REDUCING TUNNELED HEMODIALYSIS CATHETER MORBIDITY: Infection Associated with Tunneled Hemodialysis Catheters: INFECTION ASSOCIATED WITH TDC

Effect of silver nanocoatings on catheters for haemodialysis in terms of cell viability, proliferation, morphology and antibacterial activity

The onset of infections associated to bacterial proliferation and biofilm formation on indwelling medical devices represents the major risk of morbidity and mortality among patients. In order to contain the risk of infections in clinical practice, there is a growing interest nowadays in silver-based products due to the strong antimicrobial efficacy of silver against a broad spectrum of microorganisms. In this work, temporary catheters for haemodialysis were coated with silver nano-particles through the in situ photo-reduction of a silver salt in alcoholic solution. A homogeneous distribution of silver particles firmly bonded to the substrate was obtained through the adopted technique. An optimisation study was required to define the amount of silver, in order to obtain good efficacy against Gram-positive and Gram-negative bacteria and no cytotoxic effect. At this purpose, three concentrations of silver, 0.1, 0.25 and 0.5 wt%, have been deposited and tested with respect to bacterial reduction percentage and cellular response. Particularly, bacterial enumeration on Escherichia coli and Staphylococcus aureus, and BrdU incorporation, TUNEL assay and Actin staining on a selected primary cell population were performed on catheters treated with the different silver solutions. The silver percentages tested demonstrated strong antibacterial properties together with a good cellular response, thus indicating that the developed product could be proposed in clinical practice and that the lower percentage tested can be preferred with evident advantages in terms of costs.

Report of a transient increase in tunneled catheter infections following dialysis facility transfer to a prefabricated structure

PURPOSE

Despite the efforts to promote the native artero-venous fistula as dialysis access, the use of tunneled central venous catheters (tCVC) is increasing. Main complications remain infections of the access, and the environment plays an important role in determining them; however, no studies are available that report dialysis provided in prefabricated temporary buildings. The aim of our study was to assess the incidence of tCVC infections in a container building.

METHODS

Since May 2009 our Dialysis Center has been located in a container building. The occurrence of local and systemic infections of tCVC when dialysis was provided in the container was compared with the previous two years, when dialysis was provided at the "Home" center. Each year was also divided into semesters to maintain the temporary relationship between the new location and the infections.

RESULTS

tCVCs represented approximately 13% of all vascular accesses. In the first six months in the temporary building, 50% of patients presented infections, compared to 13% to 20% during the other periods (P=0.02). In the first six months in the container the incidence of infections was 1.44 per 1000 catheters-days, higher than in any other semester (P=0.02). More infections requiring systemic antibacterial agents occurred over this period.

CONCLUSIONS

Our study demonstrates that, when a dialysis center is moved to a prefabricated temporary building, the likelihood of tCVC infections increases within the initial months and returns back to the previous levels after a period of adaptation.

Complications of catheters: tunneled and nontunneled

Central venous catheters for hemodialysis remain an indispensable modality of vascular access in the United States. Despite strong recommendations by the NKF-KDOQI guidelines to reduce the dependence on catheters, > 80% of all patients initiate hemodialysis using a central venous catheter. Although the tunneled dialysis catheters have some advantages, their disadvantages are many and often dwarf the miniscule advantages. This review is intended to discuss the complications--both acute and chronic--related to the use of tunneled dialysis catheters for hemodialysis access.

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.

Role of the hemodialysis vascular access type in inflammation status and monocyte activation

PURPOSE

The aim of this study was to ascertain the role of different vascular access types in inflammatory status, monocyte activation, and senescence in hemodialysis patients.

METHODS

We recruited 126 hemodialysis patients, including 51 with arterovenous fistula (AVF), 32 with arterovenous graft (AVG), and 43 with tunneled cuffed catheters (TCC). In dialysis patients enrolled in the study and in a control group of 40 healthy subjects, we measured the serum levels of albumin, CRP, IL-6, and TNF-a, the expression of CD14, CD44, and CD32 on monocyte surface, and the percentage of monocytes exhibiting a senescent phenotype (CD14+CD32+).

RESULTS

The patients with AVG compared to those with AVF had: a) higher levels of CRP and TNF-a; b) increased expression of CD14 and CD32 on monocyte surface, with no difference in CD44 expression; c) no difference in the percentage of CD14+CD32+ monocytes. In the comparison of TCC vs. AVF group, we observed significantly higher values of: a) circulating inflammatory markers (CRP, IL-6, TNF-a); b) monocyte surface expression of cellular activation markers (CD14, CD44 and CD32); c) relative count of CD14+CD32+ monocytes. When comparing TCC vs. AVG group, we found: a) no difference in serum levels of CRP, IL-6, and TNF-a; b) no difference in the expression of CD14, CD44, and CD32 on monocyte surface; c) no difference in the percentage of CD14+CD32+ monocytes.

CONCLUSIONS

These results suggest that the use of AVG and TCC for dialysis vascular access is associated with serological and cellular indexes of inflammatory reaction, also resulting in a higher degree of monocyte activation and senescence.

The catheter-challenged patient and the need to recognize the recurrently dysfunctional tunneled dialysis catheter

Tunneled dialysis catheters (TDC) become dysfunctional because of placement problems, infection, thrombosis, and fibrin sheath formation. Occasional patients who are catheter dependant develop frequent catheter dysfunction because of thrombosis or thrombosis associated with fibrin sheath formation. This article attempts to define which dysfunctional catheters because of thrombosis and thrombosis associated with fibrin sheath formation actually represent a recurrently dysfunctional TDC (RDC) and puts forth an approach to managing the RDC.

Staphylococcus-infected tunneled dialysis catheters: is over-the-wire exchange an appropriate management option?

PURPOSE

Over-the-wire exchange of tunneled dialysis catheters is the standard of care per K/DOQI guidelines for treating catheter-related bacteremia. However, Gram-positive bacteremia, specifically with staphylococcus species, may compromise over-the-wire exchange due to certain biological properties. This study addressed the effectiveness of over-the-wire exchange of staphylococcus-infected tunneled dialysis catheters compared with non-staphylococcus-infected tunneled dialysis catheters.

METHODS

Patients who received over-the-wire exchange of their tunneled dialysis catheter due to documented or suspected bacteremia were identified from a QA database. Study patients (n = 61) had positive cultures for Staphylococcus aureus, Staphylococcus epidermidis, or coagulase-negative staphylococcus not otherwise specified. Control patients (n = 35) received over-the-wire exchange of their tunneled dialysis catheter due to infection with any organism besides staphylococcus. Overall catheter survival and catheter survival among staphylococcal species were assessed.

RESULTS

There was no difference in tunneled dialysis catheter survival between study and control groups (P = 0.46). Median survival time was 96 days for study catheters and 51 days for controls; survival curves were closely superimposed. There also was no difference among the three staphylococcal groups in terms of catheter survival (P = 0.31). The median time until catheter removal was 143 days for SE, 67 days for CNS, and 88 days for SA-infected catheters.

CONCLUSIONS

There is no significant difference in tunneled dialysis catheter survival between over-the-wire exchange of staphylococcus-infected tunneled dialysis catheters and those infected with other organisms.

Preventing catheter-related infections in children undergoing hemodialysis

The increased use of tunneled cuffed catheters in children on chronic hemodialysis is the result of their relative ease of insertion, pain-free dialysis and immediate use. The disadvantage of their use is that they are associated with catheter-related bacteremia (CRB), which in turn is related with increased morbidity, access loss and occasionally metastatic infections and even death. A CRB might be difficult to diagnose and is often associated with a previous history of CRB, exit-site infection, low serum albumin and long duration of catheter use. There is evidence that the use of arteriovenous fistulae is associated with lower infection rates. The implementation of effective strategies for the prevention of CRBs include the adoption of policies for improving arteriovenous fistula rates, appropriate surgical catheter insertion and optimal nursing care of the exit site, and a safe connection technique. Recently, the effectiveness of antimicrobial catheter solutions for preventing CRB has been documented in a number of randomized clinical trials. In addition, the application of antibiotic ointments at the exit sites of tunneled cuffed catheters might be significant for the reduction of Staphylococcus-related CRB. The upside is that education-based programs combining specific preventive measures can significantly reduce CRBs.

Effectiveness of a protocol for the prevention of hemodialysis venous catheter-related infections

PURPOSE

Infections are a major complication of the use of hemodialysis central venous catheters. In our study we evaluated the efficacy of the hemodialysis central venous catheter protocol management adopted in our center, through a retrospective analysis of all hemodialysis central venous catheters inserted over a period of 6 years.

METHODS

Seventy-three tunneled central venous catheters and 75 temporary central venous catheters were inserted in our center from 2003 to 2008 in 148 patients.

RESULTS

During the follow-up we observed 30 infective events (16 assessed as bacteremias, 14 subcutaneous tunnel or exit site infections) with a rate of 0.65/1,000 days of central venous catheter implantation.

CONCLUSIONS

Our experience confirms, in a 72-month follow-up, the importance of careful central venous catheter management as a crucial feature in reducing the incidence of infective events in patients with central venous catheters in dialytic treatment.

Antibiotic pharmacokinetic and pharmacodynamic considerations in patients with kidney disease

Although pharmacokinetic changes occurring in kidney disease are well described, pharmacodynamics in kidney disease is rarely considered. Knowledge of pharmacodynamic principles can allow a clinician to maximize an antibiotic's effectiveness while minimizing adverse effects and antibacterial resistance. An antibiotic's pharmacokinetic and pharmacodynamic profiles should drive dose adjustment decisions in patients with kidney disease. For example, although the half-lives of beta-lactams and aminoglycosides are both prolonged in these patients, beta-lactams exhibit time-dependent antibacterial activity; consequently, maintenance doses should be smaller but given at the same interval. In contrast, aminoglycosides are concentration-dependent antibiotics; hence prolongation of the dosing interval while using larger doses may be advantageous. The timing of drug administration in relation to hemodialysis may be used to achieve specific pharmacodynamic goals. Aminoglycosides given before hemodialysis generate high peaks, whereas subsequent dialytic drug removal minimizes the area under the serum concentration-time curve, potentially decreasing the risk of developing toxicity. Furthermore, new dialysis prescribing patterns (eg, automated peritoneal dialysis, nocturnal dialysis) affect pharmacokinetic and pharmacodynamic parameters in ways not appreciated by clinicians. Studies quantifying the often considerable drug removal with these therapies, as well as efforts to identify pharmacodynamic targets in patients with kidney disease are essential. This paper reviews pharmacodynamic as well as pharmacokinetic issues that should be considered when prescribing antibiotics to treat infections in this population.

Staphylococcus aureus biofilm formation and tolerance to antibiotics in response to oscillatory shear stresses of physiological levels

Bacterial infections in the blood system are usually associated with blood flow oscillation generated by some cardiovascular pathologies and insertion of indwelling devices. The influence of hydrodynamically induced shear stress fluctuations on the Staphylococcus aureus biofilm morphology and tolerance to antibiotics was investigated. Fluctuating shear stresses of physiologically relevant levels were generated in wells of a six-well microdish agitated by an orbital shaker. Numerical simulations were performed to determine the spatial distribution and local fluctuation levels of the shear stress field on the well bottom. It is found that the local biofilm deposition and morphology correlate strongly with shear stress fluctuations and maximum magnitude levels. Tolerance to killing by antibiotics correlates with morphotype and is generally higher in high shear regions.

Focused vascular access education to reduce the use of chronic tunneled hemodialysis catheters: results of a network quality improvement initiative

Tunneled hemodialysis catheters (TDCs) carry the highest mortality risk for chronic hemodialysis patients of any access modality. Recent data have emphasized that mortality risk decreases when these devices are discontinued. Herein, we present the results of a gap-reduction assisted catheter elimination strategy that Network 7 employed as its quality improvement initiative to reduce the use of TDCs. Hemodialysis facilities with high catheter rates (>90 days) were identified. Interventions included focused vascular access education, monthly follow-up and site visits to assist the facility catheter reduction program. The "goal" of interventions was defined as the gap-reduction of 50% from the baseline catheter rate to the Network mean plus sustainability of catheter reduction for at least 3 consecutive months. Fifteen facilities (n = 891) were identified with high catheter rates (31.5 +/- 5.3%) in May 2006. Interventions resulted in a catheter reduction to 12.2 +/- 8.5% in May 2007 (p = 0.0001). Five of the 15 facilities (n = 280) achieved the goal (preintervention = 31.7 +/- 5.3%, postintervention = 8.7 +/- 2.8%, p = 0.001). In May 2007, eight additional facilities (n = 438) with high catheter rates (31.7 +/- 7.8%) were added to the 10 that failed to achieve the goal previously. Interventions employed in these 18 facilities (n = 1,049) resulted in catheter reduction in all (preintervention = 31.5 +/- 5.5%, postintervention = 16.2 +/- 5%, p = 0.01). Five of these 18 met the goal (preintervention = 32 +/- 8%, postintervention = 5.9 +/- 4.3%). Overall, all 23 facilities (n = 1,329) demonstrated catheter reduction postintervention (preintervention = 31.6 +/- 6%, postintervention = 13.9 +/- 6%, p = 0.001), and 10/23 (43%) met the project goal (preintervention = 31.9 +/- 6%, postintervention = 7.3 +/- 4%, p = 0.002). Medical director's involvement had a positive impact in achieving the goal (p = 0.003). The presence or absence of a vascular access coordinator did not affect catheter reduction. The results of this analysis reveals that an organized approach implemented by an ESRD Network can have a significant impact in reducing catheter use.

Prevention of catheter-related bacteremia in children on hemodialysis: time for action

This editorial commentary discusses the strategies for prevention of catheter-related bacteremia (CRB) in children on hemodialysis, which is associated with high morbidity and the increase of hospital cost. There is evidence that the use of arteriovenous fistulae in children on hemodialysis is associated with lower infection rates. Therefore, the use of catheters in these patients should be decreased by improving arteriovenous fistulae use rates or by increasing peritoneal dialysis patient recruitment. However, despite the wide adoption of such policies, hemodialysis catheters are still being used in a significant number of cases. For these patients, implementation of effective strategies for preventing contamination of the catheter hub should be a priority. The appropriate recording and evaluation of CRB rates are important for assessing preventive policies. In addition, the successful management of a CRB is essential for preventing recurrence of bacteremia. Recently it was documented in a number of randomized clinical trials that antimicrobial lock solutions were effective for preventing CRB. It is suggested that the use of antimicrobial locks should be considered in children who are at high risk of developing CRB, with caution for their long-term use, because of the possibility of bacterial resistance. Now is the time for action, and all preventive steps should be performed simultaneously to minimize the risk of CRB.

Percutaneous Endovascular Management of Occluded HeRO Dialysis Access Device

The Hemodialysis Reliable Outflow (HeRO) device is a novel alternative for dialysis access in patients with no suitable veins in the upper extremities. We placed a HeRO device in a 67-year-old woman with end-stage renal disease and 2 months later, it was being used for hemodialysis. After 1 month of uneventful use, the device thrombosed and it was rescued with a percutaneous endovascular approach. The device remains patent 6 months after the intervention.

Bacteremia associated with tunneled hemodialysis catheters: outcome after attempted salvage

BACKGROUND AND OBJECTIVES

Treatment without catheter replacement (catheter salvage) has been described for bacteremia associated with tunneled venous catheters in hemodialysis patients, but few data are available on which to base an estimation of the likelihood of treatment success.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a prospective cohort study, all cases of catheter-associated bacteremia that occurred in a large dialysis center were identified during a 12-mo period. Catheter salvage was attempted according to a standard protocol in all cases in which a favorable early response to antibiotic therapy was seen, and patients were followed for at least 6 mo. Bacteremias, catheter changes, and all major clinical events were recorded.

RESULTS

During a period covering 252,986 catheter days, 208 episodes were identified involving 133 patients, 74% of which were selected for attempted salvage. Salvage was successful in 66.1% of incident bacteremias with a very low complication risk (0.9%). Some bacteremias, however, recurred as late as 6 mo after the initial infection; salvage was less likely to be successful in treating recurrences.

CONCLUSIONS

Appropriately used catheter salvage can be successful in approximately two thirds of cases; however, recurrences continue to occur up to 6 mo later and are unlikely to be cured without catheter replacement.