Conversion of tunneled hemodialysis catheter–consigned patients to arteriovenous fistula

Cathepsin G promotes arteriovenous fistula maturation by positively regulating the MMP2/MMP9 pathway

BACKGROUND

Arteriovenous fistula (AVF) is currently the preferred vascular access for hemodialysis patients. However, the low maturation rate of AVF severely affects its use in patients. A more comprehensive understanding and study of the mechanisms of AVF maturation is urgently needed.

METHODS AND RESULTS

In this study, we downloaded the publicly available datasets (GSE119296 and GSE220796) from the Gene Expression Omnibus (GEO) and merged them for subsequent analysis. We screened 84 differentially expressed genes (DEGs) and performed the functional enrichment analysis. Next, we integrated the results obtained from the degree algorithm provided by the Cytohubba plug-in, Molecular complex detection (MCODE) plug-in, weighted gene correlation network analysis (WGCNA), and Least absolute shrinkage and selection operator (LASSO) logistic regression. This integration allowed us to identify CTSG as a hub gene associated with AVF maturation. Through the literature search and Pearson's correlation analysis, the genes matrix metalloproteinase 2 (MMP2) and MMP9 were identified as potential downstream effectors of CTSG. We then collected three immature clinical AVF vein samples and three mature samples and validated the expression of CTSG using immunohistochemistry (IHC) and double-immunofluorescence staining. The IHC results demonstrated a significant decrease in CTSG expression levels in the immature AVF vein samples compared to the mature samples. The results of double-immunofluorescence staining revealed that CTSG was expressed in both the intima and media of AVF veins. Moreover, the expression of CTSG in vascular smooth muscle cells (VSMCs) was significantly higher in the mature samples compared to the immature samples. The results of Masson's trichrome and collagen I IHC staining demonstrated a higher extent of collagen deposition in the media of immature AVF veins compared to the mature. By constructing an in vitro CTSG overexpression model in VSMCs, we found that CTSG upregulated the expression of MMP2 and MMP9 while downregulating the expression of collagen I and collagen III. Furthermore, CTSG was found to inhibit VSMC migration.

CONCLUSIONS

CTSG may promote AVF maturation by stimulating the secretion of MMP2 and MMP9 from VSMCs and reducing the extent of medial fibrosis in AVF veins by inhibiting the secretion of collagen I and collagen III.

Central Venous Catheters for Hemodialysis-the Myth and the Evidence

Hemodialysis-central venous catheter (HD-CVC) insertion is a most often performed procedure, with approximately 80% of patients with end-stage kidney disease in the United States initiating kidney replacement therapy through a HD-CVC. Certain adverse events arising from HD-CVC placement, including catheter-related bloodstream infections (CR-BSIs), thrombosis, and central vein stenosis, can complicate the clinical course of patients and lead to considerable financial impact on the health care system. Medical professionals with different training backgrounds are responsible for performing this procedure, and therefore, comprehensive operator guidelines are crucial to improve the success rate of HD-CVC insertion and prevent complications. In this review article, we not only discuss the basic principles behind the use of HD-CVCs but also address frequently asked questions and myths regarding catheter asepsis, length selection, tip positioning, and flow rate assessment.

Vascular Access and Clinical Outcomes in Underserved Hemodialysis Patients in Mexico

INTRODUCTION

Central venous catheter (CVC) as vascular access in hemodialysis (HD) associates with adverse outcomes. Early CVC to fistula or graft conversion improves these outcomes. While socioeconomic disparities between the USA and Mexico exist, little is known about CVC prevalence and conversion rates in uninsured Mexican HD patients. We examined vascular access practice patterns and their effects on survival and hospitalization rates among uninsured Mexican HD patients, in comparison with HD patients who initiated treatment in the USA.

METHODS

In this retrospective study of incident HD patients at Hospital Civil (HC; Guadalajara, MX) and the Renal Research Institute (RRI; USA), we categorized patients by the vascular access at the first month of HD and after the following 6 months. Factors associated with continued CVC use were identified by a logistic regression model. We developed multivariate Cox proportional hazards models to investigate the effects of access and conversion on mortality and hospitalization over an 18-month follow-up period.

RESULTS

In 1,632 patients from RRI, the CVC prevalence at month 1 was 64% and 97% among 174 HC patients. The conversion rate was 31.7% in RRI and 10.6% in HC. CVC to non-central venous catheter (NON-CVC) conversion reduced the risk of hospitalization in both HC (aHR 0.38 [95% CI: 0.21-0.68], p = 0.001) and RRI (aHR 0.84 [95% CI: 0.73-0.93], p = 0.001). NON-CVC patients had a lower mortality risk in both populations.

DISCUSSION/CONCLUSION

CVC prevalence and conversion rates of CVC to NON-CVC differed between the US and Mexican patients. An association exists between vascular access type and hospitalization and mortality risk. Prospective studies are needed to evaluate if accelerated and systematic catheter use reduction would improve outcomes in these populations.

Vessel diameter and close surveillance helps predict early patency in native arteriovenous fistulas

INTRODUCTION

Arteriovenous fistulas are the preferred method of vascular access for haemodialysis. Data suggests patency rates can be low and may be related to vessel diameters prior to creation. We use specific size criteria for fistula selection. We aimed to establish patency rates in relation to vessel size and whether other factors affect fistula patency.

METHODS

Consecutive patients undergoing radiocephalic (RCF) or brachiocephalic (BCF) creation between 2016 and 2018 were analysed. Preoperative arterial and venous diameters were collected. Six-week and six-month primary and secondary patency rates were analysed to establish any impact of vessel size on patency and re-intervention rates between groups. A univariate analysis was performed.

RESULTS

Ninety four RCFs and 101 BCFs were created. Median artery and vein size for RCF were 2.7 and 3.0 mm respectively. For BCF, they were 4.6 and 4.3 mm respectively. At 6-weeks, overall satisfactory patency for RCF and BCF combined was 91.8%. 89.7% demonstrated primary patency; 2.1% secondary patency. At 6-months, overall patency was 78.7%; 58.5% demonstrated primary patency, 20.2% secondary patency. A univariate analysis, for both groups, revealed vein size was a significant predictor of overall satisfactory patency at 6-weeks, with larger veins more likely to remain patent (p = 0.025 RCF, p = 0.007 BCF). However, artery size was not predictive (p = 0.1 RCF, p = 0.5 BCF). At 6-months, neither artery nor vein diameter were predictive in either group. When comparing size of vessel based on fistula type, vessels used to create RCFs were smaller than those for BCFs (p < 0.001). RCFs were more likely to receive endovascular intervention or occlude when compared to BCFs (p = 0.014).

DISCUSSION

Excellent patency and maturation rates can be achieved using fairly strict vessel size criteria. Vein size might be the more important predictor of early success. RCFs can be challenging due to smaller vessels, but maturation rates can be optimised by close surveillance and aggressive re-intervention.

Arteriovenous Fistula Formation with Adjuvant Endovascular Maturation

INTRODUCTION

The clinical utility of the native arteriovenous fistula (AVF) is limited by a prolonged time to maturation, low overall maturation rate, and subsequent abandonment. Endovascular intervention is increasingly accepted as first line therapy to treat AVF stenosis. The objective of this study was to evaluate AVF formation outcomes when early endovascular intervention was selectively performed to bring about timely AVF maturation.

METHODS

A retrospective study (February 2014- February 2020) was performed on 82 AVF consecutive patients (mean age 62.5±13.5 (17-83); 58 male (70.7%)) with end-stage renal failure who had Vascular Access (VA) construction at a single institution. Four year AVF patency, vascular diameters, haemodialysis parameters, re-intervention rate, and mortality were analysed.

RESULTS

Radiocephalic AVF was the most common fistula constructed (71 patients; 88.6%). Post formation evaluation (46.2+/-56.0 days (5-343)) revealed 33 (40.2%) immature AVFs. Subsequently, 19 patients underwent endovascular procedures consisting of angioplasty/stenting of the juxta-anastomosis, cannulation and/or outflow segments to bring about timely maturation of the AVF. Hence 93.9% of AVFs had reached functional patency (maturation) by 6 months post formation, with a mean time to maturation of 67.8 +/- 65.9 (5-320) days. After reaching maturation, Primary Access Functional Patency was 82 +/- 4.3 % at 6 months, 58+/- 5.5% at 12 months and 34 +/- 6.8% at 48 months. Primary Assisted Access Functional Patency was 95 +/- 2.4% at 6 months, 90 +/-3.3 % at 12 months and 83 % +/- 4.7 % at 48 months. 121 endovascular interventions were performed to maintain patency, equating to an endovascular reintervention rate of .37 procedures/patient year. Mean arterial, venous and brachial flow rates did not change significantly after maturation with a mean fistula (primary assisted functional patency) survival time of 5.9 +/- 0.26 (5.33- 6.36) years from maturation. Only 12 thromboses occurred after the first post formation follow up review, which were all salvaged using endovascular techniques leading to 100% Total secondary functional patency at 4 years. 5 year estimated all-cause mortality was 45.6 +/-12.7%.

CONCLUSION

Arteriovenous fistula maturation rate and time to maturation can be improved when early endovascular intervention is selectively performed post formation. This allows for near universal maturation where, once matured, the use of ongoing endovascular re-intervention allows for a low re-intervention rate and long term patency providing for reliable long term renal vascular access.

Bedside Tunneled Hemodialysis Catheter Placement in Patients with COVID-19

Background

COVID-19, the syndrome caused by the novel SARS-CoV2, is associated with high rates of acute kidney injury requiring renal replacement therapy (RRT). It is well known that despite the ease of bedside insertion, the use of nontunneled dialysis catheters (NTDCs) is associated with increased complications compared to tunneled dialysis catheters (TDCs). Our objective was to develop a strategy for TDC placement at the bedside to provide effective dialysis access, conserve resources and decrease personnel exposure at our medical center in an epicenter of the COVID-19 pandemic.

Methods

A technique for bedside TDC insertion with ultrasound and plain radiographs in the intensive care unit was developed. Test or clinically COVID-19-positive patients requiring RRT were evaluated for bedside emergent NTDC or nonemergent TDC placement. Patients who underwent NTDC placement were monitored for ongoing RRT needs and were converted to TDC at the bedside after 3–5 days. We prospectively collected patient data focusing on complications and mortality.

Results

Of the 36 consultations for dialysis access in COVID-positive patients from March 19 through June 5, 2020, a total of 24 bedside TDCs were placed. Only one patient developed a complication, which was pneumothorax and cardiac tamponade during line placement. In-hospital mortality in the cohort was 63.9%.

Conclusions

Bedside TDC placement has served to conserve resources, prevent complications with transport to and from the operating room, and decrease personnel exposure during the COVID-19 pandemic. This strategy warrants further consideration and could be used in critically ill patients regardless of COVID status.

Quality indicators of vascular access procedures for hemodialysis

Improved quality of surgical procedures can minimize complications, the morbidity and mortality of patients, and in addition decrease costs. Quality indicators in angioaccess surgery are, however, not clearly defined. The aim of this review article is therefore to find the most important factors affecting quality in vascular access procedures. Even though autogenous arteriovenous fistula has been recognized as the best vascular access for hemodialysis, the high percentage of unsuccessful attempts associated with it raises the question about quality assessment in angioaccess procedures. Unfortunately, quality indicators in vascular access surgery are difficult to define and measure. Among those that can be obtained are: the time between the presentation of patients to a vascular access surgeon and the construction of a fistula, the percentage of autogenous fistulas, the percentage of functional fistulas in prevalent and incident hemodialysis patients, the percentage of creation of a functional fistula in the first attempt, and durability of an access. Organizational improvement and educational programs are also necessary at institutions with inferior quality indicators of vascular access care, as even small increase in quality may mean the survival of an individual patient. Quality indicators in angioaccess surgery can also serve as a helpful tool in choosing the best vascular access surgeon or vascular access center. The choice can consequently reflect on increased survival and quality of life in patients needing hemodialysis.

Radial artery diameterand and age related functional maturation of the radio-cephalic arteriovenous fistula

Background

Previous studies have not described the relationship between reducing radial artery diameter as well as increasing age and functional maturation of the radio-cephalic arteriovenous fistula (RCAVF) and no data identify these as linear relationship. The objective of this study was to perform trend analysis to assess these aspects.

Methods

Our retrospective cohort study enrolled and analyzed 353 follow-up cases that underwent first AVF creation. The artery and vein sizes were measured by ultrasound. We performed follow-up, a minimum of 3 months after surgery. Multivariable logistic regression analysis was used to identify independent risk factors inmaturation. Participant age was categorized into four groups (age ≤ 29, 30–49, 50–69, and 70–90 years). Radial artery diameter was categorized into four groups (≤ 1.9, >1.9 and ≤ 2.1, >2.1 and ≤ 2.4, >2.4 mm) according to median and interquartile ranges. We adjusted for confounders in four logistic models, and primary analyses were based on building ordered category models and tested P values for trends to estimate the relationship of radial artery diameter and each 20-year increase in age with risk of maturation.

Results

The mature RCAVF group included 301 cases, and the immature group included 52 cases. Radial artery diameter, age, and diabetes were independent risk factors of maturation. Odds ratios (ORs) associated with maturation reduced with increasing age, while ORs increased with increasing radial artery diameter. P values for trends(<0.05) were observed in all four models. A reduction in radial artery diameter and higher age were significantly associated with a higher incidence of immaturity after adjusting the multivariate models. The risks of immaturation were increased by more than 1.54 fold for each 20-year increase and increased by more than 1.34 fold for the smaller radial artery diameter group.

Conclusion

Our findings suggest that a significantly higher immaturity risk of RCAVF was associated with increasing age and a reduction in radial artery diameter. Our study identified a linear exposure-response relationship of age and radial artery diameter with immaturity incident. A careful selection of patients will be helpful in improving AVF functional maturation.

Vascular access in children requiring maintenance haemodialysis: a consensus document by the European Society for Paediatric Nephrology Dialysis Working Group

BACKGROUND

There are three principle forms of vascular access available for the treatment of children with end stage kidney disease (ESKD) by haemodialysis: tunnelled catheters placed in a central vein (central venous lines, CVLs), arteriovenous fistulas (AVF), and arteriovenous grafts (AVG) using prosthetic or biological material. Compared with the adult literature, there are few studies in children to provide evidence based guidelines for optimal vascular access type or its management and outcomes in children with ESKD.

METHODS

The European Society for Paediatric Nephrology Dialysis Working Group (ESPN Dialysis WG) have developed recommendations for the choice of access type, pre-operative evaluation, monitoring, and prevention and management of complications of different access types in children with ESKD.

RESULTS

For adults with ESKD on haemodialysis, the principle of "Fistula First" has been key to changing the attitude to vascular access for haemodialysis. However, data from multiple observational studies and the International Paediatric Haemodialysis Network registry suggest that CVLs are associated with a significantly higher rate of infections and access dysfunction, and need for access replacement. Despite this, AVFs are used in only ∼25% of children on haemodialysis. It is important to provide the right access for the right patient at the right time in their life-course of renal replacement therapy, with an emphasis on venous preservation at all times. While AVFs may not be suitable in the very young or those with an anticipated short dialysis course before transplantation, many paediatric studies have shown that AVFs are superior to CVLs.

CONCLUSIONS

Here we present clinical practice recommendations for AVFs and CVLs in children with ESKD. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system has been used to develop and GRADE the recommendations. In the absence of high quality evidence, the opinion of experts from the ESPN Dialysis WG is provided, but is clearly GRADE-ed as such and must be carefully considered by the treating physician, and adapted to local expertise and individual patient needs as appropriate.

Endovascular salvage of non-maturing autogenous arteriovenous fistulas by using angioplasty and competitive vein embolization

INTRODUCTION

The aim of this study is to evaluate the maturation and patency rates after endovascular treatment of non-maturing arteriovenous fistulas with percutaneous transluminal angioplasty, embolization of competitive veins, or a combination of both in a series of consecutive patients.

MATERIAL AND METHODS

Retrospective evaluation of patients with non-matured arteriovenous fistulas treated in our hospital was performed. Fistulography and ultrasonography was performed in all patients to evaluate the presence of stenosis and competitive veins. Significant stenoses (> 50%) were treated with balloon angioplasty and competitive veins (accessory and collateral veins) with coil embolization.

RESULTS

A total of 78 fistulas were treated. Angioplasty and coil embolization were performed in 73 and 51 patients, respectively. No major complications occurred. In 65 out of 78 arteriovenous fistulas (83%), successful cannulation with two needles was possible after endovascular treatment. Sixty-three arteriovenous fistulas (81%) were used successfully for at least 3 months. Accessory veins were the only lesion present in 14% of the arteriovenous fistulas; coil embolization of these accessory veins resulted in 100% successful maturation. The estimated 3, 6, and 12 months postintervention assisted primary patency rates were, respectively, 73%, 55%, and 45%. The estimated 3, 6, and 12 months postintervention secondary patency rates were, respectively, 81%, 78%, and 73%.

CONCLUSION AND DISCUSSION

Angioplasty and coil embolization are successful and safe procedures that can convert a non-mature fistula into a mature one in more than 80% of patients. Accessory vein embolization may be more important than collateral vein embolization in the presence of stenosis.

Relevance of a skilled vascular surgeon and optimized facility practices in the long-term patency of arteriovenous fistulas: a prospective study

Introduction:

Arteriovenous fistulas (AVF) are the best hemodialysis vascular accesses, but their failure rate remains high. Few studies have addressed the role of the vascular surgeon's skills and the facility's practices. We aimed to study these factors, with the hypothesis that the surgeon's skills and facility practices would have an important role in primary failure and patency rates at 12 months, respectively.

Methods:

This was a single-center, prospective cohort study carried out from March 2005 to March 2017. Only incident patients were included. A single surgeon made all AVFs, either in the forearm (lower) or the elbow (upper). Vascular access definitions were in accordance with the North American Vascular Access Consortium.

Results:

We studied 113 AVFs (65% lower) from 106 patients (39% diabetics, 58% started with catheter). Time to first connection was 21.5 days (IR: 14 - 31). Only 14 AVFs (12.4%) underwent primary failure and 18 failed during the first year. Functional primary patency rate was 80.9% (SE 4.1) whereas primary unassisted patency rate, which included PF, was 70.6% (4.4). Logistic regression showed that diabetes (OR = 3.3, 95%CI 1.38 - 7.88, p = .007) and forearm location (OR = 3.03, 95CI% 1.05 - 8.76, p = 0.04) were predictors of AVF failure. Patency of lower and upper AVFs was similar in non-diabetics, while patency in diabetics with lower AVFs was under 50%. (p = 0.003).

Conclusions:

Results suggest that a long-lasting, suitable AVF is feasible in almost all patients. The surgeon's skills and facility practices can have an important role in the long term outcome of AVF.

[The role of the vascular surgeon in improvement of organization of dialysis help]

Analysed herein are one-year results of formation of arteriovenous fistulas in 109 patients with end-stage chronic renal failure, as well as therapeutic decision-making after angiosurgical counselling of 144 patients presenting with 'problem' permanent vascular accesses. The counselling and formation of arteriovenous fistulas were carried out in conditions of interdepartmental collaboration between outpatient centres dealing with haemodialysis and vascular surgeons specialized in ultrasound mapping of peripheral vessels and performing different variants of arteriovenous fistulas. The angiosurgical care was as close to the patient as possible. Of the 109 operated patients, primary arteriovenous fistulas were made in 46 (42.2%) cases, secondary AVF - in 27 (24.8%) cases, and reconstruction of AVF - in 36 (33.0%) cases. Of the 144 patients with 'problem' permanent vascular assesses, correction of arteriovenous fistulas turned out impossible in 13 (9.1%). In the remaining 131 (90.9%) patients there was a possibility of different variants of open reconstruction of arteriovenous fistulas or performing angioplasty. Active policy of vascular surgeons in interdepartmental collaboration with nephrologists made it possible to bridge over the difficulties of patients routing which resulted in reduction of the terms of formation of arteriovenous fistulas by 2 months. Preventive arteriovenous fistulas were carried out in 17.4% of cases of primary permanent vascular assesses. During a year after formation of permanent vascular accesses, the number of patients with vascular catheters in ambulatory centres decreased from 22 to 17%. These positive changes in organization of the dialysis treatment made it possible to reduce the risks of infectious complications, to obtain adequate blood flow characteristics for haemodialysis procedures, as well as to decrease financial expenses and labour costs for AVF care.

Health Insurance in the First 3 Months of Hemodialysis and Early Vascular Access

BACKGROUND AND OBJECTIVES

Patients without Medicare who develop ESKD in the United States become Medicare eligible by their fourth dialysis month. Patients without insurance may experience delays in obtaining arteriovenous fistulas or grafts before obtaining Medicare coverage.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this retrospective cohort study, we used a national registry to compare uninsured patients starting in-center hemodialysis with a central venous catheter between 2010 and 2013 with similar patients with Medicare or Medicaid. We evaluated whether insurance status at dialysis start influenced the likelihoods of switching to dialysis through an arteriovenous fistula or graft and hospitalizations involving a vascular access infection. We used multivariable logistic and Cox regression models and transformed odds ratios to relative risks using marginal effects.

RESULTS

Patients with Medicare or Medicaid were more likely to switch to an arteriovenous fistula or graft by their fourth dialysis month versus uninsured patients (Medicare hazard ratio, 1.63; 95% confidence interval, 1.14 to 2.43; Medicaid hazard ratio, 1.23; 95% confidence interval, 1.12 to 1.38). There were no differences in rates of switching to arteriovenous fistulas or grafts after all patients obtained Medicare in their fourth dialysis month (Medicare hazard ratio, 1.17; 95% confidence interval, 0.97 to 1.42; Medicaid hazard ratio, 1.01; 95% confidence interval, 0.96 to 1.06). Patients with Medicare at dialysis start had fewer hospitalizations involving vascular access infection in dialysis months 4-12 (hazard ratio, 0.60; 95% confidence interval, 0.37 to 0.97).

CONCLUSIONS

Insurance-related disparities in the use of arteriovenous fistulas and grafts persist through the fourth month of dialysis, may not fully correct after all patients obtain Medicare coverage, and may lead to more frequent vascular access infections.

Predictive parameters of arteriovenous fistula maturation in patients with end-stage renal disease

Background

The objevctive of the present study was to explore the potential influence of blood markers and patient factors such as risk factors, kidney function profile, coagulation profile, lipid profile, body mass index, blood pressure, and vein diameter on the maturation of arteriovenous fistula (AVF) in patients with end-stage renal disease.

Methods

Retrospective data from 300 patients who had undergone AVF creation at the Royal Infirmary of Edinburgh were examined. A predictive logistic regression model was developed using a backward stepwise procedure. Model performance, discrimination, and calibration were assessed using the receiver operating characteristic (ROC) curve and Hosmer–Lemeshow goodness-of-fit test. The final model was externally validated by 100 prospective patients who received a new fistula at the Royal Infirmary of Edinburgh.

Results

A total of 400 (300 retrospective and 100 prospective) patients were recruited for this study, with a mean age of 60.14 ± 15.9 years (development set) and 58 ± 15 years (validation set), respectively (P = 0.208). Study results showed that males were twice as likely to undergo fistula maturation as females, while patients with no evidence of peripheral vascular disease (PVD) were three times more likely to mature their fistula and a preoperative vein diameter > 2.5 mm resulted in a fivefold increase in fistula maturation as compared with a vein size of less than 2.5 mm. The model for fistula maturation had fair discrimination, as indicated by the area under the ROC curve (0.68), but good calibration as indicated by the Hosmer–Lemeshow test (P = 0.79). The area under the receiver operating curve for the validation model in the validation set was 0.59. Similarly, in the validation set, the Hosmer–Lemeshow statistic indicated an agreement between the observed and predicted probabilities of maturation (P > 0.05).

Conclusion

Gender, PVD, and vein size are independent predictors of AVF maturation. The clinical utility of these risk categories in the maturation of AVF requires further evaluation in longer follow-up.

Endovascular management in immature arteriovenous fistula for hemodialysis

To evaluate the outcomes and prognostic factors of endovascular management in immature arteriovenous fistula (AVF) for hemodialysis.From April 2007 to September 2017, 54 patients (male:female = 31:23, mean age 65.63 years, range 33-90 years) who underwent endovascular management for the salvage of immature AVF were retrospectively reviewed. Clinical data, procedural details, and results were evaluated. Primary and secondary patency rates and factors influencing the patency were also analyzed.Technical and clinical success rates were 88.9% (48/54) and 85.2% (46/54), respectively. Mean primary and secondary patency was 42.10 (±8.85) and 91.5 (±14.77) months, respectively. Primary and secondary patency rates were 66% and 89% in 1 year, 66% and 78% in 2 years, and 51% and 78% in 3 years. In multivariate analysis, only brachiocephalic AVF and antegrade access procedures showed significantly shorter primary patency (HR 5.196; 95% CI (1.04-25.77); P = .044, HR 8.096; 95% CI (1.36-48.00); P = .021). There was no statistically significant factor associated with secondary patency in the multivariate study.Endovascular management in immature AVF is safe and effective to make the AVF available. Brachiocephalic AVF and antegrade access procedures are the factors influencing the patency in multivariate analysis.

Relationships Between Clinical Processes and Arteriovenous Fistula Cannulation and Maturation: A Multicenter Prospective Cohort Study

BACKGROUND

Half of surgically created arteriovenous fistulas (AVFs) require additional intervention to effectively support hemodialysis. Postoperative care and complications may affect clinical maturation.

STUDY DESIGN

Hemodialysis Fistula Maturation (HFM) Study, a 7-center prospective cohort study.

SETTING & PARTICIPANTS

491 patients with single-stage AVFs who had neither thrombosis nor AVF intervention before a 6-week postoperative ultrasonographic examination and who required maintenance hemodialysis.

PREDICTORS

Postoperative care processes and complications.

OUTCOMES

Attempted cannulation, successful cannulation, and unassisted and overall clinical maturation as defined by the HFM Study criteria.

RESULTS

AVF cannulation was attempted in 443 of 491 (90.2%) participants and was eventually successful in 430 of these 443 (97.1%) participants. 263 of these 430 (61.2%) reached unassisted and 118 (27.4%) reached assisted AVF maturation (overall maturation, 381/430 [88.6%]). Attempted cannulation was less likely in patients of surgeons with policies for routine 2-week versus later-than-2-week first postoperative visits (OR, 0.21; 95% CI, 0.06-0.70), routine second postoperative follow-up visits (OR, 0.39; 95% CI, 0.15-0.97), and a routine clinical postoperative ultrasound (OR, 0.28; 95% CI, 0.14-0.55). Attempted cannulation was also less likely among patients undergoing procedures to assist maturation (OR, 0.51; 95% CI, 0.27-0.98). Unassisted maturation was more likely for patients treated in facilities with access coordinators (OR, 1.91; 95% CI, 1.17-3.12), but less likely after precannulation nonstudy ultrasounds (OR per ultrasound, 0.42 [95% CI, 0.26-0.68]) and initial unsuccessful cannulation attempts (OR per each additional attempt, 0.90 [95% CI, 0.83-0.98]). Overall maturation was less likely with infiltration before successful cannulation (OR, 0.44; 95% CI, 0.22-0.89). Among participants receiving maintenance hemodialysis before AVF surgery, unassisted and overall maturation were less likely with longer intervals from surgery to initial cannulation (ORs for each additional month of 0.81 [95% CI, 0.76-0.88] and 0.93 [95% CI, 0.89-0.98], respectively) and from initial to successful cannulation (ORs for each additional week of 0.87 [95% CI, 0.81-0.94] and 0.88 [95% CI, 0.83-0.94], respectively).

LIMITATIONS

Surgeons' management policies were assessed only by questionnaire at study onset. Most participants received upper-arm AVFs, planned 2-stage AVFs were excluded, and maturation time windows were imposed. Some care processes may have been missed and the observational design limits causal attribution.

CONCLUSIONS

Multiple processes of care and complications are associated with AVF maturation outcomes.

Medicare Costs Associated With Arteriovenous Fistulas Among US Hemodialysis Patients

BACKGROUND

An arteriovenous fistula (AVF) is the recommended vascular access for hemodialysis (HD). Previous studies have not examined the resources and costs associated with creating and maintaining AVFs.

STUDY DESIGN

Retrospective observational study.

SETTING & PARTICIPANTS

Elderly US Medicare patients initiating hemodialysis therapy during 2010 to 2011.

PREDICTOR

AVF primary and secondary patency and nonuse in the first year following AVF creation.

OUTCOMES

Annualized vascular access costs per patient per year.

RESULTS

Among patients with only a catheter at HD therapy initiation, only 54% of AVFs were successfully used for HD, 10% were used but experienced secondary patency loss within 1 year of creation, and 83% experienced primary patency loss within 1 year of creation. Mean vascular access costs per patient per year in the 2.5 years after AVF creation were $7,871 for AVFs that maintained primary patency in year 1, $13,282 for AVFs that experienced primary patency loss in year 1, $17,808 for AVFs that experienced secondary patency loss in year 1, and $31,630 for AVFs that were not used. Similar patterns were seen among patients with a mature AVF at HD therapy initiation and patients with a catheter and maturing AVF at HD therapy initiation. Overall, in 2013, fee-for-service Medicare paid $2.8 billion for dialysis vascular access-related services, ∼12% of all end-stage renal disease payments.

LIMITATIONS

Lack of granularity with certain billing codes.

CONCLUSIONS

AVF failure in the first year after creation is common and results in substantially higher health care costs. Compared with patients whose AVFs maintained primary patency, vascular access costs were 2 to 3 times higher for patients whose AVFs experienced primary or secondary patency loss and 4 times higher for patients who never used their AVFs. There is a need to improve AVF outcomes and reduce costs after AVF creation.

Endovascular bypass for salvage of vascular access in hemodialysis catheter-consigned patients

PURPOSE:

This study was performed to retrospectively assess the efficacy of percutaneous creation of an intervascular bypass with or without stent graft deployment (endovascular bypass) for salvage of abandoned vascular access sites in hemodialysis catheter-consigned patients.

METHODS:

Salvage of abandoned vascular access sites was attempted in 16 patients with hemodialysis catheters. These vascular access sites were salvaged using endovascular bypass techniques to redirect the access flow to a nonarterialized vein as a new outflow conduit or cannulation segment. The postintervention primary, assisted primary, and secondary patency rates of the access site and bypass were calculated using the Kaplan-Meier method.

RESULTS:

The procedural and clinical success rates were both 100%. The postintervention primary patency rate of the bypass and access site at 360 days was 75.7 ± 12.5% and 56.8 ± 14.9%, respectively. The mean follow-up period was 461.9 days (range: 121-900 days). No major complications were observed. One bare bypass tunnel rupture and one pseudoaneurysm were noted during the procedure.

CONCLUSION:

Salvage of abandoned vascular access sites for hemodialysis catheter-consigned patients can be technically feasible and clinically successful using endovascular bypass techniques in selected patients when surgical revision is not considered or is not possible.

Pregnancy and hemodialysis access: A case for patient satisfaction in favor of a tunneled dialysis catheter

While an arteriovenous fistula is the best available access, many patients continue to rely on a tunneled hemodialysis catheter for dialysis therapy. Despite the highest risk of catheter-related bacteremia and associated morbidity and mortality, patients often prefer tunneled hemodialysis catheter to avoid pain associated with cannulation of an arteriovenous access. We report three tunneled hemodialysis catheter-dependent end-stage renal disease patients (age: 38, 35, 33 years), who became pregnant. Pregnancy was discovered at 10, 12 and 10 weeks of gestation. All three patients were switched to daily hemodialysis (six sessions/week) as soon as the pregnancy was discovered. The three patients had refused the placement of an arteriovenous access and expressed their strong preference for tunneled hemodialysis catheter. All had been educated about the risks and benefits of catheter, grafts, and fistulas. Patient preference was acknowledged and dialysis therapy was continued with tunneled hemodialysis catheter. Pregnancy was uneventful in two patients with the delivery of a healthy baby. The third patient had a miscarriage. Patient preference for tunneled hemodialysis catheter and satisfaction is important and can result in a successful outcome in pregnant patients. Nonetheless, in keeping with the National Kidney Foundation guidelines as well as the Fistula First, an arteriovenous fistula should be offered to hemodialysis patients. At the same time, patient's preference and wish should be respected and followed.

Non-tunneled versus tunneled dialysis catheters for acute kidney injury requiring renal replacement therapy: a prospective cohort study

Background

Acute kidney injury requiring renal replacement therapy (AKI-RRT) is associated with high morbidity, mortality and resource utilization. The type of vascular access placed for AKI-RRT is an important decision, for which there is a lack of evidence-based guidelines.

Methods

We conducted a prospective cohort study over a 16-month period with 154 patients initiated on AKI-RRT via either a non-tunneled dialysis catheter (NTDC) or a tunneled dialysis catheter (TDC) at an academic hospital. We compared differences in renal replacement delivery and mechanical and infectious outcomes between NTDCs and TDCs.

Results

Patients who received TDCs had significantly better RRT delivery, both with continuous venovenous hemofiltration (CVVH) and intermittent hemodialysis (IHD), compared to patients who received NTDCs; these findings were confirmed after multivariable adjustment for AKI-specific disease severity score, history of chronic kidney disease, renal consult team, and AKI cause. In CVVH and IHD, the median venous and arterial blood flow pressures were significantly higher with TDCs compared to NTDCs (p < 0.001). Additionally for CVVH, the median number of interruptions per catheter was higher with NTDCs compared to TDCs (Rate Ratio (RR) 2.7; p < 0.001), and for IHD, a higher median blood flow was seen with TDCs (p < 0.001). There were a significantly higher number of mechanical complications with NTDCs (RR 13.6 p = 0.001). No significant difference was observed between TDCs and NTDCs for positive blood cultures per catheter.

Conclusions

Compared to NTDCs, TDCs for patients with AKI-RRT had improved RRT delivery and fewer mechanical complications. Initial TDC placement for AKI-RRT should be considered when not clinically contraindicated given the potential for improved RRT delivery and outcomes.

Electronic supplementary material

The online version of this article (10.1186/s12882-017-0760-x) contains supplementary material, which is available to authorized users.

The Clinical and Economic Effect of Vascular Access Selection in Patients Initiating Hemodialysis with a Catheter

Patients in the United States frequently initiate hemodialysis with a central venous catheter (CVC) and subsequently undergo placement of a new arteriovenous fistula (AVF) or arteriovenous graft (AVG). Little is known about the clinical and economic effects of initial vascular access choice. We identified 479 patients starting hemodialysis with a CVC at a large medical center (during 2004-2012) who subsequently had an AVF (n=295) or AVG (n=105) placed or no arteriovenous access (CVC group, n=71). Compared with patients receiving an AVG, those receiving an AVF had more frequent surgical access procedures per year (1.01 [95% confidence interval, 0.95 to 1.08] versus 0.62 [95% confidence interval, 0.55 to 0.70]; P<0.001) but a similar frequency of percutaneous access procedures per year. Patients receiving an AVF had a higher median annual cost (interquartile range) of surgical access procedures than those receiving an AVG ($4857 [$2523-$8835] versus $2819 [$1411-$4274]; P<0.001), whereas the annual cost of percutaneous access procedures was similar in both groups. The AVF group had a higher median overall annual access-related cost than the AVG group ($10,642 [$5406-$19,878] versus $6810 [$3718-$13,651]; P=0.001) after controlling for patient age, sex, race, and diabetes. The CVC group had the highest median annual overall access-related cost ($28,709 [$11,793-$66,917]; P<0.001), largely attributable to the high frequency of hospitalizations due to catheter-related bacteremia. In conclusion, among patients initiating hemodialysis with a CVC, the annual cost of access-related procedures and complications is higher in patients who initially receive an AVF versus an AVG.

Dialysis-Related Parameters Influence Remodeling in the Venous Part of the Native Arteriovenous Fistula

BACKGROUND

The aim of this study was to evaluate the association of hemodynamic parameters related to hemodialysis and antropometric parameters of patients with changes in the venous part of the arteriovenous fistula (AVF) at points of needling.

METHODS

Two hundred forty-two hemodialysis (HD) patients (60.3% men), with median age 65 (interquartile range [IQR] 56-75) years, on HD treatment for a median of 49 (IQR 20-88) months with functioning fistula were recruited for the study. The history of vascular access, comorbidity, antropometric (body mass index, body surface area, and body composition), and dialysis-related parameters were analyzed. The cross-sectional area of upper extremity vessels were measured using ultrasound and included 2 points: A (arterial point for blood aspiration) and V (venous point for returning the blood after purification). The difference between A and V (A-V) was calculated.

RESULTS

The median cross-sectional area of A was larger than V (1.04 [IQR 0.58-1.7] vs. 0.74 cm² [IQR: 0.41-1.39], P <0.0001). The median difference between A and V (A-V) was 0.17 cm² and positively correlated with mean blood flow (Qb), effective Kt/V, and time of AVF use. Other analyzed factors had no influence on A-V. In the multivariate analysis, the independent factor increasing the difference (A-V) was mean blood flow measured during HD sessions.

CONCLUSIONS

The needling and utilization of AVF for hemodialysis may affect vein anatomy, namely causing dilatation at the arterial point and narrowing at venous point of AVF. We suggest that blood pump velocity of the dialysis machine may have an impact on these changes, but practical importance of these findings has to be elucidated. The significance of (A-V) factor in the prognosis of fistula complications should be further studied and confirmed in the prospective trials.

Factors associated with the receipt of antimicrobials among chronic hemodialysis patients

BACKGROUND

Antimicrobial use is common among patients receiving chronic hemodialysis (CHD) and may represent an important antimicrobial stewardship opportunity. The objective of this study is to characterize CHD patients at increased risk of receiving antimicrobials, including not indicated antimicrobials.

METHODS

We conducted a prospective cohort study over a 12-month period among patients receiving CHD in 2 outpatient dialysis units. Each parenteral antimicrobial dose administered was characterized as indicated or not indicated based on national guidelines. Patient factors associated with receipt of antimicrobials and receipt of ≥1 inappropriate antimicrobial dose were analyzed.

RESULTS

A total of 89 of 278 CHD patients (32%) received ≥1 antimicrobial doses and 52 (58%) received ≥1 inappropriately indicated dose. Patients with tunneled catheter access, a history of colonization or infection with a multidrug-resistant organism, and receiving CHD sessions during daytime shifts were more likely to receive antimicrobials (odds ratio [OR], 5.16; 95% confidence interval [CI], 2.72-9.80; OR, 5.43; 95% CI, 1.84-16.06; OR, 4.59; 95% CI, 1.20-17.52, respectively). Patients with tunneled catheter access, receiving CHD at dialysis unit B, and with a longer duration of CHD prior to enrollment were at higher risk of receiving an inappropriately indicated antimicrobial dose (incidence rate ratio, 2.23; 95% CI, 1.16-4.29; incidence rate ratio, 2.67; 95% CI, 1.34-5.35; incidence rate ratio, 1.11; 95% CI, 1.01-1.23, respectively).

CONCLUSIONS

This study of all types of antimicrobials administered in 2 outpatient dialysis units identified several important factors to consider when developing antimicrobial stewardship programs in this health care setting.

Transjugular Access for Endovascular Treatment of Immature Autogenous Arteriovenous Fistulae

PURPOSE

To assess the feasibility and outcome of transjugular access for endovascular treatment of immature arteriovenous fistulae (AVFs).

MATERIALS AND METHODS

Between August 2013 and January 2016, 90 patients (mean age, 64.5 y ± 12.8) underwent endovascular treatment of immature AVFs via transjugular access. The mean age of fistulae was 3.3 months ± 1.8. Total procedure time and technical and clinical success rates of endovascular procedures were assessed. Primary and secondary patency rates were calculated according to the Kaplan-Meier method, and complications were assessed.

RESULTS

All patients had inflow lesions, among which 19 (21.1%) had occlusions. The juxtaanastomotic segment was the most common site (44.3%). Transjugular access was successful in 83 patients (92.2%), and 7 required additional standard or transarterial access. The mean procedure time was 36.5 minutes. Technical and clinical success rates were 98.9% and 90.5%, respectively. Mean primary and secondary patency durations were 14.3 months ± 1.7 and 31.0 months ± 0.7, respectively. Primary patency rates at 3, 6, and 12 months were 84.4%, 67.3%, and 48.8%, respectively. Secondary patency rates at 6 and 18 months were 98.6% and 95.5%, respectively. Venous rupture occurred as a result of balloon inflation in 9 patients (10%), and was managed by balloon tamponade. There were no complications related to transjugular access during a mean follow-up period of 12.6 months.

CONCLUSIONS

Transjugular access for angioplasty of immature AVFs is feasible and safe. Potential problems associated with access in the outflow vein could be avoided by transjugular access.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Clinical Outcomes of Cryopreserved Arterial Allograft Used as a Vascular Conduit for Hemodialysis

This single center cohort study aimed to test the hypothesis that use of a cryopreserved arterial allograft could avoid the maturation or healing process of a new vascular access and to evaluate the patency of this technique compared with that of vascular access using a prosthetic graft. Between April 2012 and March 2013, 20 patients underwent an upper arm vascular access using a cryopreserved arterial allograft for failed or failing vascular accesses and 53 using a prosthetic graft were included in this study. The mean duration of catheter dependence, calculated as the time interval from upper arm access placement to removal of the tunneled central catheter after successful cannulation of the access, was significantly longer for accesses using a prosthetic graft than a cryopreserved arterial allograft (34.4 ± 11.39 days vs. 4.9 ± 8.5 days, P < 0.001). In the allograft group, use of vascular access started within 7 days in 16 patients (80%), as soon as from the day of surgery in 10 patients. Primary (unassisted; P = 0.314) and cumulative (assisted; P = 0.673) access survivals were similar in the two groups. There were no postoperative complications related to the use of a cryopreserved iliac arterial allograft except for one patient who experienced wound hematoma. In conclusion, upper arm vascular access using a cryopreserved arterial allograft may permit immediate hemodialysis without the maturation or healing process, resulting in access survival comparable to that of an access using a prosthetic graft.

The importance of success prediction in angioaccess surgery

Access to the circulation is an "Achilles' heel" of chronic hemodialysis. According to the current guidelines, autologous arteriovenous fistula is the best choice available. However, the impossibility of immediate use and the high rate of non-matured fistulas place fistula far from an ideal hemodialysis vascular access. The first attempt at constructing an angioaccess should result in functional access as much as possible. After failed attempts, patients and nephrologists lose their patience and confidence, which results in high percentage of central venous catheter use. Predictive models could help, but clinical judgment still remains crucial. Early referral to the nephrologist and vascular access surgeon, careful preoperative examinations, preparation of patients and duplex sonography mapping of the vessels are very important in the preoperative stage. In the operative stage, it is crucial to understand that angioaccess procedures should not be considered as minor procedures and these operations must be performed by surgeons with demonstrable interest and experience. In the postoperative stage, appropriate surveillance of the maturation process is also important, as well as good cannulation skills of the dialysis staff. The purpose of this review article is to stress the importance of success prediction in order to avoid unsuccessful attempts in angioaccess surgery.

Outcomes of arteriovenous fistulas and grafts with or without intervention before successful use

OBJECTIVE

Arteriovenous fistulas (AVFs) are considered superior to arteriovenous grafts (AVGs) because of longer secondary patency after successful cannulation for dialysis. We evaluated whether access interventions before successful cannulation affect the relative longevity of AVFs and AVGs after successful use.

METHODS

This retrospective study of a prospective database identified patients who initiated dialysis with a catheter and subsequently had a permanent access (289 AVFs and 310 AVGs) placed between January 1, 2006, and December 31, 2011, and were successfully cannulated for dialysis at a large medical center. Patients were monitored until June 30, 2014, and we evaluated the clinical outcomes (secondary patency and frequency of interventions) of the vascular accesses.

RESULTS

An intervention before successful cannulation was required more frequently with AVFs than with AVGs (50.5% vs 17.7%; odds ratio, 4.74; 95% confidence interval [CI], 3.26-6.86; P < .0001). Compared with AVFs that matured without interventions, those that required intervention had shorter secondary patency after successful cannulation (hazard ratio, 1.84; 95% CI, 1.30-2.60; P < .0001) and required more interventions per year after successful use (rate ratio [RR], 1.81; 95% CI, 1.49-2.20; P < .0001). Similarly, AVGs that required intervention before successful cannulation had shorter secondary patency than those without prior intervention (odds ratio, 1.98; 95% CI, 1.52-4.02; P < .0001) and required more interventions per year after successful use (RR, 1.49; 95% CI, 1.27-1.74; P < .0001). AVFs requiring intervention before maturation had inferior secondary patency compared with AVGs that were cannulated without prior intervention (hazard ratio, 1.45; 95% CI, 1.08-2.01; P = .01), but required fewer annual interventions after successful use (RR, 0.57; 95% CI, 0.49-0.66; P < .0001).

CONCLUSIONS

The patency advantage of AVFs over AVGs is no longer evident in patients requiring an AVF intervention before successful cannulation, but the AVFs require fewer interventions after successful use.

Accessory Vein Obliteration for Early Fistula Failure: A Myth or Reality?

Early fistula failure (EFF) is a significant clinical problem causing lower rates of arteriovenous fistulae (AVFs) use in patients with ESRD on hemodialysis. The 2 main factors amenable to treatment and widely accepted to cause EFF are stenosis anywhere in the AVF circuit and/or presence of accessory vein (av). The role of stenotic lesions in causing EFF and their treatment options are relatively better defined with clear guidelines. On the other hand, assessing the significance of an av in causing EFF and the indications for its treatment seem to lack scientific recommendations based on robust clinical data. In this article, we review the pathophysiology of EFF as pertains to the presence of av's. Current recommendations for obliteration of av, the available techniques and the evidence to support current clinical practice are discussed. The possible cons of av obliteration are highlighted, while newer concepts and the need for future clinical trials are addressed.

Provider Visits and Early Vascular Access Placement in Maintenance Hemodialysis

Medicare reimbursement policy encourages frequent provider visits for patients with ESRD undergoing hemodialysis. We hypothesize that patients seen more frequently by their nephrologist or advanced practitioner within the first 90 days of hemodialysis are more likely to undergo surgery to create an arteriovenous (AV) fistula or place an AV graft. We selected 35,959 patients aged ≥67 years starting hemodialysis in the United States from a national registry. We used multivariable regression to evaluate the associations between mean visit frequency and AV fistula creation or graft placement in the first 90 days of hemodialysis. We conducted an instrumental variable analysis to test the sensitivity of our findings to potential bias from unobserved characteristics. One additional visit per month in the first 90 days of hemodialysis was associated with a 21% increase in the odds of AV fistula creation or graft placement during that period (95% confidence interval, 19% to 24%), corresponding to an average 4.5% increase in absolute probability. An instrumental variable analysis demonstrated similar findings. Excluding visits in months when patients were hospitalized, one additional visit per month was associated with a 10% increase in odds of vascular access surgery (95% confidence interval, 8% to 13%). In conclusion, patients seen more frequently by care providers in the first 90 days of hemodialysis undergo earlier AV fistula creation or graft placement. Payment policies that encourage more frequent visits to patients at key clinical time points may yield more favorable health outcomes than policies that operate irrespective of patients' health status.

Effectiveness of collateral vein embolization for salvage of immature native arteriovenous fistulas

PURPOSE

To investigate the value of collateral vein embolization (CVE) as a salvage treatment for nonmaturing native arteriovenous fistulae (AVFs) in patients requiring hemodialysis.

MATERIALS AND METHODS

A total of 49 patients undergoing CVE (N = 65) for immature native AVFs at a single institution were reviewed. The study included 42 patients treated by 56 embolizations. Average fistula age at time of intervention was 18.2 weeks. Each patient underwent angiographic evaluation for fistula immaturity, with clinical success defined by initiation of single-session hemodialysis through the native fistula.

RESULTS

Fistula maturity was achieved in 32 of 42 patients (76.2%). No major complications occurred. Average time from CVE to fistula maturity was 38.4 days. Angioplasty done with CVE was found in a statistically higher percentage of patients with fistula success versus failure (31.3% vs 8.3%; P = .039). Radiocephalic fistulae were seen in a higher percentage of fistula failures compared with successes, but the results were not statistically significant (83.3% vs 59.4%; P = .054). Thirty-four patients underwent CVE without angioplasty, which resulted in successful fistula maturation in 22 cases (64.7%). Radiocephalic fistulae were again seen in a higher percentage of fistula failures compared with successes, but the findings did not meet statistical significance (81.8% vs 54.5%; P = .052).

CONCLUSIONS

Coil embolization of competing collateral vessels as a salvage treatment for nonfunctioning autologous AVFs is a viable treatment option in the majority of patients. Patients with radiocephalic fistulae may be at higher risk for primary fistula failure, but the present data are inconclusive.

Accessory vein obliteration criteria for immature fistulae: a modest proposal for an old paradigm

Venous stenosis and/or presence of accessory vein (av) are the two most common causes of early fistula failure. While treatment of stenosis is better defined, there are no clear criteria for obliteration of the av. Often, interventionalists rely on visual assessment of flow through the av and its diameter (significant if > 1/3 of the main fistula diameter) for intervention. The purpose of this study was to establish objective criteria for the management of av. Various computational fluid dynamics simulations were performed to analyze blood flow in the arteriovenous fistula (AVF). av of different diameters and angles was then added at various locations in the AVF and comparison of simulation results was undertaken. The computational model revealed that when the av was 33% of the diameter of the AVF, flow in av was only 7%. When diameter of the av was increased to 50% and 66% of the diameter of the AVF, flow through the av was 10% and 31% of the flow in main AVF, respectively. Location or angle of take-off of av did not alter flow. This report provides objective information regarding criteria for av obliteration. It needs to be further validated in randomized clinical trials.

Factors predicting failure of AV "fistula first" policy in the elderly

An arteriovenous fistula (AVF) is the preferential hemodialysis (HD) access. The goal of this study was to identify factors associated with pre-dialysis AVF failure in an elderly HD population. We used United States Renal Data System + Medicare claims data to identify patients ≥ 67 years old who had an AVF as their initial vascular access placed pre-dialysis. Failure of the AVF to be used for initial HD, was used as the outcome. Logistic regression model was used to identify factors associated with AVF failure. The study cohort consisted of 20,360 subjects (76.2 ± 6.02 year old, 58.5% men). Forty-eight percent of patients initiated dialysis using an AVF, while 52% used a catheter or an AVG. The following variables found to be associated with AVF failure when an AVF was created at least 4 months pre-HD initiation: older age (odds ratio [OR] 1.01; 95% confidence interval [CI] 1.00-1.02), female gender (OR 1.69; 95% CI 1.55-1.83), black race (OR 1.41; 95% CI 1.26-1.58), history of diabetes (OR 1.22; 95% CI 1.06-1.39), cardiac failure (OR 1.26; 95% CI 1.15-1.37), and shorter duration of pre-end-stage renal disease (ESRD) nephrology care (OR for a nephrology care of less than 6 months prior to ESRD of 1.22 compared with a pre-ESRD nephrology follow up of more than 12 months; 95% CI 1.07-1.38). OR for AVF failure for the entire cohort showed similar findings. In an elderly HD population, there is an association of older age, female gender, black race, diabetes, cardiac failure and shorter pre-ESRD nephrology care with predialysis AVF failure.

Early Cannulation Prosthetic Graft (Flixene™) for Arteriovenous Access

Purpose

Preferred hemodialysis (HD) access is an autologous fistula. Vascular grafts are used in patients with vessels unsuitable to accomplish an arteriovenous fistula (AVF). It is recommended that most current grafts mature in situ for 2–3 weeks before being accessed. Graft complications occur because the structure was not designed for the trauma of repeated cannulation. This study graft has a different structure that enables early use. Its design minimizes weeping through the graft walls and is meant to endure repeated access, thus minimizing the use of HD catheters. The purpose of this study was to show that the Flixene™ graft can be safely placed in patients where fistulas have failed and can be cannulated in 24–72 hr, while maintaining patency rates similar to other polytetrafluoroethylene (PTFE) grafts on the market. Flixene™ configuration should also reduce the incidence of pseudoaneurysms and seromas.

Methods

A prospective two-center study placed 33 grafts in 33 patients; graft efficacy, post-operative complications, and patency were evaluated. Ease of cannulation and dialysis center complications related to early cannulation were documented. Six month follow-up data was analyzed.

Results

Successful access was achieved in all 33 patients within 72 hr (29 patients within 24 hr). Overall primary patency at 6 months was 49%; primary-assisted patency at 6 months was 80%. No pseudoaneurysms or seromas were documented at 6 months. Complications were typical of graft access.

Conclusion

Early cannulation was successful in all patients. Primary and secondary patency rates at 6–months were equivalent to other data reported on PTFE grafts. Flixene™ successfully prevented pseudoaneurysm and seroma formation at 6 months of prospective follow-up. This graft is a better last-resort option for patients who cannot receive a fistula, compared to double-lumen cuffed catheters.

Randomized controlled trial of clopidogrel to prevent primary arteriovenous fistula failure in hemodialysis patients

The optimal vascular access for chronic maintenance hemodialysis is the arteriovenous fistula (AVF). Several studies suggest a role for antiplatelet agents in the prevention of primary AVF failure. A double-blind, randomized trial was conducted to assess the efficacy and safety of clopidogrel in hemodialysis patients. Ninety three patients were randomized to receive 75 mg/daily of clopidogrel or placebo. The treatment was initiated 7–10 days prior to scheduled access surgery and continued up to six weeks postoperatively, and then patients were monitored for six months. The primary outcome was AVF failure eight weeks after fistula creation. With a permuted block randomization schedule, 46 patients received clopidogrel and 47 patients received control placebo. The primary AVF failures at two months were 21.6% in placebo group and 5.2% in clopidogrel group (P = 0.03). The hazard ratio for the incidence of primary AVF failure was 0.72 (CI 95%, 0.41–1.01). Analysis of covariables indicated that this effect occurred principally as a result of clopidogrel administration. First hemodialysis from newly created AVF in clopidogrel group was significantly more successful than placebo group (P = 0.008). No life-threatening adverse event or severe bleeding was recorded in both groups. Clopidogrel seems to be effective and safe for prevention of primary AVF failure in hemodialysis patients.

Decreased cumulative access survival in arteriovenous fistulas requiring interventions to promote maturation

BACKGROUND AND OBJECTIVES

New arteriovenous fistulas (AVF) are frequently unsuitable for hemodialysis because of AVF nonmaturation. Aggressive endovascular or surgical interventions are often undertaken to salvage nonmaturing AVFs. The effect of early interventions to promote AVF maturation on subsequent long-term AVF outcomes is unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We evaluated 173 hemodialysis patients from two academic centers who received a new AVF. Of these, 96 (56%) required no further intervention, 54 (31%) required one intervention, and 23 (13%) required two or more interventions to achieve suitability for dialysis. We calculated AVF survival and frequency of postmaturation interventions in each group.

RESULTS

Cumulative AVF survival (access cannulation to permanent failure) in patients with two or more versus one versus zero interventions before maturation was 68% versus 78% versus 92% at 1 year, 57% versus 71% versus 85% at 2 years, and 42% versus 57% versus 75% at 3 years. Using Cox regression analysis with interventions before maturation, age, sex, race, diabetes, peripheral vascular disease, access site, and obesity in the model, intervention before maturation (two or more) was the only factor associated with cumulative AVF survival. The number of interventions required to maintain patency after maturation was 3.51 ± 2.20 versus 1.37 ± 0.31 versus 0.76 ± 0.10 per year in patients with two or more versus one versus zero interventions before maturation.

CONCLUSIONS

Compared with AVF that mature without interventions, AVF that require interventions have decreased cumulative survival and require more interventions to maintain their patency for hemodialysis.

Who should be referred for a fistula? A survey of nephrologists

BACKGROUND

There is marked variation in the use of the arteriovenous fistula (AVF) across programmes, regions and countries not explained by differences in patient demographics or comorbidities. The lack of clear criteria of who should or should not get a fistula may contribute to this, as well as barriers to creating AVFs.

METHODS

We conducted a survey of Canadian and American nephrologists to assess the patient variables considered to determine the timing and type of access requested. Perceived barriers and absolute contraindications to access were also collected.

RESULTS

An immediate referral for a fistula was more highly preferred when patients are <65 years old, have minimal comorbidities or have no history of failed accesses. In older patients, and in those with increased comorbidities or a previously failed fistula, US nephrologists selected arteriovenous grafts as an alternative to the fistula, while Canadian nephrologists selected primarily catheters. Referral for vascular mapping was more common in the USA than in Canada. Gender did not influence the timing or the type of access. Perceived barriers to establishing a mature fistula included patient refusal for creation (77%) or cannulation (58%), delay in decision regarding dialysis modality (71%), wait time for surgical creation (55%) and high failure-to-mature rate (52%). We found that 27% of Canadian and 43% of American nephrologists indicated no absolute contraindications for permanent vascular access.

CONCLUSIONS

This study demonstrated marked variability in timing and criteria used to select patients for referral for a vascular access between nephrologists practicing within Canada and the USA. Establishing minimal eligibility criteria for fistulae is an important area of future research.