REDUCING TUNNELED HEMODIALYSIS CATHETER MORBIDITY: Advances in Tunneled Central Venous Catheters for Dialysis: Design and Performance

Fluid Dynamic and in Vitro Blood Study to Understand Catheter-Related Thrombosis

PURPOSE

Central venous catheters (CVCs) provide a direct route to the venous circulation but are prone to catheter-related thrombosis (CRT). A known CRT risk factor is a high catheter-to-vein ratio (CVR), or a large catheter diameter with respect to the indwelling vein size. In this study, the CVR's effect on CVC hemodynamics and its impact on CRT is investigated with in vitro and in silico experiments.

METHODS

An in vitro flow loop is used to characterize the hemodynamics around CVCs using particle image velocimetry. In addition, CRT is investigated using an in vitro flow loop with human blood and clinical catheters. The wall shear rate of flow around the CVC is computed numerically. CVRs of 0.20, 0.33, and 0.49 and Reynolds numbers of 200, 800, and 1300 are evaluated. No flow is used through CVC lumens to model chronic indwelling catheters.

RESULTS

Results show CVR ≥ 0.33 promotes platelet-rich clot growth at the device tip and at an increased rate compared to lower CVR cases. A high wall shear rate gradient on the CVC tip and an extended wake distal to the tip exists for higher CVR cases, promoting the aggregation of platelets and subsequent stagnation for clot formation. Further, the combination of the CVR and Reynolds number are crucial to CRT potential, not the CVR alone. Specifically, thrombosis risk is increased with low (stasis driven) and/or high (platelet activation driven) flow conditions, with the CVR and CVC's geometry playing an additional role in promoting fluid mechanic driven thrombus development. A high CVR (≥ 0.33) and high flow condition (≥ 1300) results in the highest risk for clot growth at the tip of the device; other locations of the device are at risk for thrombus development in lower flow conditions, regardless of the CVR. The importance of the device geometry and flow in promoting thrombus and fibrin sheath formation is also shown for the device investigated.

CONCLUSIONS

This work demonstrates that the CVR, flow, and device geometry affect CRT. For clinical cases with CVR ≥ 0.33 and/or Re ≥ 1300, the device tip may be monitored more consistently for clot formation. Thrombosis risks remain on the entire catheter, regardless of the flow condition, for a CVR = 0.49. Device placement should be chosen carefully with respect to the combination of the Reynolds number and CVR. Further study is needed on the effect of catheterization to confirm these findings.

Comparison of side-hole and step-tip catheters for patients requiring continuous renal replacement therapy in intensive care units: study protocol for a randomised controlled trial

INTRODUCTION

In addition to various techniques involved in catheter insertion, catheter placement location, lumen diameter and operation and management during continuous renal replacement therapy (CRRT), the design of the tip and side holes, as well as the position of the tip of the catheter, can also impact catheter function. Side-hole and step-tip catheters are commonly used during CRRT. However, there is insufficient evidence comparing their efficacy for CRRT in critically ill patients. And the optimal position of the tip of catheters is not well studied and remains controversial. This study was conducted to assess whether using a step-tip catheter could reduce the rate of catheter dysfunction compared with a side-hole catheter and whether inserting a longer catheter could reduce the incidence of catheter dysfunction and increase catheter survival time.

METHODS AND ANALYSIS

A prospective, open-label, three-arm, parallel-group, single-centre randomised controlled trial will be conducted at West China Hospital of Sichuan University in China. An estimated sample of 378 participants receiving CRRT treatment will be recruited. Eligible patients will be randomly assigned to three groups to receive different dialysis catheters for the initiation of CRRT at a 1:1:1 ratio via a central randomisation system: group A, side-hole catheters (11Fr, 200 mm; GDHK-1120; Baxter International Inc., Deerfield, Illinois); group B, step-tip catheters (13Fr, 200 mm; GDHK-1320; Baxter International Inc.) and group C, step-tip catheters (13Fr, 250 mm; GDHK-1325; Baxter International Inc.). The femoral vein is the only vascular access. All catheters will be inserted under the guidance of ultrasound using the Seldinger method to reduce complications and trauma related to catheter insertion. The primary outcomes are the occurrence of catheter dysfunction and catheter survival time. Outcome assessors and data analysts will be blinded. All data will be analysed according to the group randomly assigned by an intention-to-treat analysis, in which catheters with missing data for the primary outcomes would be excluded.

ETHICS AND DISSEMINATION

The trial protocol has been approved by the Biomedical Research Ethics Committee of West China Hospital of Sichuan University (2023.1221). And the results will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ChiCTR2300075107.

Variables Leading to Usage of Alteplase Versus Heparin Lock in Patients With Tunneled Catheters in Hemodialysis Care Project Centers, Saudi Arabia

INTRODUCTION

A hemodialysis tunneled catheter is one option for vascular access used with hemodialysis patients; however, catheter complications such as thrombosis are still inevitable. To prevent thrombosis formation, a catheter-locking solution is instilled between dialysis sessions. Heparin is used as a default locking solution in our Hemodialysis Care Project centers, while a recombinant tissue plasminogen activator (rt-PA) such as alteplase is used to treat suspected catheter thrombosis. This study aimed to identify the clinical factors, catheter brands, and hemodialysis variables that influence the choice of use for alteplase versus heparin, for those patients with tunneled catheters, and reduce overprescribing of high-alert medication alteplase.

METHODS

A retrospective medical chart review study was conducted involving 230 patients with tunneled catheters; the first group of 133 patients used alteplase regularly three times a week, while the second group of 97 patients completed at least one year using the same catheter access with heparin lock only.

RESULTS

Multivariate logistic regression and logistic regression analysis showed a significant association (p < 0.05) between different variables. Results suggest that overweight and hyperlipidemia patients are more likely to use alteplase. Patients using brand-name catheters such as Hemostar/Vas-cath (BD, Franklin Lakes, NJ) are less likely to use heparin than those using Medcomp catheters (Medcomp, Yuma, AZ). In addition, patients having a history of angioplasty would be less likely to have heparin than no angioplasty. Moreover, if the patient's fluid removal were equal to or less than 2 kg, they would be more likely to use heparin and vice versa.

CONCLUSION

The study postulates that identified variables affect whether alteplase or heparin is used in hemodialysis tunneled catheters, and may be useful to increase awareness, improve practices, or judiciously control the use of alteplase within Saudi Arabia and globally.

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.

Comparative effectiveness and safety among different tip-design hemodialysis long-term catheters: A meta-analysis

PURPOSE

The aim of this meta-analysis is to compare effectiveness and safety among different tip-design long-term hemodialysis (HD) catheters.

MATERIALS AND METHODS

PubMed, Embase, and Cochrane Library databases were searched until 8 December 2021 to identify randomized controlled trials (RCTs) and cohort studies comparing step-tip, split-tip, or symmetrical-tip design catheters in patients undergoing HD will be included. The Cochrane Risk of Bias tool and the Newcastle-Ottawa Scale were used to evaluate the quality of RCTs and cohort studies. Data extracted from the articles were integrated to determine mean effective blood pump velocity (Qb), blood recirculation rates, secondary patency, catheter-related infection, catheter-related blood stream infection (CRBSI), thrombosis rates, and all-cause mortality for the three tip-designs. We performed meta-analysis on dichotomous outcomes using a random-effects model to evaluate risk ratios (RRs) and 95% confidence intervals (Cls). The effect sizes of continuous outcomes were reported as the mean difference (MD). Sensitivity and subgroup analyses were also performed. The study was registered in the PROSPERO (CRD42021297069).

RESULTS

Six RCTs and 11 cohort studies of 2617 individuals were included in our meta-analysis, of which 1088 individuals inserted split-tip catheters, 897 individuals inserted step-tip catheters and 650 received symmetrical-tip design catheters. Sym-tip performed better in mean Qb (MD = 43.85, 95% Cl = 18.13-69.56, p = 0.0008) than step-tip. Split-tip had better outcomes vs step-tip in blood recirculation (RR = 3.44, 95% Cl = 2.49-4.39, p < 0.00001). Sym-tip had significantly better outcomes compared with step-tip (RR = 0.28, 95%Cl = 0.09-0.81, Z = 2.34, p = 0.02) and split-tip (RR = 0.19, 95% Cl = 0.09-0.43, p < 0.0001) in thrombotic events. No significant difference was found in secondary patency, infection rates, CRBSI, and all-cause mortality among the three tip-designs.

CONCLUSION

The sym-tip of tunneled cuffed catheters performed better mean Qb, lower thrombotic events, and lower blood recirculation when blood line reversed, which may have an advantage over other two catheter-tips.

Comparative Clinical Performances of Tunneled Central Venous Catheters versus Arterio-Venous Accesses in Patients Receiving High-Volume Hemodiafiltration: The Case for High-Flow DualCath, a Tunneled Two-Single-Lumen Silicone Catheter

Tunneled central venous catheters (CVC) are mainly considered as a rescue vascular access option in dialysis but are still used on approximately one quarter of prevalent patients worldwide even though they are associated with poor performances and higher risks.

STUDY DESIGN

in this retrospective single-center study, we aimed to report on the clinical performances achieved with high-flow tunneled CVCs (DualCath or DCath) and compared them with arteriovenous accesses (AVAs, e.g., AV fistula, AV graft, and Thomas Shunt) in a hospital-based dialysis unit.

METHODS

Sixty-eight stage 5 chronic kidney disease dialysis-dependent patients (CKD5D) receiving high volume hemodiafiltration were followed-up with for 30 months. The study consisted of two phases: baseline cross-sectional and longitudinal follow-ups of key performance indicators. Clinical performances consisting of effective blood flow and blood volume, recirculation, urea and ionic Kt/V, total Kt, ultrafiltration volume, and percent reduction in β2-M were measured monthly as part of quality control in our unit.

RESULTS

At baseline, the effective blood flow using a DCath was close to 400 mL/min, similar to an AVA. Recirculation with a DCath (7%, 6-13%) was higher than with an AVA. The diffusive dialysis dose delivered with a DCath (spKt and eKt/V) and convective dialysis dose achieved with a DCath were slightly lower than those achieved with AVAs, but they were still much higher than is recommended by guidelines. The percent reduction in β2-M achieved with a DCath was also 4 to 10% lower than that achieved with an AVA. On longitudinal follow-up, the main clinical performance indicators of DCaths (total Kt and total ultrafiltration volume, L/session) were maintained as very stable over time and close to those achieved with AVAs.

CONCLUSIONS

As shown in this study, high-flow DualCath tunneled two-single-lumen silicone catheters may be used to deliver high volume hemodiafiltration in a reliable and consistent manner without compromising clinical performance. These results relied on the specific design of the two silicone cannulas and the strict adherence to best catheter practices.

A pig model of tunneled dialysis catheter (TDC) infection and dysfunction: Opportunities for therapeutic innovation

BACKGROUND

Although tunneled dialysis catheters (TDC) are far from ideal, they still represent the main form of vascular access for most patients beginning dialysis. Catheters are easy to place and allow patients instant access to dialysis, but regardless of these benefits, catheters are associated with a high incidence of significant complications like bloodstream infections, central venous stenosis, thrombosis, and dysfunction. In the present study, we aim to describe and characterize a swine model of catheter dysfunction and bloodstream infection, that recreates the clinical scenario, to help to serve as a platform to develop therapeutic innovations for this important clinical problem.

METHODS

Six Yorkshire cross pigs were used in this study. Non-coated commercial catheters were implanted in the external jugular recreating the main features of common clinical practice. Catheters were aseptically accessed twice a week for a mock dialysis procedure (flushing in and out) to assess for and identify catheter dysfunction. Animals were monitored daily for infections; once detected, blood samples were collected for bacterial culture and antibiograms. Study animals were euthanized when nonresponsive to treatment. Tissue samples were collected in a standardized fashion for macroscopic inspection and histological analysis.

RESULTS

The data analysis revealed an early onset of infection with a median time to infection of 9 days, 40% of the isolates were polymicrobial, and the average time to euthanasia was 20.16 ± 7.3 days. Median time to catheter dysfunction onset was 6 days post-implantation. Postmortem dissection revealed external fibrin sheath and internal thrombosis as the main causes of catheter dysfunction. There was also evidence of central venous stenosis with positive cells for αSMA, CD68, Ki67, Smoothelin, and Vimentin within the venous neointima.

CONCLUSIONS

The described model represents a reliable and reproducible large animal model of catheter dysfunction and bloodstream infection, which recreates all the main complications of TDC's and so could be used as a validated large animal model to develop new therapies for TDC related infection, thrombosis/dysfunction and central venous stenosis.

Catheter-related blood stream infection in hemodialysis patients with symmetric tunneled non-side-hole hemodialysis catheters

BACKGROUND

Tunneled hemodialysis catheter-related bloodstream infection is a major cause of morbidity and mortality in end-stage renal disease patients. Side holes positioned near the tip of catheters have been linked to formation of thrombi, which, in turn, have been implicated in predisposition to infection. In addition, side holes allow spillage of catheter locking solution, including antibiotics, thereby minimizing the lock solution's effect on the catheter tip. This study assessed the infection events that occurred in a series of hemodialysis patients using a non-side-hole catheter.

METHODS

Over a period of 2 years, a novel symmetric-tip non-side-hole catheter was placed in 60 patients. Hemodialysis was performed thrice weekly. Prescribed dialyzer flows were 300-350 mL/min. Catheters were routinely locked with heparin 5000 units/mL between treatments. Patients were followed up for any catheter related complications, specifically infection events.

RESULTS

Seven events of catheter-related bloodstream infection occurred for a rate of 0.76 events per 1000 catheter-days, with the first event occurring 9 weeks after insertion. These events were treated by locking the affected catheter with 2 g of clindamycin in 2 mL of heparin 1000 units/mL and administration of intravenous antibiotics, in most cases, for 7-14 days. Two catheters were removed due to infection.

CONCLUSIONS

Catheter-related bloodstream infections with non-side-hole hemodialysis catheters do occur at a relatively low rate and in this initial preliminary study it seems that most of these infections can be successfully treated without removal of the affected catheters.

Development of in-vitro pulsatile flow generator for evaluating the performance of hemodialysis catheters

Hemodialysis (HD) using an HD catheter is performed widely on renal failure patients. The catheter was evaluated using the recirculation ratio in pre-clinical status, which is a crucial index indicating its performance. However, pre-clinical in-vivo experiments have limitations: high cost, and ethical issues. Hence, computational and in-vitro methods have been developed as alternatives. However, computational methods require fluid dynamic knowledge, whereas in-vitro experiments are complicated and expensive. In this study, we developed a pulsatile flow generator to mimic blood flow achieving cost effectiveness and user convenience. The device used iterative learning control, achieving blood flow in the superior and inferior vena cava within a 3.3% error. Furthermore, the recirculation ratios were measured based on two insertion directions and two different external pipe materials to evaluate the catheter regarding patients' posture and blood vessel stiffness. The results provide a better understanding of cardiovascular device performance without complicated and costly pre-clinical tests.

Staphylococcus aureus accumulation at the tip of hemodialysis catheters with or without tip side holes in catheter related bloodstream infection in a large animal

BACKGROUND

Eighty percent of hemodialysis patients start their dialysis with a tunneled hemodialysis catheter. Catheter related bacteremia is the second most common cause of death in these patients. Side holes near the tips of the tunneled cuffed central venous catheters are associated with accumulation of thrombus, which can lead to catheter dysfunction and, possibly, also to catheter-related infection. To assess the hypothesis that a catheter without side holes would be associated with less bacterial growth, this study compared the susceptibility of a side-hole-free catheter to accumulation of pathogenic bacteria at the catheter tip with that of two catheters which have side holes.

METHODS

Eight tunneled cuffed double-lumen central venous catheters were inserted into both jugular veins of four sheep; one side-hole-free and one control catheter with side holes at the tip in each animal. Staphylococcus aureus bacteria were then infused intravenously to cause bacteremia. Six hours later, the catheters were removed, the clots that accumulated in their tips were collected and cultured, and the bacterial colonies were counted after additional 12 h of incubation.

RESULTS

Bacteria grew on culture plates seeded with the clot homogenate obtained from the tips of all catheters. The colony counts from the catheters with side holes at the tip exceeded the colony counts of bacteria accumulated in the tips of the side-hole-free hemodialysis catheters by one or more orders of magnitude, with a difference of at least two orders of magnitude observed in three of the four intra-animal comparisons.

CONCLUSIONS

In paired intra-animal post-inoculation comparison made in this limited study, fewer colony forming units of pathogenic bacteria accumulated at the tip of the side-hole-free catheters than at the tips of the catheters which have side holes. This may translate to a decreased rate of catheter-related blood stream infections in the side-hole-free catheters.

Tunneled catheter-related bacteremia in hemodialysis patients: incidence, risk factors and outcomes. A 14-year observational study

BACKGROUND

Tunneled catheter-related bacteremia represents one of the major complications in patients on hemodialysis, and is associated with increased morbidity and mortality. This study aimed to evaluate the incidence of tunneled catheter-related bacteremia and, secondly, to identify possible factors involved in the first episode of bacteremia.

METHODS

This is a retrospective study of all tunneled catheters inserted between 1 January, 2005 and 31 December, 2019. Data on patients with a tunneled catheter were analyzed for comorbidities, catheter characteristics, microbiological culture results and variables related to the first episode of bacteremia. Patient outcomes were also assessed.

RESULTS

In the 14-year period under study, 406 tunneled catheters were implanted in 325 patients. A total of 85 cases of tunneled catheter-related bacteremia were diagnosed, resulting in an incidence of 0.40 per 1000 catheter days (81.1% after 6 months of implantation). The predominant microorganisms isolated were Gram-positive organisms: Staphylococcus epidermidis (48.4%); Staphylococcus aureus (28.0%). We found no significant differences in time to catheter removal for infections or non-infection-related reasons. The jugular vein, the Palindrome® catheter, and being the first vascular access were protective factors for the first episode of bacteremia. The 30-day mortality rate from the first tunneled catheter-related bacteremia was 8.7%.

CONCLUSIONS

The incidence of bacteremia in our study was low and did not seem to have a relevant impact on catheter survival. S. epidermidis was the most frequently isolated microorganism, followed by S. aureus. We identified Palindrome® catheter, jugular vein, and being the first vascular access as significant protective factors against tunneled catheter-related bacteremia.

The evolving panorama of vascular access in the 21st century

There are three major types of hemodialysis vascular access: hemodialysis catheters, arteriovenous grafts, and arteriovenous fistulas. Arteriovenous fistulas provide the best access due to their reliability and long-term patency. They are recommended by the current Kidney Disease Outcomes Quality Initiatives (K-DOQI) guidelines; however, not all patients benefit from arteriovenous fistulas due to poor maturation or a lack of adequate vasculature. Currently, hemodialysis is initiated via catheters in the majority of patients. Catheters are associated with high morbidity and mortality due to infection, lower quality of dialysis, and the development of central vein stenosis. The varied responses of patients to the different access types exemplify the need to choose the "right access for the right patient" based on scores that can predict death risk and progression of chronic kidney disease. Additionally, vascular access, often referred to as the "Achilles' heel" of hemodialysis patients, represents a significant percentage of the Medicare budget that continues to increase yearly. The purpose of this paper is to review the current literature on the management of vascular access complications and infection treatment and prevention. The paper also explores emerging research regarding the devices and methods to improve access outcomes such as early cannulation arteriovenous grafts, endovascular arteriovenous fistula creation, and regenerative grafts with resorbable scaffolds, among others. The data were collected through literature searches via PubMed, Athens and web search engines.

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.

Push-pull monorail technique to overcome a difficult course through the left internal jugular vein

BACKGROUND

We assessed the outcomes of a push-pull monorail technique to overcome a difficult anatomical course through the left internal jugular vein in implantable port insertions.

METHODS

From December 2018 to May 2021, a total of 5326 patients were referred for implantable port insertion in our interventional unit, among which 472 cases were requested for insertion on the left side. Our monorail technique was applied only when the catheter tip entered the azygos vein instead of the superior vena cava (n = 8). The technique consists of a puncture at the distal tip of the port catheter with a 21-gauge micropuncture needle, advancing a 0.018-inch hair-wire to the guide, providing support for the pre-assembled port, and advancing the microsheath over the hair-wire to prevent extrusion of the catheter.

RESULTS

The push-pull monorail technique was performed in eight patients, and all cases were technically successful, exhibiting a technical success rate of 100%. There were no immediate or delayed complications.

CONCLUSIONS

The push-pull monorail technique is helpful in overcoming the difficult anatomical course through the left internal jugular vein during implantable port insertion.

Deeper may not be better: relationship between catheter dysfunction and location of the catheter tip in right-sided tunnelled haemodialysis catheters

AIM

To examine the relationship between catheter tip location and catheter dysfunction in the context of tunnelled central venous catheters (CVCs) for haemodialysis.

MATERIALS AND METHODS

This was a retrospective study of 993 haemodialysis patients who underwent insertion of tunnelled CVCs of step-tip design via the right internal jugular vein (IJV). Based on intra-procedural radiographs, the catheter tip was characterised as being in the superior vena cava (SVC), cavo-atrial junction (CAJ), or deep right atrium (DRA). Patients were tracked for 90 days post-procedure for complications resulting in catheter replacement, and these were compared between cohorts. Statistical analysis was performed with Pearson's chi-square and Fisher's exact tests for categorical variables and two-sample t-test and one-way analysis of variance (ANOVA) for continuous variables.

RESULTS

Ninety-five patients (9.6%) experienced catheter dysfunction necessitating replacement within 90 days of insertion. Tip location in SVC was associated with lower occurrence of catheter dysfunction (1.9%) as compared with the CAJ (8%) and DRA (11%; p=0.049). Catheter replacement due to other complications (catheter-associated bacteraemia, cuff dislodgement, exit-site infection, external catheter damage) showed no statistically significant relation to location of the CVC tip.

CONCLUSION

When utilising tunnelled CVCs with a step-tip design inserted via the right IJV, location of the catheter tip in the SVC is associated with reduced occurrence of catheter dysfunction as compared to either the CAJ or DRA.

Computational investigation of the haemodynamics shows criticalities of central venous lines used for chronic haemodialysis in children

BACKGROUND

Haemodialysis is a life-saving treatment for children with kidney failure. The majority of children have haemodialysis through central venous lines (CVLs). The use of CVLs in pediatric patients is often associated to complications which can lead to their replacement. The aim of this study is to investigate haemodynamics of pediatric CVLs to highlight the criticalities of different line designs.

METHODS

Four models of CVLs for pediatric use were included in this study. The selected devices varied in terms of design and sizes (from 6.5 Fr to 14 Fr). Accurate 3D models of CVLs were reconstructed from high-resolution images including venous and arterial lumens, tips and side holes. Computational fluid dynamics (CFD) analyses were carried out to simulate pediatric working conditions of CVLs in ideal and anatomically relevant conditions.

RESULTS

The arterial lumens of all tested CVLs showed the most critical conditions with the majority of blood flowing through the side-holes. A zone of low flow was identified at the lines' tip. The highest shear stresses distribution (>10 Pa) was found in the 8 Fr line while the highest platelet lysis index in the 10 Fr model. The analysis on the anatomical geometry showed an increase in wall shear stress measured in the 10 F model compared to the idealised configuration. Similarly, in anatomical models an increased disturbance and velocity of the flow was found inside the vein after line placement.

CONCLUSION

This study provided a numerical characterization of fluid dynamics in pediatric CVLs highlighting performance criticalities (i.e. high shear stresses and areas of stagnation) associated to specific sizes (8 Fr and 10 Fr) and conditions (i.e. anatomical test).

Initial Clinical Experience with a Symmetric Tip Tunneled Hemodialysis Catheter Without Side Holes

The purpose of this article is to assess the performance and safety of a novel, symmetric, side-hole-free tunneled cuffed catheter hypothesized to sustain adequate flow without the need for side holes. Between November 2016 and January 2019, Pristine hemodialysis catheters were placed de novo in 45 end-stage renal disease patients (27 males and 18 females) at a single investigational site. Forty-one catheters were placed in the right and four in the left internal jugular vein. There were no incidents of insertion failure. Patients had dialysis three times per week and were followed at four investigational sites. Nominal catheter flows, incidence of poor flow, and catheter-related infections were recorded at each dialysis session and analyzed. The average follow-up time was 161.69 days for a total of 7116 catheter days. Nine patients died from reasons unrelated to the catheter and one patient switched to fistula. Four patients had poor flows necessitating catheter replacement. Four patients had catheter-related bloodstream infections which resolved with antibiotics. These equate to 0.56 events per 1000 catheter days. Catheter survival was 100%, 97.6%, and 89.7% at 30, 90, and 180 days, respectively. The initial clinical assessment of the symmetric Pristine hemodialysis catheter featuring a Y-tip devoid of side holes revealed good catheter performance and survival and a low complication rate.

Development of New Hemodialysis Catheter Using Numerical Analysis and Experiments

A hemodialysis (HD) catheter, especially one with a symmetric tip design, plays an important role in the long-term treatment of patients with renal failure. It is well known that the design of the HD catheter has a considerable effect on blood recirculation and thrombus formation around it, which may cause inefficiencies or malfunctions during HD. However, hemodynamic analyses through parametric studies of its designs have been rarely performed; moreover, only comparisons between the existing models have been reported. In this study, we numerically analyzed the design of the HD catheter's side hole and distal tip for evaluating their effects on hemodynamic factors such as recirculation rate (RR), shear stress, and blood damage index (BDI). The results indicated that a larger side hole and a nozzle-shaped distal tip can significantly reduce the RR and shear stress around the HD catheter. Furthermore, based on these hemodynamic insights, we proposed three new HD catheter designs and compared their performances with existing catheters using numerical and in vitro methods. These new designs exhibited lower RRs and BDI values, thus providing better performance than the existing models. These results can help toward commercialization of more efficient HD catheters.

Nephronophthisis and central veins abnormalities: A case report

Patients with genetic disorders are potentially more susceptible to present vascular abnormalities compared to the general population. For these patients, unusual difficulties could appear during a CVC placement procedure that could lead to major complications if venous abnormalities are undiagnosed. Ultrasound and fluoroscopy guidance should be used routinely for all patients in order to avoid complications and catheter misplacement.

Clot accumulation at the tip of hemodialysis catheters in a large animal model

Background:

The issue of side holes in the tips of the tunneled cuffed central venous catheters is complex and has been subject to longstanding debate. This study sought to compare the clotting potential of the side-hole-free Pristine hemodialysis catheter with that of a symmetric catheter with side holes.

Methods:

Both jugular veins of five goats were catheterized with the two different catheters. The catheters were left in place for 4 weeks and were flushed and locked with heparin thrice weekly. The aspirated intraluminal clot length was assessed visually prior to each flushing. In addition, the size and weight of the clot were recorded upon catheter extraction at the end of the 4-week follow-up

Results:

The mean intraluminal clot length observed during the entire study follow-up measured up to a mean of 0.66 cm in the GlidePath (95% CI, 0.14–1.18) and 0.19 cm in the Pristine hemodialysis catheter (95% CI, −0.33 to 0.71), the difference being statistically significant (p = 0.026). On average, 0.01 g and 0.07 g of intraluminal clot were retrieved from the Pristine and GlidePath catheters, respectively (p = 0.052).

Conclusion:

The Pristine hemodialysis catheter was largely superior to a standard side hole catheter in impeding clot formation, and, contrary to the side hole catheter, allowed for complete aspiration of the intraluminal clot.

Spontaneous Dislodgement of Tunneled Dialysis Catheters after De Novo versus Over-The-Wire-Exchange Placement

PURPOSE

To evaluate dislodgement of tunneled dialysis catheters (TDCs) in de novo (DN) placement with ultrasound versus over-the-wire exchange (OTWE).

MATERIALS AND METHODS

Data were collected retrospectively on all TDC placements at this institution from 2001 to 2019 and were excluded if no removal date was recorded or if dwell time was more than 365 days. Information on TDC brand, placement, insertion/removal, and removal reason were collected. Multiple logistic regression evaluated factors associated with TDC dislodgement. DN placement and OTWE were compared for rate of dislodgement (generalized estimating equations method) and TDC dwell time (survival analysis).

RESULTS

In total, 5328 TDCs were included with 66% (3522) placed DN and 32% (1727) via OTWE. Mean dwell time was 65 ± 72 days, and dislodgement occurred in 4% (224). TDC dislodgement rates in the DN and OTWE groups were 0.48 and 0.93 per 1000 catheter days, respectively. Brand (Ash Split vs. VectorFlow), placement technique (OTWE vs. DN), laterality (left vs. right), and site (left vs. right internal jugular vein) were significant predictors of dislodgement. OTWE placement exhibited 1.7 times the odds of dislodgement (95% confidence interval, 1.2-2.6; P = .004) compared to DN and had significantly higher probability of dislodgement across time (hazard ratio = 2.0; P < .001) compared to DN. Dislodgement rates for OTWE vs. DN were 8% vs. 3% (3 months), 13% vs. 6% (6 months), and 38% vs. 17% (1 year).

CONCLUSIONS

TDC spontaneous dislodgement rates were significantly and consistently higher after OTWE compared to DN placement. These data support more careful attention to catheter fixation after OTWE placement.

Vascular access in kidney transplant recipients

Vascular access is an important element in the overall care provided to kidney transplant recipients. The transplanted kidney is not indestructible, and chronic kidney disease after transplantation may result in needing another transplant or beginning dialysis. Commonly used vascular accesses, like peripheral and central lines, can preclude the creation of future, permanent dialysis access. Therefore, there is urgent need to preserve vessels for the future access needs for hemodialysis among kidney transplant recipients without functional vascular access for dialysis. Moreover, the proper care of functional vascular access among kidney transplant recipients is crucial. In this review article, we will address the common vascular access procedures and complications among kidney transplant recipients.

New Directions in Ensuring Catheter Safety

Tunneled dialysis catheters remain the most common vascular access used to initiate hemodialysis. Unfortunately, their use is associated with higher morbidity and mortality when compared with arteriovenous fistulae or grafts. Different types of catheters with different designs and material properties function differently. Additional devices and medications can be used to decrease the rates of infection and thrombosis. The current available tunneled dialysis catheters remain far from the desired goal and innovation in the field of dialysis vascular access remains in dire need.

(F)utility of "routine" postprocedural chest radiograph after hemodialysis catheter (central venous catheter) insertion

A routine postprocedural chest radiograph had been a safe, checklist-based final step of the procedure, since the start of central venous catheter insertion for hemodialysis to check the position of the catheter tip and to rule out complications. However, the chest radiograph is a suboptimal method to rule out complications like pneumothorax and is not a reliable test to confirm its position. Although it is relatively inexpensive, it is labor-intensive and exposes patient to unnecessary radiation exposure, cost, and often results in delayed use of the catheter. Various studies question the value of a routine chest radiograph as a screening test to rule out the mechanical complications of catheter insertion. We, in this brief viewpoint, present evidence to support the futility of a routine postprocedural chest radiograph in majority of asymptomatic patients and support Choosing Wisely Initiative to avoid low-value studies. However, it should be considered under specific indications, as discussed.

Vascular access for hemodialysis: A perpetual challenge

Vascular access for hemodialysis has a long and rich history. This article highlights major innovations and milestones in the history of angioaccess for hemodialysis. Advances in achievement of lasting hemodialysis access, swift access transition, immediate and sustaining access to vascular space built the momentum at different turning points of access history and shaped the current practice of vascular access strategy. In the present era, absent of large-scale clinical trials to validate practice, the ever-changing demographic and comorbidity makeup of the dialysis population pushes against stereotypical angioaccess goals. The future of hemodialysis vascular access would benefit from proper randomized clinical trials and acclimatization to clinical contexts.

Clinical and Regulatory Considerations for Central Venous Catheters for Hemodialysis

Central venous catheters remain a vital option for access for patients receiving maintenance hemodialysis. There are many important and evolving clinical and regulatory considerations for all stakeholders for these devices. Innovation and transparent and comprehensive regulatory review of these devices is essential to stimulate innovation to help promote better outcomes for patients receiving maintenance hemodialysis. A workgroup that included representatives from academia, industry, and the US Food and Drug Administration was convened to identify the major design considerations and clinical and regulatory challenges of central venous catheters for hemodialysis. Our intent is to foster improved understanding of these devices and provide the foundation for strategies to foster innovation of these devices.

Spanish Clinical Guidelines on Vascular Access for Haemodialysis

Vascular access for haemodialysis is key in renal patients both due to its associated morbidity and mortality and due to its impact on quality of life. The process, from the creation and maintenance of vascular access to the treatment of its complications, represents a challenge when it comes to decision-making, due to the complexity of the existing disease and the diversity of the specialities involved. With a view to finding a common approach, the Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology [S.E.N.], vascular surgery [SEACV], vascular and interventional radiology [SERAM-SERVEI], infectious diseases [SEIMC] and nephrology nursing [SEDEN]), along with the methodological support of the Cochrane Center, has updated the Guidelines on Vascular Access for Haemodialysis, published in 2005. These guidelines maintain a similar structure, in that they review the evidence without compromising the educational aspects. However, on one hand, they provide an update to methodology development following the guidelines of the GRADE system in order to translate this systematic review of evidence into recommendations that facilitate decision-making in routine clinical practice, and, on the other hand, the guidelines establish quality indicators which make it possible to monitor the quality of healthcare.

In Vitro and In Vivo Activity of a Novel Catheter Lock Solution against Bacterial and Fungal Biofilms

Central-line-associated bloodstream infections are increasingly recognized to be associated with intraluminal microbial biofilms, and effective measures for the prevention and treatment of bloodstream infections remain lacking. This report evaluates a new commercially developed antimicrobial catheter lock solution (ACL), containing trimethoprim (5 mg/ml), ethanol (25%), and calcium EDTA (Ca-EDTA) (3%), for activity against bacterial and fungal biofilms, using in vitro and in vivo (rabbit) catheter biofilm models. Biofilms were formed by bacterial (seven different species, including vancomycin-resistant Enterococcus [VRE]) or fungal (Candida albicans) species on catheter materials. Biofilm formation was evaluated by quantitative culture (CFU) and scanning electron microscopy (SEM). Treatment with ACL inhibited the growth of adhesion-phase biofilms in vitro after 60 min (VRE) or 15 min (all others), while mature biofilms were completely inhibited after exposure for 2 or 4 h, compared to control. Similar results were observed for drug-resistant bacteria. Compared to the heparinized saline controls, ACL lock therapy significantly reduced the catheter bacterial (3.49 ± 0.75 versus 0.03 ± 0.06 log CFU/catheter; P = 0.016) and fungal (2.48 ± 1.60 versus 0.55 ± 1.19 log CFU/catheter segment; P = 0.013) burdens in the catheterized rabbit model. SEM also demonstrated eradication of bacterial and fungal biofilms in vivo on catheters exposed to ACL, while vigorous biofilms were observed on untreated control catheters. Our results demonstrated that ACL was efficacious against both adhesion-phase and mature biofilms formed by bacteria and fungi in vitro and in vivo.

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.

A prospective comparison of the performance and survival of two different tunnelled haemodialysis catheters: SplitCath® versus DuraMax®

BACKGROUND

Despite their well-recognised shortcomings, haemodialysis catheters (HDCs) remain an important form of haemodialysis access for many patients. There are several HDCs commercially available, each differing considerably in design, which is known to significantly influence performance and survival. We sought to determine which of two tunnelled HDCs, DuraMax® (Angiodynamics, NY, USA) or SplitCath® (MedComp, PA, USA) delivers the best performance, safety and reliability for dialysis patients.

METHODS

Eighty-six patients were prospectively randomised to receive either DuraMax® (DM) or SplitCath® (SC). Outcomes included: (i) mean flow rates (mL/min) averaged over the first 10 weeks of dialysis, and urea reduction ratio (URR); and (ii) long-term catheter survival with appraisal of any events leading to catheter dysfunction and early removal.

RESULTS

Median flow rates (interquartile range) in the DM and SC groups were 321 (309-343) and 309 (294-322) mL/min, respectively (p = 0.002). URR values for the DM and SC groups were 71 (65-76) and 74 (70-78), respectively, (p = 0.094). There was no significant difference in long-term survival or frequency of incidents that required early HDC removal (9/43 in the DM group, 5/43 patients SC). A slightly higher incidence of HDC dislodgement was noted in the DM group, although this study was not statistically powered to determine its significance.

CONCLUSIONS

We conclude that DM yields slightly higher flow rates in the first 10 weeks of dialysis, and a similar low incidence of complications and long-term survival for both DM and SC HDCs.

The Monorail Technique to Overcome Difficult Anatomical Course During Implantation of Central Venous Port via the Left Internal Jugular Vein

PURPOSE

The study aimed to introduce a monorail technique to overcome difficult anatomical course via left internal jugular vein in implantable port insertion.

METHODS

From 2007 to 2016, a total of 9346 patients were referred for implantable port insertion in our interventional unit, among which 79 cases were requested to insert on the left side. Our monorail technique was applied only when the technical challenge of the catheter tip entering the azygos vein instead of the superior vena cava occurred (n = 7). The technique consists of puncturing at the distal tip of the port catheter with a 21-gauge micropuncture needle and advancing a 0.018-in. hair-wire to guide and provide support for pre-assembled port.

RESULTS

The monorail technique was performed in seven patients and all but one case were technically successful, showing a technical success rate of 85.7%. There were no immediate or delayed complications.

CONCLUSIONS

The monorail technique is helpful to overcome the difficult anatomical course via left internal jugular vein in implantable port insertion.

Vascular access should be tailored to the patient

A cornerstone of hemodialysis treatment is the creation of a functional and durable dialysis vascular access. Every patient with chronic kidney disease should have a plan of renal replacement therapy and access site protection. Factors having a crucial impact on vascular access selection include age, comorbidity, vessel quality, prognosis, dialysis urgency, and surgeon's preferences. Our medical group have reviewed these factors in our patients and, based on recently published data, developed a clinical decision tree for dialysis access in the chronic kidney disease patient. Vascular access care should be patient-centered with the aim to maximize patient survival without loss of vascular access options; and not focused only the primary patency rates of dialysis access procedures.

Practical Aspects of Nontunneled and Tunneled Hemodialysis Catheters

Nontunneled hemodialysis catheters (NTHCs) are typically used when vascular access is required for urgent renal replacement therapy. The preferred site for NTHC insertion in acute kidney injury is the right internal jugular vein followed by the femoral vein. When aided by real-time ultrasound, mechanical complications related to NTHC insertion are significantly reduced. The preferred site for tunneled hemodialysis catheters placement is the right internal jugular vein followed by the left internal jugular vein. Ideally, the catheter should be inserted on the opposite side of a maturing or planned fistula/graft. Several dual-lumen, large-diameter catheters are available with multiple catheter tip designs, but no one catheter has shown significant superior performance.

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.

Leakage of central venous catheter locking fluid by hemodynamic transport

Central venous catheters are often filled when not in use with an anticoagulating fluid, usually heparinized saline, known as the locking fluid. However, the use of the locking fluid is associated with known risks because of "leakage" of the lock. A new hypothesis is proposed here to explain the lock fluid leakage: that the leakage is due to advective and diffusive mass transfer by blood flow around the catheter tip in situ. On the basis of previous in vitro experiments, the leakage mechanism has been hypothesized to be fluid motion driven by buoyancy forces between the heavier blood and the lighter locking fluid. The current hypothesis is justified by a simple one-dimensional mass transfer model and more sophisticated three-dimensional computational hemodynamic simulations of an idealized catheter. The results predict an initial, fast (<10 seconds) advection-dominated phase, which may deplete up to 10% of the initial lock, followed by a slow diffusion-limited phase which predicts an additional 1-2% of leakage during a 48 hour period. The current results predict leakage rates that are more consistent with published in vivo data when compared with the buoyancy hypothesis predictions, which tend to grossly overestimate leakage rates.

New Technology: Heparin and Antimicrobial-Coated Catheters

Although tunneled hemodialysis catheter must be considered the last option for vascular access, it is necessary in some circumstances in the dialysis patient. Thrombosis and infections are the main causes of catheter-related comorbidity. Fibrin sheath, intimately related with the biofilm, is the precipitating factor of this environment, determining catheter patency and patient morbidity. Its association with bacterial overgrowth and thrombosis has led to the search of multiple preventive measures. Among them is the development of catheter coatings to prevent thrombosis and infections. There are two kinds of treatments to cover the catheter surface: antithrombotic and antimicrobial coatings. In nondialysis-related settings, mainly in intensive care units, both have been shown to be efficient in the prevention of catheter-related infection. This includes heparin, silver, chlorhexidine, rifampicine and minocycline. In hemodialysis population, however, few studies on surface-treated catheters have been made and they do not provide evidence that shows complication reduction. The higher effectiveness of coatings in nontunneled catheters may depend on the short average life of these devices. Hemodialysis catheters need to be used over long periods of time and require clinical trials to show effectiveness of coatings over long periods. This also means greater knowledge of biofilm etiopathogeny and fibrin sheath development.

Hemodialysis Catheter Tip Design: Observations on Fluid Flow and Recirculation

Purpose

To observe fluid flow patterns and measure recirculation rates of tunneled hemodialysis catheters using a mechanical model that simulates hemodialysis treatment.

Materials and methods

Nine tunneled hemodialysis catheters were evaluated using a mechanical model that simulated catheter conditions during a routine hemodialysis treatment. Objective and subjective determinants of catheter performance were measured and compared. Catheters were evaluated with blood lines connected in standard and reversed configurations using a fluid flow rate of 425 ml/min.

Results

With blood lines in standard configuration the Split Cath® was the only catheter to exhibit an atypical fluid flow pattern and significant tip movement. When the blood lines were reversed, three split-tip catheters had significant tip movement. The three step-tip catheters and two symmetric tip catheters had stable fluid flow patterns and no significant tip movement with blood lines connected in standard and reverse configurations. The nine catheters had no recirculation when connected in standard configuration. When the blood lines were reversed the percentage of recirculating fluid for symmetric tip, step-tip, and split-tip catheters was 0%, 15% to 20%, and 20% to 30%, respectively. The Equistream®, Palindrome™, and Symetrex catheters had no recirculation with blood lines connected in standard or reversed configurations.

Conclusions

Eight of the nine catheters evaluated in this study performed well with blood lines connected in standard configuration. When blood lines were reversed, symmetric tip and step-tip designs had more stable fluid flow patterns, less tip movement and lower recirculation rates when compared to split-tip designs.

Comparison of Tesio and LifeCath Twin Permanent Hemodialysis Catheters: The VyTes Randomized Trial

Purpose

Central venous catheters for maintenance hemodialysis (HD) are designed to attain the required dialysis dose through sustained high blood flow rates (BFR). The authors studied the immediate and long-term performance and complications of two twin-catheter systems, the Tesio catheter (TC) and the LifeCath Twin (LC), to inform clinical practice.

Methods

This single-center randomized controlled parallel-group trial allocated 80 incident patients (1:1) to receive either a TC (MedComp) or LC (Vygon). Patients were dialyzed to target BFR 450 mL/min and followed up for 12 months. The primary outcome was achievement of target BFR during the first HD session. Secondary outcomes included thrombotic dysfunction, displacement and catheter-related infection. Catheter dysfunction was defined by a BFR ≤ 250 mL/min.

Results

More LCs reached the primary endpoint (44% vs. 10%, p=0.001) delivering a higher BFR (mean 383±82 vs. 277±79 mL/min, p<0.001). Significant differences in BFR persisted until the fourth dialysis session. Rates of catheter-related bacteremia (0.40 vs. 0.51/1,000 catheter days, p=0.7) and exit site infection were similar between groups (0.24 vs. 0.09/1,000 catheter days, p=0.4). Overall rates of catheter dysfunction were 2.8/1,000 catheter days (95% CI 2.1-3.5), with no differences in thrombolytic lock use although the LC group required more thrombolytic infusions (6 vs. 0, p=0.01).

Conclusions

The LC can deliver greater BFRs in the first three HD sessions following insertion although this did not translate into differences in performance, dialysis adequacy or complication rates with long-term use. Both catheter types can consistently deliver high BFRs over an extended period of time.

Dialysis Central Venous Catheter Types and Performance

The choice of both short-term (nontunneled) and long-term (tunneled) central venous catheters (CVCs) for hemodialysis is a difficult one, due to the large number of available catheters, with very different characteristics and cost.

CVC-related complications (in particular infections, thrombosis and inefficient dialysis) can determine ominous consequences and death, with extremely elevated costs due to prolonged hospitalization and expensive procedures. Thus, the correct balance between cost and quality of CVC is required when deciding which kind of CVC should be adopted.

In this regard, the design of CVCs has become a very active area of industrial and clinical research, with the ultimate goal of improving the long-term function of the catheter and of reducing complication rates, because even small improvements in the complication or reintervention rates have a positive impact on individual patient care and cost to society. In this article we review the general features of CVCs, including differences between tunneled and nontunneled CVCs, materials and their compatibility with lock solutions, the implications of straight versus precurved design in nontunneled CVCs, lumen and tip features with their clinical implications, catheter coatings and their effect on infection and thrombosis.

Quantification of fibrin in blood thrombi formed in hemodialysis central venous catheters: a pilot study on 43 CVCs

PURPOSE

Fibrin deposition and thrombotic occlusion represent a serious cause of access dysfunction in hemodialysis central venous catheters (CVCs). The aim of this work was to define and apply a method for imaging and quantifying fibrin in thrombi formed into the side holes of CVCs.

METHODS

Forty-three CVCs removed from a cohort of dialyzed patients were analyzed in this pilot study. Hematoxylin and eosin and a modified Carstair's staining were applied on permanent thrombus sections. Fluorescence microscopy and image analysis were performed to quantify the fibrin amount.

RESULTS

Highly fluorescent areas were invariably associated with fibrin by Carstair's method. The deposition of concentric layers of fibrin and erythrocytes was easily identified by fluorescence microscopy, showing growth features of the thrombus. Fibrin amount in diabetic patients was significantly higher than that in nondiabetic patients with median (interquartile range) values of 51% (47-68%) and 44% (30-54%), respectively (p=0.032). No significant difference in fibrin content was found by grouping data according to catheter type, permanence time, insertion site and dialysis vintage. Higher variability in fibrin values was found in thrombi from CVCs removed after 1-15 days compared with 16-60 days. A trend of an increase in fibrin amount in thrombi was noted according to blood platelet count at CVC insertion.

CONCLUSIONS

The analytical method presented here proved to be a rapid and effective way for quantifying fibrin content in thrombi formed on CVCs with potential application in future clinical studies.