Effectiveness of a New Tunneled Catheter in Preventing Catheter Malfunction: A Comparative Study

Evaluation of venocutaneous fistula as vascular access for hemodialysis: Examination of 46 limbs of 40 patients

INTRODUCTION

We have previously evaluated the usefulness of venocutaneous fistula (VCF), also called "dermatorrhea." VCF is a technique of blood removal/return by advancing a dialysis cannula to the femoral vein for each hemodialysis session using a fistula created between the great saphenous vein and skin.

METHODS

In this study, we evaluated 46 limbs of 40 patients for whom VCF was created at our hospital between May 2017 and April 2022. In all the patients, it was difficult to construct an arteriovenous fistula or arteriovenous graft because of the general/vascular conditions. The usefulness of this method was evaluated based on the results of dialysis treatment after fistula creation and the use of fistula.

RESULTS

Fundamental evaluation confirmed the progression of vascular wall thickening over time. During clinical review, no serious complications were found in any patient during or after fistula creation surgery. The infection rate was 0.30/1000 days of fistula maintenance. Secondary patency rates by the Kaplan-Meier method were 87.0% at 1 year and 42.6% at 3 years.

CONCLUSION

This method has demonstrated a good patency rate, low infection rate, and seems to be a potentially useful alternative in patients in whom it is difficult to establish vascular access.

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.

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.

May position of hemodialysis catheter tip have a direct effect on its patency? Positive results of a preliminary study on its rotation

Renal transplant therapy is essential in patients with End-Stage Renal Disease (ESRD). It is used in patients awaiting a kidney transplant or those who cannot be a transplant candidate. Central venous catheter is one of the most used access routes worldwide but has been recorded as the one with highest mortality and morbidity rate. Thromboembolic events have played a major part for that. This is a descriptive-analytical study, which conducted in a university treatment center in Tehran, Iran. A total of 225 patients were selected for this study that 108 were excluded because of our criteria. Statistical analysis was performed by SPSS v19 and a total of 117 patients were included in this study. The average age of the patients was 51.62±11.26. 79 (67.5%) and 38 (32.5%) patients had medial and lateral tip direction, respectively. The catheter of 85(72.6%) and 32(27.4%) patients was patent and occluded, respectively. The average catheter tip occlusion time in both groups was 22.5 and 7.5 months. Three-month, six-month, twelve-month, and twenty-four-month patency rate were 99%, 94%, 88%, and 30%, respectively. our findings suggest that medial direction of the tip of the catheter reduces complications caused in CVS. Because our study has been conducted in a small scale and there is lack of similar studies, our team suggests extension to a larger scale to confirm or not our results.

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.

Computational fluid dynamics of the right atrium: Assessment of modelling criteria for the evaluation of dialysis catheters

Central venous catheters are widely used in haemodialysis therapy, having to respect design requirements for appropriate performance. These are placed within the right atrium (RA); however, there is no prior computational study assessing different catheter designs while mimicking their native environment. Here, a computational fluid dynamics model of the RA, based on realistic geometry and transient physiological boundary conditions, was developed and validated. Symmetric, split and step catheter designs were virtually placed in the RA and their performance was evaluated by: assessing their interaction with the RA haemodynamic environment through prediction of flow vorticity and wall shear stress (WSS) magnitudes (1); and quantifying recirculation and tip shear stress (2). Haemodynamic predictions from our RA model showed good agreement with the literature. Catheter placement in the RA increased average vorticity, which could indicate alterations of normal blood flow, and altered WSS magnitudes and distribution, which could indicate changes in tissue mechanical properties. All designs had recirculation and elevated shear stress values, which can induce platelet activation and subsequently thrombosis. The symmetric design, however, had the lowest associated values (best performance), while step design catheters working in reverse mode were associated with worsened performance. Different tip placements also impacted on catheter performance. Our findings suggest that using a realistically anatomical RA model to study catheter performance and interaction with the haemodynamic environment is crucial, and that care needs to be given to correct tip placement within the RA for improved recirculation percentages and diminished shear stress values.

A Systematic Review and Meta-Analysis of Randomized Trials Comparing Two-Stage with One-Stage Brachio-Basilic Vein Fistulas

Purpose

There is currently debate if brachio-basilic vein fistula (BBVF) should be performed as a one-stage or two-stage procedure. The aim of the present study was to perform a systematic review and meta-analysis on BBVF staging.

Materials and Methods

On February 25, 2016, a search for randomized-controlled trials (RCTs) on BBVF procedures was performed in MEDLINE and Scopus databases. Meta-analyses were performed with fixed-effect or random-effects models as appropriate with risk ratios (RRs). The primary efficacy and safety outcome measures were BBVF maturation and development of complications, respectively. Specific types of complications, including loss of functional secondary patency and long-term complications were all secondary outcome measures.

Results

We identified three RCTs reporting on 126 patients. Maturation failure of two-stage BBVFs (3/47, 6.4%) was less frequent than one-stage BBVFs (16/79, 20.3%; RR, 0.27; P=0.02). Complication rates of two-stage and one-stage BBVFs were similar (RR, 0.80; P=0.54), but on sensitivity analysis these were less likely to occur with two-stage BBVFs (37% vs. 69% for one-stage BBVFs; RR, 0.57; P=0.03). Two-stage BBVFs were less likely to lose their functional secondary patency (21.3% vs. 31.6% for one-stage BBVFs; RR, 0.61; P=0.11). This non-significant trend became significant (RR, 0.36; P=0.02) on sensitivity analysis. There was no difference in specific complication rates of the two study groups.

Conclusion

Among candidates for BBVF fistula, there is evidence to suggest that two-stage BBVFs achieve higher maturation rates compared to one-stage BBVFs. The evidence for difference in long-term secondary patency is less robust, calling for further research.

Urea-based recirculation validation of the symmetrical palindrome catheter

BACKGROUND

High blood flow and low recirculation rates are central for adequate haemodialysis. A new symmetrical tip has been invented promising efficient haemodialysis even if the ports are reversed.

OBJECTIVE

To evaluate access recirculation of the 'palindrome' catheter and to report initial experiences in a clinical setting.

MATERIAL AND METHODS

After implantation of the new catheter in 20 patients (male: 14; female: 6; mean age 72 ± 12.2), access recirculation was evaluated using the urea-based recirculation test. After 30 minutes of haemodialysis, ultrafiltration was stopped and arterial and venous samples were taken. Afterwards, the blood flow rate was reduced to 120 ml/min. Another systemic arterial blood sample was taken 10 seconds after the blood pump was switched off.

RESULTS

All 20 interventions were performed successfully without complications. The average recirculation rate was 8.1% with a median of 2.5% ranging from 0 to 85.8%. Recirculation rates under 5% were measured in 13 patients and more than 10% recirculation were found in two patients. The median of days between catheter implantation and recirculation assessment was the day following implantation.

CONCLUSION

The new symmetrical catheter presented low recirculation rates in a clinical setting. Since there is just a single tip, fluoroscopic placement in the right atrium is facilitated.

Catheter-related bloodstream infection in end-stage kidney disease: a Canadian narrative review

Purpose of the review

Patients with end-stage renal disease (ESRD) are at a high risk of bacterial infection. We reviewed publications on risk factors, prevention, and treatment paradigms, as well as outcomes associated with bacterial infection in end-stage kidney disease. We focused in particular on studies conducted in Canada where rates of haemodialysis catheter use are high.

Sources of information

We included original research articles in English text identified from MEDLINE using search terms ‘chronic kidney failure’, ‘renal dialysis’, or ‘chronic renal insufficiency’, and ‘bacterial infection’. We focused on articles with Canadian study populations and included comparisons to international standards and outcomes where possible.

Findings

Bacterial infections in this setting are most commonly due to Gram-positive skin flora, particularly Staphylococcus, with methicillin-resistant Staphylococcus aureus (MRSA) carrying a poorer prognosis. Interventions that may decrease mortality from sepsis include a collaborative care model that includes a nephrology team, an infectious disease specialist, and use of standardized care bundles that adhere to proven quality-of-care indicators. Decreased infectious mortality may be achieved by ensuring appropriate antibiotic selection and dosing as well as avoiding catheter salvage attempts. Reduction in bloodstream infection (BSI) incidence has been observed with the use of tPA catheter-locking solutions and the use of mupirocin or polysporin as a topical agent at the catheter exit site, as well as implementing standarized hygiene protocols during catheter use.

Limitations

There has been a paucity of randomized controlled trials of prevention and treatment strategies for catheter-related BSIs in haemodialysis. Some past trials have been limited by lack of blinding and short duration of follow-up. Microbiological epidemiology, although well characterized, may vary by region and treatment centre.

Implications

With the high prevalence of catheter use in Canadian haemodialysis units, further studies on long-term treatment and preventative strategies for BSI are warranted.

Comparison of treatment delay associated with tunneled hemodialysis catheter placement between interventionists

BACKGROUND/AIMS

Fragmented care in nephrology can cause treatment delays. Nephrologists are qualified to perform vascular access-related procedures because they understand the pathophysiology of renal disease and perform physical examination for vascular access. We compared treatment delays associated with tunneled hemodialysis catheter (TDC) placement between interventional radiologists and nephrologists.

METHODS

We collected data by radiologists from January 1, 2011 through December 31, 2011 and by nephrologists from since July 1, 2012 through June 30, 2013. We compared the duration from the hemodialysis decision to TDC placement (D-P duration) and hemodialysis initiation (D-H duration), catheter success and the complication rate, and the frequency and the usage time of non-tunneled hemodialysis catheters (NDCs) before TDC placement.

RESULTS

The study analyzed 483 placed TDCs: 280 TDCs placed by radiologists and 203 by nephrologists. The D-P durations were 319 minutes (interquartile range [IQR], 180 to 1,057) in the radiologist group and 140 minutes (IQR, 0 to 792) in the nephrologist group. Additionally, the D-H durations were 415 minutes (IQR,260 to 1,091) and 275 minutes (IQR, 123 to 598), respectively. These differences were statistically significant (p = 0.00). The TDC success rate (95.3% vs. 94.5%, respectively; p = 0.32) and complication rate (16.2% vs. 11%, respectively; p = 0.11) did not differ between the groups. The frequency (24.5 vs. 26%, respectively; p = 0.72) and the usage time of NDC (8,451 vs. 8,416 minutes, respectively; p = 0.91) before TDC placement were not statistically significant.

CONCLUSIONS

Trained interventional nephrologists could perform TDC placement safely, minimizing treatment delays.

Update on Insertion and Complications of Central Venous Catheters for Hemodialysis

Central venous catheters are a popular choice for the initiation of hemodialysis or for bridging between different types of access. Despite this, they have many drawbacks including a high morbidity from thrombosis and infection. Advances in technology have allowed placement of these lines relatively safely, and national guidelines have been established to help prevent complications. There is an established algorithm for location and technique for placement that minimizes harm to the patient; however, there are significant short- and long-term complications that proceduralists who place catheters should be able to recognize and manage. This review covers insertion and complications of central venous catheters for hemodialysis, and the social and economic impact of the use of catheters for initiating dialysis is reviewed.

Randomized controlled trial comparing primary and staged basilic vein transposition

Objective

It is unclear if brachio-basilic vein fistula should be performed as a primary or staged procedure, particularly for smaller basilic veins. Our aim was to report on a randomized controlled trial comparing these two techniques.

Methods

Sixteen patients with a basilic vein ≥2.5 mm were randomized into primary transposed brachio-basilic vein (TBBV) fistula (n = 9) and staged TBBV fistula (n = 7). Patients with basilic veins enlarged by previous arteriovenous fistulas were excluded. Baseline characteristics of the two study groups, including vein size, were comparable (median basilic vein diameter 3.5 mm, range 2.8–4.1 mm). The staged group had a brachio-basilic vein fistula performed first followed by the transposition procedure performed at least 6 weeks later to allow the basilic vein to enlarge. TBBV fistula maturation at 10 weeks, primary, assisted-primary, and secondary patency were the primary outcome measures. Early failures were included in the calculation of patency rates.

Results

Transposed brachio-basilic vein fistula maturation rate after primary procedures (3/9, 33%) was lower compared to maturation rate after staged procedures (7/7, 100%, P = 0.011, Fisher’s exact test), which led to premature termination of the trial. Time to hemodialysis [median (interquartile range)] of primary and staged procedures was 54 (51.5–113.5) days and 97 (93–126) days, respectively (P = 0.16). One-year primary and assisted-primary patency rates of primary and staged procedures were equivalent (44 vs 57%, P = 0.76 and 44 vs 71%, P = 0.29, respectively); however, there was a trend toward a better 1-year secondary patency after staged procedures (86 vs 44% for primary procedures, P = 0.09).

Conclusions

Among candidates for TBBV fistula with a small basilic vein, staged transposition achieves higher maturation rates compared to primary procedures, a difference reflected in long-term secondary patency.

Trial registration

www.ClinicalTrials.gov, identifier NCT01274117.

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.

A phase III, randomized, double-blind, placebo-controlled study of tenecteplase for improvement of hemodialysis catheter function: TROPICS 3

BACKGROUND AND OBJECTIVES

Despite widespread use of tunneled hemodialysis (HD) catheters, their utility is limited by the development of thrombotic complications. To address this problem, this study investigated whether the thrombolytic agent tenecteplase can restore blood flow rates (BFRs) in dysfunctional HD catheters.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this randomized, double-blind study, patients with dysfunctional tunneled HD catheters, defined as a BFR <300 ml/min at -250 mmHg pressure in the arterial line, received 1-hour intracatheter dwell with tenecteplase (2 mg) or placebo. The primary endpoint was the percentage of patients with BFR > or =300 ml/min and an increase of > or =25 ml/min above baseline 30 minutes before and at the end of HD. Safety endpoints included the incidence of hemorrhagic, thrombotic, and infectious complications.

RESULTS

Eligible patients (n = 149) were treated with tenecteplase (n = 74) or placebo (n = 75). Mean baseline BFR was similar for the tenecteplase and placebo groups at 151 and 137 ml/min, respectively. After a 1-hour dwell, 22% of patients in the tenecteplase group had functional catheters compared with 5% among placebo controls (P = 0.004). At the end of dialysis, mean change in BFR was 47 ml/min in the tenecteplase group versus 12 ml/min in the placebo group (P = 0.008). Four catheter-related bloodstream infections (one tenecteplase, three placebo) and one thrombosis (tenecteplase) were observed. There were no reports of intracranial hemorrhage, major bleeding, embolic events, or catheter-related complications.

CONCLUSIONS

Tenecteplase improved HD catheter function and had a favorable safety profile compared with placebo.