Effect of preoperative sonographic mapping on vascular access outcomes in hemodialysis patients

Current management of vascular access

Optimizing vascular access outcomes remains an ongoing challenge for clinical nephrologists. All other things being equal, fistulas are preferred over grafts, and grafts are preferred over catheters. Mature fistulas have better longevity and require fewer interventions, as compared with mature grafts. The major hurdle to increasing fistula use is the high rate of failure to mature of newly created fistulas. There is a desperate need for enhanced understanding of the mechanisms of failure to mature and the optimal type and timing of interventions to promote maturity. Grafts are prone to frequent stenosis and thrombosis. Surveillance for graft stenosis with preemptive angioplasty may reduce graft thrombosis, but recent randomized clinical trials have questioned the efficacy of this approach. Graft stenosis results from aggressive neointimal hyperplasia, and pharmacologic approaches to slowing this process are being investigated in clinical trials. Catheters are prone to frequent thrombosis and infection. The optimal management of catheter-related bacteremia is a subject of ongoing debate. Prophylaxis of catheter-related bacteremia continues to generate important clinical research. Close collaboration among nephrologists, surgeons, radiologists, and the dialysis staff is required to optimize vascular access outcomes and can be expedited by having a dedicated access coordinator to streamline the process. The goal of this review is to provide an update on the current status of vascular access management.

Current techniques for assessment of upper extremity vasculature prior to hemodialysis vascular access creation

Vascular access problems lead to increased patient morbidity and mortality and place a large burden on care facilities, manpower and costs. Autogenous arteriovenous fistulas (AVF) are preferred over arteriovenous grafts (AVG) because of a lower incidence of vascular access related complications. An aggressive increase in the utilization of AVF, however, results in an increased incidence of AVF early failure and non-maturation. Increasing evidence suggests that routine preoperative assessment results in an increased utilization of functioning AVF by better selection of adequate vessels. To date, the reproducibility and standardization of assessment protocols are lacking and assessment of a single morphological parameter has not enabled adequate prediction of postoperative AVF function for individual patients. In this paper, we provide an overview of available diagnostic modalities and parameters that potentially enable better selection of adequate vessels for successful AVF creation.

Comparison of Survival of Upper Arm Arteriovenous Fistulas and Grafts after Failed Forearm Fistula

Although arteriovenous fistulas are considered superior to grafts, it is unknown whether that is true in the subset of patients with a previous failed fistula. For investigation of this question, a prospective vascular access database was queried retrospectively to compare the outcomes of 59 fistulas and 51 grafts that were placed in the upper arm after primary failure of an initial forearm fistula. Primary access failure was higher for subsequent fistulas than for subsequent grafts (44 versus 20%; P = 0.006). Fistulas required more interventions than grafts before their successful use (0.42 versus 0.16 per patient; P = 0.04). The time to catheter-free dialysis was longer for fistulas than for grafts (131 versus 34 d; P < 0.0001) and was associated with more episodes of bacteremia before permanent access use (1.3 versus 0.4 per patient; P = 0.003). Cumulative survival (from placement to permanent failure) was higher for fistulas than for grafts when primary failures were excluded (hazard ratio 0.51; 95% confidence interval 0.27 to 0.94; P = 0.03), but similar when primary failures were included (hazard ratio 0.99; 95% confidence interval 0.61 to 1.62; P = 0.97). Fistulas required fewer interventions to maintain long-term patency for dialysis after maturation (0.73 versus 2.38 per year; P < 0.001). In conclusion, as compared with grafts, subsequent upper arm fistulas are associated with a higher primary failure rate, more interventions to achieve maturation, longer catheter dependence, and more frequent catheter-related bacteremia. However, once the access is usable for dialysis, fistulas have superior cumulative patency than do grafts and require fewer interventions to maintain patency.

Diabetic nephropathy in the elderly

Renal impairment is frequent in aged diabetic patients, notably with type 2 diabetes. It results from a multifactorial pathogeny, particularly the combined actions of hyperglycaemia, arterial hypertension and ageing. Diabetic nephropathy (DN) is associated with an increased cardiovascular mortality. DN often leads to end stage renal failure (ESRF) which causes specific problems of decision and practical organization of extra-renal epuration in diabetic and aged patients. In the absence of renal biopsy, clinical signs are often insufficient to assess the diabetic origin of a nephropathy in an elderly diabetic patient. Prevention of DN is principally based on tight glycaemic and blood pressure control. The progression of renal lesions can be retarded by strict blood pressure control, notably by blocking of the renin-angiotensin system, if well tolerated in aged patients. It is absolutely necessary to avoid the worsening of renal lesions by potentially nephrotoxic products, notably non steroidal anti-inflammatory drugs (NSAIDs) and iodinated contrast media. At the stage of renal failure, it is important to adapt the antidiabetic treatment, and in the majority of the cases, to switch to insulin when glomerular filtration rate (GFR) is below 30 ml/mn/1.73 m2.

Aneurysm Formation in Arteriovenous Grafts: Associations and Clinical Significance

Aneurysms are a common complication of arteriovenous grafts in hemodialysis patients, resulting from repetitive needle sticks in the graft material. Although aneurysms are thought to contribute to graft failure, there are no prospective studies evaluating their risk factors or impact on graft survival. The present study evaluated aneurysms in 117 hemodialysis outpatients with upper extremity grafts at a university-affiliated dialysis center. An arterial aneurysm was defined as a cannulation site defect diameter (difference between arterial cannulation site diameter and normal graft diameter) above the median value for the study population (0.63 cm). Subsequent graft outcomes were determined by retrospective analysis of a prospective vascular access database. Thrombosis-free graft survival was compared among patient subgroups using Cox proportional hazards models. Patients with an arterial aneurysm had significantly longer median graft age, when compared with those not having a aneurysm (888 vs. 588 days, p = 0.01). However, the two groups did not differ in patient age, sex, diabetes, body mass index, or graft location. The hazard ratio for graft thrombosis was 0.45 (95% confidence interval, 0.25-0.82, p = 0.009) for grafts with an arterial aneurysm, when compared with those without a defect (1-year graft survival of 71 vs. 50%). Graft age was not associated with the likelihood of graft thrombosis (p = 0.12). In contrast to the prevailing wisdom, arterial aneurysms are associated with improved graft survival.

Impact of obesity on arteriovenous fistula outcomes in dialysis patients

Fistula use for dialysis is less frequent among obese than non-obese patients. This discrepancy may be due to a lower rate of fistula placement in obese patients, a higher primary failure rate (fistulas that are never usable for dialysis), or a higher secondary failure rate (fistulas that fail after being used successfully for dialysis). Using a prospective, computerized vascular access database, we identified all patients receiving a first fistula or graft at our institution during a 2-year period. The access outcomes were compared between obese (body mass index (BMI) >or=30 kg/m2) and non-obese (BMI<30 kg/m2) patients. Fistula placement was equally likely between obese and non-obese patients (47.4 vs 47.1%). The primary failure rate of fistulas was similar in both groups (46 vs 41%, P=0.45). Among those fistulas that were usable for dialysis, the secondary survival was worse in obese patients (hazard ratio 2.74; 95% confidence interval (CI), 1.48-7.90; P=0.004). Secondary fistula survival in obese vs non-obese patients was 68 vs 92% at 1 year, 59 vs 78% at 2 years, and 47 vs 70% at 3 years. On multiple variable survival analysis with age, sex, race, diabetes, coronary artery disease, peripheral vascular disease, fistula location, surgeon, and obesity in the model, obesity was the only significant factor predicting secondary fistula failure (hazards ratio 2.93; 95% CI, 1.44-5.93; P=0.004). In conclusion, long-term fistula survival is worse in obese than non-obese patients, owing to a higher secondary failure rate.

Cephalic vein measurement before forearm fistula creation: does use of a tourniquet to meet the venous diameter threshold increase the number of usable fistulas?

OBJECTIVE

To optimize forearm radiocephalic fistula success, many programs recommend a minimal cephalic vein diameter of 0.25 cm or greater on preoperative sonographic mapping. It is not established, however, whether a vein diameter before or after application of a tourniquet should be used in determining suitability for creation of a forearm fistula.

METHODS

Before forearm radiocephalic fistula placement, preoperative sonographic mapping measured the cephalic vein diameter before and after application of a tourniquet. The patients fell into 2 groups: those with a pretourniquet vein diameter of 0.25 cm or greater (group 1) and those with a pretourniquet vein diameter of less than 0.25 cm that increased to 0.25 cm or greater after application of the tourniquet (group 2). The adequacy of each fistula for dialysis was determined clinically.

RESULTS

Among 73 radiocephalic fistulas with known clinical outcomes, 28 were in group 1, and 45 were in group 2, on the basis of sonography. Fistula success rates were similar in group 1 patients (11 [39%] of 28) and group 2 patients (15 [33%] of 45) (P=.624, Fisher exact test). Inclusion of group 2 patients increased the number of patients recommended for placement of forearm fistulas and increased the total number of usable forearm fistulas from 11 to 26. The overall success rate of forearm fistulas was lower in women (19% versus 50%; P=.015, Fisher exact test).

CONCLUSIONS

The use of a venous tourniquet increases the number of patients eligible for forearm fistulas without decreasing the adequacy rate of these fistulas. Therefore, a tourniquet should routinely be used in patients with small cephalic veins on pretourniquet evaluation.

Interventional nephrology in Puerto Rico

Vascular access is emerging as a critical issue for hemodialysis patients in Puerto Rico. In more than 50% of the hemodialysis patients, tunneled hemodialysis catheters are the sole access for providing dialysis therapy. Most disturbing is the fact that a significant number of these catheters are nontunneled temporary catheters, sometimes placed in the subclavian vein. These facts have contributed significantly to the morbidity and mortality seen in chronic dialysis patients. In addition, many cases of early or late dysfunction of arteriovenous access are not detected and treated in a timely manner due to the lack of a comprehensive vascular access program for end-stage renal disease (ESRD) patients. In fact, monitoring programs to identify and detect vascular access dysfunction are virtually nonexistent in many chronic dialysis units. Even when diagnosed, it is not treated in a timely fashion. Recently literature has shown that procedure-related delays in the treatment of patients with renal disease can be minimized and nephrology care more efficiently delivered by a nephrologist trained in nephrology-related procedures. In an effort to optimize the care of our ESRD patients, we took the initiative to develop an interventional nephrology program that effectively deals with vascular access-related procedures in a timely manner. This approach has minimized delays, decreased hospitalizations and the use of temporary catheters, and improved the medical care of our chronic dialysis patients. So far we have performed more than 400 procedures in the 6 months since the initiation of the program. In this article we describe our initial experience with interventional nephrology in Puerto Rico.

Vascular access for hemodialysis

Establishing and maintaining adequate vascular access is essential to providing an appropriate dialysis dose in patients with end-stage renal disease. Complications related to vascular access have a significant role in dialysis-related morbidity and mortality. The National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K/DOQI) clinical practice guideline for dialysis access was last updated in 2000 and provides a framework for the optimal establishment and maintenance of dialysis access, and treatment of complications related to dialysis access. This paper reviews the 2000 K/DOQI dialysis access guideline as well as updated information published subsequently.

Forearm cephalic vein cross-sectional area changes at incremental congestion pressures: Towards a standardized and reproducible vein mapping protocol

OBJECTIVES

Duplex ultrasonography assessment of superficial forearm veins is frequently used before a hemodialysis arteriovenous fistula (AVF) is created. There is, however, no standardized preoperative duplex ultrasonography protocol. This study assessed B-mode image analysis reproducibility and reproducibility of repeated forearm superficial venous diameter measurements on different days at different venous congestion pressures (VCPs).

METHODS

Diameters were determined using B-mode ultrasonography in 10 healthy male volunteers on days 1 and 14 at incremental VCP values (10 to 80 mm Hg). Intra- and interobserver agreement was assessed for B-mode image analysis by calculating interclass correlation coefficients (ICC). Reproducibility of repeated diameter measurements (maximum and minimum diameter at days 1 and 14), cross-sectional area size increase, and shape change due to incremental VCPs were determined by calculating ICC values.

RESULTS

Analysis of intraobserver agreement of B-mode image interpretation yielded ICC values of 0.97 (95% confidence interval [CI], 0.94 to 0.99) and 0.97 (95% CI, 0.96 to 0.99) for determination of maximum and minimum diameters, respectively. Interobserver agreement analysis yielded ICC values of 0.95 (95% CI, 0.92 to 0.97) and 0.96 (95% CI, 0.96 to 0.99) for determination of maximum and minimum diameters, respectively. Reproducibility of repeated diameter measurements on days 1 and 14 improved substantially at incremental VCP values, with best reproducibility at VCPs >40 mm Hg. Repeated determination of cross-sectional area size increase and shape change due to VCP increase from 10 to 80 mm Hg yielded ICC values of 0.49 (95% CI, 0.19 to 1.00) and 0.09 (95% CI, 0.00 to 0.92), respectively. Maximum and minimum diameters as well as cross-sectional area size increased significantly (P < .01) due to VCP increase during both sessions. Cross-sectional area shape changed significantly (P < .01) due to VCP increase during both sessions.

CONCLUSIONS

Diameter measurements on B-mode images are largely observer independent. Superficial venous cross-sectional area shape is noncircular, and cross-sectional area size depends on VCP. Both maximum and minimum venous diameters should be determined at VCPs >40 mm Hg to attain the best reproducibility. Further studies are needed to determine whether a standardized preoperative vein mapping protocol can reduce AVF nonmaturation rates.

Randomized comparison of ultrasound surveillance and clinical monitoring on arteriovenous graft outcomes

Arteriovenous graft thrombosis is a frequent event in hemodialysis patients, and usually occurs in grafts with significant underlying stenosis. Regular surveillance for graft stenosis, with pre-emptive angioplasty of significant lesions, may improve graft outcomes. This prospective, randomized, clinical trial allocated 126 hemodialysis patients with grafts to either clinical monitoring alone (control group) or to regular ultrasound surveillance for graft stenosis every 4 months in addition to clinical monitoring (ultrasound group). The two randomized groups were closely matched with respect to demographic, clinical, and graft characteristics, with the exception of a lower frequency of diabetes in the ultrasound group. The primary outcome was graft survival, and the secondary outcome was thrombosis-free graft survival. The frequency of pre-emptive graft angioplasty was 64% higher in the ultrasound group than in the control group (1.05 vs 0.64 events per patient-year, P<0.001), whereas the frequency of thrombosis was not different (0.67 vs 0.78 per patient-year, P=0.37). The median time to permanent graft failure was similar between the two groups (38 vs 37 months, P=0.93). Likewise, the median time to graft thrombosis or failure did not differ (22 vs 25 months, P=0.33). There was no significant association between diabetes and time to graft failure (P=0.93) or time to graft thrombosis or failure (P=0.88). In conclusion, the addition of regular ultrasound surveillance for graft stenosis to clinical monitoring increases the frequency of pre-emptive angioplasty, but may not decrease the likelihood of graft failure or thrombosis.

Creation of secondary arteriovenous fistulas: maximizing fistulas in prevalent hemodialysis patients

National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF-DOQI) guideline 29 suggests that a patient should be evaluated for a secondary arteriovenous fistula (AVF) following each episode of dialysis access failure. Regretfully, it does not appear that this approach is used, even though recent data have emphasized that veins suitable for the creation of a secondary AVF can be identified in dialysis patients who are receiving dialysis via a synthetic arteriovenous graft (AVG) or other type of potentially dysfunctional vascular access. In this study nine patients (five with an AVG and four with an AVF) with vascular access dysfunction undergoing percutaneous interventions were evaluated for secondary AVF creation. All were found to have suitable vascular anatomy and had the AVF created. The secondary fistula was successful in all nine patients with a mean follow-up of 4.8 +/- 1.4 months in post-AVG cases and 5.6 +/- 1.7 months in the post-AVF patients. In addition, it was possible to continue uninterrupted dialysis without the use of a tunneled dialysis catheter in three of the patients with AVGs. This experience demonstrates the validity and success of this approach to the management of dialysis access dysfunction. In the ongoing effort to optimize vascular health status, we suggest that during percutaneous interventions, patients should routinely have identification of vessels suitable for creation of a secondary AVF.

Is Routine Preoperative Ultrasonographic Mapping for Arteriovenous Fistula Creation Necessary in Patients with Favorable Physical Examination Findings? Results of a Randomized Controlled Trial

INTRODUCTION

Preoperative ultrasonographic mapping (PUSM) is widely used for arteriovenous fistula creation in end-stage renal disease patients, and some authors even advocate that it be used routinely. To date, however, there are no prospective randomized data to support this suggestion.

METHODS

This prospective, randomized, controlled study compared PUSM and physical examination in relation to short-term outcome after AVF creation. Data sets from 70 hemodialysis patients who were deemed eligible for AVF surgery-according to specific physical examination (PE) criteria for vessel anatomy-were analyzed. The patients were randomly divided into two groups. In the PE group, no other investigation was performed, and the patient underwent AVF creation. The other patients (M group) underwent PUSM, and the AVF was created according to the mapping results. Early AVF success was defined as clinical detection of thrill (immediately and on postoperative day 1). Ultrasonographic parameters were recorded on the first postoperative day and at 1 and 6 months postoperatively. The need for intervention and intervention-free AVF survival and cumulative AVF survival were also noted.

RESULTS

The PE and M groups showed similar rates of early AVF success: immediate thrill, PE 24/35 (68.6%) vs. M 26/33 (78.8%), P=0.340; postoperative day 1, PE 20/34 (58.8%) vs. M 24/32 (75%), P=0.164. The groups' results for ultrasonographic parameters of AVF function were also similar on postoperative day 1 and at 1 month after surgery. The groups had similar intervention-free AVF survival (P=0.770) and cumulative AVF survival as well (P=0.916). After an average follow-up of 217.7+/-239.7 days, the two groups also had similar proportions of patent AVFs: 23/35 (65.7%) vs. 23/35 (65.7%) for PE vs. M, respectively; P=1.0).

CONCLUSIONS

The results indicate that PUSM offers no advantage over PE with regard to AVF function in patients with favorable forearm anatomy. The authors do not advocate routine use of PUSM in patients with favorable PE findings scheduled for forearm AVF creation.

Evaluation of primary failure in native AV-fistulae (early fistula failure)

The most preferable method of vascular access (VA) in maintenance hemodialysis is a native arteriovenous fistula (AVF). Advanced age as well as the rapid increase in underlying diseases such as diabetic nephropathy and nephrosclerosis in these patients also means that the veins and arteries used to establish the AVF have undergone vascular damage, making construction of an AVF more difficult compared with earlier construction. Although there are various conditions under which arterial superficialization or AV graft must be chosen, it remains the rule that the first choice for VA should be AVF whenever possible. To improve postoperative results, it is necessary to reduce malfunctions immediately following surgery. We conducted a survey of 23 dialysis facilities throughout Japan and analyzed data from the past 3 years regarding the functionality of the AVF at initial puncture following construction of 5007 examples of newly constructed AVFs. Upon initial puncture, primary failure (PF) is defined as those cases in which thrombosis or inadequate blood flow occur. Primary failure occurred in 7.6% of the cases in this series, but there was a wide distribution of PF, 0.8% to 23.6%, because of differences in quality among facilities. This difference in PF is probably affected by technical aspects, the main factor being the characteristics of the patient. Survey responses included: (1) vascular damage of the veins and arteries used in creating the AVF and (2) the suitability of the location chosen for construction. In the data collected, many methods were used to repair those primary AFVs in which PF occurred. The salvage rate was 70%. Currently, the most preferable form of VA is AVF adhering to the principle that the proper timing of the choice and construction of AVF should consider the maturation period. To accomplish this, it is vital that vascular mapping be performed preoperatively to construct the AVF. If PF does occur, the cause should be thoroughly investigated and repairs made effectively.

Arteriovenous fistula surgery: an American perspective from Italy

Hemodialysis depends on durable, long-term vascular access for the patient. In the United States, arteriovenous fistula (AVF) creation rates are lower than they are in Europe. Excess morbidity and mortality has been attributed to reliance on catheters and prosthetic grafts. In Italy, there is a high rate of fistula creation, and they are predominantly created by nephrologists. As American interventional nephrologists become more involved in the procedural aspects of renal care, consideration should be given to replicating the Italian model of dialysis access creation. Specific aspects of the surgical technique, comparison to available literature, and potential reasons for higher fistula creation rates are explored from the vantage point of an American nephrologist visiting Italy. The pertinence to American dialysis access programs is discussed, as is the opportunity for interventional nephrologists in the United States to further expand and improve upon the successes of the Italian experience.

Design of the Dialysis Access Consortium (DAC) Clopidogrel Prevention of Early AV Fistula Thrombosis Trial

BACKGROUND

The Dialysis Access Consortium (DAC) was developed to investigate interventions to improve hemodialysis vascular access outcomes. The autogenous arteriovenous fistula created by direct connection of native artery to vein is the recommended vascular access for hemodialysis. However, it fails frequently due to clotting after surgery.

PURPOSE

The DAC Early AV Fistula Thrombosis Trial tests the hypothesis that clopidogrel can prevent early fistula failure and increase the number of fistulas that ultimately become usable for hemodialysis access. This is one of two initial and concurrent trials being performed by the DAC. The companion trial investigates pharmacologic approaches to prevent venous stenosis leading to AV graft failure.

METHODS

This is a multicenter, randomized, double-blind, placebo-controlled trial that will enroll 1,284 patients over four years. Patients undergoing creation of a new native arteriovenous (AV) fistula are randomized to treatment with clopidogrel or placebo for six weeks following fistula creation surgery. The primary outcome is fistula patency at six weeks. The major secondary outcome is fistula suitability for dialysis.

RESULTS

This paper examines key aspects of this study that have broad relevance to trial design including: 1) the selection of an intermediate event as the primary outcome, 2) timing of the intervention to balance efficacy and safety concerns, 3) ethical considerations arising from required modifications of concomitant drug therapy, and 4) choosing an efficacy or effectiveness evaluation of the intervention.

CONCLUSIONS

This is the first, large, multicenter trial evaluating a pharmacologic approach to prevent early AV fistula failure and promote more usable fistulas for hemodialysis. The methodologic challenges identified and addressed during the development of this trial should help to inform the design of future vascular access trials, and are relevant to clinical trials addressing a wide range of questions.

Endovascular Treatment of the “Failing to Mature” Arteriovenous Fistula

In recent literature, surgically created hemodialysis (HD) arteriovenous fistulas (AVF) have high rates of primary failure. Endovascular treatment holds promise to salvage these fistulae. The outcomes of 119 patients who had a "failing to mature" AVF and presented for endovascular management were evaluated prospectively. All patients underwent a fistulogram. Stenotic lesions underwent balloon angioplasty, and accessory veins underwent obliteration. Technical success was determined immediately after the procedure. AVF salvage was determined by successful use during HD. Patients were followed up for 1 yr, during which primary and secondary AVF patency rates were measured. The distribution of stenoses was as follows: Artery, 6 (5.1%); arterial anastomosis, 56 (47.1%); juxta-arterial anastomosis, 76 (63.9%); peripheral vein, 70 (58.8%); and central vein, 10 (8.4%). Significant accessory veins were present in 35 (29.4%). Mixed lesions were found in 85 (71.4%). The technique was successful in 107 (89.9%), and the AVF was salvaged in 99 (83.2%). Follow-up of salvaged fistulae showed a total event rate of 0.38/access-year, thrombosis rate of 0.12/access-year, and loss rate of 0.04/access-year. Endovascular treatment of "failing to mature AVF" is safe and effective when performed in a dedicated center.

Preoperative Radiological Assessment for Vascular Access

There is increasing evidence that routine preoperative duplex scanning ultrasound cannot only increase the utilisation of native AVF for dialysis access but also allow proper selection of a target vessel with adequate luminal diameter to improve outcome. A minimum arterial diameter of 2mm is associated with successful fistula formation. A threshold for minimal venous diameter is difficult to establish. Most clinical studies use a value of 2.5mm for AVF and 4mm for prosthetic grafts. Traditional contrast venography is mandatory where there is suspicion of central vein stenosis. In predialysis patients where there is a risk of contrast nephropathy MR venography is emerging as a possible alternative.

Strategies to Minimize Tunneled Hemodialysis Catheter Use

While the use of arteriovenous grafts has recently declined, there has been an astronomical increase in hemodialysis patients dialyzing with tunneled dialysis catheters (TDCs). Recent data have indicated that over 70% of the patients with end-stage renal disease initiate dialysis with a catheter. Additionally, up to 27% of the end-stage renal disease patients in the US are using TDCs as their permanent access, with placement rates having doubled since 1996. Although most modern catheters claim to provide adequate blood flow for dialysis, they are associated with the highest incidence of complications, morbidity and mortality when compared with other types of vascular access. It is for these reasons that the National Kidney Foundation Dialysis Outcomes Quality Initiative guideline 30 as well as the Fistula First Change Concept 7 emphasize limiting the use of catheters and fostering the creation of arteriovenous fistulae. Early referral has clearly been shown to minimize the use of TDCs and maximize fistulae. This report focuses on the role of additional measures that minimize TDC use, such as dialysis modality presentation and peritoneal dialysis, vascular access education, preoperative vascular mapping and salvage of early failure and thrombosed fistulae.

Diameter measurements of the forearm cephalic vein prior to vascular access creation in end-stage renal disease patients: graduated pressure cuff versus tourniquet vessel dilatation

BACKGROUND

Preoperative assessment of forearm superficial venous diameter may predict early failure of newly created arteriovenous fistulas for haemodialysis access. However, early failure and non-maturation rates remain high (up to 30%) and reported cut-off diameters are inconsistent. We hypothesize that this inconsistency is due to differences in the methods used to achieve venous dilatation prior to diameter measurements and daily variation in superficial venous diameter. We furthermore hypothesize that the use of a cuff will lead to a better inter-observer agreement since the applied pressure can be precisely determined. The purpose of this study was to determine inter-observer agreement of superficial venous diameter measurement under venous congestion by using either a graduated pressure cuff or tourniquet and furthermore, to determine daily variations in superficial venous diameter.

METHODS

Diameter measurements were performed by two observers on days 1 and 3, in 21 end-stage renal disease patients using either a cuff (60 mmHg) or tourniquet. Measurements were carried out in random order and observers were blinded for each other's results. Inter-observer agreement was expressed as interclass correlation coefficients. Variance components analysis was used to determine possible causes of disagreement.

RESULTS

Using a cuff, mean venous diameter was 1.8 mm (range, 0.7-3.3 mm). When a tourniquet was used, the mean diameter was 1.8 mm (range, 0.6-3.2 mm). Interclass correlation coefficients between observers were 0.76 and 0.74 for the use of a cuff and tourniquet, respectively. Diameter measurements were revealed to be observer independent. Variations in venous diameter were determined by the patient and the interaction of patient and day. Repeated assessment of venous diameter on different days revealed a variation coefficient of 26.4% when using a cuff, and 26.5% when using a tourniquet.

CONCLUSIONS

Venous diameter assessment is observer and congestion method independent. Daily variations in forearm superficial venous diameters should be taken into account when defining and using cut-off diameters prior to vascular access surgery.

Early Arteriovenous Fistula Failure: A Logical Proposal for When and How to Intervene

A significant number of arteriovenous fistulae (28 to 53%) never mature to support dialysis. Often, renal physicians and surgeons wait for up to 6 months and even longer hoping that the arteriovenous fistula (AVF) will eventually grow to support dialysis before declaring that the AVF has failed. In the interim, if dialysis is needed, then a tunneled catheter is inserted, exposing the patient to the morbidity and mortality associated with the use of this device. In general, a blood flow of 500 ml/min and a diameter of at least 4 mm are needed for an AVF to be adequate to support dialysis therapy. In most successful fistulae, these parameters are met within 4 to 6 wk. Most important, commonly encountered problems (stenosis and accessory veins) that result in early AVF failure can be diagnosed easily with skillful physical examination. Recent studies have indicated that a great majority of fistulae that have failed to mature adequately can be salvaged by percutaneous interventions and become available for dialysis. Early intervention regarding identification and salvage of a nonmaturing AVF is critical for several reasons. First, an AVF is the best available type of access regarding complications, costs, morbidity, and mortality. Second, this approach minimizes catheter use and its associated complications. Finally, access stenosis is a progressive process and eventually culminates in complete occlusion, leading to access thrombosis. In this context, the opportunity to salvage the AVF that fails early may be lost. This report reviews the process of AVF maturation and suggests a strategy for when and how to intervene to identify and salvage AVF with early failure.

Reflex sympathetic dystrophy syndrome due to arteriovenous fistula

A patient with end-stage renal disease presented with reflex sympathetic dystrophy syndrome (RSDS) on her left hand 1 month after arteriovenous fistula (AVF) surgery. Magnetic resonance angiography revealed steal syndrome at the AVF level. Bone scintigraphy revealed early-stage RSDS. We considered that arterial insufficiency because of steal phenomenon following AVF surgery and underlying occlusive arterial disease triggered RSDS development.

Selective use of ultrasonographic vascular mapping in the assessment of patients before haemodialysis access surgery

Background

Use of routine preoperative ultrasonography to determine the optimum site for haemodialysis access surgery increases the number of distal arteriovenous fistulas formed and improves overall patency rates. Nevertheless its use in all patients is time consuming and costly. This study examined whether clinical parameters could be used to determine the requirement for preoperative ultrasonography.

Methods

Between March 2002 and October 2003, 145 consecutive patients were reviewed in the vascular access clinic. Patients were first assessed clinically, a site for vascular access surgery was proposed, and the need for radiological mapping studies recorded. A second, blinded, clinician determined the site for vascular access surgery using ultrasonography. The correlation between clinical and ultrasonographic findings was then examined.

Results

Ultrasonography was considered unnecessary using clinical criteria in 106 patients. Subsequent ultrasonographic mapping altered the management of only one patient. In contrast, the management of 18 of the 39 patients in whom ultrasonography was thought necessary was influenced by radiological imaging. A 1-year primary patency rate of 77·0 per cent was achieved following vascular access surgery on the study population.

Conclusion

Clinical parameters could be used to determine the need for preoperative vascular ultrasonographic mapping; imaging was not required in the majority of patients.

Tunneled Catheters in Hemodialysis Patients: Reasons and Subsequent Outcomes

BACKGROUND

Reducing the use of tunneled catheters in hemodialysis patients requires concerted efforts to convert them to a usable permanent vascular access. The goal of this study is to evaluate the reasons for tunneled catheter use in our prevalent hemodialysis population and the success in converting them to a permanent vascular access.

METHODS

We identified all catheter-dependent hemodialysis patients at our center on a single date. These patients were followed up prospectively during a 1-year period to evaluate access procedures and conversion to permanent access use.

RESULTS

Of 458 prevalent hemodialysis patients, 108 patients (23.6%) were dialyzing through cuffed tunneled catheters: 18.5% had no further options for creation of a permanent vascular access, 28.7% had an immature access, 43.5% had access placement pending, and 9.2% had repeatedly refused access surgery. For 78 catheter-dependent patients (excluding patients with no access options and those who refused permanent access surgery), the likelihood of using a permanent access was 53% by 6 months and 80% by 1 year. In patients with an immature access, 50% were using a permanent access at 3 months, and 80%, at 6 months. Of patients with access surgery pending, 45% had access surgery performed within 3 months, and 70%, at 6 months. Finally, of all patients, the likelihood of catheter-related bacteremia was 48% at 6 months. On multivariable analysis, only duration of catheter dependence predicted subsequent use of a permanent access (hazard ratio, 3.11; 95% confidence interval, 1.70 to 5.68; P = 0.0002) for catheter dependence less than versus greater than 6 months.

CONCLUSION

Almost one quarter of our hemodialysis population is catheter dependent. Despite concerted efforts, there remain very long delays in achieving a usable permanent access, attributable to delays in both surgical access placement and access maturation. In the interim, this patient population developed a high frequency of catheter-related bacteremia.

Venovenostomy for Outflow Venous Obstruction in Patients with Upper Extremity Autogenous Hemodialysis Arteriovenous Access

Outflow venous obstruction is a common problem in patients with autogenous upper extremity hemodialysis access. Surgical revision to divert blood flow into the patent vein is sometimes possible to restore unobstructed flow. The result of this type of procedure is not yet well known. The purpose of this report is to describe our experience with outflow venovenostomy (VV) to salvage dysfunctional autogenous upper extremity arterial venous access (AVF) threatened by venous outflow obstruction in hemodialysis-dependent patients. All patients who underwent VV procedures between September 1999 and October 2004 were reviewed. Data regarding patient demographics, comorbidities, procedure indications, perioperative complications, as well as postoperative AVF function and patency were gathered from patient charts and dialysis records. A total of 11 patients underwent VV in the study period. The median age of the AVF prior to VV was 14 months, with a range of 4-45 months. Two patients had radial cephalic AVF, and they had VV done in the antecubital fossa. Nine patients had brachial cephalic AVF. Seven of them underwent cephalic vein transposition VV, while two patients had basilic vein transposition. Functional AVF was achieved after 1 month in 10 out of 11 patients. Five patients had no further access interventions, four patients required angioplasty at the VV site to maintain access function, and one patient had access infection requiring surgical revision during follow-up. One patient never achieved access function. Postintervention assisted functional patency was 90% +/- 9.5% at 39 months. Median follow-up after VV was 16 months. Outflow VV is a viable surgical option for selected patients with failing AVF due to venous outflow obstruction.

Conversion of tunneled hemodialysis catheter–consigned patients to arteriovenous fistula

OBJECTIVE

Despite their high incidence of complications, costs, morbidity, and mortality, nearly 27% of the chronic hemodialysis (HD) patients are receiving treatment via a tunneled hemodialysis catheter (TDC).

METHODS

In this prospective analysis, an interventional nephrology team employed an organized program consisting of vascular access (VA) education and vascular mapping (VM) to TDC-consigned patients. A full range of surgical approaches for arteriovenous fistula (AVF) creation, including vein transpositions, was exercised. Physical examination was performed every 1 to 2 weeks after surgery to assess the development of the AVF. Fistulas that failed to develop adequately to support HD (early failure) underwent salvage [percutaneous transluminal angioplasty (PTA), accessory vein obliteration (AVL)] procedures.

RESULTS

One hundred twenty-one TDC-consigned patients received VA education. Eighty-six (71%) agreed to undergo VM. Two groups were identified. Group I (N= 66; using TDC for 7.2 +/- 1.8 SD months) had never had an arteriovenous access; group II (N= 20; using TDC for 12.3 +/- 4.0 months) had a history of one or more previously failed arteriovenous accesses. Upon VM, 64/66 (97%) in group I and 18/20 (90%) in group II were found to have adequate veins for AVF creation. Seven patients (11%) in group I and 3 (17%) in group II refused surgery. In group I, 57 (89%) received an arteriovenous access (radiocephalic AVF = 15, brachiocephalic AVF = 35, transposed brachiobasilic AVF = 3, brachiobasilic AVG = 4). In group II, 15 (83%) received a transposed AVF (radiobasilic = 2, brachiobasilic = 13). Sixteen fistulas (30%) in group I and 8 (53%) in group II had early failure. All except for one fistula in each group were salvaged using PTA and/or AVL. All 70 accesses (AVF = 66, AVG = 4) remain functional, with a mean follow-up of 8.5 +/- 3.6 months.

CONCLUSION

These results demonstrate that an organized approach based upon a comprehensive program utilizing VA counseling, VM, application of full range of surgical techniques, and salvage procedures can be very successful in providing optimum vascular access to the catheter-dependent patient.

Frequency of critical stenosis in primary arteriovenous fistulae before hemodialysis access: Should duplex ultrasound surveillance be the standard of care?

OBJECTIVE

Increasing use of primary arteriovenous fistulae (pAVFs) is a desired goal in hemodialysis patients (National Kidney Foundation /Dialysis Outcome Quality Initiative guidelines). However, in many instances, pAVFs fail to adequately mature due to ill-defined mechanisms. We therefore investigated pAVFs with color duplex ultrasound (CDU) surveillance 4 to 12 weeks postoperatively to identify hemodynamically significant abnormalities that may contribute to pAVF failure.

METHODS

From March 2001 to October 2003, 54 upper extremity pAVFs were subjected to CDU assessment before access. A peak systolic velocity ratio (SVR) of >/=2:1 was used to detect >/=50% stenosis involving arterial inflow and venous outflow, whereas an SVR of >/=3:1 was used to detect >/=50% anastomotic stenosis. CDU findings were compared with preoperative vein mapping and postoperative fistulography when available.

RESULTS

Of 54 pAVFs, there were 23 brachiocephalic, 14 radiocephalic, and 17 basilic vein transpositions. By CDU surveillance, 11 (20%) were occluded and 14 (26%) were negative. Twenty-nine (54%) pAVFs had 38 hemodynamically significant CDU abnormalities. These included 16 (42%) venous outflow, 13 (34%) anastomotic, and 2 (5%) inflow stenoses. In seven (18%), branch steal with reduced flow was found. In 35 of 54 (65%) pAVFs, preoperative vein mapping was available and demonstrated adequate vein size (>/=3 mm) and outflow in 86% of cases. Twenty-one fistulograms (38%) were available for verifying the CDU abnormalities. In each fistulogram, the arterial inflow, anastomosis, and venous outflow were compared with the CDU findings (63 segments). The sensitivity, specificity, and accuracy of CDU in detecting pAVF stenoses >/=50% were 93%, 94%, was 97%, respectively.

CONCLUSIONS

Before initiation of hemodialysis, an unexpectedly high prevalence of critical stenoses was found in patent pAVFs using CDU surveillance. These de novo stenoses appear to develop rapidly after arterialization of the upper extremity superficial veins and can be reliably detected by CDU surveillance. Turbulent flow conditions in pAVFs may play a role in inducing progressive vein wall and valve leaflet intimal thickening, although stenoses may be due to venous abnormalities that predate AVF placement. Routine CDU surveillance of pAVFs should be considered to identify and correct flow-limiting stenoses that may compromise pAVF long-term patency and use.

Risk Factors for Early Failure of Native Arteriovenous Fistulas

INTRODUCTION

Current guidelines recommend native arteriovenous fistulas (AVF) as the vascular access of choice for hemodialysis on account of the lower incidence of complications. However, this kind of vascular access has a high rate of early failure (early thrombosis or non-maturation). Our aim was to examine whether clear risk factors for early AVF failure could be identified in our patients.

SUBJECTS AND METHODS

Data of all patients who underwent creation of an AVF at the Geneva University Hospital from January 1998 to December 2002 were reviewed. Early failure was defined as a non-functioning fistula (thrombosis or absence of fistula maturation).

RESULTS

119 patients underwent the creation of 148 native AVF, 88 (59.5%) in the forearm and 60 (40.5%) in the upper arm. 48 (32.4%) fistulae were created in diabetic patients. In a multiple logistic regression analysis, significant predictive factors of early failure were a distal location (adjusted odds ratio (aOR) = 8.21, 95% CI = 2.63-25.63, p < 0.001), female gender (aOR = 4.04, 95% CI = 1.44-11.30, p = 0.008), level of surgical expertise (aOR = 3.97, 95% CI = 1.39-11.32, p = 0.010) and diabetes mellitus (aOR = 3.19, 95% CI = 1.17-8.71, p = 0.024).

CONCLUSION

Early failure of AVF occurs mainly in forearm sites among women and diabetic patients. Surgical expertise has also a significant influence. These results suggest that selection of a distal site for a native AVF has to be rigorously made for women and diabetic patients and that surgeon's dedication is of primary importance to avoid early AVF failure occurrence.

Radiocephalic wrist arteriovenous fistula for hemodialysis: meta-analysis indicates a high primary failure rate

OBJECTIVE

To improve the precision of the estimates of primary failure rates and primary and secondary 1 year patency of radial-cephalic arteriovenous fistulas (RCAVF) for hemodialysis.

DESIGN

Meta-analysis.

MATERIALS AND METHODS

A Medline search was performed of the English language medical literature between January 1970 and October 2002. Key words that were searched included radiocephalic fistula, arteriovenous shunt, Brescia-Cimino fistula and patency. Primary failure, primary and secondary patency rates were analysed using the standard mixed effects model, which allows for variability between the different studies.

RESULTS

Eight prospective and 30 retrospective studies were included. The analysis showed a pooled estimated primary failure rate of 15.3% (95% CI: 12.7-18.3%). In addition, the pooled estimated primary and secondary patency rates of 62.5% (95% CI: 54.0-70.3%) and 66.0% (95% CI: 58.2-73.0%), respectively, were calculated. Subgroup analysis concerning various study characteristics, including study year, gender and age, did not reveal statistically significant differences.

CONCLUSION

Although, the autogenous RCAVF is considered to be the primary choice for vascular access, this meta-analysis indicates a high primary failure rate and only moderate patency rates at 1 year of follow-up.

Monitoring and maintenance of arteriovenous fistulae and graft function in haemodialysis patients

PURPOSE OF REVIEW

Several options exist for detecting and preventing stenosis in polytetrafluoroethylene grafts and arteriovenous fistulae for haemodialysis. Although observational studies show a significant benefit of such strategies, data from randomized trials are limited. This review describes recently published information that has helped to advance this field during the past year.

RECENT FINDINGS

A new method for the measurement of access blood flow is discussed. This technique does not require special apparatus, which may facilitate its use in settings where resources are limited. The utility and potential shortcomings of access blood flow monitoring in grafts and fistulae are discussed, focusing on three key controlled studies published during the past year. Although much additional research is needed, regular access blood flow monitoring may improve outcomes in fistulae. Although there is less evidence that access blood flow monitoring is beneficial in grafts, regular dynamic venous pressure monitoring seems reasonable, because it can detect stenosis at a low capital cost. Neither radiotherapy nor combination therapy with aspirin and clopidogrel are useful for the prevention of stenosis in grafts.

SUMMARY

Large randomized trials of screening appear feasible for both types of permanent vascular access. Given the adverse patient outcomes associated with access failure, as well as the high costs attributable to the implementation of ineffective screening strategies, such trials should be a high priority for nephrology researchers.

The Role of Interventional Radiology in a Comprehensive Hemodialysis Program: The Access Surgeon's View

The successful hemodialysis program addressing the complex needs of the dialysis patient population employs a collaborative effort among the medical nephrologist, access surgeon, and interventional radiologist. It is imperative that all team members understand the basic tenets of hemodialysis access and afford open and continuous communication to achieve the best results. This monograph will serve to highlight the access surgeon's view of the optimal integration of the interventional radiologist in the development and maintenance of a successful hemodialysis program.

Associations with predialysis vascular access management

BACKGROUND

The Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines encourage increasing the proportion of arteriovenous fistulae among incident hemodialysis patients. Achieving optimal outcomes requires predialysis out-patient follow-up by a nephrologist, predialysis placement of a vascular access, and adequate maturation of the vascular access.

METHODS

We assessed the effect of clinical factors on predialysis vascular access management in all incident hemodialysis patients at a single institution during a 2-year period.

RESULTS

Of 157 patients initiating dialysis therapy from January 1, 2001, to December 31, 2002, a total of 73.2% had predialysis follow-up by a nephrologist, 46.5% had predialysis vascular access surgery, and 35.0% initiated their first dialysis session with a permanent access. Among patients using a permanent access on their first dialysis session, 67.3% used a fistula. Patients with diabetes were more likely than those without diabetes to have predialysis nephrology follow-up (81.5% versus 61.5%; P = 0.005), undergo predialysis vascular access surgery (56.5% versus 32.3%; P = 0.003), and initiate their first dialysis session with a fistula or graft (43.5% versus 23.1%; P = 0.008). Duration of predialysis nephrology follow-up was similar between patients with and without diabetes (median, 412 versus 300 days; P = 0.27). Patient age, sex, and race were not predictive of predialysis access management.

CONCLUSION

Despite attempts to follow the K/DOQI guidelines, 65% of incident hemodialysis patients initiated their first dialysis treatment with a catheter. Patients with diabetes were significantly more likely to have predialysis follow-up by a nephrologist and thus more likely to initiate their first dialysis session with a permanent access. Emphasis on early referral of patients with chronic kidney disease without diabetes to nephrologists may increase fistula use among incident hemodialysis patients.

Preoperative sonographic radial artery evaluation and correlation with subsequent radiocephalic fistula outcome

OBJECTIVE

Primary failure of forearm radiocephalic dialysis fistulas is common even when preoperative vascular mapping is used. Previous studies have suggested that low peak systolic velocity of the radial artery predicts subsequent fistula failure. The study goal was to evaluate whether preoperative spectral Doppler assessment of radial artery inflow can improve forearm fistula outcome prediction.

METHODS

Forearm fistulas were placed in 112 patients after preoperative sonographic mapping. Preoperative spectral Doppler sonography measured radial artery peak systolic velocity during tight fist clenching for 3 minutes and after fist relaxation. Vessel diameters and peak systolic velocity were assessed for predictive value based on subsequent fistula adequacy. Fistula flow rates were determined 6 to 12 weeks postoperatively in a subset of patients.

RESULTS

Failed and successful fistulas were similar in their preoperative arterial and vein diameters, resistive index, and peak systolic velocity during fist clenching and after fist relaxation. Specifically, there was no difference in fistula success with radial artery peak systolic velocity lower than 50 cm/s versus peak systolic velocity of 50 cm/s or higher. The change in peak systolic velocity after fist relaxation was highly predictive of subsequent fistula outcome among female patients in ad hoc analysis. Fistula adequacy for dialysis in women was 11% when the change in peak systolic velocity was lower than 0 cm/s and 50% when the change was 0 cm/sec or higher (P = .02). The postoperative fistula flow rates were lower when the preoperative change in peak systolic velocity was lower than 0 cm/s than when it was 0 cm/s or higher (316 +/- 46 versus 781 +/- 150 mL/min; P = .003).

CONCLUSIONS

There was no difference in the preoperative peak systolic velocity or the resistive index of successful and failed fistulas. Measurement of the radial artery peak systolic velocity change after release of fist clenching was not useful in predicting outcomes in male patients but identified a subset of female patients with a very low likelihood of success. This criterion may merit further investigation in future trials.

Durability and cumulative functional patency of transposed and nontransposed arteriovenous fistulas

OBJECTIVES

Preoperative duplex scanning of arm and forearm veins has increased the creation of autogenous arteriovenous (AV) fistulas. However, the cumulative functional patency and durability of transposed AV fistulas (TAVF) compared with nontransposed AV fistulas (AVF) and prosthetic bridging grafts (AVG) remains ill-defined.

METHODS

From January 1998 to December 2002, 245 dialysis access procedures were performed at University Hospital and the Veteran Affairs Medical Center in New Jersey. Follow-up data were available for 125 procedures (TAVF, n = 42; AVF, n = 30; AVG, n = 53) performed in 97 patients. All access procedures were planned on the basis of preoperative duplex scans of arm and forearm veins. Functional patency was defined as ability to cannulate and hemodialyze patients successfully. Primary and secondary cumulative functional patency of TAVFs, AVFs, and AVGs was determined with life table analysis, and differences were analyzed with the log-rank test. Differences in revision rates, including thrombolysis, thrombectomies, and operative revisions, were determined with the Fisher exact t test.

RESULTS

Mean follow-up was 18 months (range, 4-24 months). For TAVFs, AVFs, and AVGs, primary functional patency rate at 1 year was 76.2%, 53.3%, and 47.2%, respectively, and at 2 years was 67.7%, 34.4%, and 25.5%, respectively. Similarly, secondary functional patency rate at 1 year was 83.2%, 66.7%, and 58.5%, respectively, and at 2 years was 74.6%, 56.2%, and 40.2%, respectively. Primary and secondary functional patency rates for TAVFs were superior to those for AVGs at 1 and 2 years (P <.001). AVFs had superior secondary functional patency rate at 2 years, compared with AVGs (P <.05), and TAVFs had superior primary and secondary patency rates at 2 years, compared with AVFs (P <.05). AVGs required significantly more revisions than did TAVFs (28.5% vs 54.7%; P <.001) or AVFs (36.7% vs 54.7%; P <.05).

CONCLUSIONS

Preoperative duplex scanning of upper arm and forearm veins facilitated successful creation of all types of autogenous fistulas at our institution. TAVF cumulative functional patency rates were superior compared with AVGs and AVFs. Furthermore, TAVFs and AVFs were more durable and required fewer revisions than did AVGs. When preoperative duplex criteria indicate that TAVFs can be performed, they should be the initial access of choice, because of their superior long-term patency and durability.

Comparison of Arteriovenous Grafts in the Thigh and Upper Extremities in Hemodialysis Patients

ABSTRACT. Placement of a thigh graft is an option in hemodialysis patients who have exhausted all upper extremity sites for permanent vascular access. The outcome of thigh grafts has been reported only in retrospective studies. The outcomes of 409 grafts placed at a single institution during a 3.5-yr period were evaluated prospectively, including 63 thigh grafts (15% of the total). Information was recorded on surgical complications, dates of radiologic and surgical interventions, and date of graft failure. The technical failure rate was approximately twice as high for thigh grafts, as compared with upper extremity grafts (12.7versus5.8%;P= 0.046). Intervention-free survival was similar for thigh and upper extremity grafts (median, 3.9versus3.5 mo;P= 0.55). Thrombosis-free survival was also comparable for thigh and upper extremity grafts (median, 5.7versus5.5 mo;P= 0.94). Cumulative survival (time to permanent failure) was similar for thigh and upper extremity grafts (median, 14.8versus20.8 mo;P= 0.62). When technical failures were excluded, the median cumulative survival was 27.6 mo for thigh grafts and 22.5 mo for upper extremity grafts (P= 0.72). The frequency of angioplasty (0.28versus0.57 per year), thrombectomy (1.58versus0.94 per year), surgical revision (0.28versus0.18 per year), and total intervention rate (2.15versus1.70 per year) was similar between thigh and upper extremity grafts. Access loss as a result of infection tended to be higher for thigh grafts than for upper extremity grafts (11.1versus5.2%;P= 0.07). In conclusion, placement of thigh grafts should be considered a viable option among hemodialysis patients who have exhausted all options for a permanent vascular access in both upper extremities. E-mail mdallon@uab.edu

Aggressive treatment of early fistula failure

BACKGROUND

Fistula failure has been classified as early and late. Early failure refers to those cases in which the arteriovenous (AV) fistula never develops to the point that it can be used or fails within the first 3 months of usage. It has been common practice to abandon these early failures; however, aggressive evaluation and treatment of early fistula failures has been shown to result in the salvage of a large percentage. The two most common causes of the failure seen at this time are juxta-anastomotic stenosis (JAS) and the presence of accessory veins. Both of these can be easily diagnosed by physical examination. This study reports the results of early fistula failure managed aggressively in an attempt at salvage.

METHODS

These studies were conducted in six freestanding outpatient interventional facilities in different regions of the United States. Interventional nephrologists are employed at all of these facilities except one that is operated by an interventional radiologist. Each patient was first evaluated angiographically to identify the anatomy of their AV fistula and detect abnormalities that might be present. Stenotic lesions were then treated with angioplasty and accessory veins thought to be significant were obliterated. All patients were then followed to determine if the fistula was usable for dialysis.

RESULTS

One hundred patients were identified that met the definition of early failure. Venous stenosis was present in 78% of these cases. In 43% of the cases, the lesion was in the JAS location. In 15%, this was the only lesion present. In 24%, it was associated with an accessory vein, in 6% with a proximal stenosis, and in 4% with both. A proximal stenosis lesion was present in the fistula in 36%. In 6%, it was associated with an accessory vein, in 6% with a JAS, and in 4% with both. The definition of arterial anastomosis stenosis was met in 38% of the cases. This was always in association with JAS. In four cases, a stenotic lesion was present in the artery above the anastomosis. An accessory vein was present in 46% of the cases. In 12% of the cases, this was the only lesion present. In 24% of the cases, this anomaly was associated with JAS, in 6% with proximal stenosis, and in 4% with both. Angioplasty was performed to treat venous stenosis in 72% of the cases with a 98% success rate. Angioplasty of the arterial anastomosis was performed in 38 cases with a 100% success rate. Accessory vein obliteration was performed in 46% of the patients with a 100% success rate. The overall complication rate in this series was 4%, of these 3% were minor and 1% were major. It was possible to initiate dialysis using the fistula in 92% of the cases. Actuarial life-table analysis showed that 84% were functional at 3 months, 72% at 6 months, and 68% at 12 months.

CONCLUSION

If correctable pathology is detected in patients with early fistula failure, the incidence of correctable lesions is relatively high and an aggressive therapeutic approach can be expected to have a high yield.

Failure of arteriovenous fistula maturation: an unintended consequence of exceeding dialysis outcome quality Initiative guidelines for hemodialysis access

PURPOSE

The Dialysis Outcome Quality Initiative (DOQI) guidelines recommend that arteriovenous fistulas (AVF) be constructed in at least 50% of hemodialysis access procedures. Preoperative duplex ultrasound (US) scanning and venography may increase options for AVF with identification of veins that are not clinically evident. However, maturation of autogenous fistulas created on the basis of findings at duplex US scanning and venography has not been carefully examined.

METHODS

From January 1999 to July 2002, 256 new hemodialysis access procedures were performed in 202 patients in an academic tertiary care center. If physical examination failed to disclose adequate vessels for hemodialysis access, patients underwent duplex US scanning mapping. Venography was performed when no usable vein or only a basilic vein was identified at duplex US scanning. Functional maturation rate and mean maturation time (time from fistula creation to initiation of hemodialysis) were determined. This experience was compared with that in a group of 128 patients in whom 148 hemodialysis access fistulas were created before we implemented liberal use of preoperative duplex US scanning and venography (January 1997-December 1998).

RESULTS

From January 1999 to July 2002, preoperative duplex US scanning was performed in 68% of patients, and venography in 32% of patients. Autogenous fistula creation rate increased from 61% to 73% in all patients with hemodialysis access fistulas (P =.15) and from 66% to 83% in patients undergoing a first access procedure (P <.05). The use of basilic vein transposition also increased, from 3% in the earlier period to 13% in the later period (P <.05). Mean maturation time for arteriovenous fistulas was 70 days. Functional maturation rate decreased from 73% to 57% (P <.05) after implementation of preoperative imaging and more aggressive vein use.

CONCLUSION

Implementation of preoperative duplex US scanning and venography as a component of a more aggressive protocol to create native fistulas was pivotal in exceeding DOQI guidelines for hemodialysis access. However, this approach resulted in the unintended sequela of decreased fistula maturation rate. Our experience suggests that improved selection criteria based on findings at preoperative imaging are needed to further refine and optimize arteriovenous access surgery.

Impact of surgeon and surgical center characteristics on choice of permanent vascular access

BACKGROUND

The impact of the surgeon and surgical center characteristics on choice of autogenous arteriovenous (AV) fistula versus artificial AV graft as permanent vascular access for hemodialysis has not been studied.

METHODS

We used national data from the Department of Veterans Affairs Veterans Health Administration to measure the association of surgeon and surgical center characteristics with choice of initial permanent vascular access among patients undergoing their first vascular access placement procedure between October 1, 2000 and September 30, 2001 (fiscal year 2001). Data were analyzed using a hierarchical logistic regression model clustered for surgical center and surgeon.

RESULTS

The study population included 1114 patients, 74 Veterans Administration Medical Centers, and 182 surgeons. Seventy-two percent of patients received an AV fistula as their initial form of permanent vascular access. After adjusting for differences in patient, center, and surgeon characteristics, odds of AV fistula placement at high volume centers (>30 procedures per year) were more than three times greater than at low volume centers [odds ratio (OR) 3.26, 95% confidence interval (95% CI) 1.37 to 7.75, P = 0.008]. In addition, a strong clustering effect was present at the level of the surgeon (OR 1.55, 95% CI 1.19 to 2.03, P = 0.001) but not at the level of the surgical center, indicating an association with surgeon practice pattern.

CONCLUSION

Barriers to AV fistula placement can exist at the levels of the surgeon and surgical center, respectively. Future strategies to improve AV fistula placement rates should target surgeons and surgical centers in addition to patients, nephrologists, and primary care providers.

Overcoming barriers to arteriovenous fistula creation and use

National guidelines advocate the placement of arteriovenous fistulas (AVFs) as the preferred vascular access for hemodialysis (HD) patients because of their low complication rate, lower costs, and prolonged patency, once matured. The current Dialysis Outcomes Quality Initiative (DOQI) guidelines aim for an AVF incidence of 50% and a 40% prevalence in the United States. Although patients currently starting dialysis do so at an increasingly older age and with more comorbidity, they should be given every opportunity to receive an AVF. Meeting this challenge is facilitated by a multidisciplinary approach with early referral to the nephrologist in the predialysis period for access planning. Key components of a vascular access program may include the coordination by a dedicated access coordinator and outcome tracking via a prospective database. Preoperative vessel evaluation and careful selection of an appropriate surgical site, along with an experienced surgeon, improve surgical outcomes. Transposed brachiobasilic or other tertiary fistulas should be offered to patients who cannot receive a native radiocephalic or brachiocephalic fistula. The ability to routinely monitor and salvage failing AVFs is important to achieving successful AVF outcomes. Standardized definitions of AVF outcomes are important to allow individual centers and continuous quality assurance (CQA) programs to track and benchmark their outcomes against local and national standards to help them meet recommended targets.