John C. Mansour,
John E. Niederhuber
SUMMARY OF KEY POINTS
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INTRODUCTION
During the course of disease, many patients with cancer require intravenous chemotherapy, frequent blood sampling, transfusion of blood products, or total parenteral nutrition. Many of these intravenously administered therapies—especially chemotherapies—are inflammatory to small peripheral veins. Over the past three decades, techniques for obtaining and maintaining central vascular access have been developed and refined. Managing the treatment of patients with cancer requires a thorough familiarity with the special use of vascular access devices. This chapter provides a review of the pros and cons of various devices, insertion methods, and catheter maintenance techniques.
Although it would be ideal to base vascular access decisions on solid clinical information, few randomized controlled trials have examined the clinical controversies that are involved with chronic vascular access for the patient with cancer. In addition, many of the larger studies regarding central vascular access were performed in the inpatient intensive care unit (ICU) setting. Comparing ICU patients with patients with cancer who receive chemotherapy or weekly blood draws on an outpatient basis could lead to inaccurate conclusions. It is important, however, to review the available randomized trials, a number of carefully performed retrospective analyses, and pertinent ICU literature to address some of the questions concerning vascular access for the patient with cancer.
When managing a patient who requires vascular access for treatment of a malignancy, there are three important questions: (1) What device will best meet this patient's therapeutic needs? (2) How can we most safely insert and maintain central venous access? (3) What are the immediate and delayed complications of vascular access procedures that are unique to the oncology patient population?
CHOOSING THE RIGHT DEVICE
Clinical oncologists use the vascular access devices that are discussed in this chapter to aspirate blood and centrally infuse agents into central veins, such as the superior vena cava (SVC) or the inferior vena cava. Many chemotherapeutics and parenteral nutrition formulations act as vesicants to the venous intima, causing inflammation and thrombosis of smaller veins. By infusing this type of product into the higher-flow, less thrombogenic cardinal veins, the durability and safety of vascular access can be extended, and patient comfort can be enhanced significantly.
Percutaneous Central Lines
Traditional central lines are placed by using the Seldinger technique, which is described in detail later in this chapter. The subclavian vein, internal jugular vein, or femoral vein is cannulated percutaneously, and the catheter is placed by using guide-wire assistance. There is a very short distance between the skin and the catheter's entry point into the vein. Theoretically, this proximity to skin flora increases the risk of subsequent central line infection.
These central lines are in common use throughout most hospitals for oncology patients, for critically ill patients who require central access, or for any patients who require infusions that are poorly tolerated via peripheral intravenous access. Such central lines provide excellent short-term access to the central venous system. In general, percutaneous central lines are considered only for short-term use, and after the first 7 to 10 days, percutaneous central lines have a markedly higher incidence of infection despite optimal skin entrance site dressing techniques. Obviously, prolonged patient neutropenia and episodes of bacteremia could result in shorter life spans of such catheters.
Patients could benefit from these traditional central venous catheters if the patients require a relatively short course of infusion or need a bridge to placement of a more long-term catheter. Meticulous sterile dressing changes are an absolute necessity for outpatients who need short-term therapy via these lines. Patients without the resources or dexterity to care for percutaneous central lines are at a prohibitively increased risk of line infection, bacteremia, or thrombotic event and should be provided with a long-term form of central access. Certain comorbid conditions (e.g., burns, open wounds near the line site, or tracheostomy) preclude placement of this type of vascular access.
Surgically Tunneled Central Lines
Most oncology patients need a long-term form of central venous access rather than a traditional central line. Surgically tunneled central lines were developed to increase the distance between the skin entrance site and the puncture of the vein. The hypothesis was that by increasing this distance, the life span of the central access would be increased by decreasing the incidence of infection and thrombosis. Tunneled central lines are commonly referred to by the name of the first brand marketed, Hickman. Other examples include Broviac, Quinton, and Groshong ( Fig. 52-1 ). These polymeric silicone rubber venous access catheters are placed via a subcutaneous tunnel that is described in detail later in this chapter. Clinical studies have supported the hypothesis that increasing the distance between the catheter exit site in the skin and the hole in the vein decreases the incidence of externally derived infection. [1] [2] Studies suggest that the incidence of bloodstream infections associated with tunneled catheters is approximately 1 to 2 per 1000 catheter days.[3] The frequency of bacteremia among nontunneled catheters has been reported at between 1.0 and 13.0 per 1000 catheter days.[4]
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Figure 52-1 Examples of standard double- and triple-lumen Hickman catheters. The double-lumen catheter has both the standard Dacron cuff and an additional antibacterial barrier cuff. |
A Dacron cuff 3 to 4 cm from the exit site encourages scar formation to fix the catheter in place. This exaggerated scarring eliminates the need for long-term sutures holding the catheter in place to the skin. Avoiding these fixation sutures can decrease the incidence of stitch reactivity and associated localized skin infections. One drawback of this type of central access device is the inconvenience of placing and removing the lines. In most instances, surgeons insert these lines in the operating room under local anesthetic and intravenous sedation. Therefore, these procedures require coordination of the patient, the surgeon, the anesthesia staff, and the operating room staff. They are also more uncomfortable to remove than are nontunneled lines owing to the Dacron cuff scar reaction. Removal requires intravenous sedation and local anesthesia but can be accomplished outside of the operating room.
Surgically Implanted Infusion Ports
Implantable ports consist of a small injection reservoir with a self-sealing membrane; they are placed entirely beneath the skin. There is no external catheter. An internal catheter runs from the reservoir into the subclavian or internal jugular vein to provide central access. The internal catheter is essentially identical to those used for tunneled central lines. A noncoring (Huber) needle can pass directly through the skin into the reservoir for infusion or aspiration.[5] The self-sealing rubber cap on the reservoir prevents leakage from the reservoir after withdrawal of the Huber needle. The gauge of the noncoring needle—not the catheter—typically limits flow through the port system ( Fig. 52-2 ). The ports can also be used for continuous drug infusion, as shown in Figure 52-3 .
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Figure 52-2 A, Examples of implantable infusion devices: Low-profile titanium ports (top center), peripheral access port used in the arm (bottom center), single and dual polysulfone-titanium ports (left), single- and double-lumen standard profile ports (right). B, Peripheral access catheter for placement of a small port in the forearm. This system utilizes a fluoro-free thermosensor (gray wire) initially inside the white silicon catheter. An external wand over the chest determines the site of catheter top placement. |
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Figure 52-3 Placement of a deflected point (Huber) needle in a port. The lower portion of the port has been cut away to show the needle tip in the reservoir. This example of a bent needle shows how the needle can be taped and secured at the skin surface for protracted infusion using an external pump. |
The theoretical concern that bacteria more easily traverse the short distance between the skin and the “neo-vein” or reservoir and cause increased rates of infection does not prove true. [6] [7] [8] [9] [10] [11]Sterile technique and site care lead to an infection risk comparable to that of tunneled catheters. With adequate care, the rate of infection could be fourfold to fivefold less than that for tunneled catheters.[3]The low rates of infection and extravasation make infusion ports ideally suited for patients with cancer who need long-term single-lumen access and a low-maintenance catheter. Experience has shown, however, that patients with prolonged periods of neutropenia or significant risk of cutaneous eruptions might not be good candidates for port devices. The visible lump of the port could bother extremely thin patients; however, the port is hidden from plain view in most people.
Long-Line Central Access
Also known as a peripherally inserted central catheter (PICC line), this vascular access device is becoming increasingly popular. The catheter is inserted into a brachial, cephalic, or antecubital vein and advanced into the subclavian vein or higher. Successful placement rates of 75% might be improved by the addition of ultrasound guidance. [12] [13] [14] These lines can be placed simply and easily in the outpatient office setting and are well tolerated by patients, with minimal risk. Many oncology patients have poor arm veins after multiple peripheral infusions and are therefore poor candidates for this technique. The 50% risk of catheter-related thrombosis is the greatest drawback to more widespread use of PICC lines in oncology patients. This problem is secondary to the presence of a long length of catheter within the vein and to the catheter tip in the relatively low flow subclavian vein. Advancing the catheter tip into the SVC can reduce the incidence of thrombosis by more than half.[15] Accurate placement of the catheter tip in the SVC can be complicated by the large displacement of the catheter tip (up to 8 cm) with normal arm range of motion.[16]
INSERTING VASCULAR ACCESS DEVICES
Providing patients who are undergoing treatment for cancer with appropriate vascular access requires not only a thorough knowledge of available devices but also technical expertise in the procedures for placing these catheters. Although these procedures are sometimes viewed as routine, the risks of poor technique can be devastating for the patient. Before undertaking the procedure, one should carefully consider everything from choosing the site of insertion to selecting the dressing to be used at the end of the procedure ( Table 52-1 ).
Table 52-1 -- General Guidelines for Catheter and Port Use
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Type |
Advantages |
Uses |
Dressings |
Flushing |
Comments |
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Central line |
Placed at bedside |
Hospital use only |
Sterile transparent dressing |
5 mL heparinized saline (10 units/mL) in each lumen daily or after each use |
Antibiotic ointment may promote resistance |
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PICC catheter |
Safe to insert and remove |
1 week to 6 months of IV access |
Transparent antimicrobial foam dressing |
3 mL heparinized saline bid or after each use |
Flush and draw blood slowly to avoid catheter migration |
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Hickman catheter |
Multiple sizes and lumens |
Continuous infusion therapy |
Newly placed: antimicrobial dressing for 7 to 10 days |
5 mL heparinized saline daily or after each use |
Clean with chlorhexidine during dressing change |
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Groshong catheter |
Slit valve requires no heparin flushes |
Single- or double-lumen catheter for long-term use |
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Port |
Completely under skin |
One lumen access and low maintenance |
None |
5 mL heparinized saline daily or after each use |
Clean with chlorhexidine before use, access with noncoring needle |
Choosing Insertion Location
Vascular access devices can be placed by using a number of different access points, including the internal jugular, subclavian, external jugular, and femoral veins. The vast majority of catheters that are used for long-term vascular access in patients with cancer are placed in the internal jugular and subclavian veins. We will limit this discussion to these most common access sites.
The most frequent site for insertion of vascular access devices in the oncology population is the subclavian vein. Clavicular fracture or previous median sternotomy can alter the anatomy of this location. For a patient with such a history, an alternative site should be considered. Even for patients with standard venous anatomy, the acute angle at the confluence of the subclavian and internal jugular veins at the brachiocephalic vein can complicate the passing of the guide wire into the SVC. There is a higher incidence of pneumothorax, hemothorax, and catheter malposition among inexperienced operators, and there is a higher incidence of vein stenosis with subclavian vein placement than with internal jugular placement. [17] [18] [19] A subclavian artery puncture during line placement can be difficult to control, owing to the position of the artery posterior to the clavicle. A catheter placed on the anterior chest wall is more comfortable and easier to cover with clothing, however, than is a line in the neck. Additionally, some authors have concluded that with lines that are in place for more than 4 days, the risk of line infection is less for subclavian catheters than for internal jugular catheters. [17] [18]
In many ways, the internal jugular vein is the ideal location with regard to ease of placement of a central catheter. The path of the guide wire during placement is straight, thereby limiting many guide-wire complications and catheter malposition. In the event of carotid artery puncture, arterial bleeding can be controlled safely with the application of direct pressure. This advantage is especially important in the thrombocytopenic patient. The incidence of central venous occlusion is decreased, which could be important for patients who are likely to need an arteriovenous fistula for hemodialysis in the future. Unfortunately, patients often complain of pain with neck and shoulder movements after placement of an internal jugular catheter.
Preparing to Place the Vascular Access Device
Adequate preparation for placing a central venous catheter for oncology patients includes several steps before the actual line insertion. The surgeon must make several decisions that can limit the incidence of both immediate and delayed complications and ensure optimal line function.
Studies suggest that providing a single dose of prophylactic antibiotic to cover common skin flora before inserting the vascular access device reduces central line infection. It is difficult, however, to determine how this small benefit affects antibiotic resistance and subsequent infections. Using central venous catheters impregnated with antibiotics could be more effective in dealing with infectious complications and will be discussed later in this chapter. [20] [21]
A sterile surgical field with mask, gown, cap, gloves, and a large sterile drape should be used to minimize the risk of line infection.[22] The skin of the entire anterior neck and chest should be prepared with chlorhexidine, which is superior to povidone-iodine or alcohol in limiting line infections. [23] [24] [25] [26]
The choice to use ultrasound guidance to identify the vein during cannulation should be addressed before beginning the procedure. Less experienced operators will likely benefit from the use of ultrasound guidance as an adjunct to the anatomic landmarks technique. [13] [27] Ultrasound can decrease the incidence of arterial puncture and placement failure. Although a few reports in the literature exist regarding the advantage of these techniques, such superiority is often judged when compared with high rates of complications using the landmark approach as the control group.
The operator must also decide where to position the catheter tip within the central vein. Clearly, catheters that are positioned with the tip in the right atrium will function longer as a source for aspirating blood samples than will those with the tip positioned in the SVC. [28] [29] A case review of thrombosed catheters documents that the position of the tip of the catheter at the time of thrombosis seems to be the most important contributing factor. [30] [31] [32] [33] The closer the catheter tip is to the right atrium, the lower is the frequency of thrombosis and infection. The risk of a catheter tip in the right atrial position is primarily that of cardiac arrhythmias when the tip is near the tricuspid valve. An additional risk of right atrial catheter placement is right atrial thrombus or right atrial erosion.[32] These risks have led the Food and Drug Administration to publicly warn operators to avoid placement of the catheter tip within the right atrium. Instead, the catheter tip should sit at the junction of the SVC and the right atrium.
Insertion Technique
After informed consent is obtained, a rolled towel is placed directly under the vertebral column at the shoulders to extend the clavicles. A peripheral line is established, and the patient is connected to an EKG monitor and a pulse oximeter. Intravenous sedation is typically established by using small doses of benzodiazepines. The fluoroscopy operating table and patient are placed in the Trendelenburg position. The skin of the neck and entire upper anterior thorax is prepared, and sterile drapes are positioned. The skin and deep tissues are anesthetized with 1% lidocaine using a 25-gauge needle for the skin followed by a 22-gauge needle for the anticipated insertion tract ( Fig. 52-4A ).
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Figure 52-4 A, Placement of a catheter using the Seldinger technique. The long insertion needle is shown entering the vein through skin and subcutaneous tissues. B, Demonstration of a catheter passing over the guide wire. |
For subclavian vein puncture, the site of skin puncture is usually 1 cm below the angle of the lateral third of the clavicle. The long insertion needle, as depicted in Figure 52-4A , is slowly inserted below the clavicle, aiming for a point approximately one fingerbreadth above the sternal notch. During insertion, a small amount of negative pressure is maintained on the syringe. With experience, the physician develops a feel for the actual puncture of the vein, and when this occurs, the syringe fills easily with venous blood.
As the position of the needle is being carefully maintained, the syringe is removed, and the guide wire is inserted ( Fig. 52-4B ). If the patient experiences discomfort in the neck, the guide wire is partially withdrawn. Turning the patient's head away from the site of insertion and exerting a downward pull on the ipsilateral arm could facilitate entrance of the catheter or guide wire into the SVC. Cardiac ectopy indicates that the guide wire has entered the right atrium, and the wire should be withdrawn slightly.
Fluoroscopy may be used to pass the wire when difficulty is experienced. The correct position of the catheter is confirmed by fluoroscopy or chest x-ray before the catheter is secured with a 3–0-nylon suture at the skin exit site. The tip of the catheter is positioned 1 cm above the SVC-atrial junction when the patient is in the Trendelenburg position. A chest x-ray is obtained to document the absence of pneumothorax and accurate placement of the catheter within the SVC.
When it is necessary to use the veins in the neck, the right internal jugular provides more direct access to the SVC and right atrium. In this case, the patient's head is turned to the opposite side. The insertion site is located just lateral to the carotid artery and approximately two fingerbreadths above the head of the clavicle. Another useful landmark for the insertion site is the angle formed by the sternal and clavicular heads of the sternocleidomastoid muscle ( Fig. 52-5 ).
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Figure 52-5 Demonstration of catheter insertion technique when utilizing a vein in the neck (right internal jugular). |
Placement of a permanent Silastic catheter, such as a Hickman, is depicted in Figure 52-6 . Placement of the introducing needle and guide wire is as described in previous figures except that a 1-cm incision is made before insertion of the introduction needle. A prophylactic antibiotic is given before the procedure. It is often beneficial to provide the patient with intravenous sedation.
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Figure 52-6 A, Placement of a permanent Silastic catheter (such as a Hickman). The first and second incision sites are shown, as is the path of the tunneler. B, The catheter is pulled through the tract by using a heavy suture. The catheter cuff is secured 3 to 4 cm from the skin exit site. C, The catheter is trimmed and positioned 1 cm below SVC-RA junction. The introducer and tear-away sheath are shown passing over the guide wire. The catheter is inserted into the sheath, and the sheath and introducer are removed. |
A second 1-cm incision is placed lower on the anterior chest, usually at the level of the fourth or fifth interspace. The skin and subcutaneous tissues are first anesthetized with 1% lidocaine. The projected course of the tunneled catheter is also infiltrated with lidocaine. A tunneler is passed from the lower incision to the upper incision, where the guide wire is exiting. A heavy suture is tied to the end of the tunneler and brought down through the tract. The suture is tied to the end of the catheter and used to pull the catheter up through the tract, securing the cuff 3 to 4 cm from the skin exit site. The catheter is trimmed to the correct length that will position it about 1 cm above the SVC-RA junction with the patient in Trendelenburg position. This location is approximately four fingerbreadths below the sternal notch.
Care is taken to cut the catheter squarely and smoothly. An introducer and a tear-away sheath are passed over the guide wire into the vein ( Fig. 52-7 ). A slight rotary motion facilitates the introduction of the sheath and avoids crimping. To avoid developing a false passage, the guide wire should be withdrawn occasionally as the introducer is inserted. The guide wire is then removed, and a syringe is attached to the introducer to confirm that blood can be aspirated. The introducer is removed, and the thumb is used to control bleeding or air intake through the sheath. It is important to have the catheter tip poised to insert as the introducer is removed. The passage of the catheter could meet some resistance as it is passed between the clavicle and first rib.
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Figure 52-7 Example of an introducer kit. The kit includes a guide wire and introducer (dilator) with tear-away sheath (two different sizes shown). The upper, longer blunt object is a tunneler, which is included in some kits. |
Fluoroscopy or a chest x-ray is obtained to confirm correct positioning and the absence of pneumothorax. The catheter is aspirated and flushed to confirm function. Care should be taken to avoid any angulations of the catheter through the subcutaneous tract, especially at the bend toward the subclavian vein. The incision below the clavicle is closed with a subcutaneous absorbable suture. The catheter is secured at the exit site with a 3-0 nylon suture, which is maintained for approximately 3 weeks to allow the fibrous tissue ingrowth into the subcutaneous cuff. The exit site is covered with a sterile gauze dressing.
Similar techniques apply to the use of neck veins. The catheter is tunneled over the clavicle, the exit site being the same as for subclavian vein placement. When other sites are required (e.g., the femoral vein with the catheter tip in the inferior vena cava), direct cut-down exposure of the saphenous vein or other large femoral branch is preferred.
Figure 52-8 illustrates the placement of an implanted injection port. A 1-cm incision is placed below the clavicle at the site planned for subclavian venipuncture. A second, 3-cm incision is placed lower on the chest in a position that provides a relatively flat surface and stability for the port chamber. Local anesthesia is 1% lidocaine with 1 : 200,000 epinephrine. A subcutaneous pocket just large enough to accommodate the port is dissected inferior to the incision. Ideally, the level of this pocket is over the underlying pectoral fascia. The skin coverage needs to be thick, but the port must be percutaneously accessible. A tunneler is passed subcutaneously from the pocket through the infraclavicular incision. A suture is tied to the tunneler and brought down through the tract. The suture is tied to the end of the port catheter and used to pull the catheter through the tract to the intraclavicular incision. Care should be taken to position with a gentle curve and to avoid catheter angulation. The port is secured in the pocket with three sutures of 0-prolene. It is necessary to anchor the port adequately to prevent flipping or rotation of the device.
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Figure 52-8 A, Placement of an implanted injection port. First and second inclusion sites are shown, as is dissected pocket to accommodate port. B, Demonstration of placement of a port into a subcutaneous pocket. |
The guide wire is inserted as described, and the dilator and sheath are passed over it. The catheter is cut to the desired length. The dilator and guide wire are removed, and the catheter is inserted through the sheath as described. The incision for the port pocket is closed with interrupted 3-0 absorbable sutures placed in the subcutaneous layer. The skin is approximated with a running subarticular 4-0 absorbable suture. A transparent nonpermeable dressing is used at the port incision.
Open insertion methods are quite safe in a skilled surgeon's hands. The major complication of the open technique is the possibility of air embolus during the actual catheter insertion. This is most likely to occur in patients who are hypovolemic, cachectic, or unable to tolerate positioning in Trendelenburg position. An air embolus happens most frequently when the internal jugular vein is used, and extreme care with the use of the purse-string suture around the insertion site and venous occlusion with vascular clamps should limit the possibility of introduction of air into the vascular system. With open direct surgical placement, although it takes considerably longer than the closed Seldinger technique, complications should be much lower than 5%. [33] [34] [35] In the Hopkins series, the open method results in a complication rate of less than 1%. Although this is a safer technique, it requires more training, more experienced operative personnel, and larger incisions. Any patient who has had repeated problems with closed insertions should be approached in an open fashion, however, as this is the most controlled and safest format for that patient. Sometimes, previous operations or radiation therapy in the region of the cardinal veins makes the open operative approach more difficult, but generally such problems are limited.
COMPLICATIONS OF VASCULAR ACCESS DEVICES
When complication rates are examined as a whole, certain patient factors, catheter factors, and operator factors seem to predict the occurrence of complications. Patient-related factors that predict higher complication rates include the presence of multiple comorbid conditions, atherosclerosis, abnormal anatomy, thrombocytopenia, immunocompromise, prior radiation therapy to insertion area, recent myocardial infarction, and patient restlessness.[36] In addition, multiple-lumen or stiffer catheters carry increased risks of complications. [37] [38] [39] [40] Factors related to the person performing the insertion of the catheter also influence risk of complications. Risk increases if the operator has inserted fewer than 50 central venous catheters, if more than two tries at cannulating the vein are required, or if the insertion of the catheter is difficult. [16] [41] [42] Risk factors for specific complications are discussed in the sections that follow.
Immediate Complications
Pneumothorax
Published complication rates for pneumothorax after jugular vein central line placement are approximately 0.5% and up to four times higher for subclavian vein procedures. [16] [37] [38] [43] The risk of this technical complication can be reduced dramatically among experienced operators or physicians who have experienced supervisors.[36]
Bleeding
Many patients with cancer are at increased risk of bleeding complications owing to thrombocytopenia, uremia, other platelet dysfunction, or anticoagulant therapy. Bleeding complications are associated most frequently with thrombocytopenia.[39] For patients with platelet counts less than 50 or International Normalized Ratio greater than 2.0, we consider administration of platelets or fresh-frozen plasma. Experienced physicians should perform these procedures with access to ultrasound guidance if necessary.
Cardiac Arrhythmias
Disruptions in the normal cardiac conduction pathway can be caused by contact between the catheter and the right atrium. Most of these arrhythmias are short-lived and self-limiting.[16] These problems are more common with insertion of pulmonary artery catheters than with catheters that are typically inserted for oncologic vascular access. They are associated with more significant sequelae in patients who have recently suffered a myocardial infarction or who have a history of left bundle branch block. [40] [44]
Delayed Complications
Infectious Complications
Infectious complications are the most common complications of long-term vascular access devices in the oncology patient population. Two factors make the interpretation of this relatively well-studied topic challenging. First, many of the large randomized controlled trials that have studied central line infections have concentrated on ICU patients. The ICU population has different risk factors and susceptibilities from those of the outpatient population of people with cancer. Nevertheless, by carefully reviewing the available data, we can make some conclusions regarding the pathogenesis, prevention, and treatment of line-related infections among oncology patients. In studies of ICU patients with central lines, factors that predispose to line infection have included malignancy, neutropenia, extended duration of indwelling time, and coincident parenteral nutrition. All of these factors can contribute to the incidence of infection among patients with vascular access for oncologic treatment. [45] [46]
Second, the confusing terminology regarding line-related infections can make the literature on this topic difficult to interpret. Local infection is a positive culture at the catheter insertion site. Catheter colonization or infection is the positive culture of a segment of removed catheter. Catheter-associated bacteremia is evidenced by a positive blood culture from a site other than the catheter and the positive culture of a segment of removed catheter with the same pathogen.
Understanding the pathophysiology of catheter-associated bacteremia can help to limit the incidence of this complication. Up to 50% of catheter-associated bacteremia is caused by coagulase-negative staphylococcus. This common skin flora can colonize the catheter during insertion or later. A thrombus that forms at or along the catheter tip can become a nidus for bacterial proliferation, with resultant bacteremia. Thrombosis significantly increases the risks of colonization and infection.[47] Bacteria can also be introduced into the bloodstream by hub contamination, by hematogenous seeding from another focus of infection, and, rarely, by the infusate itself.
Factors that increase the risk of catheter infection include prolonged indwelling time, multiple-lumen catheters, femoral or internal jugular vein location, difficult catheter placement, and non-catheter-related bacteremia. [45] [48] As was mentioned previously, nontunneled catheters are at increased risk of catheter infection compared with tunneled catheters, and totally implantable devices are even less susceptible than tunneled catheters. [49] [50]
Multiple-lumen catheters have demonstrated higher infection rates than single-lumen catheters. The addition of each lumen exponentially increases incidence of infection. [51] [52] [53] [54] There are two possible explanations for this observation. First, the increased internal lumen diameter of the line is associated with a higher thrombosis rate and accumulation of loose thrombus at the catheter tip. Thrombosis causes more breaking of the line and more line manipulation when attempting to declot, leading to subsequent infection. Second, the multiple ports invite multiple interruptions of the line for access and result in a greater likelihood of introduction of bacteria. Despite their greater risk of iatrogenic infection, multiple-lumen catheters have great appeal for patients who need multiple simultaneous infusions of incompatible drugs. Very strict nursing guidelines must be followed in the management of multiple-lumen catheters to prevent iatrogenic infections and thrombosis. [55] [56]
Diagnosis and management of catheter-related infection differs between nontunneled and tunneled catheters. However, some diagnostic principles apply to both tunneled and nontunneled catheters. Routine surveillance blood cultures should not be performed. When a catheter-related infection is suspected due to fever, chills, or purulence around the catheter site, percutaneous and catheter blood samples should be submitted for culture. [57] [58] [59] [60] Qualitative culture with continuously monitored differential time to positivity compares the time to positivity for catheter blood cultures to percutaneous peripheral-blood cultures. This technique has demonstrated excellent specificity and sensitivity for detecting catheter-related infection in tunneled catheters. [61] [62]
In most patients with nontunneled central venous catheters, the line should be removed if the patient demonstrates signs of site infection or sepsis or if blood culture results from the catheter and percutaneous blood samples are positive. [61] [62] Seven to 10 days of narrow-spectrum antibiotic therapy is generally recommended. In certain cases of clinically stable patients with a single episode of coagulase-negative staphylococcus, a trial of antibiotic therapy might salvage the catheter.[53] For any patient with persistent bacteremia despite antibiotic therapy and removal of the infected catheter, a thorough investigation of possible septic sources, such as endocarditis or septic thrombus, is warranted.
Tunneled catheters or infusion ports should be removed in cases of sepsis, complicated infections, tunnel tract infections, or port abscesses.[63] A thorough evaluation confirming the surgically implanted catheter as the source of infection should precede the removal of any of these vascular access devices. In the absence of complicated infection, catheter salvage could be indicated. Antibiotic lock therapy is a reasonable approach for attempting to salvage lines with common coagulase-negative staphylococcus, Staphylococcus aureus, or gram-negative bacilli intraluminal infections. This therapy consists of instilling the catheter lumen with high concentrations of antibiotics and leaving them there for several days. [64] [65] [66] [67] If salvage therapy fails, a new tunneled catheter can be placed after removing the infected catheter, treating with an appropriate course of antimicrobial therapy, and repeating blood cultures with negative results.
Catheter Thrombus
Thrombus of central vein access devices predisposes to both line malfunction and line infection. The most common site of thrombus formation with prolonged indwelling central catheters is where the catheter enters the vein. At this point, a fibrin sleeve progresses distally toward the tip of the catheter. The precipitating event is likely local trauma from line insertion with subsequent endothelial damage and disruption of intraluminal laminar flow. The venous intima exposed to blood flow activates the coagulation cascade. Understanding this pathophysiology helps to explain why difficult line placements often lead to shorter catheter survival and increased rates of infection.
The incidence of central venous catheter-related thrombus as demonstrated by ultrasound is greater than 30% for catheters that are in place longer than 7 days.[68] This problem typically presents as progressive difficulty in flushing the catheter. A change in posture or the Valsalva maneuver could allow aspiration of blood. Occasionally, thrombosis can present as extremity edema. This can be especially devastating after axillary nodal resection or axillary irradiation. Management of a nonfunctioning catheter is discussed later.
Acute line obstruction can also be caused by precipitation of incompatible medications. Common offenders include total parenteral nutrition, etoposide salts, lipid emulsions, calcium salts, antibiotics, and sodium bicarbonate. Infusion of a solution specifically matched to the precipitated material might flush the line.[69]
Extravasation
Extravasation is defined here as the leaking of infusate into the subcutaneous tissue surrounding a central venous catheter. This complication can be caused by needle displacement from an implanted port, a defect in the catheter tubing, or withdrawal of the catheter from the vein due to inadequate fixation. Additionally, “backtracking” can occur when the catheter is partially occluded and infusate tracks up along the fibrin sleeve and into the subcutaneous tissue. Findings that are suggestive of extravasation include sudden swelling at the line site, increased patient discomfort during infusion, and sudden loss of blood return.[70]
Clavicular–First Rib Compression
This infrequently discussed complication may occur up to 1% of the time in long-term indwelling catheters.[71] When the subclavian vein is cannulated more medially than usual in the narrow space between the clavicle and first rib, the line can be compressed between the first rib and the clavicle. Patients who report difficulty infusing while in the sitting position or when the ipsilateral arm is elevated or abducted should be suspected of this compression. This malposition can be observed on chest x-ray as kinking of the line over the first rib. The catheter can break free and embolize if the line is not promptly removed. An interventional radiologist using a percutaneous retrograde femoral catheterization approach can retrieve an embolized section of catheter.
MANAGEMENT OF NONFUNCTIONING CATHETERS
When a central venous catheter does not return blood or infuse solution, the malfunction should be assessed systematically to maximize catheter durability and to minimize the incidence of catheter-related complications. The first step in this assessment is reviewing the most recent chest x-ray to confirm appropriate placement. The next step is checking for gravity flow. Connecting a bag of normal saline to gravity flow and asking the patient to change position, cough, and breathe deeply will demonstrate whether flow is positional. If the catheter is patent to gravity flow, lower the bag below the catheter and assess for blood return. With this information, one can make a decision as to whether to remove, reposition, or declot the catheter (Table 52-2 and 52-3 [2] [3]).
Table 52-2 -- Management of a Suspected Clot
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Complications |
Cause |
Gravity Flow Observation |
Corrective Action |
|
Fibrin sheath[*] |
Fibrin collects on the tip or encases the catheter |
Excellent in all positions but no blood return in any position |
May be declotted following the declotting procedure |
|
Occluded catheter[*] |
Fibrin and platelets collect inside catheter |
Inability to infuse solutions and draw blood |
May be declotted following the declotting procedure; drug precipitate cannot be corrected with tPA or heparin |
|
* |
These are the only two instances in which it is safe to declot after checking the chest x-ray for proper placement. |
Table 52-3 -- Management of an Unknown Clot
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Complications |
Cause |
Gravity Flow Observation |
Corrective Action |
|
Do not attempt to declot any of the following conditions. |
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|
Malposition |
Catheter cut short and abutting vessel wall |
Positional; no blood return in any position |
Must be removed; do not attempt declot, which may erode vessel wall |
|
Pinch-off syndrome |
Insertion site too close to first rib and clavicle |
Excellent when lying down but absent when standing |
Must be removed to avoid catheter breakage |
|
Transverse catheter |
Catheter crosses into opposite subclavian |
Positional flow, slow blood return, position noted on chest x-ray |
Interventional radiology can reposition via femoral vein access |
|
Arrhythmia |
Catheter in right atrium |
Positional; position noted on chest x-ray |
Catheter must be pulled back into SVC or removed |
|
Flipped up |
Catheter tip in jugular vein; can occur in association with vomiting or coughing |
Positional, blood return may be positional, patient complaint of tinnitus or headache with catheter flushing, position noted on chest X-ray |
Interventional radiology may be able to reposition if catheter not cut too short |
|
Major vessel thrombus |
External thrombus within vessel due to insertion trauma |
No change; good blood return; arm, hand, or neck swelling |
Documentation of thrombus with ultrasound or venogram, treatment with thrombolytics after consultation with hematology |
Two conditions are appropriate for thrombolysis of the catheter with alteplase or tissue plasminogen activator (TPA): fibrin sheaths and intraluminal thrombus occlusions. Contraindications for declotting procedures include high bleeding risk and known recent or current episode of bleeding.
Catheter malfunction caused by fibrin sheaths usually demonstrates good gravity flow and no blood return because the sheath acts as a one-way valve, allowing outflow but not inflow through the catheter. When intraluminal fibrin and platelets occlude the catheter, the catheter will demonstrate neither gravity flow nor return, regardless of any positional changes. If the caregiver is convinced that the catheter malfunction fits one of these categories and appropriate catheter position is confirmed on chest x-ray, catheter thrombolysis is indicated. Contrast venography is not necessary before using TPA to open nonmechanical catheter occlusions.
Techniques for declotting catheters vary from institution to institution but follow the same general principles. We recommend instilling 500 μg of TPA and allowing the infusate to dwell for 1 hour. If patency is not restored after 1 hour, instill an additional milligram of TPA and allow the infusate to dwell for another hour. Using a very similar technique, the authors of the Cardiovascular Thrombolytic to Open Occluded Lines Trial (COOL-2) studied nearly 1000 patients with occluded central venous catheters. These patients in a predominantly oncology population did not undergo prethrombolysis contrast studies. No deaths or major bleeding episodes were directly attributable to the thrombolysis. More than 87% of the catheters were opened with the TPA. At 3-month follow-up, nearly 75% of the catheters were still patent.[72] A similar study in the oncologic population reported a success rate greater than 80%.[73]
VASCULAR ACCESS DEVICE MAINTENANCE
The risk of complications with a long-term vascular access device does not end with insertion of the device. Proper care and maintenance of each type of central catheter can dramatically reduce the incidence of catheter-related bacteremia, catheter thrombosis, and line failure.[74] Maintenance is performed not only by qualified staff of oncology centers but also by patients and family members in the outpatient setting. In Table 52-1 and Box 52-1 , we have detailed our recommendations for central catheter care after a thorough review of the best available literature.
Box 52-1
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PROBLEM SOLVING IN CATHETER USE |
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Troubleshooting Guidelines If a catheter does not have a blood return or will not infuse solution, perform the following troubleshooting techniques to diagnose the problem before proceeding with the declotting procedure:
Declotting Procedure See the preceding guidelines before proceeding to declot, as follows:
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SUMMARY
Patients and physicians have a large variety of vascular access devices from which to choose, and no individual catheter is the ideal solution for all clinical situations. By understanding the strengths and weaknesses of each catheter system, insertion site, and maintenance technique, we hope to minimize the morbidity associated with these commonly used devices. Clearly, having a great deal of experience in placing vascular access devices in the oncology population minimizes the number of problems. Line care is the joint responsibility of the health care team and can be a major source of patient morbidity if each and every member of the oncology team does not maintain the highest quality of care.
More than 750,000 vascular access devices are used in the United States each year. We must continue to conduct clinical studies to make the safest, most cost-effective choice for each cancer patient.
REFERENCES