Central venous catheter failure is induced by injury and can be prevented by stabilizing the catheter tip

Numerical Study on the Impact of Central Venous Catheter Placement on Blood Flow in the Cavo-Atrial Junction

An in silico study is performed to investigate fluid dynamic effects of central venous catheter (CVC) placement within patient-specific cavo-atrial junctions. Prior studies show the CVC infusing a liquid, but this study focuses on the placement without any liquid emerging from the CVC. A 7 or 15-French double-lumen CVC is placed virtually in two patient-specific models; the CVC tip location is altered to understand its effect on the venous flow field. Results show that the CVC impact is trivial on flow in the superior vena cava when the catheter-to-vein ratio ranges from 0.15 to 0.33. Results further demonstrate that when the CVC tip is directly in the right atrium, flow vortices in the right atrium result in elevated wall shear stress near the tip hole. A recirculation region characterizes a spatially variable flow field inside the CVC side hole. Furthermore, flow stagnation is present near the internal side hole corners but an elevated wall shear stress near the curvature of the side hole's exit. These results suggest that optimal CVC tip location is within the superior vena cava, so as to lower the potential for platelet activation due to elevated shear stresses and that CVC geometry and location depth in the central vein significantly influences the local CVC fluid dynamics. A thrombosis model also shows thrombus formation at the side hole and tip hole. After modifying the catheter design, the hemodynamics change, which alter thrombus formation. Future studies are warranted to study CVC design and placement location in an effort to minimize CVC-induced thrombosis incidence.

Macro- and microscopic changes in veins with short-term central venous catheters: an observational autopsy study

BACKGROUND

Centrally inserted central catheters (CICCs) are indispensable in modern healthcare, but unfortunately, come with complications. Catheter-related thrombosis is a well-known complication reported to occur in 5-30% of patients with CICC. There is a paucity of studies that report the incidence of catheter-related thrombosis after the introduction of real-time ultrasound insertion guidance as clinical practice. This study aimed to demonstrate any pathological macro- or microscopic changes in the vein wall associated with CICCs.

METHODS

The study was approved by the Swedish Ethical Review Authority and was conducted at a large university hospital. The study included 12 patients with a short-term CICC who were subject to autopsies. Vessels with inserted catheters were macroscopically and microscopically examined.

RESULTS

In total, seven female and five male patients with a median age of 70 (interquartile range 63-76) were included. With one exception, all patients received routine thromboprophylaxis throughout the period with CICC. Most inserted CICCs were 9.5 French (54%) and were inserted in the internal jugular vein (92%). The median time with CICC was seven days (interquartile range 1.8-20). At autopsy, thrombi were observed in all cases (100%), macroscopically and microscopically, attached to the distal portion of the CICC and/or the adjacent vessel wall. Inflammatory changes in the vessel walls were seen in all cases, and varying degrees of fibrosis were demonstrated in eight cases (67%).

CONCLUSIONS

This autopsy study demonstrated that catheter-related thrombus formation with adjacent inflammatory and fibrotic vessel wall thickening was very common, despite a limited period of catheter use. The consequences of these findings are important, as thrombi may cause pulmonary embolism and possibly lead to catheter-related infections, and since inflammatory and fibrotic vessel wall thickening may evolve into chronic venous stenosis. Furthermore, the findings are a cause of concern, as CICCs are indispensable in modern healthcare and complications may be masked by the general disease that was the indication for CICC insertion.

Trimmed central venous catheters do not increase endothelial injury in an ovine model

INTRODUCTION

Central venous catheters (CVCs) are often trimmed during heart transplantation and pediatric cardiac surgery. However, the risk of endothelial injury caused by the cut tip of the CVC has not been evaluated. We hypothesized that there is no difference in the degree of endothelial injury associated with trimmed CVCs versus standard untrimmed CVCs.

METHODS

In four adult male sheep, the left external jugular vein was exposed in three segments, one designated for an untouched control group, one for the trimmed CVC group, and one for the untrimmed CVC group. Trimmed and untrimmed CVC tips were rotated circumferentially within their respective segments to abrade the lumen of the vein. The vein samples were explanted, and two representative sections from each sample were analyzed using hematoxylin and eosin (H&E) staining, as well as with immunohistochemistry against CD31, von Willebrand factor (vWF), endothelial nitric oxide synthase (eNOS), and caveolin. Higher immunohistochemical stain distributions and intensities are associated with normal health and function of the venous endothelium. Data are presented as counts with percentages or as means with standard error.

RESULTS

H&E staining revealed no evidence of endothelial injury in 6/8 (75%) samples from the untouched control group, and no injury in 4/8 (50%) samples from both the trimmed and untrimmed CVC groups (p = 0.504). In all remaining samples from each group, only mild endothelial injury was observed. Immunohistochemical analysis comparing trimmed CVCs versus untrimmed CVCs revealed no difference in the percentage of endothelial cells staining positive for CD31 (57.5% ± 7.2% vs 55.0% ± 9.2%, p = 0.982), vWF (73.8% ± 8.0% vs 62.5% ± 9.6%, p = 0.579), eNOS (66.3% ± 4.2% vs 63.8% ± 7.5%, p = 0.962), and caveolin (53.8% ± 5.0% vs 51.3% ± 4.4%, p = 0.922). There were no significant differences between the groups in the distributions of stain intensity for CD31, vWF, eNOS, and caveolin.

CONCLUSION

Trimmed CVCs do not increase endothelial injury compared to standard untrimmed CVCs.

Minimally invasive ultrasound-guided technique for central venous catheterization via the external jugular vein in pigs

OBJECTIVE

To describe an ultrasound-guided technique for central venous catheter placement via the external jugular vein (EJV) in pigs.

ANIMALS

96 healthy Landrace-Poland China barrows (approx 16 weeks old with a mean weight of 70 kg).

PROCEDURES

Pigs were anesthetized. With ultrasound guidance, a needle was inserted into the EJV without a large incision or cutdown procedure. A guidewire was inserted through the needle into the vein. A modified Seldinger technique was used to advance a catheter into the vessel until the tip was in the cranial vena cava near the right atrium. A trocar was used to create a tunnel through the subcutaneous tissues from the catheter insertion site to between the dorsal borders of the scapulae. The free end of the catheter was passed through that tunnel. An extension was attached to the catheter and secured to the skin. Pigs were euthanized and underwent necropsy at completion of the study for which they were catheterized.

RESULTS

Central venous catheters were successfully placed in all 96 pigs and facilitated collection of serial blood samples with minimal stress. Catheters remained in place for a mean of 6 days (range, 4 to 10 days). Necropsy revealed abscesses along the subcutaneous catheter tract in 9 pigs. Twenty pigs had histologic evidence of phlebitis and fibroplasia in the cranial vena cava.

CONCLUSIONS AND CLINICAL RELEVANCE

The described technique, in combination with extensive socialization, allowed serial collection of blood samples with minimal stress and restraint and is an alternative to surgical cutdown procedures for catheter placement.

A minimally invasive catheterization of the external jugular vein in suckling piglets using ultrasound guidance

There is a growing interest for minimally invasive surgical procedures to improve experimental animal welfare. Minimally invasive catheterization procedures in pigs have been already developed using Seldinger technique but reproducibility is low, especially in young pigs. A novel method for a minimally invasive catheterization of external jugular vein was evaluated in suckling piglets of 21 days of age. Growth performance and haptoglobin concentration in plasma were measured throughout a four-week study in a group of seven catheterized piglets and a group of seven non-catheterized piglets. Catheterization was performed using Seldinger technique under continuous ultrasound monitoring for vein detection and needle insertion. The surgical procedure was quick and showed a great reproducibility. All catheters remained functional during the first week after catheterization. Catheterization in piglets did not significantly affect body weight (BW) and feed intake during four weeks after the surgical intervention compared to non-catheterized piglets (P > 0.10). Haptoglobin concentration in plasma was greater in catheterized piglets compared with non-catheterized piglets, with a significant increase over two weeks after catheter insertion (P < 0.05), suggesting the development of a chronic inflammation in catheterized piglets. This method can be easily performed in piglets with minimal effect on growth and feeding behaviour. Transposition to heavier pigs should be considered.

Durability of tunneled catheters in children is associated with catheter tip depth: A single-center report

The aim of this study was to examine the impact of different catheter tip positions on catheter duration and dysfunction of tunneled catheters in children. Catheters were evaluated for place of insertion, time of insertion, catheter tip depth and position, duration of use, and reason for removal. The mean duration of implanted catheters with tips placed in cavo-atrial junction/right atrium was significantly longer with significantly lower percentage of complications than tips placed in superior vena cava. Only catheter tips placed in cavo-atrial junction/right atrium was a predictor of catheter functionality and survival. Shorter catheter survival in children with tunneled catheters is a consequence of a catheter tip depth proximal of CAJ and RA. Our results showed that the main factor responsible for better catheter functionality was not laterality but the depth of the catheter tip, which reduces need for future catheter insertions with increased catheter durability.

Vascular endothelium damage from catheter-induced mechanical stimulation causes catheter sleeve formation in a rabbit model

BACKGROUND

Intravenous catheters are widely used but are often removed due to complications associated with catheter sleeve formation. A catheter sleeve can develop from a thrombus, and catheter-induced vascular endothelium damage may be a critical factor for thrombus formation. We investigated the effect of catheter-induced mechanical stimulation on venous endothelial cells and catheter sleeve formation and the efficacy of anti-thrombogenic technology for preventing catheter sleeve formation in vivo.

METHODS

We surgically implanted poly(2-methoxyethyl acrylate)-coated and uncoated catheters with and without a stylet into the right external jugular vein of a rabbit model for 14 days. Catheter sleeve formation and the ratio of residual venous endothelial cells were compared using histological examination and immunostaining with an anti-CD31 antibody, respectively.

RESULTS

Stiffening an uncoated catheter with a stylet induced catheter sleeve formation along more than two-thirds of the length of the catheter. The ratios of residual venous endothelial cells at the tip of uncoated catheters with and without a stylet were 3% and 36%, respectively. While poly(2-methoxyethyl acrylate) coating also reduced the ratio of venous endothelial cells at the tip of the stiffened catheter (12%), it prevented external thrombus and catheter sleeve formation.

CONCLUSION

High levels of mechanical stimulation can affect catheter-related thrombosis and promote catheter sleeve formation, and anti-thrombogenic technology such as a poly(2-methoxyethyl acrylate) coating reduces thrombus formation and can prevent catheter sleeve formation on stiffened catheters. Further studies are required to determine the maximum degree of venous endothelial cell damage before catheter sleeve formation and to compare other anti-thrombogenic technologies with poly(2-methoxyethyl acrylate) for preventing catheter sleeve formation.

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.

The development of central venous thrombosis in hemodialyzed patients is associated with catheter tip depth and localization

INTRODUCTION

The aim of our work was to analyze the incidence of tunneled hemodialysis catheters-related thrombosis in hemodialyzed patients depending on catheter tip depth and position and to evaluate the impact of other established risk factors responsible for development of central venous thrombosis.

METHODS

The presence of central vein thrombosis, location, and the depth of the catheter tip was reviewed by two experienced radiologists. All patients with suspected central venous thrombosis had factor V Leiden, lupus anticoagulant, and cardiolipin antibodies checked (acIgM and acIgG) and were evaluated with cat-scan venography.

FINDINGS

A total of 68 tunneled hemodialysis catheters were analyzed with CT venography for central venous thrombosis. There were no signs of central venous thrombosis when catheter tips were placed in the right atrium. There was significantly higher number of catheter tips located on the vein wall than located centrally in patients with central venous thrombosis. Higher percentage of central venous thrombosis, smaller number of tips placed in the right atrium, higher values of IgM cardiolipin antibodies, and higher number of patients with positive factor V Leiden mutation were found in group of patients with catheter tips located on vein wall.

DISCUSSION

Higher incidence of central venous thrombosis in patients with the catheter tip placed on the vein wall is a consequence of a catheter tip depth proximal of the right atrium. Increased factor V Leiden mutation and acIgM values in these patients should be observed as a result of the vein stasis caused by inappropriate catheter tip depth and localization.

Salvage Insertion of Tunneled Central Venous Catheters in the Internal Jugular Vein after Accidental Catheter Removal

Purpose

Tunneled catheters are widely used for intermediate to long-term hemodialysis (HD) access, but are prone to several complications that can require catheter replacement. Replacing malfunctioning catheters with a new line, placed in a different access site, can lead to problems with multiple vein occlusions. This has led many nephrologists to continue using the same vein as long as possible by guidewire catheter exchanges, to preserve other veins for future use. We describe a guidewire exchange technique for the Ash-Split catheter in the internal jugular vein.

Methods

In three patients, the exchange was performed because of partial catheter removal, as evidenced by the outward dislocation of the Dacron cuff. In these patients, the guidewire was inserted through the catheter. In two additional patients, the catheter had been completely removed by accident: the replacement of the dislodged tunneled venous catheters was attempted 5 hr and 1 day after accidental removal. In these patients, the guidewire was inserted through the previous tunnel. After guidewire placement, a skin incision was made in the supraclavicular region. The metal guidewire was easily located inside the fibrous structure that had previously surrounded the catheter. The guidewire was then extracted from the subcutaneous tunnel and used to insert a new catheter safely and easily after creating a new tunnel. Patients were routinely given antibiotic prophylaxis (1 g of cefazolin) immediately before the procedure. A strict aseptic technique was used, including several sterile glove changes.

Results

No infections developed following this procedure, which has the potential for bacterial contamination. All procedures were successful. Only in one patient did we have to convert to a different catheter: it was not possible to replace the old Ash-Split catheter with the same dual-lumen catheter because of difficulties in inserting the peel away introducer-catheter complex. In this patient, rather than forcing it with larger dilators or trying to disrupt the fibrin sheath with balloon dilatation, a single lumen Tesio catheter was successfully placed. In both patients who completely lost the previous catheter, the guidewire was readily reinserted through the subcutaneous tunnel into the vein. Catheter function was excellent in all patients, with a test blood flow rate on the 1st catheter use >350 ml/min.

Conclusions

We described a new method for catheter exchange, which allows the easy insertion of a new catheter and the creation of a new and safer subcutaneous tunnel. In addition, we demonstrated that in cases of complete catheter removal, it is possible to reinsert a catheter in the same vein through a guidewire, even when reinsertion was attempted up to 1 day later.

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&lt;0.01) and 28 days (I/M ratio S1 vs S2: p&lt;0.01, S3 vs S4: p&lt;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.

Central vein stenosis

Central vein stenosis (CVS) is commonly seen in patients receiving hemodialysis through an arteriovenous access, threatening the usability of arteriovenous access for dialysis. Subclavian and internal jugular catheters are prime reasons for the development of CVS, especially in the setting of long-term use of multiple catheters. CVS related to cardiac rhythm devices also is seen frequently. Idiopathic CVS can be encountered, although it is less common. Clinical features ultimately become sufficiently prominent to prompt angiographic evaluation. CVS should be evaluated carefully because management must be individualized. The primary method for treatment of CVS is endovascular intervention, including angioplasty and stent placement, whereas surgical options should be pursued in only refractory cases due to the invasiveness of the intervention. Early referral of patients for chronic kidney disease care; timely discussion of kidney replacement modality choices, including nonhemodialysis options such as peritoneal dialysis and kidney transplantation; placement of arteriovenous access prior to the onset of dialysis; and avoidance of catheters and other central vein instrumentation will prevent the development of CVS in most patients with kidney disease.

Trimming long-term tunneled central venous catheters in pediatric patients

Long-term tunneled central venous catheters (CVC) are employed in critically ill patients. Manufacturers do not provide patient-customized devices; therefore, trimming is required for pediatric use. Scanning Electron Microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) was used to assess changes induced by different trimming methods on single and double lumen Hickman-Broviac catheters. Increased roughness, exposure of inorganic macroaggreagates and increase in surface inorganic charges were generated by the trimming procedure, with the scalpel producing a smoother surface compared to scissors. Trimming produces changes on the CVC surface that may influence the rate of long-term complications.

Central vein stenosis in an Asian hemodialysis population

Objective and background: Central vein stenosis occurs commonly after instrumentation of the major thoracic veins. We aimed to investigate factors that contributed to this condition in an Asian hemodialysis population, and the results of intervention.

Patients and methods: Hemodialysis patients diagnosed with central vein stenosis between January 2003 and December 2008, were identified from the records of the National University Hospital, Singapore. Eligible controls had a minimum of 2 years of hemodialysis via an arteriovenous fistula and/or central venous catheter, without clinical or radiological evidence of central vein stenosis.

Results: Central vein stenosis was diagnosed in 108 patients. The most common presenting features were arm swelling (32%) and failed hemodialysis catheter insertion (28%). The median frequency of permanent hemodialysis catheter insertion in those who subsequently developed venous stenosis (1.44 per patient per year) was 4 times that of controls (0.36 per patient per year; p < 0.001). Ischemic heart disease ( p = 0.03) and in certain patients, arteriovenous fistula surgery were associated with the development of central vein stenosis; whereas line sepsis, diabetes, and hypertension were not. Central vein angioplasty was attempted in 53 patients; the primary patency was 52% at 1 year.

Conclusion: Central vein stenosis is associated with a higher frequency of hemodialysis catheter insertion and access surgery. Efforts to decrease permanent hemodialysis catheter use should reduce the incidence of central vein stenosis.

Central vein stenosis: current concepts

Central vein stenosis (CVS) is a common complication of the central venous catheter (CVC) placement. The prevalence of CVS has mostly been studied in those who present with symptoms such as swelling of the extremity, neck and breast. CVS compromises arteriovenous access and can be resistant to treatment. A previous history of CVC placement is the most important risk factor for the development of CVS later. Pacemaker and defibrillator wires are associated with a high incidence of CVS. Increasingly liberal use of peripherally inserted central catheters (PICC) is likely to increase the incidence of CVS. The trauma and inflammation related to the catheter placement is thought to result in microthrombi formation, intimal hyperplasia and fibrotic response, with development of CVS. Treatment of CVS by endovascular procedures involves angioplasty of the stenosis. An elastic or recurrent stenosis may require a stent placement. The long-term benefits of the endovascular procedures, although improved with newer technology, remain modest. Surgical options are usually limited. Future studies to explore the pathogenesis and the use of novel therapies to prevent and treat CVS are needed. The key to reducing the prevalence of CVS is in reducing CVC placement and placement of arteriovenous accesses prior to initiating dialysis. Early referral of the patients to the nephrologists by the primary care physicians is important. Timely vein mapping and referral to the surgeon for fistula creation can obviate the need for a CVC and decrease incidence of CVS.

A rare complication of hemodialysis catheters: superior vena cava syndrome

Central venous catheters in hemodialysis patients may result in superior vena cava (SVC) syndrome. With the increasing use of these catheters, the SVC syndrome will probably be more common among hemodialysis patients. This report describes 3 cases of SVC syndrome due to central venous catheters that developed in hemodialysis patients with previous multiple catheter placements.

Central vein stenosis: a nephrologist's perspective

Central vein stenosis is commonly associated with placement of central venous catheters and devices. Central vein stenosis can jeopardize the future of arteriovenous fistula and arteriovenous graft in the ipsilateral extremity. Occurrence of central vein stenosis in association with indwelling intravascular devices including short-term, small-diameter catheters such as peripherally inserted central catheters, long-term hemodialysis catheters, as well as pacemaker wires, has been recognized for over two decades. Placement of multiple catheters, longer duration, location in subclavian vein, and placement on the left-hand side of neck seem to predispose to the development of central vein stenosis. Endothelial injury with subsequent changes in the vessel wall results in development of microthrombi, smooth muscle proliferation, and central vein stenosis. Central vein stenosis is often asymptomatic in nondialysis patients, but can result in edema of ipsilateral extremity and breast when challenged by increased flow from an arteriovenous fistula or arteriovenous graft. Bilateral central vein stenosis or superior vena cava stenosis can produce a clinical picture of superior vena cava syndrome, associated with engorgement of face and neck. Endovascular interventions are the mainstay of management of central vein stenosis. Percutaneous angioplasty and stent placement for elastic and recurring lesions can restore the functionality of the vascular access, at least temporarily. Frequent or multiple interventions are usually required. In recalcitrant cases, surgical bypass of the obstruction is an option. In resistant cases with severe symptoms, occlusion of the functioning vascular access will usually provide relief of symptoms. Further study of mechanisms of development of central vein stenosis and search for a targeted therapy is likely to lead to better ways of managing central vein stenosis. Prevention of central vein stenosis is the key to avoid access failure and other complications from central vein stenosis and relies upon avoidance of central vein stenosis placement and timely placement of arteriovenous fistula in prospective dialysis patient.

Jugular Vein Catheter Placement: Histologic Features and Development of Catheter-related (Fibrin) Sheaths in a Swine Model

PURPOSE

To evaluate the development and histologic features of jugular vein catheter-related (fibrin) sheaths in a swine model.

MATERIALS AND METHODS

The proposal was approved by the University Committee on the Use and Care of Animals. Tunneled silicone 7-F catheters were placed via a jugular vein in eight swine. The animals were separated into four groups of two pigs each according to catheter indwelling times of 7, 14, 30, and 45 days. After the animals were sacrificed, the catheter, access vein, and cranial vena cava were dissected, removed en bloc, and fixed in formalin. Histologic evaluation was performed by using standard light microscopy on hematoxylin-eosin stained specimens; immunohistochemistry was also performed to confirm specific cell populations.

RESULTS

Catheter-related sheaths that covered 33%-100% of the intravascular catheter length were identified in all eight catheter specimens. After 7 days, catheters had a partial or circumferential mixed cellular and noncellular covering consisting of smooth muscle cells, thrombus, and areas with endothelial cell populations. Sheaths from catheters excised at 14 days were characterized by prominent endothelial cell and smooth muscle cell proliferation. Catheters excised at 30 and 45 days showed less prominent cellularity and more prominent collagen content, in a well-developed sheath, than did those excised at 7 and 14 days. With longer catheter indwelling times, an endothelial layer, indistinguishable from the adjacent vein wall, covered the catheter surface.

CONCLUSION

The sheath that develops around central venous catheters in the swine model consists of cellular and noncellular components. A substantial proportion of the sheath is made up of a smooth muscle cell and collagen layer with overlying endothelial cells.

Impact of short-term hemodialysis catheters on the central veins: a catheter venographic study

OBJECTIVE

To determine the incidence of pericatheter sleeve formation, thrombus formation, and stenosis of the central veins in hemodialysis patients with temporary catheters.

METHODS AND MATERIAL

In this prospective study, 57 patients (40 males, 17 females) with temporary dialysis catheters had catheter venography by pulling back the catheter just before removal. Patient's age range was 25-87 years (mean age, 51 years). The venographic studies were evaluated for pericatheter sleeve formation, thrombus formation, and stenosis of the brachiocephalic vein (BCV) and the superior vena cava (SVC). The IJV could only be evaluated if there was adequate filling during contrast administration. In a subgroup of patients who had had only right IJV or only right SCV catheters, impact of these catheters on the central veins was compared.

RESULTS

The catheter location was right internal jugular vein (IJV) in 26 cases, right subclavian vein (SCV) in 27 cases, left IJV in 1 case, and left SCV in 3 cases. Thirty-two patients (56%) had had only one temporary catheter and the rest had had more than one inserted. The mean dwell time for the catheters was 21 days (range 7-59 days). A pericatheter sleeve was detected on venography in 32 (56%) patients and thrombus formation was noted in 16 patients (28%). A total of 41 patients (72%) exhibited pericatheter sleeve and/or thrombus formation. While 19 of the 32 patients (59%) without previous catheterization had a sleeve around the catheter, only 13 (52%) of 25 patients who had had multiple catheters inserted had a sleeve (P > 0.005). Of the eight patients (14%) with BCV stenosis, two had >50% stenosis. Only one patient (2%) had mild stenosis of the SVC. Three patients out of 15 (20%) who had diagnostic venography for the IJV had severe stenosis of the vein. Pericatheter sleeve formation was more frequent in women (P < 0.005). However, there were no statistical differences with respect to pericatheter sleeve formation, luminal filling defect and BCV stenosis when patients were grouped according to age, dwell time of the catheter, number of catheters inserted, and diameter of the SVC. Forty-two of the fifty-seven patients had had only right IJV (n =16) or right SCV (n = 26) catheters. There were no differences between these groups with respect to rates of pericatheter sleeve formation, thrombus formation, or BCV stenosis.

CONCLUSION

This study showed that even short-term catheters result in significantly high rates of pericatheter sleeve and thrombus formation which are two of the important causes of catheter malfunction. The IJV route is known to be much safer than the SCV route with respect to stenosis formation in the vein in which the catheter is inserted; however, the result showed no differences between the two routes with respect to frequencies of pericatheter sleeve formation, thrombus formation, and BCV stenosis. These findings remind us again that we should avoid unnecessary catheter insertion even for short-term in these chronically ill patients.

Central venous catheters: choosing the most appropriate access route

Intravenous therapy and care is a complex and intricate area of practice, which is being subsumed into the core role of registered nurses. As more patients become recipients of a vascular access device (VAD), particularly those requiring intermediate to long-term central venous access, it is important to ensure that not only the device but also the most appropriate vein meets their clinical physiological and psychological needs. There is much research and literature on the insertion and care of central venous catheters (CVCs) as well as the detection and treatment of complications. However, apart from a few small studies comparing the performance of devices placed either in the subclavian or jugular veins, there is little to guide doctors or nurses as to which vein is preferable, if secondary complications are to be avoided. This article will describe a number of primary and secondary complications associated with both the subclavian and internal jugular veins and how these can be minimized by selecting the most appropriate vessel. The article concludes with the author's suggestions for correct patient assessment in order that the correct vein is utilized.

Role of Platelet Activation in Catheter-Induced Vascular Wall Injury

PURPOSE

To investigate the role of smooth muscle cell (SMC) response and platelet activation in peripheral venous catheterization using a model of catheter injury associated with thrombocytopenic treatment.

METHODS

Silicon elastic catheters were inserted into New Zealand White rabbit external jugular veins from 24 hours to 60 days. Immunocytochemical procedures with antibodies to differentiation markers specific for SMCs, myofibroblasts, and endothelial cells were used to ascertain the phenotypic features of injured venous SMCs and the tissue sleeve formed around the catheter. Thrombocytopenia was induced in rabbits by busulfan treatment and the effect on catheter injury development examined after 15 days. The putative direct effect of this drug on the venous SMC proliferation, migration, and differentiation was assayed in vitro for 48 hours.

RESULTS

Catheter injury is characterized by the progressive formation of (1) a neointima, containing differentiating SMCs, which are derived from the media and adventitial layer, and (2) by the organizing thrombus formed around the catheter, which contains myofibroblasts. In busulfan-treated thrombocytopenic animals, there was no evidence for either neointimal development or thrombus formation. A direct role of this drug in the unresponsiveness of vascular wall can be excluded by the unchanged proliferation and migration pattern of cultured venous SMCs treated with busulfan compared to control cultures.

CONCLUSIONS

In our model, accumulation of differentiated SMCs in the neointima and myofibroblast appearance in the thrombus are linked, although distinct, events regulated by platelet activation, which is able to furnish the appropriate microenvironment for vascular SMC recruitment from the media/adventitial layer.

Histologic Changes in the Human Vein Wall Adjacent to Indwelling Central Venous Catheters

PURPOSE

Central venous catheter dysfunction can be caused by thrombosis (of the catheter or vessel itself), fibrin sheath formation, or infection. These sequelae can lead to costly interventions, loss of the access device, or loss of access sites in as many as one-third of patients. This study examined the histologic changes in the access vein and superior vena cava wall that is adjacent to central venous catheters in humans.

MATERIALS AND METHODS

The access vein, brachiocephalic vein, and superior vena cava were excised en bloc at autopsy from six patients with central venous catheters. The specimens were processed and stained with hematoxylin and eosin. The specimens were examined for histologic changes in the vein wall adjacent to the catheters, changes in the intima, and the presence of associated thrombus.

RESULTS

Three catheters had been in place <14 days (short term), and three for >90 days (long term). Two microscopic patterns were observed. The short-term catheters displayed foci of local intimal injury with endothelial denudation and a layer of adherent thrombus. The second pattern, seen in the long-term catheters, consisted of smooth muscle cell proliferation leading to vein wall thickening. Focal areas of catheter attachment to the vein wall, composed of thrombus in varying stages of organization, collagen, and endothelial cells, were also observed.

CONCLUSIONS

After short-term catheter placement, focal areas of endothelial injury were seen in the vein wall adjacent to the catheter. Associated thrombus may or may not be present. Long-term catheters displayed vein wall thickening and bridges from the vein wall to the catheter. These observations represent a progressive reaction of the human vein wall to access devices.

Hemodialysis catheters and ports

Percutaneous placement of cuffed tunneled catheters for hemodialysis access has become a firmly established method of providing vascular access to patients with end-stage renal disease. Considerable evidence supports the right internal jugular vein as the preferred site for catheter insertion. The use of real-time imaging using both ultrasound and fluoroscopy permits simple, safe, and effective placement of the catheter for hemodialysis. The use of these imaging techniques has significantly reduced the number of and severity of complications associated with catheter placement. A specific method of placement is described including variations for specific catheter types. The new subcutaneous port as an alternative to the cuffed tunneled catheter appears to provide another option for vascular access; preliminary data suggests higher flow rates and lower infection rates compared with externalized cuffed tunneled catheters. Finally, the criteria for obtaining training and proficiency in placement of cuffed tunneled catheters are outlined.

Chronic catheter placement

Since the 1997 publication of the Disease Outcomes Quality Initiative (DOQI) vascular access guidelines for cuffed, tunneled catheter placement, additional evidence supporting these recommendations has been published, including additional documentation supporting the right internal jugular vein as the preferred site for insertion. Placing the catheter tip in the right atrium rather than in the superior vena cava will provide adequate blood flow to support effective hemodialysis. The right atrial positioning of the catheter tip will also accommodate catheter tip retraction and decrease the likelihood of malfunction. Overwhelming evidence now supports the use of ultrasound guidance to assist cannulation of the internal jugular vein. This evidence is based on several studies documenting anatomical variations of the internal jugular vein. Ultrasound guidance has significantly decreased the incidence of serious complications of jugular vein cannulation. Finally, a specific technique of catheter placement with variations for catheter types is described.

Hemodialysis catheter placement and management

Hemodialysis catheters are an integral part of the delivery of hemodialysis. While catheters play an important role in the patient undergoing hemodialysis, catheters should be considered a bridge to more permanent forms of dialysis access in most patients. Recent advances in catheter technology, access techniques, and choice of access sites have improved outcomes associated with hemodialysis catheters. The placement and management of hemodialysis catheters by interventional radiologists have played an important role in these advances, and interventional radiologists are taking an increasingly active role in the research and development of catheters and catheter insertion techniques. The present status of hemodialysis catheters is reviewed.