a Predictor for Fistula Dysfunction

The aim of the present study was to evaluate resistive index (RI) in the feeding artery of the functioning and dysfunctioning arteriovenous fistulas (AVFs). Measurement of RI in the feeding artery using Doppler ultrasound was performed in 48 patients on hemodialysis. Twenty-seven upper arm AVFs and 21 radiocephalic AVFs were studied. The patients were categorized into three groups according to clinical function: group 1, AVFs with normal function (n = 21); group 2, AVFs with abnormal clinical function (reduced pump flow) (n = 20); and group 3, AVFs with abnormal clinical function (increased venous pressure) (n = 7). Resistive index measurements and morphologic changes were compared between functioning and dysfunctioning AVFs. Increased RI values were detected in the AVFs with reduced pump flow. The average RI values of feeding artery were 0.47 +/- 0.07 in group 1, 0.67 +/- 0.18 in group 2, and 0.49 +/- 0.05 in group 3. Two brachial artery aneurysms, one brachial artery pseudoaneurysm, ten venous stenoses, and six venous thromboses were detected in the AVFs with diminished pump flow (18/20 patients, 90%). Both increased RI values and vascular complications were detected by Doppler ultrasound in the patients with reduced pump flow during dialysis. This study shows that Doppler ultrasound examination of AVF feeding artery may provide useful data on morphologic and functional characteristics of AVF.

Preventing vascular access dysfunction: which policy to follow

In the USA, three Clinical Performance Measures are currently in place: increasing the number of autologous arteriovenous fistulas (AVFs) among incident hemodialysis patients to 50% and to 40% in prevalent hemodialysis patients; to foster the surveillance of accesses with preemptive correction of problems before accesses thrombose or fail, and to reduce the use of catheters in prevalent patients to less than 10%. Reduction of catheters will automatically result from initiatives that increase the construction of AVFs and preemptive monitoring and surveillance of accesses for dysfunction. Therefore, policies that promote the latter two vascular access aspects are most important to develop and follow. Of these two, however, the most impact will be made by promoting a policy to increase AVF creation in the timeliest manner possible. Strategies and resources needed to achieve these policies are presented. The need for a team approach is emphasized.

Creation, cannulation and survival of arteriovenous fistulae: data from the Dialysis Outcomes and Practice Patterns Study

BACKGROUND

An arteriovenous (A-V) fistula is the optimal vascular access for hemodialysis. The National Kidney Foundation Dialysis Outcomes Quality Initiative (DOQI) recommends that fistulae should mature for at least one month before cannulation, but this recommendation is not evidence-based. If fistulae are created prior to ESRD and cannulation is possible earlier without compromising fistula survival, the need for temporary catheters would be reduced.

METHODS

Prospective observational data were analyzed for a random sample (N = 3674) of incident patients at the time of initiating hemodialysis, hemofiltration or hemodiafiltration in 309 facilities in France, Germany, Italy, Japan, Spain, the United Kingdom, and the United States, taking part in the Dialysis Outcomes and Practice Patterns Study (DOPPS).

RESULTS

Although the proportion of patients who had pre-dialysis care by a nephrologist differed little between countries, there were large variations in the proportion of patients who commenced hemodialysis via an A-V fistula, A-V graft or central venous catheter. The usual time interval between referral and creation of A-V fistulae also differed greatly between countries. For new hemodialysis (HD) patients initiating HD with an A-V fistula (N = 894) the following results were observed: (1). median time to first cannulation varied greatly between countries: Japan and Italy (25 and 27 days), Germany (42 days), Spain and France (80 and 86 days), UK and US (96 and 98 days). (2). No association was found between cannulation <or=28 days versus>28 days for patient characteristics of age, gender, and fifteen different classes of patient co-morbid factors. (3). Risk of A-V fistula failure was increased for incident patients who had a prior temporary access [relative risk (RR) = 1.81, P = 0.01] or who were female (RR = 1.52, P = 0.02). (4). Cannulation <or=14 days after creation was associated with a 2.1-fold increased risk of subsequent fistula failure (P = 0.006) compared to fistulae cannulated>14 days. (5) No significant difference in A-V fistula failure was seen for fistulae cannulated in 15 to 28 days compared with 43 to 84 days.

CONCLUSION

Significant differences in clinical practice currently exist between countries regarding the creation of A-V fistulae prior to starting hemodialysis and the timing of initial cannulation. Cannulation within 14 days of creation is associated with reduced long-term fistula survival. Fistulae ideally should be left to mature for at least 14 days before first cannulation.

Prospective evaluation of the intra-access flow of recently created native arteriovenous fistulae

BACKGROUND

The aim of this study is to assess the evolution of intra-access flow (Q(ac)) in recently created native arteriovenous fistulae (AVFs) during the first few months of use.

METHODS

All AVFs were monitored by means of ultrasound dilution using Transonic (Transonic Systems Inc, Ithaca, NY). First Q(ac) measurements were obtained between 6 to 10 weeks after creation and subsequently every 3 to 6 weeks during the following 4 months. Per routine, AVFs are cannulated 6 weeks after their creation in our unit. Fifty-seven patients with new AVFs were initially enrolled, but 12 patients were lost at follow-up. There was a 69% to 31% ratio of brachiocephalic (BC) to radiocephalic (RC) AVFs, and diabetes affected an equal proportion of patients in both subtypes.

RESULTS

Mean initial and final Q(ac)s were 1,132 +/- 681 and 1,097 +/- 644 mL/min, respectively; there was no significant difference during the study period. However, the Q(ac) of BC AVFs remained approximately twice as high as the Q(ac) of RC AVFs during the observation period (initial Q(ac), 1,336 +/- 689 versus 645 +/- 332 mL/min; final Q(ac), 1,285 +/- 652 versus 647 +/- 331 mL/min, respectively). Male sex was associated with a greater Q(ac) throughout the evaluation (1,263 +/- 754 versus 852 +/- 375 mL/min for women). No significant difference was noted between different age groups, and diabetes did not significantly affect Q(ac). Finally, the initial Q(ac) of a BC AVF was influenced by the presence of a previously functioning RC AVF on the same arm. The initial Q(ac) in BC AVFs was 1,800 +/- 919 mL/min in that subgroup (and decreased to 1,302 +/- 733 mL/min by the end of the study, therefore becoming similar to the mean Q(ac) of other BC AVFs).

CONCLUSION

From these results, we conclude that newly created native AVFs have an initial Q(ac) that does not vary significantly during the first 6 months and may already be maximal at 6 weeks or at the time of first needle puncture in our hands. Among demographic factors, sex influences the Q(ac) of native AVFs, whereas age and diabetes do not.

Transition to all-autogenous hemodialysis access: the role of preoperative vein mapping

Safe, reliable, and efficient hemodialysis access (DA) remains an unrealized ideal. Autogenous dialysis access (ADA) may improve outcome for renal failure patients. We now place ADA in 9 out of 10 new patients in an effort to maximize primary patency and minimize access-related complications. We reviewed our recent DA experience to determine whether our increased reliance on autogenous access (ADA) has improved outcomes, and to evaluate the impact of preoperative duplex venous imaging (vein mapping) on early and intermediate results. We conducted a retrospective database review of 108 consecutive patients undergoing initial permanent DA between 10/97 and 8/01. Mean follow-up was 13.1 months. Our results showed that increased ADA utilization decreases the need for secondary access procedures. The functional superiority of ADA vs. prosthetic dialysis access (PDA) in this series may be due to optimal autogenous conduit selection facilitated by preoperative vein mapping.