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Temporary Vascular Access for Hemodialysis
C H A P T E R
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Temporary Vascular Access for Hemodialysis John J. White, MD; Matthew J. Oliver, MD; and Steve J. Schwab, MD
When immediate hemodialysis is necessary, rapid access to the circulation is essential. Acute vascular access is created by inserting a catheter into a central vein. Catheter access is temporary if the renal failure resolves or if another form of functional permanent access can be created. Unfortunately, catheters initially thought to be temporary when they are placed often go on to provide access for months to years. Data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) show that 60% of patients starting dialysis in the United States do so with an acute catheter. Consequently, catheters are now under a greater burden because they must be capable of providing adequate dialysis with a low rate of complications over longer periods of time.
Catheter Design Although brand names such as Quinton catheter, VasCath, and PermCath are commonly used as slang to describe hemodialysis catheters, in actuality there is a wide assortment of available catheters. Catheters are designed to accommodate easy insertion and good positioning, and to provide maximal flows. Catheters differ by material, length, lumen size, lumen configuration, inlet/ outlet holes, and method of connection to bloodlines (Figure 2.1). Temporary (nontunneled, uncuffed) catheters are primarily composed of polyurethane, which is stiff at room temperature to facilitate insertion but softens at body temperature to minimize vessel trauma. Tunneled cuffed catheters (long-term catheters) are primarily composed of silicone and silicone elastomers that are flexible and require a stylet and/or sheath for insertion. The walls of the lumens of silicone catheters must be thicker than polyurethane catheters because silicone provides less structural support. Silicone and polyurethrane are less thrombogenic than materials such as Teflon and polyvinyl used in the past. Catheter lumen sizes range from 9 to 16 French (0.75- to 2.2-mm inner diameter). Catheter length varies greatly to accommodate 23
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Temporary Vascular Access for Hemodialysis
D
A Needle
E
B F Needle
G
C
Caoxial
H
Double D
Shotgun
Circle C
Triple Lumen
Figure 2–1 Hemodialysis catheter designs. Catheters traditionally connect to bloodlines with luer locks (A), but new implantable ports are accessed with dialysis needles (B, C). Lumens may be conjoined through their length (D, E), or completely (F) or partially separated (G). If the lumens are conjoined, various lumen configurations are available (H). The figure is approximate and is not intended to represent the exact design of any particular manufacturer’s catheter.
proper positioning of the tip. In general, 15-cm temporary catheters are inserted in the right internal jugular vein, 20-cm catheters in the left internal jugular vein, and 20- or 24-cm catheters in the femoral vein to minimize recirculation and to reach the great veins. Tunneled cuffed catheters are much longer (up to 70 cm in overall length) to accommodate the creation of tunnels and
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allow the tip to be placed in the right atrium or inferior vena cava as required. The arterial and venous lumens can be completely separated (e.g., Tesio catheter), partially separated (Ash split catheter), or conjoined throughout their length. The lumens of conjoined catheters can be configured as a shotgun design (e.g., Niagara, Permcath), single round catheter with midline septum (“double D”; e.g., Opti-Flow), Circle C, coaxial (e.g., Duoflow), and triple lumen design (e.g., Trialysis). Inlet and outlet holes can be a single large hole or multiple small holes in various patterns. Traditionally, connector ports have been of luer lock design. Midline septums or shotgun designs theoretically prevent kinking. Implantable devices (e.g., LifeSite, Dialock) allow dialysis needles to be inserted directly into subcutaneous ports. These devices are accessed by percutaneous puncture and consist of a titanium alloy port connected to a central venous silicone cannula. Two of these are implanted beneath the clavicle and tunneled in the right atrium via the jugular vein. When used with 70% isopropyl alcohol as a sterilant, retrospective and nonrandomized prospective studies have shown a decreased incidence of infection and catheter-related complications using these devices when compared to cuffed-tunneled catheters. Although promising, off-label use and a number of possibly related deaths in patients who were not candidates for other permanent access have drawn concerns from the Food and Drug Administration. Currently, these catheters are not available to the U.S. market. Despite the myriad of designs and purported advantages, at present there is little evidence that one design is superior to others. Most catheters are tested in ideal circumstances and over short periods of time. Comparisons between devices have included few randomized controlled trials and have failed to show differences in clinically important outcomes such as solute clearance, rates of bacteremia, or catheter malfunction requiring intervention. For example, in a study comparing a twin-dialysis catheter system (Tesio), a split-tip design (Ash-Split), and a steptip design (Opti-flow) there were no differences in catheter flow rates or rates of infection. The catheters only differed in time of insertion, with the split-tip and step-tip catheters being easier and faster to insert than the twin-dialysis system.
Catheter Insertion Catheter insertion varies by operator, site of insertion, and insertion technique. The operator should be well experienced or be
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Temporary Vascular Access for Hemodialysis
supervised by an experienced operator. In general, tunneled cuffed catheters are inserted in operating rooms or clean interventional suites under fluoroscopy—with the operator gowned, gloved, and masked. Full surgical drapes are used, and the patient may be masked as well as given a mild sedative. Temporary catheters are generally inserted at the bedside or in the dialysis unit and do not warrant sterile precautions as rigorous as those required by tunneled cuffed catheters—but in general full-barrier precautions consisting of a mask, sterile gloves, gown, and a large drape should be used. The skin can be disinfected with chlorhexidine, povidone-iodine, or alcohol. Alcohol disinfects instantly, whereas povidone-iodine should be allowed to dry for 2 to 3 minutes to maximize antibacterial effect. Studies in nondialysis patients suggest that chlorhexidine reduces infection rates, but this has not been tested in dialysis patients. When available, insertion should be performed with ultrasound guidance. Ultrasound allows the operator to examine the vein for anatomic abnormalities and to directly visualize insertion. Ultrasound guidance has been shown to minimize insertion complications in both the internal jugular and femoral sites and results in a decrease in immediate catheter dysfunction. Using ultrasound guidance, inexperienced operators can increase their success rate to 95%. The NKF-K/DOQI (Kidney Disease Outcomes Quality Initiative) guidelines support this practice. The preferred site of placement is the right internal jugular vein. Catheters placed in the left internal jugular vein provide significantly less blood flow than right-sided catheters, and are nearly four times as likely to require removal for malfunction. Catheters should not be inserted into the subclavian vein if possible. Although studies have shown a decrease in infection rate with the use of subclavian catheters, these catheters have been associated with an increase in central vein stenosis (which may compromise future permanent access). In a prospective study in which patients underwent routine venography after removal of their first subclavian catheter, 52% of patients had subclavian vein thrombosis/stenosis. Half of these recanalized within 3 months, but the other half remained. In practice, thrombosis/stenosis of the subclavian vein is often subclinical until an arteriovenous access is placed in the ipsilateral arm—after which severe arm swelling occurs. Treatment of the stenosis with angioplasty or stent is difficult and requires repeated procedures to maintain patency. Often the stenosis requires takedown of the permanent access and renders the arm unusable for future access. Thrombosis/stenosis of the internal jugular vein is
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less frequent than the subclavian vein (approximately 6% in one series) and does not generally compromise future access unless it extends to the superior vena cava. Temporary catheters placed in the subclavian or internal jugular vein should have their position checked by chest X-ray or fluoroscopy before commencing dialysis. The tips of temporary catheters should rest in the superior vena cava (subclavian) or inferior vena cava (internal jugular vein). Temporary catheters are commonly placed in the femoral vein in bed-bound patients, but infection rates are higher than either neck location. Tunneled cuffed catheters may be placed in the femoral vein as well—and as a last resort catheters may be inserted via the translumbar and transhepatic routes. Catheters can be dressed with either standard or adhesive dry gauze or breathable transparent dressings. Patients and caregivers may feel that an adhesive dressing better secures the catheter or better protects the exit site from contamination. Some randomized studies of nondialysis catheters show higher infection rates when catheters were dressed with nonbreathable dressings as compared with dry gauze. However, a large randomized study by Maki and colleagues of Swan-Ganz catheters showed no difference between dry gauze and breathable transparent dressings. Antibiotic ointments such as povidone-iodine and mupirocin, when used in conjunction with dry gauze dressings, reduce bacteremia related to temporary hemodialysis catheters. Ointment may not be as effective for tunneled cuffed catheters, but this has not been studied. Patients may resist povidone-iodine ointment when used with gauze dressing because leakage of ointment will stain clothes. Many complications have been associated with hemodialysis catheter insertion. Some radiologic series report no serious complications despite hundreds of insertions. Average rates and ranges of complications in the literature are outlined in Table 2.1.
Catheter Performance Dialysis catheter lumens must be of large bore in order to provide blood flows to achieve adequate clearance. It therefore follows that catheter malfunction occurs when the catheter cannot provide blood flow sufficient to achieve adequate dialysis. For short periods of dialysis, blood flows of 200 to 250 mL/minute are usually sufficient to correct the metabolic disturbances associated with renal failure. For longer use, blood flows greater than 300 cc/minute are generally needed to achieve adequate clearance and reduce treatment durations. The exact amount of blood flow
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Table 2–1
Complications from Hemodialysis Catheter Insertion Complication Arterial puncture Local bleeding Aspiration Recurrent laryngeal palsy Hemo/pneumothorax Air embolism Cardiac arrhythmia Hemomediastinum Vessel perforation Pericardial tamponade Retroperitoneal bleedingb
Mean (%) 4.4 4.0 2.2 1.6 1.35 1.2 1.1 0.74 0.7 0.56 0.06
Range (%) 0–11.9 0–18.1 NAa NA 0–3.0 0–2.2 NA 0–1.2 0–1.3 0.5–0.6 NA
a. NA = not available. b. Femoral catheterization only.
and clearance required varies by patient. For acute dialysis, the dose prescribed can be significantly less than the dose delivered. This occurs for a variety of reasons unrelated to the device itself. However, femoral catheters are clearly associated with lower delivered dialysis dose. Recirculation from catheters is generally negligible because the arterial inlet is usually positioned proximal to the venous outlet and there is a high blood-flow rate in the large central veins (e.g., superior vena cava at approximately 2 L/minute). Our studies indicate that there is essentially no recirculation from tunneled catheters placed in the right atrium. However, if the tip of the catheter is placed in an area of restricted blood flow or if the lumens are reversed recirculation increases. Recirculation of malfunctioning catheters is 7 to 8% if they are reversed, and 14 to 19% if well-functioning catheters are inadvertently reversed. If the tips of femoral catheters are too short to reach the venous segment of high blood flow, recirculation is high. One study found that femoral catheters shorter than 20 cm had recirculation of 26.3% versus 8.3% for those longer than 20 cm.
Catheter Malfunction NKF-K/DOQI guidelines define catheter malfunction as failure to achieve blood flow rate equal to 300 mL/minute. The two primary mechanisms of malfunction are thrombosis and malposition of
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the catheter relative to the central veins. Catheter malposition is more likely if the catheter never worked well (early malfunction). Malposition of the tip or kinking of the catheter have been reported in up to 68% of early malfunctions. Catheters with early malfunction should be imaged to diagnose malposition. Late malfunction is more likely caused by thrombosis. Thrombosis can occur within the catheter lumen, at the catheter tip, or around the catheter (fibrin sheath); can involve the entire vein (mural thrombus); or can form in the right atrium. In a careful study of central venous catheters in oncology patients in whom all malfunctioning catheters were imaged, thrombosis was confirmed to be the cause in 64%. The incidence of the specific forms of thrombosis is poorly defined. Isolated studies report an incidence of mural thrombosis of 7.6% and fibrin sheaths of 60%. The latter catheters were imaged only if they were refractory to urokinase dwells. One-year patency rates for tunneled cuffed catheters are estimated at 30 to 74%. Efforts to prevent thrombosis have been disappointing. Fixed mini-dose warfarin has not proved effective, and systemic anticoagulation is generally undesirable. Regardless of the etiology of malfunction, simple measures— such as patient repositioning, flushing the catheter with saline, rotating the catheter (uncuffed catheters), and lumen reversal—are usually tried to improve blood flow. It is not clear how effective these interventions are, but they are commonly performed. For instance, in one randomized study of temporary catheters 25 to 57% of dialysis treatments required lumen reversal (depending on the catheter design). Catheters that are refractory to simple measures may be treated with thrombolytics, guide-wire insertion, guide-wire exchange, or catheter stripping. A thrombolytic dwell is usually the first line of treatment because it can be given in the dialysis unit. Currently available thrombolytics include streptokinase, reteplase, and alteplase (t-PA). Urokinase has been removed from the market. Streptokinase is highly antigenic. Reteplase has been shown to be effective for catheter malfunction but like urokinase has to be aliquotted and frozen. Alteplase has none of these issues and is the only FDA-approved thrombolytic for the treatment of catheter malfunction. During dwells, thrombolytic is infused into the catheter to fill the dead space in the lumen. Urokinase is usually given in a dose of 5000 units per mL, and t-PA in a dose of 1 to 2 mg/mL. Some protocols use a fixed amount of drug (e.g., 5000 units of urokinase or 1 mg of t-PA) followed by saline. Others use a fixed concentration per lumen.
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The malfunctioning lumen only may be infused, or routinely both lumens may be infused regardless of which is malfunctioning. The drug is usually left to dwell for 20 to 60 minutes, but dwells of 1 to 4 days have been described. During the dwell, active drug can be periodically advanced toward the tip with saline. Thrombolytics are effective in approximately 80% of cases, even though most thrombus appears to reside outside the catheter lumen (Table 2.2). A direct comparison of urokinase with t-PA to treat catheter malfunction in oncology suggests that t-PA may be more effective. Larger doses of urokinase (250,000 units) and t-PA (50 mg) have been infused to treat refractory catheter malfunction or specific thrombotic complications (e.g., right atrial thrombus). Despite the increased dose, only minimal effects on bleeding parameters have been shown. The only major reported adverse event was an episode of hematuria requiring transfusion in a patient with known bladder cancer who was given 250,000 units of urokinase as a bolus. Catheter malfunction may also be treated with guide-wire insertion, fibrin sheath stripping, or exchange over a guide wire. The immediate success of most techniques is good. However, the effect is short-lived and usually requires repeated intervention (Table 2.2). Guide-wire insertion has only been described in one report and is not recommended. Catheter exchange avoids femoral puncture, and any fibrin sheath may be disrupted at the time of the procedure with either a snare or balloon. One small study resulted in greater long-term patency rates for catheter exchange compared to fibrin sheath stripping. Catheter exchange does not increase the risk of subsequent infection. Therefore,
Table 2–2
Treatment of Catheter Malfunction Immediate Intervention Urokinase dwell t-PA Urokinase infusion Guide-wire insertion Catheter exchange Catheter stripping
Primary Success (%)a 80 91 87 88 97 91
a. Success rates are averaged across available studies. b. NA = not available.
Patency (Days) NAb 30 30 29 65 40
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catheter exchange is probably the best solution to catheter malfunction. However, this requires further investigation.
Catheter-Related Infections Hemodialysis catheters can be complicated by exit site infections, tunnel infections, bacteremia, and distant infections (Figure 2.1). The exact definition of these infectious outcomes varies by source (see ”Recommended Reading” for Centers for Disease Control definitions). A practical and simple definition of exitsite infection is “purulent drainage at the exit site.” Redness, swelling, crusting, and pain may accompany this discharge—but these findings are more subjective than purulent drainage. Tunnel infections occur if inflammation extends 5 cm beyond the exit site or beyond the Dacron cuff. Bacteremia is defined by positive peripheral blood cultures in a patient with signs and symptoms of infection such as fever, chills, nausea, headache, hypotension, and elevated white blood cell count. Bacteremia is confirmed to be catheter related if no other source is found and the same organism is cultured from the catheter (usually a semiquantitative culture from the tip), or if symptoms rapidly resolve after catheter removal. Distant infections occur when organisms seed during bacteremia. The most common distant infections are endocarditis (3.9–4.1%), osteomyelitis (0.5–5.9%), and septic arthritis (1.0–3.8%). Other reported complications are septic phlebitis, septic pulmonary emboli, spinal abscess, myocardial abscess, and septic death. The incidence and rate of infectious complications according to catheter type are outlined in Table 2.3. Table 2–3
Infections Related to Hemodialysis Cathetersa Type of Infection (Number per 1000 CDs, %) Exit-site infection Tunnel infection Bacteremia Distant infection
Temporary 3.6 (9.0) NAb 6.2 (10.0) 1.1 (1.6)
Tunneled Cuffed 1.4 (22) 0.02 (0.2) 1.8 (39) 0.4 (5.3)
a. Rates calculated from prospective studies if available. Distant infection includes endocarditis, spinal abscess, osteomyelitis, septic arthritis, and septic death. b. NA = not available.
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Gram-positive organisms cause approximately 75% of catheterrelated bacteremias, with an increasing incidence of methacillinresistant Staphylococcus aureus. The remainder are caused by gram-negative organisms (17%), fungi (1%), and mixed organisms (7%). A similar spectrum of organisms is cultured from exit-site infections. Coagulase-negative staphylococci and diphtheria frequently cause catheter-related infection, but can also be contaminants. Therefore, it is more likely that they are the true source if both blood culture bottles grow one of the organisms. The utility of cultures from catheters, cultures from dialysis lines connected to catheters, and surveillance cultures has not been established. Patients with diabetes, immunosuppression, chronic kidney disease, a history of bacteremia, and Staphylococcus aureus nasal carriage are at increased risk for catheter-related bacteremia. Acute catheters inserted in the femoral vein are at greater risk than either internal jugular or subclavian sites. However, a recent study found no difference in infection rates for cuffed-tunneled femoral catheters compared to those placed in the internal jugular vein. Duration of placement is the most consistent risk factor (i.e., the longer the use the higher incidence of infection). A prospective study of temporary catheters reports the incidence of bacteremia to be approximately 10% for femoral catheters and internal jugular catheters after 1 week and 3 weeks of use, respectively. A recent study from the University of Alabama (Birmingham) showed that the overall likelihood of catheterrelated bacteremia was nearly 50% at 6 months in their patients having tunneled catheters.
Prevention of Catheter-Related Infections Duration of use is the strongest risk factor for infection. Therefore, minimizing the duration of use is the best method of preventing infection. The NKF-K/DOQI recommends that temporary femoral catheters remain in place for a maximum of 7 days, and that internal jugular vein catheters remain in place for a maximum of 3 weeks. If a catheter is still required, a tunneled cuffed catheter should be considered. There is no data to support the routine changing of other types of central venous catheters and this is generally not recommended. However, in bed-bound patients the risk of bacteremia at 1 week may justify the removal of the catheter and a subsequent “catheter holiday.” A risk/benefit analysis of this strategy (compared to leaving the catheter in place) has not been rigorously performed as a randomized trial.
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Table 2–4
Considerations for Accessing the Bloodstream Using Hemodialysis Catheters • The catheter hubcaps or bloodline connectors should be soaked for 3 to 5 minutes in povidone-iodine and then allowed to dry prior to separation. • Catheter lumens should be kept sterile. • To prevent contamination, the lumen and tip should never remain open to the air. A cap or syringe should be placed on or within the catheter lumen, while maintaining a clean field under the catheter connectors. • Patient should wear a surgical mask for all catheter procedures that remove the catheter caps and access the patient’s bloodstream. • Dialysis staff should wear gloves and a surgical mask or face shield for all procedures that remove the catheter caps and access the patient’s bloodstream. • A surgical mask for the patient and mask of face shield for the dialysis staff should be worn for all catheter-dressing changes. Source: National Kidney Foundation. Dialysis Outcome Quality Initiative: Clinical Practice Guidelines for Vascular Access. New York: National Kidney Foundation 1997:47. Used with permission.
Meticulous handling of catheters also prevents infections. Starting at insertion, proper disinfection and sterile technique are crucial whenever the catheter is handled. The importance of these simple measures is emphasized and standardized in the NKF-K/DOQI guidelines (Table 2.4). For temporary catheters, 2% mupirocin placed at the exit site significantly reduced bacteremia rates (from 6.0 to 0.4 per 1000 catheter days) and 10% povidone-iodine ointment reduced bacteremia rates from 4.5 to 0.4 bacteremias per 1000 catheter days. Exit sites should be inspected at each dialysis treatment, and dressings should be changed weekly (or more often if warranted). There is mounting evidence to suggest that either citrate or antibiotic catheter locks (gentamicin with or without cefazolin) are more effective than heparin alone. A cost analysis is justified before widespread use. Finally, in efforts to decrease catheter-related infection investigators have impregnated catheters with a variety of antiseptic (e.g. silver, chlorhexadine) and antibiotic materials (e.g., minocycline plus rifampin or gentamicin). Several studies
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have been performed involving acute and long-term catheters, both tunneled and non-tunneled. Few have investigated hemodialysis catheters specifically. One study of acute (short-term) nontunneled hemodialysis catheters bonded with minocyclinerifampin compared to non-bonded catheters found a significant decrease in catheter-related infections (11 versus 0%, respectively). The majority of trials have reported a benefit of central venous antibiotic-bonded catheters. These devices seem to perform well in carefully conducted trials, but they are expensive and have potential drawbacks (such as a risk of allergic reaction and the emergence of anti-biotic resistance). Pending further study, we cannot currently recommend the use of antiseptic- or antibiotic-bonded catheters for acute or long-term hemodialysis.
Management of Catheter-Related Infection Temporary catheters with exit-site infections should be removed immediately in light of the fact that the bacteremia rate is greater than 10% after 24 hours from the onset of exit-site infection. Exitsite infection from tunneled cuffed catheters may be treated with topical antibiotics. All other catheter-related infections should be treated with parenteral antibiotics. Antibiotics for tunnel infections should be active against staphylococci and streptococci. Methicillin-resistant Staphylococcus aureus (MRSA) should be treated empirically with vancomycin if there is a high prevalence of MRSA in the patient population. Exit-site infections and tunnel infections that do not respond to antibiotics should prompt catheter removal. Treatment of catheter-related bacteremia is usually started in the dialysis unit in which the patient first develops symptoms. Empiric therapy with vancomycin (20 mg/kg initially postdialysis, followed by 500 to 1000 mg after each treatment for maintenance) and gentamicin or tobramycin (1 mg/kg postdialysis) is used to cover enterococci, MRSA, and gram-negative organisms. After cultures are available, vancomycin should if possible be replaced with a narrower-spectrum antibiotic such as cefazolin (2–3 g post-dialysis) to avoid the development of vancomycin resistance. If the catheter is temporary, or if the patient with a tunneled cuffed catheter is symptomatic, the catheter should be removed as soon as possible. For tunneled cuffed catheters, if the patient’s symptoms are mild and resolve with antibiotics the catheter can be exchanged by guide wire within 24 to 48 hours.
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Negative blood cultures are not necessary prior to catheter exchange. Nevertheless, some interventionalists insist on negative blood cultures. If no exit-site or tunnel infection is present, the same exit site and tunnel can be used. This technique eradicates infection 80 to 100% of the time. When an exit-site or tunnel infection is present, the catheter should be tunneled out through a new exit site. The success rate decreases to 64% with this technique. In a single-center nonrandomized comparison of guidewire exchange versus immediate removal, there was no significant difference in time to infection recurrence between the two techniques [relative risk for removal compared to exchange of 0.88 (95% CI, 0.45–1.79). Catheters should not be left in place and treated with antibiotics because there is only a 32% chance the infection will be eradicated. Parenteral antibiotics should be continued for 3 weeks and are usually administered post-dialysis. Vancomycin, gentamicin, and the combination of the two can cause ototoxicity and should be used with caution when prescribed for more than 1 week.
Conclusions Acute vascular access is synonymous with catheter use. but unfortunately catheter use is often not temporary. Although catheters are designed for use in acute renal failure and as a bridge to permanent access, they also play an increasing role as “permanent access” because many patients do not have reliable arteriovenous access. For end-stage renal disease patients initiating dialysis, early referral is the key to minimizing exposure to catheters. Ideally, a usable arteriovenous access should be ready when dialysis is started so that catheters are avoided altogether. Unfortunately, patients are often referred late or the need for dialysis is unanticipated and thus the patient begins dialysis with a catheter. Frequently, the circumstances leading to catheter placement are out of the dialysis caregiver’s control. After a catheter is inserted, however, it is imperative that a permanent access be placed as quickly as possible and that the catheter be removed as soon as the permanent access is functional. Furthermore, permanent accesses ultimately fail and catheters must fill the gap. Patients are becoming more dependent on catheters to provide adequate dialysis and are therefore at greater risk for the many complications associated with them. To improve vascular access for patients, we must continue to strive to better understand how to optimize catheter performance and minimize complications.
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Recommended Reading National Kidney Foundation. Dialysis Outcome Quality Initiative: Clinical Practice Guidelines for Vascular Access. New York: National Kidney Foundation 1997. NKF-K/DOQI. Clinical Practice Guidelines for Vascular Access: Acute hemodialysis vascular access, noncuffed catheters. Am J Kidney Dis 2001;37(1):S146. Evidence-based national guidelines that have become the standard of care for vascular access. O’Grady NP, Alexander M, Dellinger EP, et al. Guidelines for the prevention of intravascular catheter-related infections. MMWR Recomm Rep 2002; 51(RR-10):1–29. Guidelines for practictioners who insert catheters and for persons responsible for surveillance and control of infections in hospital, outpatient, and home healthcare settings. Oliver, MJ. Acute dialysis catheters. Seminars in Dialysis 2001;14:432–35. Reviews of temporary and tunneled dialysis catheters. Pisoni RL, Young EW, Dykstra DM, et al. Vascular access use in Europe and the United States: Results from the DOPPS. Kidney Int 2002;61:305–16. The Dialysis Outcomes and Practice Patterns Study (DOPPS) is an ongoing observational study of hemodialysis patients in 12 countries. The study seeks to identify dialysis practices that contribute to improved mortality rates, hospitalization rates, health-related quality of life, and vascular access outcomes. Schwab SJ. Acute hemodialysis vascular access. In UptoDate Online 14.2, www.uptodate.com. Schwab SJ, Beathard G. The hemodialysis catheter conundrum: Hate living with them, but can’t live without them. Kidney Int 1999;56:1–17. Schwab SJ, Harrington JT, Singh A, et al. Vascular access for hemodialysis. Kidney Int 1999;55:2078–90. Review and discussion focusing on arteriovenous fistulas and grafts.
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Temporary Vascular Access for Hemodialysis John J. White, MD; Matthew J. Oliver, MD; and Steve J. Schwab, MD
When immediate hemodialysis is necessary, rapid access to the circulation is essential. Acute vascular access is created by inserting a catheter into a central vein. Catheter access is temporary if the renal failure resolves or if another form of functional permanent access can be created. Unfortunately, catheters initially thought to be temporary when they are placed often go on to provide access for months to years. Data from the Dialysis Outcomes and Practice Patterns Study (DOPPS) show that 60% of patients starting dialysis in the United States do so with an acute catheter. Consequently, catheters are now under a greater burden because they must be capable of providing adequate dialysis with a low rate of complications over longer periods of time.
Catheter Design Although brand names such as Quinton catheter, VasCath, and PermCath are commonly used as slang to describe hemodialysis catheters, in actuality there is a wide assortment of available catheters. Catheters are designed to accommodate easy insertion and good positioning, and to provide maximal flows. Catheters differ by material, length, lumen size, lumen configuration, inlet/ outlet holes, and method of connection to bloodlines (Figure 2.1). Temporary (nontunneled, uncuffed) catheters are primarily composed of polyurethane, which is stiff at room temperature to facilitate insertion but softens at body temperature to minimize vessel trauma. Tunneled cuffed catheters (long-term catheters) are primarily composed of silicone and silicone elastomers that are flexible and require a stylet and/or sheath for insertion. The walls of the lumens of silicone catheters must be thicker than polyurethane catheters because silicone provides less structural support. Silicone and polyurethrane are less thrombogenic than materials such as Teflon and polyvinyl used in the past. Catheter lumen sizes range from 9 to 16 French (0.75- to 2.2-mm inner diameter). Catheter length varies greatly to accommodate 23
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D
A Needle
E
B F Needle
G
C
Caoxial
H
Double D
Shotgun
Circle C
Triple Lumen
Figure 2–1 Hemodialysis catheter designs. Catheters traditionally connect to bloodlines with luer locks (A), but new implantable ports are accessed with dialysis needles (B, C). Lumens may be conjoined through their length (D, E), or completely (F) or partially separated (G). If the lumens are conjoined, various lumen configurations are available (H). The figure is approximate and is not intended to represent the exact design of any particular manufacturer’s catheter.
proper positioning of the tip. In general, 15-cm temporary catheters are inserted in the right internal jugular vein, 20-cm catheters in the left internal jugular vein, and 20- or 24-cm catheters in the femoral vein to minimize recirculation and to reach the great veins. Tunneled cuffed catheters are much longer (up to 70 cm in overall length) to accommodate the creation of tunnels and
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allow the tip to be placed in the right atrium or inferior vena cava as required. The arterial and venous lumens can be completely separated (e.g., Tesio catheter), partially separated (Ash split catheter), or conjoined throughout their length. The lumens of conjoined catheters can be configured as a shotgun design (e.g., Niagara, Permcath), single round catheter with midline septum (“double D”; e.g., Opti-Flow), Circle C, coaxial (e.g., Duoflow), and triple lumen design (e.g., Trialysis). Inlet and outlet holes can be a single large hole or multiple small holes in various patterns. Traditionally, connector ports have been of luer lock design. Midline septums or shotgun designs theoretically prevent kinking. Implantable devices (e.g., LifeSite, Dialock) allow dialysis needles to be inserted directly into subcutaneous ports. These devices are accessed by percutaneous puncture and consist of a titanium alloy port connected to a central venous silicone cannula. Two of these are implanted beneath the clavicle and tunneled in the right atrium via the jugular vein. When used with 70% isopropyl alcohol as a sterilant, retrospective and nonrandomized prospective studies have shown a decreased incidence of infection and catheter-related complications using these devices when compared to cuffed-tunneled catheters. Although promising, off-label use and a number of possibly related deaths in patients who were not candidates for other permanent access have drawn concerns from the Food and Drug Administration. Currently, these catheters are not available to the U.S. market. Despite the myriad of designs and purported advantages, at present there is little evidence that one design is superior to others. Most catheters are tested in ideal circumstances and over short periods of time. Comparisons between devices have included few randomized controlled trials and have failed to show differences in clinically important outcomes such as solute clearance, rates of bacteremia, or catheter malfunction requiring intervention. For example, in a study comparing a twin-dialysis catheter system (Tesio), a split-tip design (Ash-Split), and a steptip design (Opti-flow) there were no differences in catheter flow rates or rates of infection. The catheters only differed in time of insertion, with the split-tip and step-tip catheters being easier and faster to insert than the twin-dialysis system.
Catheter Insertion Catheter insertion varies by operator, site of insertion, and insertion technique. The operator should be well experienced or be
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supervised by an experienced operator. In general, tunneled cuffed catheters are inserted in operating rooms or clean interventional suites under fluoroscopy—with the operator gowned, gloved, and masked. Full surgical drapes are used, and the patient may be masked as well as given a mild sedative. Temporary catheters are generally inserted at the bedside or in the dialysis unit and do not warrant sterile precautions as rigorous as those required by tunneled cuffed catheters—but in general full-barrier precautions consisting of a mask, sterile gloves, gown, and a large drape should be used. The skin can be disinfected with chlorhexidine, povidone-iodine, or alcohol. Alcohol disinfects instantly, whereas povidone-iodine should be allowed to dry for 2 to 3 minutes to maximize antibacterial effect. Studies in nondialysis patients suggest that chlorhexidine reduces infection rates, but this has not been tested in dialysis patients. When available, insertion should be performed with ultrasound guidance. Ultrasound allows the operator to examine the vein for anatomic abnormalities and to directly visualize insertion. Ultrasound guidance has been shown to minimize insertion complications in both the internal jugular and femoral sites and results in a decrease in immediate catheter dysfunction. Using ultrasound guidance, inexperienced operators can increase their success rate to 95%. The NKF-K/DOQI (Kidney Disease Outcomes Quality Initiative) guidelines support this practice. The preferred site of placement is the right internal jugular vein. Catheters placed in the left internal jugular vein provide significantly less blood flow than right-sided catheters, and are nearly four times as likely to require removal for malfunction. Catheters should not be inserted into the subclavian vein if possible. Although studies have shown a decrease in infection rate with the use of subclavian catheters, these catheters have been associated with an increase in central vein stenosis (which may compromise future permanent access). In a prospective study in which patients underwent routine venography after removal of their first subclavian catheter, 52% of patients had subclavian vein thrombosis/stenosis. Half of these recanalized within 3 months, but the other half remained. In practice, thrombosis/stenosis of the subclavian vein is often subclinical until an arteriovenous access is placed in the ipsilateral arm—after which severe arm swelling occurs. Treatment of the stenosis with angioplasty or stent is difficult and requires repeated procedures to maintain patency. Often the stenosis requires takedown of the permanent access and renders the arm unusable for future access. Thrombosis/stenosis of the internal jugular vein is
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less frequent than the subclavian vein (approximately 6% in one series) and does not generally compromise future access unless it extends to the superior vena cava. Temporary catheters placed in the subclavian or internal jugular vein should have their position checked by chest X-ray or fluoroscopy before commencing dialysis. The tips of temporary catheters should rest in the superior vena cava (subclavian) or inferior vena cava (internal jugular vein). Temporary catheters are commonly placed in the femoral vein in bed-bound patients, but infection rates are higher than either neck location. Tunneled cuffed catheters may be placed in the femoral vein as well—and as a last resort catheters may be inserted via the translumbar and transhepatic routes. Catheters can be dressed with either standard or adhesive dry gauze or breathable transparent dressings. Patients and caregivers may feel that an adhesive dressing better secures the catheter or better protects the exit site from contamination. Some randomized studies of nondialysis catheters show higher infection rates when catheters were dressed with nonbreathable dressings as compared with dry gauze. However, a large randomized study by Maki and colleagues of Swan-Ganz catheters showed no difference between dry gauze and breathable transparent dressings. Antibiotic ointments such as povidone-iodine and mupirocin, when used in conjunction with dry gauze dressings, reduce bacteremia related to temporary hemodialysis catheters. Ointment may not be as effective for tunneled cuffed catheters, but this has not been studied. Patients may resist povidone-iodine ointment when used with gauze dressing because leakage of ointment will stain clothes. Many complications have been associated with hemodialysis catheter insertion. Some radiologic series report no serious complications despite hundreds of insertions. Average rates and ranges of complications in the literature are outlined in Table 2.1.
Catheter Performance Dialysis catheter lumens must be of large bore in order to provide blood flows to achieve adequate clearance. It therefore follows that catheter malfunction occurs when the catheter cannot provide blood flow sufficient to achieve adequate dialysis. For short periods of dialysis, blood flows of 200 to 250 mL/minute are usually sufficient to correct the metabolic disturbances associated with renal failure. For longer use, blood flows greater than 300 cc/minute are generally needed to achieve adequate clearance and reduce treatment durations. The exact amount of blood flow
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Table 2–1
Complications from Hemodialysis Catheter Insertion Complication Arterial puncture Local bleeding Aspiration Recurrent laryngeal palsy Hemo/pneumothorax Air embolism Cardiac arrhythmia Hemomediastinum Vessel perforation Pericardial tamponade Retroperitoneal bleedingb
Mean (%) 4.4 4.0 2.2 1.6 1.35 1.2 1.1 0.74 0.7 0.56 0.06
Range (%) 0–11.9 0–18.1 NAa NA 0–3.0 0–2.2 NA 0–1.2 0–1.3 0.5–0.6 NA
a. NA = not available. b. Femoral catheterization only.
and clearance required varies by patient. For acute dialysis, the dose prescribed can be significantly less than the dose delivered. This occurs for a variety of reasons unrelated to the device itself. However, femoral catheters are clearly associated with lower delivered dialysis dose. Recirculation from catheters is generally negligible because the arterial inlet is usually positioned proximal to the venous outlet and there is a high blood-flow rate in the large central veins (e.g., superior vena cava at approximately 2 L/minute). Our studies indicate that there is essentially no recirculation from tunneled catheters placed in the right atrium. However, if the tip of the catheter is placed in an area of restricted blood flow or if the lumens are reversed recirculation increases. Recirculation of malfunctioning catheters is 7 to 8% if they are reversed, and 14 to 19% if well-functioning catheters are inadvertently reversed. If the tips of femoral catheters are too short to reach the venous segment of high blood flow, recirculation is high. One study found that femoral catheters shorter than 20 cm had recirculation of 26.3% versus 8.3% for those longer than 20 cm.
Catheter Malfunction NKF-K/DOQI guidelines define catheter malfunction as failure to achieve blood flow rate equal to 300 mL/minute. The two primary mechanisms of malfunction are thrombosis and malposition of
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the catheter relative to the central veins. Catheter malposition is more likely if the catheter never worked well (early malfunction). Malposition of the tip or kinking of the catheter have been reported in up to 68% of early malfunctions. Catheters with early malfunction should be imaged to diagnose malposition. Late malfunction is more likely caused by thrombosis. Thrombosis can occur within the catheter lumen, at the catheter tip, or around the catheter (fibrin sheath); can involve the entire vein (mural thrombus); or can form in the right atrium. In a careful study of central venous catheters in oncology patients in whom all malfunctioning catheters were imaged, thrombosis was confirmed to be the cause in 64%. The incidence of the specific forms of thrombosis is poorly defined. Isolated studies report an incidence of mural thrombosis of 7.6% and fibrin sheaths of 60%. The latter catheters were imaged only if they were refractory to urokinase dwells. One-year patency rates for tunneled cuffed catheters are estimated at 30 to 74%. Efforts to prevent thrombosis have been disappointing. Fixed mini-dose warfarin has not proved effective, and systemic anticoagulation is generally undesirable. Regardless of the etiology of malfunction, simple measures— such as patient repositioning, flushing the catheter with saline, rotating the catheter (uncuffed catheters), and lumen reversal—are usually tried to improve blood flow. It is not clear how effective these interventions are, but they are commonly performed. For instance, in one randomized study of temporary catheters 25 to 57% of dialysis treatments required lumen reversal (depending on the catheter design). Catheters that are refractory to simple measures may be treated with thrombolytics, guide-wire insertion, guide-wire exchange, or catheter stripping. A thrombolytic dwell is usually the first line of treatment because it can be given in the dialysis unit. Currently available thrombolytics include streptokinase, reteplase, and alteplase (t-PA). Urokinase has been removed from the market. Streptokinase is highly antigenic. Reteplase has been shown to be effective for catheter malfunction but like urokinase has to be aliquotted and frozen. Alteplase has none of these issues and is the only FDA-approved thrombolytic for the treatment of catheter malfunction. During dwells, thrombolytic is infused into the catheter to fill the dead space in the lumen. Urokinase is usually given in a dose of 5000 units per mL, and t-PA in a dose of 1 to 2 mg/mL. Some protocols use a fixed amount of drug (e.g., 5000 units of urokinase or 1 mg of t-PA) followed by saline. Others use a fixed concentration per lumen.
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The malfunctioning lumen only may be infused, or routinely both lumens may be infused regardless of which is malfunctioning. The drug is usually left to dwell for 20 to 60 minutes, but dwells of 1 to 4 days have been described. During the dwell, active drug can be periodically advanced toward the tip with saline. Thrombolytics are effective in approximately 80% of cases, even though most thrombus appears to reside outside the catheter lumen (Table 2.2). A direct comparison of urokinase with t-PA to treat catheter malfunction in oncology suggests that t-PA may be more effective. Larger doses of urokinase (250,000 units) and t-PA (50 mg) have been infused to treat refractory catheter malfunction or specific thrombotic complications (e.g., right atrial thrombus). Despite the increased dose, only minimal effects on bleeding parameters have been shown. The only major reported adverse event was an episode of hematuria requiring transfusion in a patient with known bladder cancer who was given 250,000 units of urokinase as a bolus. Catheter malfunction may also be treated with guide-wire insertion, fibrin sheath stripping, or exchange over a guide wire. The immediate success of most techniques is good. However, the effect is short-lived and usually requires repeated intervention (Table 2.2). Guide-wire insertion has only been described in one report and is not recommended. Catheter exchange avoids femoral puncture, and any fibrin sheath may be disrupted at the time of the procedure with either a snare or balloon. One small study resulted in greater long-term patency rates for catheter exchange compared to fibrin sheath stripping. Catheter exchange does not increase the risk of subsequent infection. Therefore,
Table 2–2
Treatment of Catheter Malfunction Immediate Intervention Urokinase dwell t-PA Urokinase infusion Guide-wire insertion Catheter exchange Catheter stripping
Primary Success (%)a 80 91 87 88 97 91
a. Success rates are averaged across available studies. b. NA = not available.
Patency (Days) NAb 30 30 29 65 40
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catheter exchange is probably the best solution to catheter malfunction. However, this requires further investigation.
Catheter-Related Infections Hemodialysis catheters can be complicated by exit site infections, tunnel infections, bacteremia, and distant infections (Figure 2.1). The exact definition of these infectious outcomes varies by source (see ”Recommended Reading” for Centers for Disease Control definitions). A practical and simple definition of exitsite infection is “purulent drainage at the exit site.” Redness, swelling, crusting, and pain may accompany this discharge—but these findings are more subjective than purulent drainage. Tunnel infections occur if inflammation extends 5 cm beyond the exit site or beyond the Dacron cuff. Bacteremia is defined by positive peripheral blood cultures in a patient with signs and symptoms of infection such as fever, chills, nausea, headache, hypotension, and elevated white blood cell count. Bacteremia is confirmed to be catheter related if no other source is found and the same organism is cultured from the catheter (usually a semiquantitative culture from the tip), or if symptoms rapidly resolve after catheter removal. Distant infections occur when organisms seed during bacteremia. The most common distant infections are endocarditis (3.9–4.1%), osteomyelitis (0.5–5.9%), and septic arthritis (1.0–3.8%). Other reported complications are septic phlebitis, septic pulmonary emboli, spinal abscess, myocardial abscess, and septic death. The incidence and rate of infectious complications according to catheter type are outlined in Table 2.3. Table 2–3
Infections Related to Hemodialysis Cathetersa Type of Infection (Number per 1000 CDs, %) Exit-site infection Tunnel infection Bacteremia Distant infection
Temporary 3.6 (9.0) NAb 6.2 (10.0) 1.1 (1.6)
Tunneled Cuffed 1.4 (22) 0.02 (0.2) 1.8 (39) 0.4 (5.3)
a. Rates calculated from prospective studies if available. Distant infection includes endocarditis, spinal abscess, osteomyelitis, septic arthritis, and septic death. b. NA = not available.
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Gram-positive organisms cause approximately 75% of catheterrelated bacteremias, with an increasing incidence of methacillinresistant Staphylococcus aureus. The remainder are caused by gram-negative organisms (17%), fungi (1%), and mixed organisms (7%). A similar spectrum of organisms is cultured from exit-site infections. Coagulase-negative staphylococci and diphtheria frequently cause catheter-related infection, but can also be contaminants. Therefore, it is more likely that they are the true source if both blood culture bottles grow one of the organisms. The utility of cultures from catheters, cultures from dialysis lines connected to catheters, and surveillance cultures has not been established. Patients with diabetes, immunosuppression, chronic kidney disease, a history of bacteremia, and Staphylococcus aureus nasal carriage are at increased risk for catheter-related bacteremia. Acute catheters inserted in the femoral vein are at greater risk than either internal jugular or subclavian sites. However, a recent study found no difference in infection rates for cuffed-tunneled femoral catheters compared to those placed in the internal jugular vein. Duration of placement is the most consistent risk factor (i.e., the longer the use the higher incidence of infection). A prospective study of temporary catheters reports the incidence of bacteremia to be approximately 10% for femoral catheters and internal jugular catheters after 1 week and 3 weeks of use, respectively. A recent study from the University of Alabama (Birmingham) showed that the overall likelihood of catheterrelated bacteremia was nearly 50% at 6 months in their patients having tunneled catheters.
Prevention of Catheter-Related Infections Duration of use is the strongest risk factor for infection. Therefore, minimizing the duration of use is the best method of preventing infection. The NKF-K/DOQI recommends that temporary femoral catheters remain in place for a maximum of 7 days, and that internal jugular vein catheters remain in place for a maximum of 3 weeks. If a catheter is still required, a tunneled cuffed catheter should be considered. There is no data to support the routine changing of other types of central venous catheters and this is generally not recommended. However, in bed-bound patients the risk of bacteremia at 1 week may justify the removal of the catheter and a subsequent “catheter holiday.” A risk/benefit analysis of this strategy (compared to leaving the catheter in place) has not been rigorously performed as a randomized trial.
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Table 2–4
Considerations for Accessing the Bloodstream Using Hemodialysis Catheters • The catheter hubcaps or bloodline connectors should be soaked for 3 to 5 minutes in povidone-iodine and then allowed to dry prior to separation. • Catheter lumens should be kept sterile. • To prevent contamination, the lumen and tip should never remain open to the air. A cap or syringe should be placed on or within the catheter lumen, while maintaining a clean field under the catheter connectors. • Patient should wear a surgical mask for all catheter procedures that remove the catheter caps and access the patient’s bloodstream. • Dialysis staff should wear gloves and a surgical mask or face shield for all procedures that remove the catheter caps and access the patient’s bloodstream. • A surgical mask for the patient and mask of face shield for the dialysis staff should be worn for all catheter-dressing changes. Source: National Kidney Foundation. Dialysis Outcome Quality Initiative: Clinical Practice Guidelines for Vascular Access. New York: National Kidney Foundation 1997:47. Used with permission.
Meticulous handling of catheters also prevents infections. Starting at insertion, proper disinfection and sterile technique are crucial whenever the catheter is handled. The importance of these simple measures is emphasized and standardized in the NKF-K/DOQI guidelines (Table 2.4). For temporary catheters, 2% mupirocin placed at the exit site significantly reduced bacteremia rates (from 6.0 to 0.4 per 1000 catheter days) and 10% povidone-iodine ointment reduced bacteremia rates from 4.5 to 0.4 bacteremias per 1000 catheter days. Exit sites should be inspected at each dialysis treatment, and dressings should be changed weekly (or more often if warranted). There is mounting evidence to suggest that either citrate or antibiotic catheter locks (gentamicin with or without cefazolin) are more effective than heparin alone. A cost analysis is justified before widespread use. Finally, in efforts to decrease catheter-related infection investigators have impregnated catheters with a variety of antiseptic (e.g. silver, chlorhexadine) and antibiotic materials (e.g., minocycline plus rifampin or gentamicin). Several studies
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have been performed involving acute and long-term catheters, both tunneled and non-tunneled. Few have investigated hemodialysis catheters specifically. One study of acute (short-term) nontunneled hemodialysis catheters bonded with minocyclinerifampin compared to non-bonded catheters found a significant decrease in catheter-related infections (11 versus 0%, respectively). The majority of trials have reported a benefit of central venous antibiotic-bonded catheters. These devices seem to perform well in carefully conducted trials, but they are expensive and have potential drawbacks (such as a risk of allergic reaction and the emergence of anti-biotic resistance). Pending further study, we cannot currently recommend the use of antiseptic- or antibiotic-bonded catheters for acute or long-term hemodialysis.
Management of Catheter-Related Infection Temporary catheters with exit-site infections should be removed immediately in light of the fact that the bacteremia rate is greater than 10% after 24 hours from the onset of exit-site infection. Exitsite infection from tunneled cuffed catheters may be treated with topical antibiotics. All other catheter-related infections should be treated with parenteral antibiotics. Antibiotics for tunnel infections should be active against staphylococci and streptococci. Methicillin-resistant Staphylococcus aureus (MRSA) should be treated empirically with vancomycin if there is a high prevalence of MRSA in the patient population. Exit-site infections and tunnel infections that do not respond to antibiotics should prompt catheter removal. Treatment of catheter-related bacteremia is usually started in the dialysis unit in which the patient first develops symptoms. Empiric therapy with vancomycin (20 mg/kg initially postdialysis, followed by 500 to 1000 mg after each treatment for maintenance) and gentamicin or tobramycin (1 mg/kg postdialysis) is used to cover enterococci, MRSA, and gram-negative organisms. After cultures are available, vancomycin should if possible be replaced with a narrower-spectrum antibiotic such as cefazolin (2–3 g post-dialysis) to avoid the development of vancomycin resistance. If the catheter is temporary, or if the patient with a tunneled cuffed catheter is symptomatic, the catheter should be removed as soon as possible. For tunneled cuffed catheters, if the patient’s symptoms are mild and resolve with antibiotics the catheter can be exchanged by guide wire within 24 to 48 hours.
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Negative blood cultures are not necessary prior to catheter exchange. Nevertheless, some interventionalists insist on negative blood cultures. If no exit-site or tunnel infection is present, the same exit site and tunnel can be used. This technique eradicates infection 80 to 100% of the time. When an exit-site or tunnel infection is present, the catheter should be tunneled out through a new exit site. The success rate decreases to 64% with this technique. In a single-center nonrandomized comparison of guidewire exchange versus immediate removal, there was no significant difference in time to infection recurrence between the two techniques [relative risk for removal compared to exchange of 0.88 (95% CI, 0.45–1.79). Catheters should not be left in place and treated with antibiotics because there is only a 32% chance the infection will be eradicated. Parenteral antibiotics should be continued for 3 weeks and are usually administered post-dialysis. Vancomycin, gentamicin, and the combination of the two can cause ototoxicity and should be used with caution when prescribed for more than 1 week.
Conclusions Acute vascular access is synonymous with catheter use. but unfortunately catheter use is often not temporary. Although catheters are designed for use in acute renal failure and as a bridge to permanent access, they also play an increasing role as “permanent access” because many patients do not have reliable arteriovenous access. For end-stage renal disease patients initiating dialysis, early referral is the key to minimizing exposure to catheters. Ideally, a usable arteriovenous access should be ready when dialysis is started so that catheters are avoided altogether. Unfortunately, patients are often referred late or the need for dialysis is unanticipated and thus the patient begins dialysis with a catheter. Frequently, the circumstances leading to catheter placement are out of the dialysis caregiver’s control. After a catheter is inserted, however, it is imperative that a permanent access be placed as quickly as possible and that the catheter be removed as soon as the permanent access is functional. Furthermore, permanent accesses ultimately fail and catheters must fill the gap. Patients are becoming more dependent on catheters to provide adequate dialysis and are therefore at greater risk for the many complications associated with them. To improve vascular access for patients, we must continue to strive to better understand how to optimize catheter performance and minimize complications.
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Recommended Reading National Kidney Foundation. Dialysis Outcome Quality Initiative: Clinical Practice Guidelines for Vascular Access. New York: National Kidney Foundation 1997. NKF-K/DOQI. Clinical Practice Guidelines for Vascular Access: Acute hemodialysis vascular access, noncuffed catheters. Am J Kidney Dis 2001;37(1):S146. Evidence-based national guidelines that have become the standard of care for vascular access. O’Grady NP, Alexander M, Dellinger EP, et al. Guidelines for the prevention of intravascular catheter-related infections. MMWR Recomm Rep 2002; 51(RR-10):1–29. Guidelines for practictioners who insert catheters and for persons responsible for surveillance and control of infections in hospital, outpatient, and home healthcare settings. Oliver, MJ. Acute dialysis catheters. Seminars in Dialysis 2001;14:432–35. Reviews of temporary and tunneled dialysis catheters. Pisoni RL, Young EW, Dykstra DM, et al. Vascular access use in Europe and the United States: Results from the DOPPS. Kidney Int 2002;61:305–16. The Dialysis Outcomes and Practice Patterns Study (DOPPS) is an ongoing observational study of hemodialysis patients in 12 countries. The study seeks to identify dialysis practices that contribute to improved mortality rates, hospitalization rates, health-related quality of life, and vascular access outcomes. Schwab SJ. Acute hemodialysis vascular access. In UptoDate Online 14.2, www.uptodate.com. Schwab SJ, Beathard G. The hemodialysis catheter conundrum: Hate living with them, but can’t live without them. Kidney Int 1999;56:1–17. Schwab SJ, Harrington JT, Singh A, et al. Vascular access for hemodialysis. Kidney Int 1999;55:2078–90. Review and discussion focusing on arteriovenous fistulas and grafts.