Traditional and non-traditional strategies to optimize catheter function: go with more flow

Tunneled Hemodialysis Catheter Tip Design and Risk of Catheter Dysfunction: An Australian Nationwide Cohort Study

RATIONALE & OBJECTIVE

Hemodialysis catheter dysfunction is an important problem for patients with kidney failure. The optimal design of the tunneled catheter tip is unknown. This study evaluated the association of catheter tip design with the duration of catheter function.

STUDY DESIGN

Observational cohort study using data from the nationwide REDUCCTION trial.

SETTING & PARTICIPANTS

4,722 adults who each received hemodialysis via 1 or more tunneled central venous catheters in 37 Australian nephrology services from December 2016 to March 2020.

EXPOSURE

Design of tunneled hemodialysis catheter tip, classified as symmetrical, step, or split.

OUTCOME

Time to catheter dysfunction requiring removal due to inadequate dialysis blood flow assessed by the treating clinician.

ANALYTICAL APPROACH

Mixed, 3-level accelerated failure time model, assuming a log-normal survival distribution. Secular trends, the intervention, and baseline differences in service, patient, and catheter factors were included in the adjusted model. In a sensitivity analysis, survival times and proportional hazards were compared among participants' first tunneled catheters.

RESULTS

Among the study group, 355 of 3,871 (9.2%), 262 of 1,888 (13.9%), and 38 of 455 (8.4%) tunneled catheters with symmetrical, step, and split tip designs, respectively, required removal due to dysfunction. Step tip catheters required removal for dysfunction at a rate 53% faster than symmetrical tip catheters (adjusted time ratio, 0.47 [95% CI, 0.33-0.67) and 76% faster than split tip catheters (adjusted time ratio, 0.24 [95% CI, 0.11-0.51) in the adjusted accelerated failure time models. Only symmetrical tip catheters had performance superior to step tip catheters in unadjusted and sensitivity analyses. Split tip catheters were infrequently used and had risks of dysfunction similar to symmetrical tip catheters. The cumulative incidence of other complications requiring catheter removal, routine removal, and death before removal were similar across the 3 tip designs.

LIMITATIONS

Tip design was not randomized.

CONCLUSIONS

Symmetrical and split tip catheters had a lower risk of catheter dysfunction requiring removal than step tip catheters.

FUNDING

Grants from government (Queensland Health, Safer Care Victoria, Medical Research Future Fund, National Health and Medical Research Council, Australia), academic (Monash University), and not-for-profit (ANZDATA Registry, Kidney Health Australia) sources.

TRIAL REGISTRATION

Registered at ANZCTR with study number ACTRN12616000830493.

PLAIN-LANGUAGE SUMMARY

Central venous catheters are widely used to facilitate vascular access for life-sustaining hemodialysis treatments but often fail due to blood clots or other mechanical problems that impede blood flow. A range of adaptations to the design of tunneled hemodialysis catheters have been developed, but it is unclear which designs have the greatest longevity. We analyzed data from an Australian nationwide cohort of patients who received hemodialysis via a tunneled catheter and found that catheters with a step tip design failed more quickly than those with a symmetrical tip. Split tip catheters performed well but were infrequently used and require further study. Use of symmetrical rather than step tip hemodialysis catheters may reduce mechanical failures and unnecessary procedures for patients.

Effect of a Multifaceted Intervention on the Incidence of Hemodialysis Catheter Dysfunction in a National Stepped-Wedge Cluster Randomized Trial

Introduction

Effective strategies to prevent hemodialysis (HD) catheter dysfunction are lacking and there is wide variation in practice.

Methods

In this post hoc analysis of the REDUcing the burden of dialysis Catheter ComplicaTIOns: a national (REDUCCTION) stepped-wedge cluster randomized trial, encompassing 37 Australian nephrology services, 6361 participants, and 9872 catheters, we investigated whether the trial intervention, which promoted a suite of evidence-based practices for HD catheter insertion and management, reduced the incidence of catheter dysfunction, which is defined by catheter removal due to inadequate dialysis blood flow. We also analyzed outcomes among tunneled cuffed catheters and sources of event variability.

Results

A total of 873 HD catheters were removed because of dysfunction over 1.12 million catheter days. The raw incidence was 0.91 events per 1000 catheter days during the baseline phase and 0.68 events per 1000 catheter days during the intervention phase. The service-wide incidence of catheter dysfunction was 33% lower during the intervention after adjustment for calendar time (incidence rate ratio = 0.67; 95% confidence interval [CI], 0.50-0.89; P = 0.006). Results were consistent among tunneled cuffed catheters (adjusted incidence rate ratio = 0.68; 95% CI, 0.49-0.94), which accounted for 75% of catheters (n = 7403), 97.4% of catheter exposure time and 88.2% of events (n = 770). Among tunneled catheters that survived for 6 months (21.5% of tunneled catheters), between 2% and 5% of the unexplained variation in the number of catheter dysfunction events was attributable to service-level differences, and 18% to 36% was attributable to patient-level differences.

Conclusion

Multifaceted interventions that promote evidence-based catheter care may prevent dysfunction, and patient factors are an important source of variation in events.

Pathology of catheter-related complications: what we need to know and what should be discovered

Despite the considerable efforts made to increase the prevalence of autogenous fistula in patients on hemodialysis, tunneled cuffed catheters are still an important access modality and used in a high percentage of the hemodialysis population. However, because of the conundrum posed by tunneled cuffed catheters, patients can develop a multitude of complications, including thrombosis, infections, formation of a fibrin sheath, and central vein stenosis, resulting in increased morbidity and mortality as well as placing a heavy burden on the healthcare system. However, with an increasing number of studies now focusing on how to manage these catheter-related complications, there has been less translational research on the pathology of these complications. This review of the most recent literature provides an update on the pathological aspects of catheter-related complications, highlighting what we need to know and what is yet to be discovered. The future research strategies and innovations needed to prevent these complications are also addressed.

Are There Differences in Arteriovenous Fistulae Created for Hemodialysis between Nephrologists and Vascular Surgeons?

OBJECTIVE

Many studies have reported insufficient support from surgical services, resulting in nephrologists creating arteriovenous fistulas in many centers. The aim of this study was to compare risk factors of arteriovenous fistula dysfunction in patients whose fistulas were created by nephrologists versus vascular surgeons.

METHODS

This was a retrospective, analytical study of interventions by nephrologists and vascular surgeons during a period of 15 years. Out of a total of 1,048 fistulas, 764 (72.9%) were created by nephrologists patients, while vascular surgeons were responsible for 284 (27.1%) fistulae. Laboratory, demographic, and clinical parameters which might affect functioning of these arteriovenous fistulae were analyzed.

RESULTS

Patients whose arteriovenous fistula was formed by nephrologists differed significantly from those created by vascular surgeons in relation to the preventive character of the arteriovenous fistula (p = 0.011), lumen of the vein (p < 0.001) and systolic blood pressure (p = 0.047). Multivariate logistic regression of arteriovenous fistula dysfunction showed that risk factors were female gender (odds ratio [OR] = 1.56, 95% CI 1.16-2.07), whether the fistulae were created by vascular surgeons or nephrologists (OR = 1.38; 95% CI 1.01-1.89) and the site of the arteriovenous fistula (OR = 0.64; 95% CI 0.48-0.85).

CONCLUSIONS

Arteriovenous fistulae created by vascular surgeons, female gender, and the location are risk factors of dysfunction.

KDOQI Clinical Practice Guideline for Vascular Access: 2019 Update

The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for hemodialysis vascular access since 1996. Since the last update in 2006, there has been a great accumulation of new evidence and sophistication in the guidelines process. The 2019 update to the KDOQI Clinical Practice Guideline for Vascular Access is a comprehensive document intended to assist multidisciplinary practitioners care for chronic kidney disease patients and their vascular access. New topics include the end-stage kidney disease "Life-Plan" and related concepts, guidance on vascular access choice, new targets for arteriovenous access (fistulas and grafts) and central venous catheters, management of specific complications, and renewed approaches to some older topics. Appraisal of the quality of the evidence was independently conducted by using a Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, and interpretation and application followed the GRADE Evidence to Decision frameworks. As applicable, each guideline statement is accompanied by rationale/background information, a detailed justification, monitoring and evaluation guidance, implementation considerations, special discussions, and recommendations for future research.

Efficacy of alteplase 1 versus 2 mg dose in restoring haemodialysis catheter function (Alte-dose 2): A randomized double-blind controlled study

AIM

Data about the optimal alteplase dose required to treat haemodialysis catheter occlusion (HDC) are scarce. The purpose of the clinical trial was to examine the effectiveness of alteplase 2 mg as compared with 1 mg in restoring HDC function.

METHODS

A double-blind, randomized, controlled clinical trial was conducted in a single-centre in southwestern Ontario, Canada. Rate of clot resolution, catheter replacements, catheter stripping, and mean catheter survival time were assessed using Kaplan-Meier, Cox-proportional hazard and clustered logic regression analyses.

RESULTS

On a sample of 48 haemodialysis patients who provided 252 catheter occlusion events, the rate of clot resolution at the catheter site in the 2 mg group was 85.7% as opposed to 84.9% in the 1 mg group. There were only six catheter removals and 10 catheter stripping events. Cox regression analysis revealed no difference between the two groups in the hazard of occlusion on the primary 48 observations after the initial alteplase management (P = 0.267; hazard ratio = 0.72; 95% confidence interval 0.40-1.3). Correlated logistic regression on all 252 observations indicated no difference in the rate of post alteplase clot resolution (P = 0.336; odds ratio = 2.4, 95% confidence interval 0.399-14.6) between the two groups.

CONCLUSION

Alteplase 1 mg is as effective as 2 mg in restoring HDC malfunction and may result in cost reduction in haemodialysis units.

Vascular Access Choice, Complications, and Outcomes in Children on Maintenance Hemodialysis: Findings From the International Pediatric Hemodialysis Network (IPHN) Registry

RATIONALE & OBJECTIVE

Arteriovenous fistulas (AVFs) have been recommended as the preferred vascular access for pediatric patients on maintenance hemodialysis (HD), but data comparing AVFs with other access types are scant. We studied vascular access choice, placement, complications, and outcomes in children.

STUDY DESIGN

Prospective observational cohort study.

SETTING & PARTICIPANTS

552 children and adolescents from 27 countries on maintenance HD followed up prospectively by the International Pediatric HD Network (IPHN) Registry between 2012 and 2017.

PREDICTOR

Type of vascular access: AVF, central venous catheter (CVC), or arteriovenous graft.

OUTCOME

Infectious and noninfectious vascular access complication rates, dialysis performance, biochemical and hematologic parameters, and clinical outcomes.

ANALYTICAL APPROACH

Univariate and multivariable linear mixed models, generalized linear mixed models, and proportional hazards models; cumulative incidence functions.

RESULTS

During 314 cumulative patient-years, 628 CVCs, 225 AVFs, and 17 arteriovenous grafts were placed. One-third of the children with an AVF required a temporary CVC until fistula maturation. Vascular access choice was associated with age and expectations for early transplantation. There was a 3-fold higher living related transplantation rate and lower median time to transplantation of 14 (IQR, 6-23) versus 20 (IQR, 14-36) months with CVCs compared with AVFs. Higher blood flow rates and Kt/V_urea were achieved with AVFs than with CVCs. Infectious complications were reported only with CVCs (1.3/1,000 catheter-days) and required vascular access replacement in 47%. CVC dysfunction rates were 2.5/1,000 catheter-days compared to 1.2/1,000 fistula-days. CVCs required 82% more revisions and almost 3-fold more vascular access replacements to a different site than AVFs (P<0.001).

LIMITATIONS

Clinical rather than population-based data.

CONCLUSIONS

CVCs are the predominant vascular access choice in children receiving HD within the IPHN. Age-related anatomical limitations and expected early living related transplantation were associated with CVC use. CVCs were associated with poorer dialysis efficacy, higher complication rates, and more frequent need for vascular access replacement. Such findings call for a re-evaluation of pediatric CVC use and practices.

Vascular Access in Patients Treated with Continuous Renal Replacement Therapy: A Report from a Single Center in China

Our aim was to analyze the practice pattern of vascular access use and complication rates in patients receiving continuous renal replacement therapy from a large Chinese urban medical center. Patients who had received continuous renal replacement therapy (CRRT) from April to October 2014 in our center were included in this study. Demographic data, primary disease, department for hospitalization, blood pressure, heart rate, Sequential Organ Failure Assessment (SOFA) score, Acute Physiology and Chronic Health Evaluation (APACHE II) score, presence of mechanical ventilation, CRRT modalities, choice of functioning vascular access, site and duration of catheter insertion, presence of recatheterization, cumulative catheter indwelling time, catheter malfunction and catheter-related infections, as well as laboratory test results, were collected. A total of 292 patients were enrolled in our study, including 175 males (59.9%) and 117 females (40.1%), aged 50.8 ± 18.6 years (range, 12 to 94 years). Acute kidney injury, multiple organ dysfunction syndrome, and systemic inflammatory response syndrome were the main indications for treatment with CRRT. Initial vascular access was non-cuffed temporary catheters in 280 patients and was preferentially obtained in the right internal jugular vein (54.3%). There were 32 (11.4%) patients requiring re-catheterization. Catheter malfunction occurred in 7.14% of all patients, and the median time of catheter malfunction was found at the 5th day. By multivariate analysis, it was found that the main risk factors of catheter malfunction were cumulative treatment time of CRRT and the level of hemoglobin. The average time of catheter-related infections was 10.7 days after insertion and the catheter-related infections occurred at a rate of 7.19 per 1000 catheter days. The main risk factors for catheter-related infections were cumulative time of catheterization and the level of serum albumin. In this cohort of critically ill patients, the main risk factors for catheter malfunction were cumulative CRRT time and the level of hemoglobin. In addition, the main risk factors for catheter-related infections were cumulative time of catheterization and the level of serum albumin.

Renal replacement therapy: a practical update

Acute kidney injury (AKI) is defined as an abrupt decrease in kidney function, with the most severe form requiring some method of renal replacement therapy (RRT). The use of RRT is required in 5-10% of critically ill patients who develop severe AKI. Renal replacement therapy can be provided as either intermittent hemodialysis or one of the various modes of continuous renal replacement therapy (CRRT), with CRRT potentially conferring an advantage with respect to renal recovery and dialysis independence. There is no difference in mortality when comparing low (< 25 mL·kg^-1·hr^-1) vs high (> 40 mL·kg^-1·hr^-1) RRT dosing. Continuous renal replacement therapy may be run in different modes of increasing complexity depending on a given patient's clinical needs. Regional citrate anticoagulation is recommended as the therapy of choice for the majority of critically ill patients requiring CRRT.

Recommended Clinical Trial End Points for Dialysis Catheters

Central venous catheters are used frequently in patients on hemodialysis as a bridge to a permanent vascular access. They are prone to frequent complications, including catheter-related bloodstream infection, catheter dysfunction, and central vein obstruction. There is a compelling need to develop new drugs or devices to prevent central venous catheter complications. We convened a multidisciplinary panel of experts to propose standardized definitions of catheter end points to guide the design of future clinical trials seeking approval from the Food and Drug Administration. Our workgroup suggests diagnosing catheter-related bloodstream infection in catheter-dependent patients on hemodialysis with a clinical suspicion of infection (fever, rigors, altered mental status, or unexplained hypotension), blood cultures growing the same organism from the catheter hub and a peripheral vein (or the dialysis bloodline), and absence of evidence for an alternative source of infection. Catheter dysfunction is defined as the inability of a central venous catheter to (1) complete a single dialysis session without triggering recurrent pressure alarms or (2) reproducibly deliver a mean dialysis blood flow of >300 ml/min (with arterial and venous pressures being within the hemodialysis unit parameters) on two consecutive dialysis sessions or provide a Kt/V≥1.2 in 4 hours or less. Catheter dysfunction is defined only if it persists, despite attempts to reposition the patient, reverse the arterial and venous lines, or forcefully flush the catheter. Central vein obstruction is suspected in patients with >70% stenosis of a central vein by contrast venography or the equivalent, ipsilateral upper extremity edema, and an existing or prior history of a central venous catheter. There is some uncertainty about the specific criteria for these diagnoses, and the workgroup has also proposed future high-priority studies to resolve these questions.

Predicting tissue plasminogen activator use and success in in-center hemodialysis patients

INTRODUCTION

Hemodialysis catheter malfunction is problematic. We aimed to determine clinical, catheter, and hemodialysis variables that predict: (i) catheter malfunction requiring recombinant tissue-plasminogen activator (TPA) treatment and (ii) the success of TPA administration.

METHODS

Clinical, catheter, and hemodialysis variables were collected from a cohort of 559 catheters (141,526 catheter days) in 175 hemodialysis patients (2008-2011). Time to, and predictors of, catheter malfunction were determined for all catheters and primary catheters only, analyzed by Cox-proportional hazard model, multi-variable logistic regression model, and mixed-effect logistic regression models. Success of TPA use was determined immediately, next day, and two weeks after use.

RESULTS

Shorter time to first TPA administration in all patient's catheters was associated with increased body mass index (hazard ratio [HR] = 1.06, 1.01-1.11, p = 0.03) and being of black race (HR = 3.05, 1.65-5.67, p<0.01). Primary TPA administration success at two weeks among primary catheters was associated with increased mean peak venous pressure before TPA administration (odds ratio [OR] = 1.03, 1.01-1.06, p<0.01) and decreased mean of the lowest systolic blood pressure measure for the three dialysis sessions prior to TPA administration (OR = 0.95, 0.91-0.99, p = 0.02). TPA administration success at two weeks among all catheters was associated with decreasing body mass index (OR = 0.84, CI 0.73-0.96, p = 0.01) and having diabetes (OR = 7.19, 1.40-36.81, p = 0.02).

CONCLUSIONS

Both patient and dialysis predictors of TPA use and success were identified in this study, which may be useful for fine-tuning catheter management protocols to target hemodialysis patients at high risk of catheter malfunction.

Interventions for treating central venous haemodialysis catheter malfunction

BACKGROUND

Adequate haemodialysis (HD) in people with end-stage kidney disease (ESKD) is reliant upon establishment of vascular access, which may consist of arteriovenous fistula, arteriovenous graft, or central venous catheters (CVC). Although discouraged due to high rates of infectious and thrombotic complications as well as technical issues that limit their life span, CVC have the significant advantage of being immediately usable and are the only means of vascular access in a significant number of patients. Previous studies have established the role of thrombolytic agents (TLA) in the prevention of catheter malfunction. Systematic review of different thrombolytic agents has also identified their utility in restoration of catheter patency following catheter malfunction. To date the use and efficacy of fibrin sheath stripping and catheter exchange have not been evaluated against thrombolytic agents.

OBJECTIVES

This review aimed to evaluate the benefits and harms of TLA, preparations, doses and administration as well as fibrin-sheath stripping, over-the-wire catheter exchange or any other intervention proposed for management of tunnelled CVC malfunction in patients with ESKD on HD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register up to 17 August 2017 through contact with the Information Specialist using search terms relevant to this review. Studies in the Specialised Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included all studies conducted in people with ESKD who rely on tunnelled CVC for either initiation or maintenance of HD access and who require restoration of catheter patency following late-onset catheter malfunction and evaluated the role of TLA, fibrin sheath stripping or over-the-wire catheter exchange to restore catheter function. The primary outcome was be restoration of line patency defined as ≥ 300 mL/min or adequate to complete a HD session or as defined by the study authors. Secondary outcomes included dialysis adequacy and adverse outcomes.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed retrieved studies to determine which studies satisfy the inclusion criteria and carried out data extraction. Included studies were assessed for risk of bias. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using GRADE.

MAIN RESULTS

Our search strategy identified 8 studies (580 participants) as eligible for inclusion in this review. Interventions included: thrombolytic therapy versus placebo (1 study); low versus high dose thrombolytic therapy (1); alteplase versus urokinase (1); short versus long thrombolytic dwell (1); thrombolytic therapy versus percutaneous fibrin sheath stripping (1); fibrin sheath stripping versus over-the-wire catheter exchange (1); and over-the-wire catheter exchange versus exchange with and without angioplasty sheath disruption (1). No two studies compared the same interventions. Most studies had a high risk of bias due to poor study design, broad inclusion criteria, low patient numbers and industry involvement.Based on low certainty evidence, thrombolytic therapy may restore catheter function when compared to placebo (149 participants: RR 4.05, 95% CI 1.42 to 11.56) but there is no data available to suggest an optimal dose or administration method. The certainty of this evidence is reduced due to the fact that it is based on only a single study with wide confidence limits, high risk of bias and imprecision in the estimates of adverse events (149 participants: RR 2.03, 95% CI 0.38 to 10.73).Based on the available evidence, physical disruption of a fibrin sheath using interventional radiology techniques appears to be equally efficacious as the use of a pharmaceutical thrombolytic agent for the immediate management of dysfunctional catheters (57 participants: RR 0.92, 95% CI 0.80 to 1.07).Catheter patency is poor following use of thrombolytic agents with studies reporting median catheter survival rates of 14 to 42 days and was reported to improve significantly by fibrin sheath stripping or catheter exchange (37 participants: MD -27.70 days, 95% CI -51.00 to -4.40). Catheter exchange was reported to be superior to sheath disruption with respect to catheter survival (30 participants: MD 213.00 days, 95% CI 205.70 to 220.30).There is insufficient evidence to suggest any specific intervention is superior in terms of ensuring either dialysis adequacy or reduced risk of adverse events.

AUTHORS' CONCLUSIONS

Thrombolysis, fibrin sheath disruption and over-the-wire catheter exchange are effective and appropriate therapies for immediately restoring catheter patency in dysfunctional cuffed and tunnelled HD catheters. On current data there is no evidence to support physical intervention over the use of pharmaceutical agents in the acute setting. Pharmacological interventions appear to have a bridging role and long-term catheter survival may be improved by fibrin sheath disruption and is probably superior following catheter exchange. There is no evidence favouring any of these approaches with respect to dialysis adequacy or risk of adverse events.The current review is limited by the small number of available studies with limited numbers of patients enrolled. Most of the studies included in this review were judged to have a high risk of bias and were potentially influenced by pharmaceutical industry involvement.Further research is required to adequately address the question of the most efficacious and clinically appropriate technique for HD catheter dysfunction.

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.

Post-operative intracranial hemorrhage related to using t-PA for declotting an occluded hemodialysis catheter: A cautionary tale

Heparin and thrombolytic agents such as tissue plasminogen activator (t-PA) are frequently used to prevent and treat occluded hemodialysis (HD) catheters. Thrombolytic agents have not been well studied for systemic effects. We present a post-operative neurosurgical patient who experienced a symptomatic intracranial hemorrhage (ICH) after t-PA was used to treat an occluded HD catheter. This case highlights that using t-PA to treat dysfunctional catheters may be associated with ICH in neurosurgical patients. Management strategies are discussed with a review of pertinent literature.

Optimization of Dialysis Catheter Function

Central venous catheters (CVCs) are essential in the management of hemodialysis patients, but they also carry unintended negative consequences and in particular thrombosis and infection, adversely affecting patient morbidity and mortality. This review will focus on the etiology, prevention, and management of CVC-related dysfunction, which is mainly associated with inadequate blood flow. CVC dysfunction is a major cause of inadequate depuration. Thrombus, intraluminal and extrinsic, as well as fibrous connective tissue sheath (traditionally indicated as fibrin sheath) formation play a central role in establishing CVC dysfunction. Thrombolysis with urokinase or recombinant tissue plasminogen activator (rTPA) can be undertaken in the dialysis unit, restoring adequate blood flow in most patients, preserving the existing catheter, and avoiding an interventional procedure. If thrombolytics fail, mainly because of the presence of fibrous connective tissue sheath, catheter exchange with fibrin sheath disruption may be successful and preserve the venous access site. Prevention of CVC dysfunction is important for containing costly pharmacologic and interventional treatments, which also affect patients’ quality of life. Prevention is based on the use of anticoagulant and/or thrombolytic CVC locks, which are only partially effective. Chronic oral anticoagulation with warfarin has also been proposed, but its use for this indication is controversial and its overall risk-benefit profile has not been clearly established.

Comparison of intensive versus standard hemodialysis central venous catheter dysfunction protocol using rt-PA: a quality assurance initiative

PURPOSE

Catheter locking solutions such as recombinant tissue plasminogen activator (rt-PA) are used to treat and prevent clotting of hemodialysis (HD) catheters during HD treatments and the interdialytic period. However, evidence to guide the use of rt-PA for catheter dysfunction is limited.

METHODS

We evaluated outcomes using two catheter dysfunction protocols in a cohort of consecutive prevalent dialysis patients (Jan 2013 to Sep 2014) undergoing HD with a tunneled catheter. In the intensive protocol, rt-PA was administered to all catheters based on blood flow and/or line reversal. In the standard protocol, rt-PA administration was based only on blood flow. The primary outcome was the rate of rt-PA use for catheter malfunction (rt-PA treatment days/1000 total line days; [TLD]). Secondary outcomes included the cost of rt-PA/TLD and the rate of catheter-related bacteremia.

RESULTS

There were 26 and 35 patients managed by the intensive and standard protocols, respectively. The rate of rt-PA use was 52/1000 TLD (intensive) versus 39/1000 TLD (standard) (rate ratio 1.30, 95% CI 1.12-1.52 CI, p&lt;0.001). The rate of bacteremia was 0.43 and 0.22/1000 TLD for the intensive and standard protocols, respectively (p = 0.491). The cost of rt-PA was CDN $5.58 and CDN $6.15 per TLD for the intensive protocol and standard protocol groups (p&lt;0.001).

CONCLUSIONS

Managing catheter dysfunction based on line reversal and blood flow as opposed to only blood flow was associated with a higher rate of rt-PA use, but at a reduced overall cost.

Use of tissue plasminogen activator in catheters used for extracorporeal renal replacement therapy

Background

Intraluminal thrombosis of central venous catheters used for renal replacement therapy (RRT) decreases the ability to provide adequate treatment. Alteplase is a recombinant tissue plasminogen activator that has been used to improve the function of catheters used for RRT in humans.

Objectives

To retrospectively review alteplase instillation in dysfunctional catheters used for RRT in dogs and cats.

Animals

Seventeen dogs and 8 cats receiving RRT for kidney failure.

Methods

Medical records of patients in which alteplase was used for RRT catheter dysfunction from 2004 to 2012 were retrospectively reviewed to characterize reasons for use, improvement in function, increase in blood flow, and duration of improvement.

Results

Alteplase was instilled 43 times in 29 catheters, most commonly because of suspicion that the catheter would not provide sufficient flow on the next treatment (n = 21). The second most common reason was inability to start a dialysis treatment (n = 12). Catheter function improved after alteplase instillation in 34 of 43 treatments (79%). Median blood flow rate increased by 13% (18 mL/min) in the dialysis session after alteplase instillation. Seven of 29 catheters (24%) were treated with alteplase on >1 occasion (median time to second treatment, 8 days), and 1 catheter had to be replaced because of intractable dysfunction.

Conclusions and Clinical Importance

Alteplase is effective at improving function of central venous catheters used to provide RRT, but the results are short‐lived.

Vascular access in therapeutic apheresis: update 2013

This review addresses the types of vascular access available for patients who need therapeutic apheresis (TA). As in hemodialysis, vascular access for TA is chosen based on type of procedure prescribed, the patient's vascular anatomy, the acuity, frequency and duration of treatment, and the underlying disease state. The types of access available include peripheral vein cannulation, central venous catheters: including nontunneled and tunneled catheters, arterio-venous grafts and arterio-venous fistulas. Peripheral veins and central venous catheters are most frequently utilized for the acute administration of TA, and may be used over a period of weeks to months. Arterio-venous grafts and fistulas are not commonly used in TA procedures, but are an option in patients with an anticipated long course of TA, usually for a period of several months or years. The types and frequency of complications associated with various types of vascular access, including: access dysfunction and infections are reviewed, and strategies for their prevention and management are offered.

Natural history of tunneled dialysis catheters placed for hemodialysis initiation

PURPOSE

More than 80% of hemodialysis recipients in the United States initiate hemodialysis with a tunneled dialysis catheter (TDC). Published data on TDC outcomes are based on a case mix of prevalent and incident TDCs. The present study analyzes factors affecting patency and complications of first TDCs placed in a large cohort of incident hemodialysis recipients.

MATERIALS AND METHODS

A prospective, computerized vascular access database was retrospectively queried to identify 472 patients receiving a first-ever TDC. Multiple-variable survival analysis was used to identify clinical parameters affecting TDC patency (from placement to nonelective removal) and infection (from placement to first episode of catheter-related bacteremia [CRB]).

RESULTS

The median patency of all TDCs was 202 days. Left-sided placement of TDCs was the only variable associated with inferior TDC patency (hazard ratio, 1.98; 95% confidence interval, 1.39-2.81; P < .0001). The 6-month TDC patency rate was 37% for left internal jugular vein (LIJV) catheters, versus 54% for right internal jugular vein (RIJV) catheters. The 1-year patency rate was 6% for LIJV catheters, versus 35% for RIJV catheters. Catheter patency was not associated with patient age, sex, race, hypertension, diabetes, coronary artery disease, peripheral vascular disease, cerebrovascular disease, or heart failure. The median time to the first episode of CRB was 163 days. None of the clinical variables was associated with TDC infection.

CONCLUSIONS

TDCs are plagued by high rates of infection. RIJV TDCs should be used preferentially to maximize catheter patency.

Use and safety of heparin-free maintenance hemodialysis in the USA

BACKGROUND

Although heparin is used to anticoagulate the extracorporeal circuit for most patients on maintenance hemodialysis (HD), some patients undergo heparin-free HD. We describe the determinants of heparin-free HD and its association with adverse outcomes using data from a national dialysis provider merged with Medicare claims.

METHODS

We identified patients aged ≥67 years with no recent history of warfarin use who initiated maintenance HD from 2007 to 2008. We applied the Cox regression to a propensity score-matched cohort to estimate the hazards of all-cause mortality, bleeding (gastrointestinal hemorrhage, hemorrhagic stroke, other hemorrhage), atherothrombosis (ischemic stroke, myocardial infarction) and venous thromboembolism (VTE) (deep vein thrombosis, pulmonary embolism).

RESULTS

Among 12 468 patients, 836 (6.7%) were dialyzed heparin-free. In multivariable-adjusted analyses, a history of gastrointestinal bleeding, hemorrhagic stroke and lower hemoglobin and platelet counts were associated with higher odds of heparin-free HD. Heparin-free HD use also varied as much as 4-fold by facility region. We found no significant association of heparin-free HD with all-cause mortality [hazard ratio (HR) 1.08; 95% confidence interval (CI): 0.94-1.26], bleeding (HR 1.15; 95% CI: 0.83-1.60), atherothrombosis (HR 1.09, 95% CI: 0.90-1.31) or VTE (HR 1.23, 95% CI: 0.93-1.64) compared with HD with heparin.

CONCLUSIONS

Patient markers of increased risk of bleeding and facility region associated with heparin-free HD use. Despite the potential benefits of avoiding heparin use, heparin-free HD was not significantly associated with decreased hazards of death, bleeding or thrombosis, suggesting that it may be no safer than HD with heparin.

Vascular access: choice and complications in European paediatric haemodialysis units

BACKGROUND

European and U.S. guidelines emphasise that permanent vascular access in the form of arteriovenous fistulae (AVF) or grafts (AVG) are preferable to central venous catheters (CVC) in paediatric patients on long-term haemodialysis. We report vascular access choice and complication rates in 13 European paediatric nephrology units.

METHODS

A survey of units participating in the European Pediatric Dialysis Working Group requesting data on type of vascular access, routine care and complications in patients on chronic haemodialysis between March 2010 and February 2011.

RESULTS

Information was complied on 111 patients in 13 participating centres with a median age of 14 (range 0.25-20.2) years. Central venous catheters were used in 67 of 111 (60%) patients, with 42 patients (38%) having an AVF and two patients (2%) having an AVG. Choice of vascular access was significantly related to patient age, with patients with AVF/AVG having a median age of 16 years compared to 12 years for patients with CVCs (p < 0.001). Routine CVC exit site care and catheter lock solution use differed between centres. CVC infections requiring intravenous antibiotics were reported at a rate of 1.9 and exit site infections at a rate of 1.8 episodes/1000 catheter days. Overall infective complications necessitating CVC change occurred at a rate of 0.9 episodes/1000 catheter days. No infective complications were reported in patients with AVF/AVG access. The rate of CVC infections requiring intravenous antibiotics was significantly lower in patients in whom CVC exit sites were cleaned weekly as opposed to every dialysis session (relative risk with every session cleaning vs. weekly cleaning 2.58, 95% confidence interval 1.17-5.69). Catheter malfunction (inadequate blood flow) was a more prevalent complication necessitating 22.4 thrombolytic interventions/1000 catheter days and 2.1 CVC changes/1000 catheter days.

CONCLUSIONS

Central venous catheters remain the predominant choice of vascular access in Europe despite problems of malfunction and infection. AVF/AVG were predominantly used in adolescents without reported complications. More regular exit site cleaning may predispose to CVC infection, but this observation requires prospective evaluation.

The choice of vascular access for therapeutic apheresis

Therapeutic apheresis (TA) is performed using either centrifugation-based or filter-based systems. The blood flow rate (BFR) used for TA using centrifugation-based systems is less than 100 mL/min. Because of this low BFR requirement, even peripheral veins can be considered as an option for TA, especially for less-frequent treatments and those performed for short periods. Other options for vascular access (VA) include central venous catheters (temporary or tunneled), totally implantable ports, and arteriovenous fistulae (AVF) or grafts (AVG). Nontunneled catheters should be considered as the choice of VA for relatively short-term treatments mainly in the inpatient settings. For long-term treatments, ports and tunneled catheters should be considered because of lower rates of infections compared to nontunneled catheters. However, studies in hemodialysis (HD) patients have demonstrated significantly higher morbidity and mortality rates associated with the use of tunneled catheters as compared to AVF. Therefore, if TA is being considered for several years, AVG and AVF would be the preferred options of VA. Studies in HD population indicate far better outcomes with the use of AVF as compared to AVG. This article, as presented at the Therapeutic Apheresis Academy in September 2011, is an overview of the available VA options for TA based on indication and duration of treatment. Pros and cons of each option are mentioned briefly. Finally, for those considered for AVF placement for chronic TA, specific recommendations are made for the care of AVF based on our own experience at University of Virginia.

Standardized definitions for hemodialysis vascular access

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

Therapeutic apheresis: a review of complications and recommendations for prevention and management

Therapeutic apheresis procedures are a form of extracorporeal therapy that use different techniques to separate blood into the different components out of which the part containing the etiological agent in a disease process is discarded and the rest of the components of blood are re-infused into the patient, frequently with the addition of a replacement fluid or volume. These complex procedures have inherent risks of adverse events and factors that may impact on the incidence these events include the underlying disease state, anticoagulation techniques, replacement fluid type including the volume, issues related to the vascular access used, and the therapeutic apheresis procedure type and technique. We present a representative case based review of common complications of therapeutic apheresis and suggestions about how to prevent or manage these as presented at the 2010 Therapeutic Apheresis Academy.