Hemodialysis arteriovenous fistula patency revisited: results of a prospective, multicenter initiative

Randomized clinical trial of selective versus routine preoperative duplex ultrasound imaging before arteriovenous fistula surgery

Background

Anatomical suitability for arteriovenous fistula (AVF) formation was formerly determined by clinical examination alone. There are potential benefits from imaging to assess anatomical suitability. Existing studies examined the role of routine preoperative ultrasonography versus clinical examination alone. The role of a selective duplex ultrasound imaging policy is unknown. This study aimed to compare a policy of selective versus routine ultrasound assessment before AVF formation.

Methods

All patients referred for fistula formation were assessed for inclusion. Suitable patients were randomized to either routine or selective preoperative ultrasound imaging; selective imaging was performed only when clinical criteria were not met. The primary outcome measures were site of AVF formation and 30-day primary failure rate, and secondary outcome measures included the rate of complications.

Results

A total of 106 patients were assessed, and 94 were randomized: 47 to selective and 47 to routine duplex ultrasonography. The groups were well matched for age, co-morbidities and medications. The primary failure rate (29 per cent overall) was not significantly different between the selective and routine imaging groups: 36 per cent (14 of 39) and 21 per cent (8 of 38) respectively (P = 0·144). There were no significant differences in the sites of AVF formation or complication rates.

Conclusion

Routine preoperative ultrasound vessel imaging did not significantly reduce early failure rates, influence the site of AVF formation or reduce complications. If clinical evaluation detects anatomy suitable for AVF formation, duplex imaging may not be needed. Registration number: NCT01004627 (http://www.clinicaltrials.gov).

Type of vascular access and location in online hemodiafiltration and its association with patient's perception of health-related quality of life

PURPOSE

The aim of this work is to evaluate the patient-reported health-related quality of life (HRQOL), according to the type and location of vascular access used for dialysis procedure.

METHODS

In this transversal study, 322 end-stage renal disease (ESRD) patients under online hemodiafiltration (OL-HDF, 59.63% males; 64.9±14.3 years) were enrolled. Arteriovenous fistula (AVF) was used by 252 patients (78.3%), whereas 70 patients (21.7%) had a central venous catheter (CVC). Besides AVF location, data on comorbidities, hematological data, iron status, dialysis adequacy, nutritional and inflammatory markers were collected. Moreover, the patients' reported HRQOL score, using the Kidney Disease Quality of Life-Short Form, was evaluated.

RESULTS

ESRD patients using CVC as vascular access presented a decrease in four SF-36 domain scores, namely physical functioning, emotional well-being, role-emotional and energy/fatigue when compared with those using AVF as vascular access. Additionally, these patients also showed significant differences in ESRD target areas, namely decline in cognitive function and quality of social interaction domains. When comparing the variables according to the localization of the AVF, significant differences were found in three SF-36 domain scores, namely physical functioning, pain and general health. Moreover, we also found significant differences in ESRD target areas, namely symptoms/problem list, effects of kidney disease and quality of social interaction domains.

CONCLUSIONS

Our results showed that ESRD patients under OL-HDF using AVF as vascular access had higher HRQOL scores in several domains when compared with those using CVC. Additionally, we also found that dialysis patients using AVF in the left forearm presented with higher HRQOL scores.

Objectives and design of the hemodialysis fistula maturation study

BACKGROUND

A large proportion of newly created arteriovenous fistulas cannot be used for dialysis because they fail to mature adequately to support the hemodialysis blood circuit. The Hemodialysis Fistula Maturation (HFM) Study was designed to elucidate clinical and biological factors associated with fistula maturation outcomes.

STUDY DESIGN

Multicenter prospective cohort study.

SETTING & PARTICIPANTS

Approximately 600 patients undergoing creation of a new hemodialysis fistula will be enrolled at 7 centers in the United States and followed up for as long as 4 years.

PREDICTORS

Clinical, anatomical, biological, and process-of-care attributes identified pre-, intra-, or postoperatively.

OUTCOMES

The primary outcome is unassisted clinical maturation, defined as successful use of the fistula for dialysis for 4 weeks without maturation-enhancing procedures. Secondary outcomes include assisted clinical maturation, ultrasound-based anatomical maturation, fistula procedures, fistula abandonment, and central venous catheter use.

MEASUREMENTS

Preoperative ultrasound arterial and venous mapping, flow-mediated and nitroglycerin-mediated brachial artery dilation, arterial pulse wave velocity, and venous distensibility; intraoperative vein tissue collection for histopathologic and molecular analyses; postoperative ultrasounds at 1 day, 2 weeks, 6 weeks, and prior to fistula intervention and initial cannulation.

RESULTS

Assuming complete data, no covariate adjustment, and unassisted clinical maturation of 50%, there will be 80% power to detect ORs of 1.83 and 1.61 for dichotomous predictor variables with exposure prevalences of 20% and 50%, respectively.

LIMITATIONS

Exclusion of 2-stage transposition fistulas limits generalizability. The requirement for study visits may result in a cohort that is healthier than the overall population of patients undergoing fistula creation.

CONCLUSIONS

The HFM Study will be of sufficient size and scope to: (1) evaluate a broad range of mechanistic hypotheses, (2) identify clinical practices associated with maturation outcomes, (3) assess the predictive utility of early indicators of fistula outcome, and (4) establish targets for novel therapeutic interventions to improve fistula maturation.

The impact of inflammatory factors associated with primary arteriovenous failure

PURPOSE

Very scarce data exist regarding the relationship between differential white blood cell (WBC) counts and primary arteriovenous fistula (AVF) failure. Thus, the current study aimed to investigate the specific relationship between primary AVF failure and differential WBC counts.


METHODS

Sociodemographic, clinical, and laboratory parameters including automatically determined complete blood counts of the patients (from medical records and hospital charts) prior to AVF fistula surgery were recorded. Primary AVF failure was described as a complication of the AVF before the first successful cannulation for HD treatment.


RESULTS

In total 94 patients (Male/Female: 49/45, Aged: 50.9 ± 15.0 years) were included. Ferritin, high sensitive C-reactive protein (hs-crp), total WBC count, neutrophil count, red cell distribution width (RDW) were higher in patients with primary AVF failure compared to patients without primary AVF failure. Logistic regression analysis showed that presence of diabetes (OR = 3.654, p = 0.035), RDW (OR = 0.449, p = 0.033) and ferritin (OR = 1.097, p = 0.021) were independently related with primary AVF failure.


CONCLUSIONS

Neither total WBC counts nor WBC subtypes were related with primary AVF failure. Higher RDW and ferritin levels had a prognostic value for development of primary AVF failure.

Vascular Access Outcome in the Elderly Dialysis Patient in Combination With the Quality of Life

Purpose:

We performed a retrospective study on hemodialysis fistulae in patients aged 75 years and older.

Methods:

Dialysis records of 2 hospitals were searched for patients of 75 years and older who had primary autologous radiocephalic arteriovenous fistulae (RCAVFs) and brachiocephalic arteriovenous fistulae (BCAVFs). Outcome measures were primary, primary-assisted, and secondary patency rates. Also, quality of life (QOL) was measured.

Results:

A total of 107 fistulae were placed in 90 patients; 65 (61%) RCAVFs and 42 (39%) BCAVFs were created. The primary patency rate ( P = .026) and the primary-assisted patency rate ( P = .016) of BCAVFs were significantly higher than that of RCAVFs. Secondary patency rates at 1 year ( P = .01) and 2 years ( P = .035) were higher in BCAVFs than in RCAVFs.

Conclusions:

The BCAVFs give significantly higher primary and primary-assisted patency rates and also significantly higher secondary patency rates at 1 and 2 years. Therefore, we suggest the placement of elbow fistulae in the elderly patients. The QOL was surprisingly high in this population despite a high mortality rate.

Thrombin-anti-thrombin levels and patency of arterio-venous fistula in patients undergoing haemodialysis compared to healthy volunteers: a prospective analysis

Background

Patients on haemodialysis (HD) are at an increased risk of sustaining thrombotic events especially to their vascular access which is essential for maintenance of HD.

Objectives

To assess whether 1) markers of coagulation, fibrinolysis or endothelial activation are increased in patients on HD compared to controls and 2) if measurement of any of these factors could help to identify patients at increased risk of arteriovenous (AVF) access occlusion.

Patients/Methods

Venous blood samples were taken from 70 patients immediately before a session of HD and from 78 resting healthy volunteers. Thrombin-antithrombin (TAT), D-dimer, von Willebrand factor (vWF), plasminogen activator inhibitor-1 antigen (PAI-1) and soluble p-selectin were measured by ELISA. C-reactive protein (hsCRP) was measured by an immunonephelometric kinetic assay. Determination of the patency of the AVF was based upon international standards and was prospectively followed up for a minimum of four years or until the AVF was non-functioning.

Results

A total of 70 patients were studied with a median follow-up of 740 days (range 72-1788 days). TAT, D-dimer, vWF, p-selectin and hsCRP were elevated in patients on HD compared with controls. At one year follow-up, primary patency was 66% (46 patients). In multivariate analysis TAT was inversely associated with primary assisted patency (r= -0.250, p= 0.044) and secondary patency (r = -0.267, p= 0.031).

Conclusions

The novel finding of this study is that in patients on haemodialysis, TAT levels were increased and inversely correlated with primary assisted patency and secondary patency. Further evaluation is required into the possible role of TAT as a biomarker of AVF occlusion.

Validation of a patient-specific hemodynamic computational model for surgical planning of vascular access in hemodialysis patients

Vascular access dysfunction is one of the main causes of morbidity and hospitalization in hemodialysis patients. This major clinical problem points out the need for prediction of hemodynamic changes induced by vascular access surgery. Here we reviewed the potential of a patient-specific computational vascular network model that includes vessel wall remodeling to predict blood flow change within 6 weeks after surgery for different arteriovenous fistula configurations. For model validation, we performed a multicenter, prospective clinical study to collect longitudinal data on arm vasculature before and after surgery. Sixty-three patients with newly created arteriovenous fistula were included in the validation data set and divided into four groups based on fistula configuration. Predicted brachial artery blood flow volumes 40 days after surgery had a significantly high correlation with measured values. Deviation of predicted from measured brachial artery blood flow averaged 3% with a root mean squared error of 19.5%, showing that the computational tool reliably predicted patient-specific blood flow increase resulting from vascular access surgery and subsequent vascular adaptation. This innovative approach may help the surgeon to plan the most appropriate fistula configuration to optimize access blood flow for hemodialysis, potentially reducing the incidence of vascular access dysfunctions and the need of patient hospitalization.

Retrospective analysis of 271 arteriovenous fistulas as vascular access for hemodialysis

This report describes our experience of arteriovenous fistula (AVF) creation as vascular access for hemodialysis (HD). Study has been carried out in Deenanath Mangeshkar Hospital, Pune from January 2004 to December 2009. A total of 271 AVFs were created in 249 patients. Maximum follow up was 7 years and minimum was 1 year. In this study of 271 cases of AVFs, there were 196 (72.3%) successful cases and 75 (27.7%) failures. Basilic vein was used in 77 (28.4%) cases, cephalic vein in 186 (68.6%), and antecubital vein in 8 (3%) cases. End (vein) to side (artery) anastomosis was done in 170 (63%) cases. Side to side anastomosis was done in 100 (37%) cases. On table bruit was present in 244 (90%) and thrill in 232 (85.6%) cases. During dialysis, flow rate >250 ml/min was obtained in 136 (50.4%) cases. In complications, 16 (5.9%) patients developed distal edema, 32 (11.8%) developed steal phenomenon. Presence of on table thrill and bruit are indicators of successful AVF. If vein diameter is <2 mm, chances of AVF failure are high. During proximal side to side fistula between antecubital/basilic vein and brachial artery, breaking of first valve toward wrist helps to develop distal veins in forearm by retrograde flow. This technique avoids requirement of superficialization of basilic vein in arm.

Type of arteriovenous vascular access and association with patency and mortality

BACKGROUND

There are only a few risk factors known for primary patency loss in patients with an arteriovenous graft or fistula. Furthermore, a limited number of studies have investigated the association between arteriovenous access modality and primary patency loss and mortality. The aim of this study was to investigate risk factors for patency loss and to investigate the association between graft versus fistula use and outcomes (patency loss and mortality).

METHODS

We prospectively followed 919 incident hemodialysis patients and calculated hazard ratios (HRs) for putative risk factors of primary patency loss using Cox regression. Furthermore, HRs were calculated to study the association between graft versus fistula use and two-year primary patency loss and two-year mortality.

RESULTS

Cardiovascular disease, prior catheter use, lowest tertile of albumin, highest tertile of hsCRP, and lowest tertile of fetuin-A were associated with primary patency loss in both patients with grafts and fistulas. Increased age, female sex, and diabetes mellitus were only associated with primary patency loss in patients with a fistula. We did not observe an association between primary patency loss and BMI, residual GFR, levels of calcium, phosphorus, and total cholesterol. Furthermore, graft use as compared with fistula use was associated with an 1.4-fold (95% CI 1.0-1.9) increased risk of primary patency loss and with an 1.5-fold(95% CI 1.0-2.2) increased mortality risk.

CONCLUSION

Cardiovascular disease, prior catheter use, albumin, hsCRP, and fetuin-A are risk factors for patency loss. Graft use as compared with fistula use was associated with an increased risk of patency loss and mortality.

Thrombophilia and arteriovenous fistula survival in ESRD

BACKGROUND AND OBJECTIVES

The role of thrombophilia in failing arteriovenous fistula (AVF) among patients with ESRD undergoing hemodialysis is not established. This study aimed to assess whether AVF primary patency is associated with thrombophilia and coagulation abnormalities.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This observational study screened 219 patients between 2002 and 2004 for thrombophilia before AVF surgery. Thrombophilia included factor V Leiden and prothrombin G20210A mutations, protein C and antithrombin activities, and protein S. Coagulation abnormalities included high factor VIII:C, homocysteine, fibrinogen, and d-dimer levels; presence of antiphospholipid antibodies; and short thrombin time. We reviewed patient charts for comorbid conditions, AVF maturation and interventions, kidney transplantation, and patient survival (mean follow-up duration, 3.6 [range, 2.3-5.8] years). Primary patency from the AVF placement and functional primary patency from the first AVF cannulation were analyzed with Kaplan-Meier and Cox proportional hazards models.

RESULTS

Thrombophilia was present in 9% of the patients, and coagulation abnormalities occurred in 77%. One-year primary patency was 68%; 46% of the AVF failures occurred before the initiation of hemodialysis. Female sex (hazard ratio [HR], 2.6; 95% confidence interval [CI], 1.7-4.1) and thrombophilia (HR, 2.2; 95% CI, 1.2-4.2) were independent risk factors for loss of primary patency. Thrombophilia mutations or low antithrombin level (HR, 3.8), female sex (HR, 2.5), and diabetes (HR, 1.9) were associated with shortened functional primary patency of AVF.

CONCLUSIONS

Against the background of frequent coagulation abnormalities, thrombophilia and female sex predispose patients with ESRD to access failure, mostly due to thrombosis or stenosis.

Cumulative patency of contemporary fistulas versus grafts (2000-2010)

BACKGROUND AND OBJECTIVES

Comparisons of fistulas and grafts often overlook the high primary failure rate of fistulas. This study compared cumulative patency (time from access creation to permanent failure) of fistulas and grafts.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Vascular accesses of 1140 hemodialysis patients from two centers (Toronto and London, Ontario, Canada, 2000-2010) were analyzed. Cumulative patency was compared between groups using Kaplan-Meier survival curves and log-rank tests. Hazard ratios (HRs) for fistula failure relative to grafts and 95% confidence intervals (95% CIs) are reported.

RESULTS

There were 1012 (88.8%) fistulas and 128 (11.2%) grafts. The primary failure rate was two times greater for fistulas than for grafts: 40% versus 19% (P<0.001). Cumulative patency did not differ between fistulas and grafts for the patients' first access (median, 7.4 versus 15.0 months, respectively [HR, 0.99; 95% CI, 0.79-1.23; P=0.85]) or for 600 with a subsequent access (7.0 versus 9.0 months [HR, 0.93; 95% CI, 0.77-1.13; P=0.39]). However, when primary failures were excluded, cumulative patency became significantly longer for fistulas than for grafts for both first and subsequent accesses (61.9 versus 23.8 months [HR, 0.56; 95% CI, 0.43-0.74; P<0.001] and 42.8 versus 15.9 months [HR, 0.56; 95% CI, 0.44-0.72; P<0.001]). Results were similar for forearm and upper-arm accesses. Compared with functioning fistulas, grafts necessitated twice as many angioplasties (1.4 versus 3.2/1000 days, respectively; P<0.001) and significantly more thrombolysis interventions (0.06 versus 0.98/1000 days; P<0.001) to maintain patency once matured and successfully used for dialysis.

CONCLUSIONS

Cumulative patency did not differ between fistulas and grafts; however, grafts necessitated more interventions to maintain functional patency.

Radiocephalic fistula: review and update

Since initially described in 1966, radiocephalic fistula or Brescia-Cimino fistula is one of the most commonly performed fistulas in the world of arteriovenous access. The indications for insertion include, but are not limited to, hemodialysis. Although this is a frequently performed procedure, the primary and secondary patency rates and predictors of failure are not well defined. The review of this topic is difficult because of the diversity in reporting and the absence of consensus between series. Following the current published recommendations by the Society of Vascular Surgery regarding standardization of terminology to facilitate meaningful comparison between the diversity of published data, this review is an attempt to summarize and highlight the relevant information with regard to primary patency, secondary patency, and predictors of failure of radiocephalic fistula using the available English literature.

Primary patency rate of native AV fistula: long term follow up

The number of end stage of renal disease patients that need dialysis or renal transplantation increased in the world. Insertion and maintenance functional vascular access remain the challenging problem. Arteriovenous fistula is the common access for dialysis but complication and its failure is the main problem. The aim of this study is to evaluate patients with arteriovenous fistula during 4 years and describe the probable influenced factors on fistula patency. In this analytical descriptive study, we fallowed 245 patients during 4 years and evaluated them for primary failures and effective factors on vascular patency. The patients were asked about demographic data, how to caring condition arteriovenous fistula, dialysis and complications. The mean age of the patients was 47.77 years. The underline diseases were hypertension (43.3%), hypertension and diabetes mellitus (21.2%) and diabetes mellitus (4.5%). According Log rank test there were meaningful results between arteriovenous patency with sex and dialysis (P < 0.05). Our result of primary patency at 6 months, 1, 2, 3 and 4 years for all patients were 79.5%, 70%, 65%, 60.5% and 48%. Our study showed dialysis could increase the fistula patency rate. Other factors were not associated with primary patency. It seems ESRD patients undergoing dialysis have better fistula patency, may be due to homeostasis abnormalities induced by their particular conditions.

Effects of secondary amyloidosis on arteriovenous hemodialysis fistula outcomes and intradialytic hypotension: a case-control study

Amyloid fibrils can affect vascular structure through deposition and by causing nitric oxide depletion and increase of asymmetric dimethyl arginine. Patients with amyloidosis are prone to development of hypotension. Hypotension may also affect the maturation of arteriovenous fistula (AVF) and may set the stage for formation of thrombosis and fistula failure. Thus, we aimed to evaluate effects of secondary amyloidosis on AVF outcomes and intradialytic hypotension. This is a case-control study which included 20 hemodialysis patients with amyloidosis and 20 hemodialysis patients without amyloidosis as control group. All patients underwent Doppler ultrasound of AVF. A thorough fistula history and baseline laboratory values along with episodes of intradialytic hypotension and blood pressure measurements were recorded. There was no difference between the groups regarding age, gender, body mass index, presence of comorbidities, hypertension, and drug use. Systolic and diastolic blood pressures were similar (119 ± 28/75 ± 17 and 120 ± 14/75 ± 10 mmHg for patients with and without amyloidosis, respectively). Intradialytic hypotension episodes were also similar. Patients with amyloidosis had significantly lower serum albumin and higher C-reactive protein values compared to control hemodialysis patients. AVF sites and total number of created fistulas were similar in both groups. Flow rates of current functional AVFs were not different between the groups (1084 ± 875 and 845 ± 466 mL/minute for patients with and without amyloidosis, respectively, p:0.67). Patency duration of first AVF was not different between the groups. Clinical fistula outcomes and rate of intradialytic hypotension episodes were not significantly different between patients with and without secondary systemic amyloidosis.

Likelihood of starting dialysis after incident fistula creation

BACKGROUND AND OBJECTIVES

Guidelines promote early fistula creation to avoid central venous catheter use. This practice may lead to fistula creations in patients who never receive dialysis. The objective of this study was to estimate the risk of fistula nonuse with long-term follow-up.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Administrative health data identified 1929 predialysis adults who had their first fistula creation between April of 2002 and March of 2006. Patients were followed for a minimum of 2 years or until they began dialysis, received a kidney transplant, or died.

RESULTS

The median follow-up times in patients who started dialysis, died without receiving dialysis, and remained in predialysis were 6.1, 11.5, and 38.7 months, respectively. Eighty-one percent of patients initiated dialysis; 9% of patients died without receiving dialysis, and 10% of patients remained predialysis. Forty percent of patients had their first fistula creation 3-12 months before initiating dialysis (the recommended window). Thirty percent were created within 90 days of starting dialysis; 30% were created more than 1 year before starting dialysis, and 10% were created more than 2 years before starting dialysis. Older patients, females, and patients with less comorbidity were not as likely to initiate dialysis after incident fistula creation.

CONCLUSIONS

Most patients who underwent fistula creation before starting dialysis eventually received dialysis with extended follow-up, but the risk was significantly modified by age, sex, and comorbidity. Many patients had fistula creations earlier or later than recommended.

The effect of new clinical pathways on the outcome of vascular access surgery

PURPOSE

Prior to 2007, the waiting time for vascular access surgery at our center was approximately 107 days compared to a UK average of 45 days. Two new pathways were developed; the rapid and super-rapid pathways incorporating an access liaison nurse who organized vessel mapping and referred patients for surgery. This audit was to determine whether the pathways were effective in reducing the waiting times and improving vascular accesses outcomes.

METHODS

All 210 patients with established renal failure undergoing 232 vascular access procedures between January 2008 and March 2011 were studied. Detailed patient information including type of procedure and cause of access failure were stored in an Excel spreadsheet and analyzed using SPSS for Windows.

RESULTS

One hundred and twenty patients had a brachiocephalic fistula, 61 a radiocephalic fistula, 39 an access using the basilic vein ± transposition, and 11 a transposition of the long saphenous vein and one a brachio-axillary graft. Overall median waiting time from referral to access surgery was 23 days. Patients were followed up for a median of 248 days after surgery. The overall primary failure rate was 9.1% and 25 of 27 accesses failed because of thrombosis. The overall cumulative survival probability of accesses at one year was 61.4% with a mean survival of 621.2 days (SEM = 34.8).

CONCLUSION

The clinical pathways have improved VA service to patients with a drastic reduction in waiting times, elimination of synthetic access, and maintenance of satisfactory results.

Synthetic vascular hemodialysis access versus native arteriovenous fistula: a cost-utility analysis

OBJECTIVE

To determine the cost-effectiveness of 2 different vascular access strategies among incident dialysis patients.

BACKGROUND

Vascular access is a principal cause of morbidity and cost in hemodialysis patients. Recent guidelines and initiatives are intended to increase the proportion of patients with a fistula. However, there is growing awareness of the high prevalence of fistula failures and attendant complications.

METHODS

A decision analysis using a Markov model was implemented to compare 2 different vascular access strategies among incident dialysis patients: (1) placing an arteriovenous fistula (AVF1st) as the initial access followed by a synthetic vascular access if the AVF did not mature compared to (2) placing a synthetic vascular access (SVA1st) as the initial access device. The cost-utility was evaluated across a range of the risk of complications from temporary catheters and SVA.

RESULTS

Under base case assumptions, the AVF1st strategy yielded 2.19 quality-adjusted life years (QALYs) compared with 2.06 QALYs from the SVA1st strategy. The incremental cost-effectiveness was $9389 per QALY for AVF1st compared to SVA1st and was less than $50,000 per QALY as long as the probability of maturation is 36% or greater. AVF1st was the dominant strategy when the AVF maturation rate was 69% or greater.

CONCLUSION

The high risk of complications of temporary catheters and the overall low AVF maturation rate explain why a universal policy of AVF1st for all incident dialysis patients may not optimize clinical outcomes. Strong consideration should be given to a more patient-centered approach taking into account the likelihood of AVF maturation.

Should the arteriovenous fistula be created before starting dialysis?: a decision analytic approach

Background

An arteriovenous fistula (AVF) is considered the vascular access of choice, but uncertainty exists about the optimal time for its creation in pre-dialysis patients. The aim of this study was to determine the optimal vascular access referral strategy for stage 4 (glomerular filtration rate <30 ml/min/1.73 m²) chronic kidney disease patients using a decision analytic framework.

Methods

A Markov model was created to compare two strategies: refer all stage 4 chronic kidney disease patients for an AVF versus wait until the patient starts dialysis. Data from published observational studies were used to estimate the probabilities used in the model. A Markov cohort analysis was used to determine the optimal strategy with life expectancy and quality adjusted life expectancy as the outcomes. Sensitivity analyses, including a probabilistic sensitivity analysis, were performed using Monte Carlo simulation.

Results

The wait strategy results in a higher life expectancy (66.6 versus 65.9 months) and quality adjusted life expectancy (38.9 versus 38.5 quality adjusted life months) than immediate AVF creation. It was robust across all the parameters except at higher rates of progression and lower rates of ischemic steal syndrome.

Conclusions

Early creation of an AVF, as recommended by most guidelines, may not be the preferred strategy in all pre-dialysis patients. Further research on cost implications and patient preferences for treatment options needs to be done before recommending early AVF creation.

The Middle Arm Arteriovenous Fistula is an Additional Option to Expand Autogenous Hemodialysis Access

Purpose

the native artero-venous fistula is the gold standard for hemodialysis access. Unfortunately, the wrist fistula is often not practical and the upper arm fistula is hindered by several complications. The aim of this study is to assess the safety of the middle-arm fistula as additional native access.

Methods

we reviewed and compared the patency rates at 12, 48, and 60 months of distal, middle, and upper arm fistula performed from January 2003 to December 2008. For diabetic and old patients we compared distal and middle-arm fistulas.

Results

of 273 native access, 149 (54.6%) were distal, 92 (33.7%) middle-arm, and 32 (11.7%) upper fistula. Patency rates were 81%, 58%, and 52% for distal, 85%, 69%, and 69% for middle-arm, and 82%, 46%, and 29% for upper arm fistula (P NS). Patency rates were 92%, 70%, and 54% in middle-arm fistula as first access and 80%, 71%, and 71% in middle-arm fistula as a rescue access (P NS). Among patients > 75 years patency rates were 78%, 62%, and 62% for distal and 87%, 67%, and 67% for middle-arm fistula. Among diabetic subjects patency rates were 81%, 58%, and 58% for middle-arm and 65%, 57%, and 57% for distal fistula at 12, 48, and 60 months (P NS) respectively.

Conclusions

A middle-arm fistula is as safe as a distal fistula among dialyzed patients, even diabetic and elderly. This could be considered a reliable option to expand native accesses.

Pre-Operative Regional Block Anesthesia Enhances Operative Strategy for Arteriovenous Fistula Creation

Purpose

We aim to assess the effect of regional block anesthesia on vein diameter, type of AVF placement, and fistula size and flow volume.

Methods

30 patients presenting for AV access procedures were followed prospectively. Vein diameters via venous ultrasound and planned location for AV access were documented. Supraclavicular brachial plexus block was followed by repeat ultrasound and alterations in operative plan were noted. Patients returned to clinic for duplex ultrasound assessment.

Results

Average increase from baseline vein diameter with regional block was most pronounced in the lower cephalic (34%), upper cephalic (24.2%), and basilic veins (31.3%) and less in the brachial vein (8.7%). Type of AVF was modified following regional block in 14%. The rate of native AVF placement improved from 89% to 93% with regional block. Twenty-three AVF patients were available for follow-up (mean 24 weeks). Average fistula size was 7.9 mm (CI 6.9–8.9) and all patent fistulas developed flow volume >600 mL/min. Primary patency was attained in 83%. One thrombosis occurred after a basilic artery was lacerated during dialysis access. The average fistula increased 0.33 cm from post-block diameter (SD 0.22, P<.05).

Conclusions

Vein diameter increases significantly in the basilic and cephalic veins following regional block anesthesia and may improve the rate of native fistula placement. Propensity to dilate after regional block anesthesia does not predict size of the fistula.

Intradialytic hypotension and vascular access thrombosis

Identifying potential modifiable risk factors to reduce the incidence of vascular access thrombosis in hemodialysis could reduce considerable morbidity and health care costs. We analyzed data from a subset of 1426 HEMO study subjects to determine whether more frequent intradialytic hypotension and/or lower predialysis systolic BP were associated with higher rates of vascular access thrombosis. Our primary outcome measure was episodes of vascular access thrombosis occurring within a given 6-month period during HEMO study follow-up. There were 2005 total episodes of vascular access thrombosis during a median 3.1 years of follow-up. The relative rate of thrombosis of native arteriovenous fistulas for the highest quartile of intradialytic hypotension was approximately twice that of the lowest quartile, independent of predialysis systolic BP and other covariates. There was no significant association of intradialytic hypotension with prosthetic arteriovenous graft thrombosis after multivariable adjustment. Higher predialysis systolic BP was associated with a lower rate of fistula and graft thrombosis, independent of intradialytic hypotension and other covariates. In conclusion, more frequent episodes of intradialytic hypotension and lower predialysis systolic BP associate with increased rates of vascular access thrombosis. These results underscore the importance of including vascular access patency in future studies of BP management in hemodialysis.

Veterans more likely to start hemodialysis with an arteriovenous fistula

Hemodialysis via arteriovenous fistulas (AVFs) is associated with reduced morbidity and mortality when compared to alternative vascular accesses, yet few patients in the United States start dialysis with AVFs. Recent studies have demonstrated higher quality of care for many conditions in Veterans Affairs' Medical Centers (VAMC); however, differences in quality of vascular access care are unknown. We used patient-level data (6/05-5/06) from Medicare claims (n = 25,912) to compare the proportions of AVF among incident patients at VAMC-affiliated (n = 20) and unaffiliated dialysis (n = 1631) facilities. Multivariate logistic regression was used to determine whether associations of access type with facility type were independent. Compared to non-VAMC patients, a larger proportion of VAMC patients started dialysis with AVFs (20.9% versus 11.6% in non-VAMC patients; OR 1.99, [95% CI 1.55-2.56]). Although attenuated, this finding persisted in models adjusted for demographics (OR 1.65 [95% CI 1.28-2.13]) and demographics with comorbidities (OR 1.70 [95% CI 1.31-2.20]). However, after accounting for pre end-stage renal disease (ESRD) care, similar proportions of VAMC and non-VAMC patients started hemodialysis with an AVF (OR 1.28 [95% CI 0.98-1.66]). In conclusion, patients receiving care at VAMC-associated facilities were more likely to start hemodialysis with AVFs, perhaps because of better pre-ESRD care. Nonetheless, AVF rates remain suboptimal, indicating a need for ongoing vascular access evaluation and improvement.

Standardized definitions for hemodialysis vascular access

Vascular access dysfunction is one of the leading causes of morbidity and mortality among end-stage renal disease patients. Vascular access dysfunction exists in all three types of available accesses: arteriovenous fistulas, arteriovenous grafts, and tunneled catheters. To improve clinical research and outcomes in hemodialysis (HD) access dysfunction, the development of a multidisciplinary network of collaborative investigators with various areas of expertise, and common standards for terminology and classification in all vascular access types, is required. The North American Vascular Access Consortium (NAVAC) is a newly formed multidisciplinary and multicenter network of experts in the area of HD vascular access, who include nephrologists and interventional nephrologists from the United States and Canada with: (1) a primary clinical and research focus in HD vascular access dysfunction, (2) national and internationally recognized experts in vascular access, and (3) a history of productivity measured by peer-reviewed publications and funding among members of this consortium. The consortium's mission is to improve the quality and efficiency in vascular access research, and impact the research in the area of HD vascular access by conducting observational studies and randomized controlled trials. The purpose of the consortium's initial manuscript is to provide working and standard vascular access definitions relating to (1) epidemiology, (2) vascular access function, (3) vascular access patency, and (4) complications in vascular accesses relating to each of the vascular access types.

Outcomes of arteriovenous fistula creation after the Fistula First Initiative

BACKGROUND AND OBJECTIVES

The arteriovenous fistula (AVF) is the preferred hemodialysis access, but AVF-failure rate is high, and complications from AVF placement are rarely reported. There is no clear consensus on predictors of AVF patency. This study determined AVF outcomes and patency predictors at Mayo Clinic Rochester following the Fistula First Initiative.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A retrospective cohort study of AVFs placed at Mayo Clinic from January 2006 through December 2008 was performed. The AVF placement-associated primary and secondary failure rates, complications, interventions, and hospitalizations were examined. Kaplan-Meier survival curves and Cox proportional hazard models were used to determine primary and secondary patency and associated predictors.

RESULTS

During this time frame, 317 AVFs were placed in 293 individual patients. The primary failure rate was 37.1% after excluding patients not initiated on hemodialysis during follow-up (n = 38) or those with indeterminate outcome (37 lost to follow-up; six died; two transplanted). Of usable AVFs, 11.4% later failed. AVF creation incurred complications and hospitalization in 21.2% and 12.3% of patients, respectively. The risk for reduced primary patency was increased by diabetes (HR, 1.54; 95% CI, 1.14 to 2.07); the risk for reduced primary and secondary patency was decreased with larger arteries (HR, 0.83; 95% CI, 0.73 to 0.94; and HR, 0.69; 95% CI, 0.56 to 0.84, respectively).

CONCLUSIONS

Primary failure remains a major issue in the post-Fistula First era. Complications from AVF placement must be considered when planning AVF placement. Our data demonstrate that artery size is the main predictor of AVF patency.

Choosing peritoneal dialysis reduces the risk of invasive access interventions

BACKGROUND

Patients choosing between hemodialysis (HD) and peritoneal dialysis (PD) should be well informed of the risks and benefits of each modality. Invasive access interventions are important outcomes because frequent interventions lower patient's quality of life and consume limited resources. The objective of this study was to compare the risk of access interventions between the two modalities.

METHODS

Three hundred and sixty-nine incident chronic dialysis patients were prospectively enrolled at four Canadian centers that were eligible for both modalities, received at least 4 months of pre-dialysis care and started dialysis electively as an outpatient. Two hundred and twenty-four (61%) chose PD and 145 (39%) chose HD. Patients were followed for an average of 1.3 years (range 0.07-3.6 years).

RESULTS

In the PD group, there were fewer access interventions (2.5 versus 3.1 interventions per patient, adjusted odds ratio of 0.79 for PD versus HD, P = 0.005) and a lower intervention rate (2.3 versus 1.9 per patient-year, adjusted rate ratio of 0.81 for PD versus HD, P = 0.04). PD catheters were less likely to experience primary failure (4.6 versus 32%, P < 0.0001), showed a trend toward lower intervention rates during use (0.8 versus 1.2 per patient-year, P = 0.06), and had equal patency compared to fistulae (1-year patency of 84 versus 88%, P = 0.48). Patients managed exclusively with HD catheters (28% of the HD group) required 1.7 interventions per patient and an intervention rate of 1.9 per patient-year.

CONCLUSION

Patients who choose PD require fewer access interventions to maintain dialysis access than patients choosing HD.

[Acquired von Willebrand's disease type 2A following arteriovenous fistula for haemodialysis?]

Acquired von Willebrand's disease (aVWD) is considered to be an underestimated cause of unexplained bleeding. Adsorption of von Willebrand factor (VWF) to tumour cells or hydroxyethyl starch and elimination of VWF by autoantibodies as well as shear stress-induced mechanical alteration of VWF with concomitant cleavage by enzymes may lead to an acquired deficiency of VWF and a bleeding disorder. We report a 39-year-old woman who developed spontaneous bleeding five years after surgical creation of an arteriovenous fistula (AVF) for haemodialysis treatment. AVWD type 2A was diagnosed after successful renal transplantation. One year after surgical closure of the AVF, the aVWD could not be verified again. Thus, the aVWD may have developed because of altered blood flow and shear stress inside the arteriovenous fistula.

Superior patency of upper arm arteriovenous fistulae in high risk patients

BACKGROUND

Despite an increased propensity to primary failure in forearm arteriovenous fistulae compared with upper arm fistulae, forearm fistulae remain the preferred primary access type for chronic hemodialysis patients. In a high risk patient population with multiple medical comorbidities associated with requirement for intravenous access we compared the rates of access failure in forearm and upper arm fistulae.

MATERIALS AND METHODS

The records of all patients having primary native arteriovenous fistulae placed between 2004 and 2009 at the VA Connecticut Healthcare system were reviewed (n = 118). Primary and secondary patency of upper arm and forearm fistulae were evaluated using Kaplan-Meier survival analysis. The effects of medical comorbidities on access patency were analyzed with Cox regression.

RESULTS

The median time to primary failure of the vascular access was 0.288 y in the forearm group compared with 0.940 y in the upper arm group (P = 0.028). Secondary patency was 52% at 4.9 y in upper arm fistulae compared with 52% at 1.1 y in the forearm group (P = 0.036). There was no significant effect of patient comorbidities on fistula failure; however, there was a trend toward upper arm surgical site as a protective factor for primary fistula patency (hazard ratio = 0.573, P = 0.076).

CONCLUSIONS

In veterans needing hemodialysis, a high risk population with extensive comorbid factors often requiring intravascular access, upper arm fistulae are not only a viable option for primary vascular access, but are likely to be a superior option to classic forearm fistulae.

Results of a seven-year, single-centre experience of the long-term outcomes of bovine ureter grafts used as novel conduits for haemodialysis fistulas

PURPOSE

To report the long-term outcomes of bovine ureter grafts as novel conduits for haemodialysis fistulas.

MATERIALS AND METHODS

Thirty-five patients underwent placement of a total of 40 SynerGraft 100 (SG100; CryoLife Europa(®), Guildford, UK) bovine ureter grafts between April 2002 and February 2009. Prospective data were collected on all patients, including active surveillance with blood flow studies and 6-monthly duplex ultrasound studies. Main outcome measures were primary and secondary patency rates.

RESULTS

Mean follow-up time was 97 weeks (range 4-270). Thirteen patients died from unrelated causes during the study period; 12 of these patients had a functioning graft at the time of death. Five patients underwent transplantation, and all had a functioning graft at transplantation. Twelve patients had a functioning graft at the end of the study period. One hundred and ten stenoses were detected, and 97 venoplasty procedures were performed. Of the stenoses, 41.8% were located at the venous anastomosis, 12.7% within the graft, 17.3% in the outflow veins, and 28.1% in central veins. No arterial stenoses were detected. Primary patency rates were 53% at 6 months and 14% at 1 year. Secondary patency rates were 81% at 6 months, 75% at 1 year, and 56% at 2 years.

CONCLUSIONS

Active surveillance and intervention was able to achieve satisfactory long-term secondary patency for these novel conduits compared with those made of PTFE seen in other studies [1].

Choice of vascular access among incident hemodialysis patients: a decision and cost-utility analysis

BACKGROUND AND OBJECTIVES

Arteriovenous fistulas (AVFs) are widely accepted as the preferred hemodialysis vascular access type. However, supporting data have failed to consider morbidity and mortality incurred during failed creation attempts and may therefore overstate potential advantages. This study compares survival, quality-adjusted survival, and costs among incident hemodialysis patients after attempted placement of AVFs or arteriovenous grafts (AVGs).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Analogous Markov models were created, one each for AVF and AVG. Patients entered consideration at the time of first access creation, contemporaneous with dialysis initiation. Subsequent outcomes were determined probabilistically; transition probabilities, utilities, and costs were gathered from published sources. To ensure comparability between AVFs and AVGs, the timing and likelihood of access maturation were measured in a contemporary cohort of incident hemodialysis patients.

RESULTS

Mean (SD) overall survival was 39.2 (0.8) and 36.7 (1.0) months for AVFs and AVGs, respectively: difference (95% confidence interval [CI]) 2.6 (1.8, 3.3) months. Quality-adjusted survival was 36.1 (0.8) and 32.5 (0.9) quality-adjusted life months (QALMs) for AVFs and AVGs, respectively: difference (95% CI) 3.6 (2.8, 4.3) QALMs. The incremental cost-effectiveness ratio (95% CI) for AVFs relative to AVGs was $446 (-6023, 6994) per quality-adjusted life year saved.

CONCLUSIONS

AVFs are associated with greater overall and quality-adjusted survival than AVGs. Observed differences were much less pronounced than might be expected from existing literature, suggesting that prospective identification of patients at high risk for AVF maturational failure might enable improvements in health outcomes via individualization of access planning.

Clinical Outcome of Overlapping Stents in Hemodialysis Access

Purpose

Endovascular stents have recently been shown to extend access patency in thrombosed and stenotic arteriovenous grafts. Given this improved patency, stent placement has outpaced balloon angioplasty in hemodialysis (HD) access interventions. However, concern remains over localized corrosion and increased neointimal hyperplasia of overlapping stents in the access circuit and whether this promotes premature stent failure.

Methods

This is a retrospective analysis of HD patients referred for access dysfunction during a 2-yr period. Using a prospectively collected, vascular access database, we identified 76 patients seen for follow-up angiography due to access dysfunction after stent placement. We compared the outcomes of overlapping vs. non-overlapping stents in measured primary assisted patency and mean percent luminal diameter as a marker of lesion severity.

Results

The two groups did not differ significantly in demographics or comorbid conditions. Only gender had a significant discrepancy between the two groups, with 65.5% vs. 42.9% male (p=0.01) in the overlapping vs. non-overlapping stent groups, respectively. The mean percent luminal stenosis was found to be 83.7 ± 17.3 and 85.5 ± 12.6 (p=0.55) for the overlapping vs. non-overlapping stent groups, respectively. For overlapping and non-overlapping stents, 30-day primary patency was 94% and 89%, respectively, 60-day primary patency was 77% and 63%, respectively, and 90-day primary patency was 68% and 50%, respectively. Using multiple regression analysis, no risk factors were identified to be associated with the severity of luminal stenosis. No identifiable risk factors were found to be associated with improved primary patency. In particular, overlapping vs. non-overlapping stents were not identified as a statistically significant factor influencing primary (assisted) patency (hazards ratio 0.60; 95% cI 0.34 to 1.06; p>0.05).

Conclusions

This study provides evidence that the theoretical concern of metal on metal corrosion and increased neointimal hyperplasia that can be seen with overlapping stents does not play a significant clinical role.

Arteriovenous fistulas constructed using side-to-side anastomosis with ligation and division of distal venous arm; a tertiary care hospital experience

BACKGROUND AND OBJECTIVE

The rising prevalence of end-stage renal disease has added to the demands of renal replacement therapy in the form of hemodialysis (HD) in lieu of unmitigated needs of renal transplants. The best available angioaccess for HD is the autogenous arteriovenous fistula. Many techniques for arteriovenous anastomosis have been reported, but there is dearth of data which study the side-to-side arteriovenous anastomosis with concomitant ligation and division of the distal venous arm. This study aimed to describe the clinical outcome of the fistulae constructed with this particular technique.

METHODS

It is a descriptive and retrospective review in which all patients who underwent the operation with this particular technique in a certain time period were included. The data entry and analysis was done using SPSS 15. Only descriptive statistics are used. Demographic details, primary patency, end point patency and fistula survival were calculated.

RESULTS

There were 77 patients, 61 males and 16 females. Radiocephalic arteriovenous anastomosis was constructed in 65 patients, brachiocephalic in 11 patients and brachiobasilic in one patient. Primary patency was 96.1% and end point patency was 90.9% with a median survival of 44 weeks at the end point.

CONCLUSION

This particular technique of fistula construction has excellent patency rates, fistula survival and lesser complications when compared to what has been reported for other methods. It is therefore recommended that the technique of angioaccess reported in this study may be considered as a first option.

Risk factors associated with patency loss of hemodialysis vascular access within 6 months

BACKGROUND AND OBJECTIVES

Clinical guidelines support vascular access surveillance to detect access dysfunction and alter the clinical course by radiologic or surgical intervention. The objective of this study was to explore the association between loss of primary functional patency within 6 months of first use and demographic and clinical characteristics of patients receiving chronic renal replacement therapy with arteriovenous fistulas.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a retrospective study of all chronic hemodialysis patients followed by the Southern Alberta Renal Program from January 1, 2005 to June 30, 2008. Demographic and clinical variables and initial intra-access blood flow (IABF) were compared between those with and without loss of primary functional patency. To determine the contribution of independent variables to the dependant variable of loss of primary functional patency, a multivariable analysis using logistic regression was performed.

RESULTS

The incidence of primary failure was 10% (81 of 831). Multivariable analysis found that older age (>65 years, odds ratio [OR] 3.6, P < 0.001), history of diabetes (OR 2.3, P = 0.007), history of smoking (OR 4.3, P < 0.001), presence of forearm fistulas (OR 4.0, P < 0.001), and low initial IABF (<500 ml/min, OR 29, P < 0.001) were independently associated with loss of primary patency.

CONCLUSIONS

The set of patient risk factors identified in this study, particularly initial IABF, can be used to identify patients who are most at risk for developing vascular access failure and to guide a more directed approach for a vascular access screening protocol.