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

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.

Post-procedural Care in Interventional Radiology: What Every Interventional Radiologist Should Know-Part II: Catheter Care and Management of Common Systemic Post-procedural Complications

Interventional radiology (IR) has evolved into a full-fledged clinical specialty with attendant comprehensive patient care responsibilities. Providing excellent and thorough clinical care is as essential to the practice of IR as achieving technical success in procedures. Basic clinical skills that every interventional radiologist should learn include routine management of percutaneously inserted drainage and vascular catheters and rapid effective management of common systemic post-procedural complications. A structured approach to post-procedural care, including routine follow-up and early identification and management of complications, facilitates efficient and thorough management with an emphasis on quality and patient safety. The aim of this second part, in conjunction with part 1, is to complete the comprehensive review of post-procedural care in patients undergoing interventional radiology procedures. We discuss common problems encountered after insertion of drainage and vascular catheters and describe effective methods of troubleshooting these problems. Commonly encountered systemic complications in IR are described, and ways for immediate identification and management of these complications are provided.

Management of dysfunctional catheters and tubes inserted by interventional radiology

Minimally invasive percutaneous interventions are often used for enteral nutrition, biliary and urinary diversion, intra-abdominal fluid collection drainage, and central venous access. In most cases, radiologic and endoscopic placement of catheters and tubes has replaced the comparable surgical alternative. As experience with catheters and tubes grows, it becomes increasingly evident that the interventional radiologist needs to be an expert not only on device placement but also on device management. Tube dysfunction represents the most common complication requiring repeat intervention, which can be distressing for patients and other health care professionals. This manuscript addresses the etiologies and solutions to leaking and obstructed feeding tubes, percutaneous biliary drains, percutaneous catheter nephrostomies, and drainage catheters, including abscess drains. In addition, we will address the obstructed central venous catheter.

Fibrin sheath formation and intimal thickening after catheter placement in dog model: role of hemodynamic wall shear stress

PURPOSE

To investigate the role of wall shear stress in aspects of the formation of fibrin sheath and intimal thickening in a dog model.

METHODS

Tunneled silicone 14.5-F catheters were inserted into the left internal jugular vein in eight dogs. The dogs were separated into two groups according to catheter indwelling time of 14 and 28 days. All dogs underwent extracorporeal circulation three times a week. Multidetector computed tomography venography (MDCTV) examination was used to examine the catheter tip thrombus. After the animals were sacrificed, histological and immunohistochemistry evaluations were performed to confirm specific cell populations. We used computer modeling to generate wall shear stress profiles for the blood flow through the catheter.

RESULTS

Catheter-related sheaths were identified in all catheter specimens, but there was no fibrin sheath around the catheter tip. There were also differences in wall shear stress between the different venous wall sites. Differences in vein wall thickening at different sites have been found at both 14 days (intima to media (I/M) ratio S1 vs S2: p = 0.01, S3 vs S4: p<0.01) and 28 days (I/M ratio S1 vs S2: p<0.01, S3 vs S4: p<0.05).

CONCLUSIONS

After catheter placement, fibrin sheath formation partially covered the catheter. Meanwhile, focal areas of intimal thickening were also seen in the venous wall adjacent to the sites of high wall shear stress. These findings indicate an important role of wall shear stress profiles in fibrin sheath formation and intimal thickening.

Ethanol causes protein precipitation--new safety issues for catheter locking techniques

OBJECTIVE

The ethanol lock technique has shown great potential to eradicate organisms in biofilms and to treat or prevent central venous catheter related infections. Following instillation of ethanol lock solution, however, the inherent density gradient between blood and ethanol causes gravity induced seepage of ethanol out of the catheter and blood influx into the catheter. Plasma proteins so are exposed to highly concentrated ethanol, which is a classic agent for protein precipitation. We aimed to investigate the precipitating effect of ethanol locks on plasma proteins as a possible cause for reported catheter occlusions.

METHODS

Plasma samples were exposed in-vitro to ethanol (concentrations ranging from 7 to 70 v/v%) and heparin lock solutions. In catheter studies designed to mimic different in-vivo situations, the catheter tip was placed in a plasma reservoir and the material contained within the catheter was analyzed after ethanol lock instillation. The samples underwent standardized investigation for protein precipitation.

RESULTS

Protein precipitation was observed in plasma samples containing ethanol solutions above a concentration of 28%, as well as in material retrieved from vertically positioned femoral catheters and jugular (subclavian) catheters simulating recumbent or head down tilt body positions. Precipitates could not be re-dissolved by dilution with plasma, urokinase or alteplase. Plasma samples containing heparin lock solutions showed no signs of precipitation.

CONCLUSIONS

Our in-vitro results demonstrate that ethanol locks may be associated with plasma protein precipitation in central venous catheters. This phenomenon could be related to occlusion of vascular access devices locked with ethanol, as has been reported. Concerns should be raised regarding possible complications upon injection or spontaneous gravity induced leakage of such irreversibly precipitated protein particles into the systemic circulation. We suggest limiting the maximum advisable concentration of ethanol to 28 v/v% in catheter lock solutions.

Tunneled internal jugular hemodialysis catheters: impact of laterality and tip position on catheter dysfunction and infection rates

PURPOSE

To determine rates of dysfunction and infection for tunneled internal jugular vein hemodialysis catheters based on laterality of insertion and catheter tip position.

MATERIALS AND METHODS

Retrospective review of a procedural database for tunneled internal jugular vein hemodialysis catheter placements between January 2008 and December 2009 revealed 532 catheter insertions in 409 patients (234 male; mean age, 54.9 y). Of these, 398 catheters were placed on the right and 134 on the left. The catheter tip location was categorized as superior vena cava (SVC), pericavoatrial junction, or mid- to deep right atrium based on review of the final intraprocedural radiograph. The rates of catheter dysfunction and catheter-related infection (reported as events per 100 catheter-days) were analyzed.

RESULTS

Catheters terminating in the SVC or pericavoatrial junction inserted from the left showed significantly higher rates of infection (0.50 vs 0.27; P = .005) and dysfunction (0.25 vs 0.11; P = .036) compared with those inserted from the right. No difference was identified based on laterality for catheter tip position in the mid- to deep right atrium. Left-sided catheters terminating in the SVC or pericavoatrial junction had significantly more episodes of catheter dysfunction or infection than catheters terminating in the mid- to deep right atrium (0.84 vs 0.35; P = .006), whereas no significant difference was identified for right-sided catheters based on tip position.

CONCLUSIONS

When inserted from the left internal jugular vein, catheter tip position demonstrated a significant impact on catheter-related dysfunction and infection; this relationship was not demonstrated for right-sided catheters.

Fibrin sheath and its relation to subsequent events after tunneled dialysis catheter exchange

The use of tunneled catheters (TDC) for chronic hemodialysis is frequent and often fails due to fibrin or thrombus and infection. We hypothesized that the presence of fibrin sheath in TDC increases the risk for subsequent catheter malfunction and infection. We did a retrospective review of TDC exchanges and de novo placements from January 2005 to September 2011. Demographic data, information about the catheter procedure, and radiological data were collected. Final outcome analysis included 168 procedure events. Three groups of catheter procedures were identified: catheter exchange without a fibrin sheath (CE), catheter exchange with a treated fibrin sheath (CEF), and de novo catheter placements (DCP). Fibrin sheath incidence was 47%. In the CEF group, there was no statistical difference in the incidence of subsequent infections or dysfunctions (7% and 60%, respectively), when compared with the CE group (9% and 43%, respectively), (p=0.3). Mean time to subsequent dysfunction or infection was similar for CEF and CE (135 vs. 136 days, p-value, 0.98). Fibrin sheaths are common and should be evaluated when performing TDC exchange. If the fibrin sheath is treated, there is no increased incidence in subsequent catheter dysfunction or infection compared with patients without a fibrin sheath.