Vascular access today

Long-term outcomes following thrombolysis of arteriovenous grafts

BACKGROUND

Thrombolysis for arteriovenous grafts (AVG) yields high technical success rates, however, long-term outcomes are unclear. We conducted a multicenter retrospective cohort study to analyze 5-year patency rates following AVG thrombolysis.

METHODS

All patients who underwent AVG thrombolysis between 2005 and 2015 at three academic hospitals were included. Prospectively maintained institutional nephrology and radiology databases were used to record demographic, clinical, and AVG characteristics. The primary outcome was primary patency, defined as AVG access survival without re-intervention including angioplasty ± stent with/without re-thrombolysis. Secondary outcomes were assisted primary patency and cumulative patency, defined as AVG access survival until re-thrombosis requiring re-thrombolysis or abandonment, respectively. Technical success was defined as restoration of flow with <30% residual stenosis. Patients were followed until 2017. Patency rates were assessed using Kaplan-Meier survival analysis and Cox proportional hazards were calculated to determine associations between covariates and patency loss.

RESULTS

Seventy-four patients underwent AVG thrombolysis during the study period with a median follow-up period of 21.4 (IQR 8.3-42.8) months. The average age was 58.6 years with a high rate of comorbidities, including hypertension (82.4%) and diabetes (54.1%). Thrombolysis technical success was 96%. There were 147 re-interventions in 46 patients, of which 98 were re-thrombolysis (mean re-intervention rate of 1.27/patient/year). Primary patency at 1, 3, and 5 years were 43.2%, 20.2%, and 7.7%. Assisted primary patency at 1, 3, and 5 years were 47.5%, 20.2%, and 7.7%. Cumulative patency at 1, 3, and 5 years were 75.0%, 38.8%, and 22.6%. Cox proportional hazards analysis demonstrated no associations between demographic, clinical, and procedural characteristics and patency rates.

CONCLUSIONS

Despite a high technical success rate, thrombolysis for AVG dysfunction is associated with poor long-term patency. Future studies are needed to determine risk factors for re-thrombosis to identify patients who will benefit from AVG thrombolysis in the long-term.

The reasons for comparative effectiveness clinical trials of arteriovenous fistula versus graft strategy in older adults on hemodialysis with a catheter

Clinicians and patients are guided by observational studies to make one of the most consequential decisions for patients with advanced kidney disease: the selection of the "right" hemodialysis vascular access. More than a decade ago, a call for randomized clinical trials was made to equitably compare clinical outcomes between arteriovenous (AV) fistulas (AVFs) and AV grafts (AVGs). Mounting evidence suggests that trade-offs between AVF- and AVGrelated outcomes are context dependent. In this article, we summarize four streams of evidence that collectively underpin the burden of equipoise between the two types of AV access in older adults with comorbidities who are on hemodialysis with a central venous catheter.

Acute hemodialysis catheter follows the path of least resistance

The placement of large bore double-lumen catheters for hemodialysis (HD) is one of the most frequent procedures performed in HD patients. However, these procedures are associated with complications, the most common being catheter malposition. In this context, catheter deviation to the left superior intercostal vein (LISV) is a very uncommon malposition, which must be differentiated from intrathoracic extravascular catheter lodgment. We report a case of an adult male patient on hemodialysis who presented with a thrombosed arteriovenous fistula and requiring urgent HD. His past medical history included hemophilia, allergy to contrast media, and multiple previous central vein catheterizations. A non-tunneled HD catheter was placed without any difficulty in the left internal jugular vein. However, the arterial lumen failed to pull any blood with free flow in the venous lumen. A chest X-ray revealed a surprising finding. The malpositioned catheter was removed successfully without any complications.

Study protocol of a randomized controlled trial of fistula vs. graft arteriovenous vascular access in older adults with end-stage kidney disease on hemodialysis: the AV access trial

BACKGROUND

Treatment of end-stage kidney disease (ESKD) with hemodialysis requires surgical creation of an arteriovenous (AV) vascular access-fistula (AVF) or graft (AVG)-to avoid (or limit) the use of a central venous catheter (CVC). AVFs have long been considered the first-line vascular access option, with AVGs as second best. Recent studies have suggested that, in older adults, AVGs may be a better strategy than AVFs. Lacking evidence from well-powered randomized clinical trials, integration of these results into clinical decision making is challenging. The main objective of the AV Access Study is to compare, between the two types of AV access, clinical outcomes that are important to patients, physicians, and policy makers.

METHODS

This is a prospective, multicenter, randomized controlled trial in adults ≥ 60 years old receiving chronic hemodialysis via a CVC. Eligible participants must have co-existing cardiovascular disease, peripheral arterial disease, and/or diabetes mellitus; and vascular anatomy suitable for placement of either type of AV access. Participants are randomized, in a 1:1 ratio, to a strategy of AVG or AVF creation. An estimated 262 participants will be recruited across 7 healthcare systems, with average follow-up of 2 years. Questionnaires will be administered at baseline and semi-annually. The primary outcome is the rate of CVC-free days per 100 patient-days. The primary safety outcome is the cumulative incidence of vascular access (CVC or AV access)-related severe infections-defined as access infections that lead to hospitalization or death. Secondary outcomes include access-related healthcare costs and patients' experiences with vascular access care between the two treatment groups.

DISCUSSION

In the absence of studies using robust and unbiased research methodology to address vascular access care for hemodialysis patients, clinical decisions are limited to inferences from observational studies. The goal of the AV Access Study is to generate evidence to optimize vascular access care, based on objective, age-specific criteria, while incorporating goals of care and patient preference for vascular access type in clinical decision-making.

TRIAL REGISTRATION

This study is being conducted in accordance with the tenets of the Helsinki Declaration, and has been approved by the central institutional review board (IRB) of Wake Forest University Health Sciences (approval number: 00069593) and local IRB of each participating clinical center; and was registered on Nov 27, 2020, at ClinicalTrials.gov (NCT04646226).

The predictors of catheter-related bloodstream infections in patients undergoing hemodialysis: A single center experience

BACKGROUND

Here we aimed to investigate the predictors of catheter-related bloodstream infections (CRBSI) in patients with acute kidney injury or chronic kidney disease who required renal replacement therapy through a non-tunneled hemodialysis catheter.

METHODS

A total of 111 patients who received non-tunneled hemodialysis catheters were retrospectively evaluated. Patients were divided into two groups; those who developed CRBSI and those who did not. Patient's demographic data, laboratory results at admission, information regarding catheter infections, and culture results were obtained from electronic medical records.

RESULTS

The mean age of the patients was 64 ± 16 years, and 51 of them were male. CRBSI occurred in 14 patients (12.6%). Admission serum albumin level (OR: 0.119, 95% CI: 0.019-0.756, p = 0.024), admission mean platelet volume (OR: 2.207, 95% CI: 1.188-4.100, p = 0.012) and catheter duration (OR: 1.580, 95% CI: 1.210-2.064, p = 0.001) were independent predictors for the CRBSI development. ROC curve analysis demonstrated that a catheter duration of 22 days was predictive for presence of CRBSI (78% sensitivity, 76% specificity, AUC: 0.825, 95% CI: 0.724-0.925, p < 0.001).

CONCLUSIONS

Prolonged catheter duration, low serum albumin, and high mean platelet volume independently predict the development of CRBSI in patients undergoing hemodialysis for acute kidney injury or chronic kidney disease.

Nanofiber-coated, tacrolimus-eluting sutures inhibit post-operative neointimal hyperplasia in rats

Post-operative complications of vascular anastomosis procedures remain a significant clinical challenge and health burden globally. Each year, millions of anastomosis procedures connect arteries and/or veins in vascular bypass, vascular access, organ transplant, and reconstructive surgeries, generally via suturing. Dysfunction of these anastomoses, primarily due to neointimal hyperplasia and the resulting narrowing of the vessel lumen, results in failure rates of up to 50% and billions of dollars in costs to the healthcare system. Non-absorbable sutures are the gold standard for vessel anastomosis; however, damage from the surgical procedure and closure itself causes an inflammatory cascade that leads to neointimal hyperplasia at the anastomosis site. Here, we demonstrate the development of a novel, scalable manufacturing system for fabrication of high strength sutures with nanofiber-based coatings composed of generally regarded as safe (GRAS) polymers and either sirolimus, tacrolimus, everolimus, or pimecrolimus. These sutures provided sufficient tensile strength for maintenance of the vascular anastomosis and sustained drug delivery at the site of the anastomosis. Tacrolimus-eluting sutures provided a significant reduction in neointimal hyperplasia in rats over a period of 14 days with similar vessel endothelialization in comparison to conventional nylon sutures. In contrast, systemically delivered tacrolimus caused significant weight loss and mortality due to toxicity. Thus, drug-eluting sutures provide a promising platform to improve the outcomes of vascular interventions without modifying the clinical workflow and without the risks associated with systemic drug delivery.

Are continued policies of prioritizing native vascular access in patients on hemodialysis programs useful?

The guidelines recommend establishing native vascular access as opposed to prosthetic or catheter-based access despite information relating to its effectiveness being scarce from a patient-orientated perspective. We analyzed the effectiveness of a continued policy of native vascular access (CPNVA) in patients undergoing hemodialysis. A retrospective, observational study, including 150 patients undergoing hemodialysis between 2006 and 2012 at our center, and who underwent a CPNVA. Statistical analysis was based on treatment intention. In 138 patients (92%), the first useful access (FUA) was native, and in 12 patients (8%), it was prosthetic. In 50 patients (33.3%), more than one procedure had to be carried out in to order to achieve FUA. The probability of dialysis occurring via a FUA was 67.1% and 45.3% at 1 and 5 years respectively. Over the follow-up period (mean time = 30 months), 84 patients (56%) required repairs or new access, extending the effectiveness of the CPNVA to 88.3% and 73.2% at 1 and 5 years respectively. The effectiveness of the CPNVA was reduced if the patient: required a catheter initially (HR: 3.6, p = 0.007); in cases of initially elevated glomerular filtration rate (HR: 1.1, p = 0.040); in cases of history of previous access failure before FUA (HR: 3.9, p = 0.001); and in female patients (HR: 2.4, p = 0.031). The long-term effectiveness of a CPNVA is high. However, the percentage of patients requiring diverse procedures in order to achieve FUA and the need for re-interventions yield the necessity to optimize preoperative evaluation and postoperative follow-up.

Simple thrombin-based method for eliminating fibrinogen interference in serum protein electrophoresis of haemodialysed patients

Introduction

Serum samples of haemodialysed patients collected through vascular access devices, e.g. central venous catheter (CVC) can contain residual heparin, which can cause incomplete clotting and consequently fibrinogen interference in serum protein electrophoresis (SPE). We hypothesized that this problem may be overcome by addition of thrombin and aimed to find a simple thrombin-based method for fibrinogen interference removal.

Materials and methods

Blood samples of 51 haemodialysed patients with CVC were drawn through catheter into Clot Activator Tube (CAT) and Rapid Serum Tube Thrombin (RST) vacutainers (Becton Dickinson, New Jersey, USA) following the routine hospital protocols and analysed with gel-electrophoresis (Sebia, Lisses, France). Samples were redrawn in the CAT tubes and re-analysed after being treated with thrombin using two methods: transferring CAT serum into RST vacutainer and treatment of CAT serum with fibrinogen reagent (Multifibren U, Siemens, Marburg, Germany).

Results

Direct blood collection in RST proved to be slightly more efficient than CAT in removing the interfering band in beta fraction (CAT removed 6/51 and RST removed 12/51, P = 0.031). Transferring CAT serum into the RST vacutainer proved to be more efficient for subsequent removal of interfering band from CAT serum than the addition of fibrinogen reagent (39/45 vs. 0/45 samples with efficiently removed interfering band, P < 0.001).

Conclusion

Fibrinogen interference caused by incomplete clotting because of residual heparin can be overcome by addition of thrombin. Transferring CAT serum into the RST vacutainer was the most efficient method.

The diagnostic value of duplex ultrasound in detecting the presence and location of a stenosis in an autologous arteriovenous fistula

OBJECTIVE

To determine the value of duplex ultrasound in the detection of significant (⩾50%) stenosis and the location of the stenosis in arteriovenous fistula, compared to angiography.

METHODS

Patients who underwent construction of an autologous arteriovenous fistula between January 2007 and December 2013 in Treant Care Group, hospital location Emmen, were included in this study. In all patients with a significantly decreased blood flow (flow <400 mL/min and/or ⩾20% decrease) measured by Transonic flowmeter before December 2016, duplex ultrasound was performed. Concordance between duplex ultrasound and angiography was analysed in all patients with a haemodynamically significant stenosis detected by duplex ultrasound.

RESULTS

In all, 63 patients had a significant decrease in blood flow leading to duplex ultrasound. In 51 (80.9%) of the 63 duplex ultrasound, a haemodynamically significant stenosis was detected. In 45 (88.2%) of these, angiography was performed, all confirming the presence of significant stenosis. In eight patients, no angiography was performed (sufficient residual blood flow (n = 7), death (n = 1)). Most stenoses were located in the venous outflow tract (75.6%). In 95.6%, a venous approach was possible during angiography. After intervention, a significant increase in blood flow was observed (from 530 mL/min to 910 mL/min (p < 0.001)).

CONCLUSION

We show that duplex ultrasound is likely reliable to ascertain the presence of arteriovenous fistula stenosis in addition to flow criteria. Also, it provides important information to select the most effective and safe approach for cannulation. Duplex ultrasound may reduce costs and burden of diagnosing stenoses.

New insertion support device assisted the accurate placement of tunneled cuffed catheter: First experience of 10 cases

INTRODUCTION

The tunneled cuffed catheter is used in hemodialysis patients for whom an arteriovenous fistula or arteriovenous graft is not suitable or for bridging usage of them. Accurate placement of a tunneled cuffed catheter is necessary for safe hemodialysis, but placement is sometimes difficult because of individual body differences. We developed a new device to support accurate placement of the tunneled cuffed catheter. In this study, we report our first clinical experience of the device.

METHODS

We made the device by expanded polytetrafluoroethylene with some special processes. The processes enable it to maintain plasticity and temporary shape in the autoclaved condition. The device is laid on the surface of the patient's body to mark the root of the catheter with a felt-tipped marker before catheterization. That enables us to know the accurate catheter root and tunneled cuffed catheter exit site on the body surface. Ten patients underwent tunneled cuffed catheter insertion according to the marking.

CASE DESCRIPTION

The mean age was 71.3 ± 12.8 years. The tunneled cuffed catheter was safely placed according to the marking in all patients, and all catheter tips were placed in the right atrium. The mean verification tip location difference before and after catheterization was 0.70 ± 0.48 cm. This result indicated that the device could assist in inserting a catheter accurately within an error of 1.18 cm. The tunneled cuffed catheters were patent in all the cases, without replacement and complications until the end of bridging use or during the observation period.

CONCLUSION

Our newly developed insertion support device enhances safety and prevents catheter waste during replacement.

A comparison of efficacy of endovascular versus surgical repair for the treatment of arteriovenous fistula stenosis in Taiwan

BACKGROUND

Percutaneous transluminal angioplasty (PTA) and fistula reconstruction surgery are therapeutic options for vascular access occlusion in hemodialysis patients. However, owing to its convenience, PTA has gradually become the preferred therapeutic option for fistula stenosis or occlusion. This study investigated the effects of the two therapeutic methods on the vascular access maintenance duration (number of days) and maintenance costs of fistula in dialysis patients from different dialysis units.

METHODOLOGY

In this study, 544 hemodialysis patients from 2 dialysis units in a teaching hospital in the southern area of Taiwan were included in the analysis of the frequency of PTA or revascularization surgery and the use of related medical resources by conducting a retrospective chart review.

RESULTS

The frequency of PTA in the patients undergoing long-term hemodialysis was not significantly associated with their demographic characteristics. The efficacy of PTA has declined with shorter maintenance duration with increasing PTA frequency. The cost profile of PTA was more expensive than that of fistula revascularization surgery.

CONCLUSIONS

In this study, PTA was found to be just a temporary solution for fistula thrombosis, whereas fistula reconstruction surgery is inexpensive and improves survival time. Therefore, dialysis units should establish an appropriate standard of care to avoid over-reliance on PTA in order to reduce the fistula failure rate, improve the dialysis efficacy, and reduce the psychological stress in patients, as well as to reduce the maintenance costs and rationalize the medical expenses.

Surveillance of Dialysis Events: one-year experience at 33 outpatient hemodialysis centers in China

A multicenter prospective surveillance on dialysis events was carried in 33 dialysis centers in China. Maintenance hemodialysis (HD) outpatients who were dialyzed on the first two days of each month during 2014 were monitored for dialysis events and other infections. During the one-year period, 52,680 patient-months were monitored. Fistula and tunneled or non-tunneled central line were used for 73.70%, 15.70% and 8.85% of vascular access, respectively. There were 773 dialysis events occurred in 671 patients including 589 IV antimicrobial starts, 74 positive blood cultures and 110 local access site infections (LASI). The incidence of dialysis events was 1.47 per 100 patient-months. Among the 74 cases with bloodstream infection (BSI), 38 were access-related BSI (ARB) and there were therefore 148 cases with vascular-related infection (VAI; 38 ARB and 110 LASI). There were 740 cases (1.40 per 100 patient-months) with infections other than BSI and LASI, most (79.19%) of which were respiratory tract infections. For those with dialysis events, there were 425 cases (425/671, 63.34%) admitted to hospital and 12 cases of death (12/671, 1.79%). In conclusion, the surveillance revealed a relatively low incidence of dialysis events and the surveillance may be tailored to target those using central lines in resource-limited settings.

Clinical results of biologic prosthesis: A systematic review and meta-analysis of comparative studies

Background

Biologic prosthesis (BP) has been reported as a safe alternative to polytetrafluoroethylene (PTFE) in vascular reconstruction. However, efficacy of BP remains controversial. We, therefore, conducted a systematic review to summarize previous available evidences comparing the BP and PTFE in terms of clinical outcomes.

Materials and methods

A literature search of the MEDLINE and Scopus was performed to identify comparative studies reporting outcomes of BP, PTFE, and/or autologous veins graft (VG) in vascular access for hemodialysis or femoropopliteal bypass. The outcome of interest was graft patency. Two reviewers independently extracted data. Meta-analysis with a random-effect model was applied to pool a risk ratio (RR) across studies.

Results

Among 584 articles identified, 11 studies (4 randomized controlled trials (RCT) and 7 cohorts) comprising 2627 patients were eligible for pooling. Seven studies compared BP with PTFE and 3 studies compared PTFE with VG. Among BP vs PTFE, pooling based on 3 RCTs yielded the pooled RR of 1.54 (95% CI: 1.10, 2.16), indicating 54% higher graft patency in VG than PTFE. Adding the 7 cohorts in this pooling yield similar results with the pooled RR of 1.29 (95% CI: 1.15, 1.45). The pooled RR of graft patency for BP vs VG was 0.74 (95% CI, 0.55, 1.00), indicating 26% lower graft patency in BP than VG.

Conclusions

Our first meta-analysis indicated that the biosynthetic prosthesis might be benefit over PTFE by increasing graft patency. An updated meta-analysis or a large scale randomized control trial is required to confirm this benefit.

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This study summarized the gap of knowledge of clinical outcome when compare with biologic prosthesis and PTFE.

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This first meta-analysis was shown clearly about results and high performance of study were collected.

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For the conclusion, high efficacy of alternative treatment was shown, however, further study needed to confirm the results.

Tunnelled haemodialysis catheter and haemodialysis outcomes: a retrospective cohort study in Zagreb, Croatia

OBJECTIVES

Studies have reported that the tunnelled dialysis catheter (TDC) is associated with inferior haemodialysis (HD) patient survival, in comparison with arteriovenous fistula (AVF). Since many cofactors may also affect survival of HD patients, it is unclear whether the greater risk for survival arises from TDC per se, or from associated conditions. Therefore, the aim of this study was to determine, in a multivariate analysis, the long-term outcome of HD patients, with respect to vascular access (VA).

DESIGN

Retrospective cohort study.

PARTICIPANTS

This retrospective cohort study included all 156 patients with a TDC admitted at University Hospital Merkur, from 2010 to 2012. The control group consisted of 97 patients dialysed via AVF. The groups were matched according to dialysis unit and time of VA placement. The site of choice for the placement of the TDC was the right jugular vein. Kaplan-Meier analysis with log-rank test was used to assess patient survival. Multivariate Cox regression analysis was used to determine independent variables associated with patient survival.

PRIMARY OUTCOME MEASURES

Patient survival with respect to VA.

RESULTS

The cumulative 1-year survival of patients who were dialysed exclusively via TDC was 86.4% and of those who were dialysed exclusively via AVF, survival was 97.1% (p=0.002). In multivariate Cox regression analysis, male sex and older age were independently negatively associated with the survival of HD patients, while shorter HD vintage before the creation of the observed VA, hypertensive renal disease and glomerulonephritis were positively associated with survival. TDC was an independent risk factor for survival of HD patients (HR 23.0, 95% CI 6.2 to 85.3).

CONCLUSION

TDC may be an independent negative risk factor for HD patient survival.

On Postoperative Day Balloon Angioplasty for Salvage of Newly-Placed, Flow-Limiting Native Arteriovenous Fistula

Purpose:

To report result and usefulness of immediate postoperative balloon angioplasty of de novo arteriovenous fistula (AVF) with limited flow just after creation.

Materials and Methods:

From January 1, 2012 to March 31, 2014, 1,270 patients received native AVF creations in a single vascular clinic. In twenty-four patients (1.9% of total AVF creation), immediate postoperative balloon angioplasty was performed because of limited flow on palpation (only pulsation or no thrill) just after AVF creation. Medical records were reviewed retrospectively; technical success (restoration of AVF flow)/clinical success (growing as functional AVF) rate, maturation time, primary patency rate and fistula survival outcome were analyzed during a mean 10.8 months of follow-up.

Results:

Technical/clinical success rate was 95.8% (23/24 cases); AVF flow was restored after balloon angioplasty, and all the flow-restorated AVFs grew as functional AVFs with mean±standard deviation, 4.5±1.5 weeks of maturation time. In seven (30.4%) patients, a secondary balloon angioplasty was needed to enhance maturation. The overall primary patency after immediate postoperative balloon angioplasty was 69.6% at 1 and 6 months and 59.0% at 12 months. There was 1 complication (operation site hematoma).

Conclusion:

Immediate postoperative balloon angioplasty for salvage of newly-placed, flow-limiting native AVF is a useful, effective and safe procedure.

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.