Association of risk stratification score with dialysis vascular access stenosis.

BACKGROUNDS: Clinical monitoring is the recommended standard for identifying dialysis access dysfunction; however, clinical monitoring requires skill and training, which is challenging for understaffed clinics and overburdened healthcare personnel. A vascular access risk stratification score was recently proposed to assist in detecting dialysis access dysfunction. PURPOSE: Our objective was to evaluate the utility of using vascular access risk scores to assess venous stenosis in hemodialysis vascular accesses. METHODS: We prospectively enrolled adult patients who were receiving hemodialysis through an arteriovenous access and who had a risk score ⩽3 (low-risk) or ⩾8 (high-risk). We compared the occurrence of access stenosis (>50% on ultrasonography or angiography) between low-risk and high-risk groups and assessed clinical monitoring results for each group. RESULTS: Of the 38 patients analyzed (18 low-risk; 20 high-risk), 16 (42%) had significant stenosis. Clinical monitoring results were positive in 39% of the low-risk and 60% of the high-risk group (p = 0.19). The high-risk group had significantly higher occurrence of stenosis than the low-risk group (65% vs 17%; p = 0.003). Sensitivity and specificity of a high score for identifying stenosis were 81% and 68%, respectively. The positive predictive value of a high-risk score was 65%, and the negative predictive value was 80%. Only 11 (58%) of 19 subjects with positive clinical monitoring had significant stenosis. In a multivariable model, the high-risk group had seven-fold higher odds of stenosis than the low-risk group (aOR = 7.38; 95% CI, 1.44-37.82; p = 0.02). Positive clinical monitoring results and previous stenotic history were not associated with stenosis. Every unit increase in the score was associated with 34% higher odds of stenosis (aOR = 1.34; 95% CI, 1.05-1.70; p = 0.02). CONCLUSIONS: A calculated risk score may help predict the development of hemodialysis vascular access stenosis and may provide a simple and reliable objective measure for risk stratification.

Considerations in Access Cannulation: Traditional and Evolving Approaches.

Needle cannulation of hemodialysis access is the soft underbelly of hemodialysis access care that has remained unchanged for a long time. Cannulation error results in complications such as infiltration, hematoma, subsequent revision procedures, and potential loss of hard-earned access. The "best" cannulation method is contingent upon access type and characteristics along with local expertise. The rope ladder technique of cannulation, characterized by successive rotation of puncture sites with each hemodialysis session, permits sufficient time for healing of prior cannulation sites, and reduction in complications such as bleeding, infection, and aneurysm development. A steeper needle angle, higher blood flow rates, and deep needle tip can lead to wall stress on the posterior wall and up to 10 cm from the needle cannulation site. Plastic cannulas provide a viable alternative to metallic needles; they have lower complications and a favorable cost-benefit ratio. There is lack of evidence to support an optimal arterial needle direction configuration. Needle injury may promote intimal thickening, but its effect on access outcomes is currently unknown. Percutaneous creation of arteriovenous fistula presents new challenges in dialysis access cannulation. Point-of-care ultrasound-guided cannulation will likely lead to a paradigm shift in access cannulation. Novel care delivery using cannulation stations is a promising development.

Post-anastomotic venous stenosis after Optiflow deployment: An unexpected outcome.

Arteriovenous fistula failure represents a major cause of hospitalization and a significant economic burden for end-stage renal disease patients on hemodialysis. The Optiflow (Bioconnect Systems Inc., Ambler, PA) is a new device developed to improve arteriovenous fistula outcomes and decrease failure rates by reducing the risk of stenosis and improving maturation rates. This case report describes a 50-year-old male with hypertensive nephropathy on dialysis who had multiple arteriovenous fistula failures in the past. He was scheduled to undergo brachiocephalic fistula construction using the Optiflow device. After 8 months of use, the new fistula developed a peri-anastomotic venous stenosis, just distal to the Optiflow device. To our knowledge, this is the first time such a complication has been reported.

Current Concepts in Hemodialysis Vascular Access Infections.

Infection-related causes are second only to cardiovascular events for mortality among end-stage renal disease patients. This review will provide an overview of hemodialysis catheter-, graft-, and fistula-related infections with emphasis on diagnosis and management in specific settings. Use of catheters at the initiation of dialysis has remained unchanged at 80%. Of all access-related bloodstream infections (BSIs), 70% occur in patients with catheters. The risk factors for BSIs in tunneled, cuffed catheters include the duration of the catheter, past catheter-related bacteremia, left-sided internal jugular vein catheters, hypoalbuminemia, and immunosuppression. Surprisingly, human immunodeficiency virus infection has not been associated with a higher risk of catheter-related bacteremia. Catheter-related bloodstream infection is a clinical definition that requires specific laboratory testing to identify the catheter as the source of the BSI. A central line-associated bloodstream infection is a primary BSI in a patient who had a catheter within the 48-h period before the development of the BSI with no other identifiable source. Guidewire exchange of catheter is a viable alternative in select patients to aid in preserving venous access sites. Catheter lock therapy can decrease infectious complications and mortality. Arteriovenous graft infections are prevalent with significant morbidity. Studies evaluating the impact of stent use in infection risks of the arteriovenous graft are sorely needed.

Sentinel vascular access monitoring after endovascular intervention predicts access outcome.

BACKGROUND AND OBJECTIVES: The vascular access pressure ratio test identifies dialysis vascular access dysfunction when three consecutive vascular access pressure ratios are >0.55. We tested whether the magnitude of the decline in vascular access pressure ratio 1-week post-intervention could alert of subsequent access failure. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: The retrospective study included all vascular access procedures at one institution from March 2014 to June 2016. Data included demographics, comorbidities, vascular access features, %ΔVAPR = ((Pre-Post)/Pre] × 100% assessed within the first 2 weeks post-percutaneous transluminal balloon angioplasty, time-to-next procedure, and patency. The log-rank test compared the area under the curve, receiver operating curve, Kaplan-Meier arteriovenous graft and arteriovenous fistula survival curves. A multivariable Cox proportional hazard (CP) model was used to determine the association of %ΔVAPR with access patency. RESULTS: Analysis of 138 subjects (females 51%; Black 87%) included 64 arteriovenous fistulas with 104 angioplasties and 74 arteriovenous grafts with 134 angioplasties. The area under the receiver operating characteristic curve for fistula failure at 3 months was 0.59, with optimal screening characteristics of 33.3%, sensitivity of 56.1%, and specificity of 63.2%. Arteriovenous fistula with <33.3% decline compared to >33.3% required earlier subsequent procedure (136 vs 231 days), lower survival on Kaplan-Meier analysis (P = 0.01), and twofold greater risk of failure (P = .006). Area under the receiver operating characteristic for arteriovenous graft failure at 3 months had a sensitivity of 52.3% and specificity of 67.4%. Arteriovenous graft with a post-intervention vascular access pressure ratio decline of <28.8% also required earlier subsequent procedure (144 vs 189 days), lower survival on Kaplan-Meier (P = 0.04), and a 59% higher risk for failure. The area under the receiver operating characteristic curve for combined access failure (arteriovenous fistula + arteriovenous graft) at 3 months had an optimal cut-point value of 31.2%, a sensitivity of 54.6%, and a specificity of 63.1%. Access with a <31.2% drop had a 62% increase in the risk of failure (hazard ratio 1.62; confidence interval 1.16, 2.27; P = 0.005). CONCLUSION: The magnitude of post-intervention reduction in vascular access pressure ratio provides a novel predictive measure of access outcomes.

How arteriovenous grafts could help to optimize vascular access management.

A one-size-fits-all approach to vascular access for dialysis may be prejudicial. Arteriovenous fistulae (AVF) have high primary failure, failure to mature rate, and late-stage complications making them unsuitable choice for many patients. Aging of population with chronic kidney disease (CKD) coupled with venous injury during CKD stages depletes suitable superficial veins for AVF creation. The National Institutes of Health consortium demonstrated the difficulty in attaining a functional AVF in hemodialysis patients. Recognition of flaws in AVF and the quest to reduce catheter use bring to the fore the benefits of arteriovenous grafts (AVG). Advances in catheter technologies, flow, care, and antibiotic locks have resulted in significant improvement in catheter-related infections. However, widespread recognition of catheter-related complications like central vein stenosis, metastatic infections, and exhaustion of venous access sites preclude their being a viable alternative to AVF, furthering the need to explore AVG as a substitute. Placement of "early cannulation" AVG is a catheter sparing option in patients who are likely to have inadequate fistula maturation. Advances in biohybrid technology and tissue-engineered grafts are providing a robust opportunity to develop biocompatible graft materials with minimal tissue reactivity and thrombogenicity. Xenografts (bovine carotid artery grafts) are proving to be comparable and, in many cases, better than conventional polytetrafluoroethylene material. Older age, dialysis dependence, and smaller vein size are related to the appropriateness of AVG creation. An individualized approach in selecting optimal upper extremity vascular access option using patient-specific factors while incorporating the benefits of an AVG would greatly aid in achieving low catheter usage in the dialysis population.

Coronal mode ultrasound guided hemodialysis cannulation: A pilot randomized comparison with standard cannulation technique.

BACKGROUND: Infiltrations from cannulation result in significant morbidity including loss of hemodialysis (HD) vascular access (VA). Cannulation is dependent on personnel skill and VA characteristics. Surface marking of VA lacks real-time information and traditional ultrasound (US) devices are large, expensive, requiring skilled operators. Sonic Window© (Analogic Ultrasound, Peabody, MA, USA) is a coronal mode ultrasound device (CMUD) approved for VA cannulation. METHODS: Single center randomized, prospective pilot study comparing handheld US-guided cannulation of new arteriovenous fistula (AVF) to standard cannulation practices. Patients with end stage renal disease (ESRD) on in-center HD who had a new AVF cleared for cannulation and dialysis were enrolled. Patients with new AVF received either standard cannulation (control group) or image guidance using CMUD (study group) for 3 weeks. Ultrasound characteristics of VA, cannulation practices and complications end points were obtained. RESULTS: An infiltration rate of 9.7% was noted during the study. Slightly lower odds ratio (OR) of infiltration was observed in the study group (OR 0.94, 95% CI: 0.26-3.41, P value = 0.93). Study group yielded longer time for assessment (101.8 ± 80.2 vs. 22.3 ± 22.5 seconds, P = < 0.001), increased cannulation time (41.1 ± 70.6 vs. 25.0 ± 27.9 seconds, P = 0.04), and increased patient satisfaction (94.6% vs. 82%, P = 0.04) compared to control group. Number of cannulation attempts, needle size, arterial or venous needle insertion, and tourniquet usage between groups were not statistically different. CONCLUSION: Handheld ultrasound is a safe and useful aid in cannulation of dialysis access.

Roxadustat (FG-4592): Correction of Anemia in Incident Dialysis Patients.

Safety concerns with erythropoietin analogues and intravenous (IV) iron for treatment of anemia in CKD necessitate development of safer therapies. Roxadustat (FG-4592) is an orally bioavailable hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor that promotes coordinated erythropoiesis through HIF-mediated transcription. We performed an open-label, randomized hemoglobin (Hb) correction study in anemic (Hb≤10.0 g/dl) patients incident to hemodialysis (HD) or peritoneal dialysis (PD). Sixty patients received no iron, oral iron, or IV iron while treated with roxadustat for 12 weeks. Mean±SD baseline Hb was 8.3±1.0 g/dl in enrolled patients. Roxadustat at titrated doses increased mean Hb by ≥2.0 g/dl within 7 weeks regardless of baseline iron repletion status, C-reactive protein level, iron regimen, or dialysis modality. Mean±SEM maximal change in Hb from baseline (ΔHb(max)), the primary endpoint, was 3.1±0.2 g/dl over 12 weeks in efficacy-evaluable patients (n=55). In groups receiving oral or IV iron, ΔHb(max) was similar and larger than in the no-iron group. Hb response (increase in Hb of ≥1.0 g/dl from baseline) was achieved in 96% of efficacy-evaluable patients. Mean serum hepcidin decreased significantly 4 weeks into study: by 80% in HD patients receiving no iron (n=22), 52% in HD and PD patients receiving oral iron (n=21), and 41% in HD patients receiving IV iron (n=9). In summary, roxadustat was well tolerated and corrected anemia in incident HD and PD patients, regardless of baseline iron repletion status or C-reactive protein level and with oral or IV iron supplementation; it also reduced serum hepcidin levels.

Vascular Access Creation and Care--Perspective From India.

India has one of the fastest growing economies in the world and is home to nearly one sixth of world's population. Chronic diseases such as diabetes mellitus and hypertension are common. Kidney disease is a known complication of these chronic diseases and is on the rise. Improving affordability with advanced care delivery has led to the increasing use of maintenance hemodialysis. Along with this hemodialysis comes the inevitable need for vascular access. Interventional nephrology in India is a fast-evolving discipline and promises to be a critical component of hemodialysis care in the future. This review provides a background on the current state of the CKD burden in India and the various vascular access options in use currently. In addition, we describe the experience of 2 centers in western and southern India in managing vascular access needs in hopes that they will serve as a model of the proliferation of vascular access care throughout India and in other developing countries.

Vascular access cannulation practices and outcomes.

Vascular access cannulation practices such as the dialysis prescription for blood pump flow and dialysis duration vary significantly among countries. Choice of needle gauge and cannulation practice with the needle in terms of direction relative to the flow stream and rotation after insertion are dictated in part by practicalities but appear to be mostly the result of 'cultural' practices within dialysis centers. Prospective studies of cannulation are needed to improve access outcomes.

Complications of arteriovenous fistulae: beyond venous stenosis.

Vascular access is the lifeline of hemodialysis patients. Currently, arteriovenous fistulae and grafts are considered permanent options for vascular access, and they share common access problems. The successful creation of a permanent vascular access depends on patient characteristics, vessel parameters, and possibly genetic factors. Utilization of a dialysis access at least 3 times a week leads to significant wear and tear of the access. The buttonhole technique is associated with a higher incidence of infection, and evidence regarding various perceived advantages remain contradictory. Infiltration and aneurysm formation of an access are common, and the literature on its impact on vascular access outcomes is limited. A patient who undergoes hemodialysis often requires multiple accesses during his or her lifetime, and the maintenance of a persistent vascular access may require creative solutions. Intensified research is crucial to comprehending the pathophysiology and treatment options for some of the common problems of vascular accesses.

Surveillance and monitoring of dialysis access.

Vascular access is the lifeline of a hemodialysis patient. Currently arteriovenous fistula and graft are considered the permanent options for vascular access. Monitoring and surveillance of vascular access are an integral part of the care of hemodialysis patient. Although different techniques and methods are available for identifying access dysfunction, the scientific evidence for the optimal methodology is lacking. A small number of randomized controlled trials have been performed evaluating different surveillance techniques. We performed a study of the recent literature published in the PUBMED, to review the scientific evidence on different methodologies currently being used for surveillance and monitoring and their impact on the care of the dialysis access. The limited randomized studies especially involving fistulae and small sample size of the published studies with conflicting results highlight the need for a larger multicentered randomized study with hard clinical end points to evaluate the optimal surveillance strategy for both fistula and graft.

Pulmonary hypertension in peritoneal dialysis patients.

The information available in the literature regarding pulmonary hypertension (PH) in peritoneal dialysis (PD) patients is limited. The objective of the present study was to examine the prevalence and characteristics of PH in PD patients. We retrospectively collected the clinical profile, echocardiographic (ECHO) findings, and biochemical data for 36 PD patients for which ECHO findings were available. We compared characteristics between patients with and without PH. We found PH, defined as pulmonary arterial pressure (PAP) > or = 35 mmHg, in 15 patients. The prevalence of PH was 42%. Mean age (+/- standard deviation) of the patients with and without PH was 58 +/- 15 years and 52 +/- 15 years respectively (p = 0.30). Mean PAP of the PH patients was 43.8 +/- 9.0 mmHg (range: 35-65 mmHg). Patients with PH had a lower ejection fraction than did patients without PH (46.3% +/- 19.8% vs. 56.5% +/- 11.8% respectively, p = 0.07). Patients with PH also had a higher prevalence of global hypokinesia (60% vs. 29%, p = 0. 059) and dilated left ventricular chamber (53% vs. 19%, p = 0.03). In PH patients, body mass index (24 +/- 4.5 kg/m2 vs. 28 +/- 5.0 kg/m2, p = 0.024), normalized protein catabolic rate (0. 78 +/- 0.21 g/kg vs. 0.95 +/- 0.27 g/kg daily, p = 0.049), and ferritin (226 +/- 210 ng/mL vs. 873 +/- 965 ng/mL, p = 0.005) were significantly lower and lactate dehydrogenase was higher (264 +/- 99 U/L vs. 206 +/- 79 U/L, p = 0.06) than in patients without PH. We observed no significant differences in race or sex, incidence of hypertension or cardiovascular disease, or vitamin D analog use between the two groups of patients. During the study period, 60% of PH patients and 38% of patients without PH died (p = 0.19). Values of PAP correlated directly with serum levels of phosphorus (r = 0.44, p = 0.02), CaxP product (r = 0.40, p = 0.04), and parathyroid hormone (r = 0.42, p = 0.03). Of continuous ambulatory PD and continuous cycling PD patients, 21% and 55% respectively had PH (p = 0. 049). In PD patients, PH is highly prevalent and may be associated with higher mortality risk.