Vascular Catheter–Related Infections

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128 Vascular Catheter–Related Infections

Catheter-related bloodstream infection (CRBSI) is the third leading device-related infection among U.S. hospitals and ambulatory surgical centers in the United States participating in the National Healthcare Safety Network (NHSN) that report to the Centers for Disease Control and Prevention (CDC).¹ In the 2009 report, 14,332 primary bloodstream infections over 7.4 million catheter days (1.93 infections per 1000 catheter days) were identified. This infection rate ranks third in magnitude behind catheter-associated urinary tract infections and ventilator-associated pneumonias.¹ CRBSI ranks second worldwide only to ventilator-associated pneumonia.² The estimates in both of these reports are limited to only central venous catheter (CVC) infections. However, peripheral venous catheters, more permanent cuffed and tunneled catheters, arterial catheters, and peripherally inserted central catheters (PICC) also have associated bloodstream infection rates.³^–⁴

The cost of CRBSI in terms of morbidity is significant to both the patient and the healthcare provider. The impact on resource utilization was summarized by Dimick et al., who conducted a prospective cohort study among surgical ICU patients at a large tertiary care center. A single CRBSI increased hospital costs by $56,167 and hospital length of stay by 22 days.⁵ The increased mortality of CRBSI was estimated in a meta-analysis by Siempos et al. He analyzed eight different studies that included 2540 ICU patients and determined the relative risk of mortality to be 1.57.⁶ In a mixed cohort of 2201 medical and surgical patients hospitalized in 15 French ICUs, CRBSI was associated with an estimated excess mortality of 11.5% to 20%.⁷

Because of the burden of mortality to patient populations and the increased costs to payers, CRBSI was included in the list of eight hospital-acquired conditions, the so-called “never events.” By inclusion as a “never event,” the Centers for Medicare and Medicaid Services (CMS) are prohibited by Congress from reimbursing hospitals for charges associated with these conditions after October 1, 2008.⁸ Thus, prevention of CRBSI has attracted substantial attention from multiple stakeholders in the healthcare industry.

This chapter will clarify some commonly used terms associated with CRBSI, discuss various pathogenic theories, analyze patient- and hospital-related risk factors, discuss available diagnostic techniques, and review the existing data on infections associated with the most commonly employed types of vascular catheters.

Definitions

Clinicians and researchers historically have used different definitions for vascular catheter–related infections. Infections can be linked to peripheral, central, venous, and arterial catheters. These catheters can further be designated as permanent, short-term, or long-term. The clinical presentation of a catheter-related infection can be designated as either local (site inflammation, purulent drainage, tenderness) or systemic (bacteremia with or without systemic sepsis). Although it is certain that inanimate objects do not become “infected,” there is strong evidence to suggest that bacteria may be able to live and multiply on catheter surfaces, possibly deriving nutrients from catheter polymers, the deposited glycocalyx of certain bacterial species, and other nonviable bacteria.^9,¹⁰ Earlier clinical investigations used erroneous descriptions and definitions for catheter contamination, colonization, and infection. These different definitions have led to confusion and incorrect interpretations by previous investigators.¹¹ This is further complicated by confusion regarding subtle differences between surveillance definitions by the NHSN¹ and clinical definitions. The commonly accepted clinical definitions have been previously published^11,¹²:

Localized catheter colonization: significant growth of a microorganism in a semiquantitative or quantitative culture of the catheter tip, subcutaneous segment of the catheter, or the catheter hub (see Diagnostic Techniques), without evidence of systemic infection.

Microbiological exit site infection: exudate at the catheter exit site yields bacterial or fungal growth on a standard qualitative culture with or without concomitant bloodstream infection.

Clinical exit site infection: tenderness, erythema or site induration greater than 2 cm from the catheter exit site, with or without other signs or symptoms of infection.

Tunnel infection: tenderness, erythema, and/or induration greater than 2 cm from the catheter exit site, along the subcutaneous tract of a tunneled catheter.

Pocket infection: purulent fluid in the subcutaneous pocket of a totally implanted intravascular device that might or might not be associated with spontaneous rupture and drainage or necrosis of the overlying skin, in the absence of concomitant bacteremia.

It is important to understand that both microbiological and clinical exit site infections, tunnel infections, and pocket infections, when accompanied by a positive blood culture, will be classified as a CRBSI for hospital surveillance purposes.^1,^11,¹²

Culture of drainage around a catheter insertion site may in some situations be helpful in that a positive bacterial culture result assists in confirming the presence of an exit site infection. It is important to also understand that values of 15 CFUs or less for semiquantitative and 10³ CFUs or less for quantitative cultures may be regarded as a negative culture, a contaminant, or an insignificant infection that does not require treatment in the absence of a confirmatory blood culture. Insertion site manifestations of inflammation are neither sensitive nor specific for diagnosing CRBSI or catheter colonization. Immunosuppressed patients may manifest local signs of inflammation, and other patient groups may develop intense local insertion site inflammation without associated CRBSI.¹⁴

Pathogenesis

Microbial colonization and biofilm formation on intravascular catheters are universal, occurring soon after catheter insertion.^9,^10,¹⁵ The final determinate of whether colonization progresses to clinical infection is multifactorial. A variety of host factors, catheter composition, and the interaction between microorganisms and the catheter surface may all contribute to the ultimate development of CRBSI.

There are four established routes for catheter contamination leading to CRBSI:

1 Microorganisms migrate from the skin at the insertion site into the subcutaneous tract along the external surface of the catheter and ultimately gain access to the distal intravascular catheter segment.¹⁶ This is the most common mechanism for developing infection of short-term non-cuffed non-tunneled central venous catheters.

2 Microorganisms gain access to the catheter through the hubs or ports of the vascular device. The most common sources for contamination are the hands of healthcare workers or the infusion of minimally contaminated fluids (contaminated at the bedside) or attachment of contaminated tubing. This route of infection is more commonly identified in patients with long-term tunneled catheters (Hickman, Broviac, Groshong) or mediports.¹⁶ Bacteria can be introduced via one or more hubs from frequent manipulations. As the biofilm grows, bacteria migrate into the inner luminal surface and gain access to the venous circulation. In low-flow regions, the biofilm attachment is weaker and breaks more easily, allowing entry of bacteria into the venous circulation.¹⁶

3 Remote infections may produce bacteremia and hematogenously seed an intravascular device. Although this scenario is plausible, hematogenous catheter seeding is considered a rare cause of CRBSI.¹⁶

4 Infusate contamination is a rare fourth mechanism for development of CRBSI. Parenteral nutrition solutions, lipid emulsions and heparin flush solutions can support bacterial and fungal growth, but the risk from infusate contamination today is considered very low.^17,¹⁸

Following insertion, the intravascular portion of the catheter is quickly coated with a thrombin layer covering both the external and internal surfaces. Thrombin contains a number of proteins including fibronectin, thrombospondin, and laminin which create an adhesive surface on the catheter that promotes adherence of microbial pathogens. Multiple species of Staphylococcus epidermidis, Staphylococcus aureus, Candida albicans, and various gram-negative organisms are all capable of adhering to catheter surfaces.¹⁹ A mature biofilm can shield organisms from antibiotics at 10 to 1000 times the concentration required to kill planktonic bacteria.²⁰

This helps explain why the commonly reported pathogens for hospital-acquired bloodstream infections remain coagulase-negative staphylococci (Staphylococcus epidermidis), Staphylococcus aureus, enterococci, and Candida species.²⁰ Gram-negative bacilli account for approximately 20% of CRBSIs reported.^20,²¹

Risk Factors

A number of factors potentiate the risk for CRBSI. These are generally similar to the same factors that increase the risk for any hospital-acquired infection. Extremes of age (i.e., pediatric, elderly), immunodeficiency, chronic disease states, remote infection sites, and heavy colonization of the skin with bacteria or fungi may all increase the risk. Alterations in skin integrity (psoriasis, burns) also increase risk. Whereas patient-related factors cannot be significantly modified during an acute illness, they must be considered when developing catheter maintenance protocols. Penel et al. identified age younger than 10 years, difficulties with catheter insertion, and the need for total parenteral nutrition as significant risk factors for intravascular device–related infections.²²

In contradistinction to patient-related risk factors, many hospital-related risk factors can be significantly modified, and prevention protocols are designed to focus on these risks.^22,²³ A number of interventions have been proposed by the CDC to assist in the prevention of CRBSI.^24,²⁵ Implementation of educational programs for hospital personnel regarding proper insertion and maintenance of intravascular catheters and appropriate preventive control measures should reduce infection rates. A number of other interventions and measures are also recommended collectively as the “central line bundle.” These recommended procedures and interventions are: hand washing, using full sterile-barrier precautions during insertion of central venous catheters, preparing the insertion skin site with chlorhexidine, avoiding the femoral site if possible, and removing central venous catheters as soon as possible when no longer needed.²³ In a large multicenter trial involving 108 intensive care units (ICUs), a central line bundle was initiated to determine its effect on reduction of catheter-related bloodstream infections. Implementing these strategies reduced the mean rate of CRBSI from 7.7 to 1.4 per 1000 catheter-days at 16 to 18 months follow-up (P < 0.002).²⁶ This large multicenter study provided evidence that the guidelines recommended by the CDC^24,²⁵ are indeed beneficial in reducing CRBSI rates. Others have suggested that the act of prospective surveillance alone without any specific intervention to reduce CRBSI will also have a beneficial result in decreasing infection rates.²⁷

Although the number of catheter manipulations and the experience of the individual performing the catheter insertion may be risk factors, these often cannot be changed or controlled for the individual patient at risk. The need for total parenteral nutrition, the area within the hospital where the insertion is performed, and the number of catheter lumens have all been associated with increased risk for catheter-related infection.²⁸ Cutdowns should be avoided whenever possible because of the historically high incidence of catheter-related complications.²⁹ The most common risk factors for catheter colonization and CRBSI that can be successfully altered are separately discussed.

Anatomic Insertion Site

An early study by Mermel showed that the use of the internal jugular site, particularly for pulmonary artery catheters, is a significant risk factor for catheter-related infection.³⁰ This may be related to the closer proximity of oropharyngeal secretions, greater catheter motion from neck movement, and greater difficulty in maintaining a sterile occlusive dressing.³⁰ However, it is still recommended that the internal jugular or the femoral vein site be used over the subclavian vein site for short-term hemodialysis catheters to reduce the risk of subsequent subclavian vein stenosis.^24,²⁵

The femoral site is also more likely to become heavily colonized and thus is also at higher risk for CRBSI. Merrer et al. in a randomized controlled clinical trial involving eight different ICUs identified a threefold higher incidence of clinical sepsis (with or without bloodstream infection) and a tenfold increase in thrombotic complications when femoral catheters were compared to subclavian catheters.³¹

Data collected in our own center suggest that colonization rates for femoral sites, even with the use of chlorhexidine and silver sulfadiazine-bonded catheters, are significantly higher than for subclavian or internal jugular catheter sites.³²

Duration of Catheter Use

Bacterial colonization of catheter surfaces begins shortly after insertion and is directly proportional to the length of time a catheter remains in place. The risk of CRBSI increases over time. Nonetheless, the optimal timing of catheter removal remains uncertain. The risk of an individual catheter causing CRBSI is low if inserted under optimal sterile conditions and removed within 4 to 7 days. However, critically ill patients typically require venous access for prolonged periods, and the timing of catheter removal must be weighed against clinical necessity. Central venous catheters and pulmonary artery catheters do not have predetermined lifespans.³³

Recommendations and guidelines for catheter exchange may be used to minimize CRBSI and to prolong site use on the basis of existing published data. However, it is important to realize that CRBSI risk factors are multifactorial and that global recommendations for catheter maintenance or removal may not be applicable to the individual patient. Generally, catheters should be removed (1) when they are no longer needed, or (2) if CRBSI is suspected clinically and appropriate cultures confirm clinical suspicions (see Diagnostic Techniques). Individual hospitals, individual ICUs, and in certain situations individual practitioners should study their catheter infection rates to develop specific guidelines appropriate to their practice patterns and environment. Rates of CRBSI per 1000 catheters-days can be calculated and compared with published standards.^1,^2,^24,²⁵

Diagnostic Techniques

The clinical diagnosis of CRBSI is often inaccurate, leading to premature catheter removal. Assuming that appropriate sterile technique during insertion and appropriate site care have been followed, the presence of entry-site inflammation is neither sensitive nor specific for CRBSI.¹⁴ Qualitative broth cultures collected through the CVC are generally discouraged for determining CRBSI for short-term, non-tunneled catheters. The positive predictive value of blood cultures obtained through the catheter is significantly less than from a peripheral venipuncture,^34,³⁵ and additional cultures are usually necessary to make the definitive diagnosis. However, a negative culture from either a peripheral venipuncture or a CVC has excellent negative predictive value, and cultures obtained through the catheter are frequently performed to rule out CRBSI.³⁵

The unreliability of clinical diagnosis and qualitative blood cultures has led to a variety of microbiological diagnostic techniques. These can be categorized into diagnostic methods that require catheter removal and catheter-sparing diagnostic methods. Because each method has advantages and disadvantages, some investigators have suggested that simply performing peripheral blood cultures and clinical evaluation may be all that is necessary and cost-effective. Clinical diagnosis alone and qualitative blood cultures will both significantly overestimate the rate of CRBSI and should generally be avoided.

Diagnostic Techniques Requiring Removal of the Central Venous Catheter

Quantitative Catheter Cultures

This type of culture involves flushing, sonicating, or vortexing the catheter segment with broth. This is designed to retrieve organisms from both the internal and external catheter surface. This technique is particularly useful for catheters in situ for more than 7 days.¹¹ In this situation, intraluminal spread from the hub is the most likely mechanism for catheter colonization. Therefore, obtaining a culture from both the internal and external surface should be more sensitive and specific. A culture yielding over 10³ CFU is diagnostic for CRBSI if accompanied by the appropriate clinical diagnosis, a positive peripheral blood culture with the same organism, and no other likely source for the infection. A meta-analysis conducted by Safdar in 2005 showed that the pooled sensitivity and specificity for this culture technique was 83% and 87% respectively.³⁶

Semiquantitative Catheter Culture

The semiquantitative (roll-plate) technique developed by Maki and colleagues remains the most common diagnostic technique for determining catheter-related infection.³⁷ A 5-cm segment (either catheter tip or intracutaneous segment) is rolled across a blood-agar plate in a reproducible, defined manner. In the original study, a positive result was defined as more than 15 CFUs per plate, although most of the culture-positive catheters in the original study yielded confluent growth.³⁷ A positive catheter segment culture result (>15 CFUs) resulted in a 16% risk of CRBSI. This technique is probably most accurate for catheters that are removed within the first 7 days.³⁶ It may become less sensitive for more long-term catheters, because this technique does not culture the internal lumen. A recent meta-analysis of 19 studies using the semiquantitative catheter culture technique identified an overall sensitivity of 85% and specificity of 82%.³⁶

Central Venous Catheter–Sparing Diagnostic Techniques

A number of techniques have been developed as an alternative for diagnosing CRBSI in patients for whom catheter removal is undesirable because of limited vascular access.¹¹

Paired Device–Collected Quantitative Blood Cultures

This technique involves obtaining quantitative cultures of paired blood samples—one obtained through the central venous catheter hub and the other from a peripheral venipuncture site. The samples should be obtained less than 10 minutes apart using the same blood volume for each culture. Central venous catheter cultures yielding a colony count at least fivefold greater than the colony count obtained from the peripheral venipuncture sample is considered predictive of CRBSI.^11,³⁸ This technique is used more frequently for long-term tunneled catheters. A comparative meta-analysis of various diagnostic methods reviewed 7 studies utilizing the differential quantitative blood culture method. The overall pooled sensitivity was 75% to 93%, and the specificity was 97% to 100%.³⁶

Differential Time to Positivity for Central Venous Catheter versus Peripheral Blood Cultures

This method makes use of continuous blood culture monitoring for positivity.¹¹ Radiometric methods are utilized comparing the differential time to positivity for qualitative cultures of blood samples drawn from the catheter and from a peripheral vein. This test is based on the hypothesis that the time to positivity of a culture is closely related to the inoculum size of the microorganisms. The difference between the time required for culture positivity in simultaneously drawn samples of catheter blood and peripheral blood are measured. Raad determined that the cutoff time for positivity was 120 minutes.³⁹ A subsequent meta-analysis revealed an overall sensitivity of 85% and a specificity of 81%.³⁶

Catheter and Site Maintenance

Skin preparation before insertion and appropriate site and catheter maintenance are crucial factors in preventing CRBSI. The long-term maintenance of catheters and insertion sites has been extensively studied, including the type and frequency of dressing changes, intravenous (IV) tubing changes, skin antiseptics, topical ointments, antibiotic lock solutions, and guidewire exchange to diagnose or prevent infection. Great care should be taken in preparing the insertion site, practicing sterile precautions during catheter insertion, and maintaining sterility in the day-to-day use of the catheter. All members of the multidisciplinary patient care team, including physicians, nurses, nursing assistants, technicians, and pharmacists, should be educated about the critical importance of hand hygiene, standards of catheter care, and the aseptic preparation of infusate solutions. Hospital-wide and ICU policies should be regularly reviewed and reinforced with all team members to maintain an environment of conscientious patient safety.

Adjuncts to Catheter and Site Maintenance

Several trials have compared various antiseptic solutions’ efficacy in preventing CRBSI. Parienti et al. randomized 223 catheters to either a 10% aqueous povidone-iodine solution or a 5% povidone-iodine solution in 70% ethanol.⁴⁰ They observed that the ethanol-based solution was associated with a lower catheter colonization rate and a longer time to catheter colonization compared to the aqueous solution. However, the rates of catheter-related bacteremia were similar in both groups.⁴⁰ Mimoz et al. compared 5% povidone-iodine in 70% ethanol to a solution of 0.25% chlorhexidine gluconate, 0.025% benzalkonium chloride, and 4% benzylic alcohol.⁴¹ A total of 538 catheters were randomized, with 481 of these providing evaluable culture results. The solutions were used for skin preparation and then as a single application during subsequent dressing changes. There was a 50% decrease in the incidence of catheter colonization and a trend toward lower rates of CRBSI in the chlorhexidine group.⁴¹ Other studies have focused on trials of chlorhexidine-impregnated dressing materials as a strategy to decrease CRBSI. A meta-analysis of eight studies was conducted by Ho et al.⁴² The chlorhexidine-impregnated dressing demonstrated an odds ratio (OR) for catheter or exit site bacterial colonization of 0.47, P <0.001. Like other investigators, they observed a trend towards reduction in CRBSI. Interestingly, they estimated that the dressings would have to be used on 142 catheters, with a total cost of $532.50, to prevent one episode of CRBSI.⁴² It is noteworthy that although the studies cited here achieved impressive reductions in colonization, none demonstrated significant reduction in CRBSI. Thus, dressing materials alone are not sufficient to realize decreases in CRBSI rates.

Timsit et al. performed a prospective randomized multicenter study in 2009 comparing standard catheter dressings and site care to a chlorhexidine gluconate–impregnated sponge dressing to determine the effect on catheter colonization and the incidence of major catheter-related infection (defined as either catheter-related clinical sepsis without bloodstream infection or catheter-related bloodstream infection).⁴³ This study also randomized patients to receive dressing changes at either 3 or 7 days. The novel chlorhexidine dressing reduced catheter colonization from 15.8/1000 catheter-days to 6.3/1000 catheter-days (hazard ratio 0.36, 0.28–0.46, P < .001). Similar hazard risk reduction was identified for both major catheter-related infection (1.4/1000 catheter-days versus 0.6/1000 catheter-days) and CRBSI (1.3/1000 catheter-days versus 0.4/1000 catheter-days). It should be mentioned that almost 50% of the catheters studied were arterial catheters. Also, the majority of the catheter sites required more frequent dressing changes before the 3- or 7-day time periods expired. The authors concluded that 117 catheters would require management with the chlorhexidine gluconate–impregnated sponges to prevent one major catheter-related infection.⁴³ Use of these dressings with central venous catheters and arterial catheters in the ICU reduced the risk of infection even when background infection rates were low. Reducing the frequency of changing unsoiled adherent dressings from every 3 days to every 7 days modestly decreased the total number of dressing changes and appeared to be safe.⁴³

Investigation to find other effective adjuncts to CRBSI prevention has extended into use of antimicrobials as flush (or lock) solutions. Safdar and Maki published a meta-analysis of seven prospective, randomized trials comparing vancomycin-heparin to heparin alone as lock solutions for prevention of CRBSI. The study cohorts included patients with cancer, those requiring parenteral nutrition, and critically ill neonates. The vancomycin-heparin lock solution was associated with an odds reduction of 0.49 for CRBSI compared to heparin alone.⁴⁴ When vancomycin was used as a true lock solution, it conferred a greater benefit, with an OR of 0.34. The authors concluded that this strategy warranted consideration for high-risk patients requiring central access.⁴⁴ Other antibiotic-based solutions have been tested in various populations, with similarly impressive reductions in CRBSI rates.⁴⁵

In addition to evaluating topical application of antimicrobial solutions and lock solutions, investigators have tested various strategies of catheter replacement as a means to reduce CRBSI by decreasing prolonged exposure to any individual catheter. Both new-site replacement and guidewire exchange protocols have been examined. Cook et al. systematically reviewed the literature consisting of 12 relevant trials of catheter replacement over a guidewire versus new-site placement.⁴⁶ They observed that new-site placement presented a higher risk of mechanical complications compared to guidewire exchange. However, guidewire exchange, regardless of whether the patient was suspected of having an infection, was associated with trends toward higher rates of catheter site infection and CRBSI. Additionally, exchanging catheters routinely every 3 days, either by new-site placement or by guidewire exchange, was not effective in reducing CRBSI compared to exchange on an as-needed basis. They concluded that if guidewire exchange is necessary, meticulous sterile technique is required.⁴⁶

Suggested Method for Guidewire Exchange

The following procedure of guidewire exchange is recommended:

1 Guidewire exchange begins with a complete sterilization of the external portion of the exiting catheter before the guidewire is placed. All IV tubing, including parenteral nutrition tubing, is carefully separated from the catheter hubs and replaced with sterile caps or plugs. The separated IV tubing tips are also sterilely protected until they are reconnected to the new catheter or preferably replaced with new tubing.

2 Sterile disposable gowns and gloves are worn by personnel performing the procedure, along with surgical hats and masks, and a sterile field for the necessary equipment is prepared on a bedside table.

3 The distal ports of the catheter to be exchanged are placed on a sterile paper or cloth towel barrier (usually provided in the new catheter kit), and the insertion site, along with a 10-cm circumferential area of skin and the entire external portion of the catheter from insertion site to capped hubs, is scrubbed for 5 minutes with 10 × 10-cm gauze pads soaked in 4% chlorhexidine skin cleanser. The most important aspect of this preparation is that chlorhexidine be allowed to remain in contact with the skin and the entire external portion of the catheter for at least 5 minutes.

4 After this scrub, the excess soap is carefully removed from the area with dry 10 × 10-cm gauze pads, and the skin sutures securing the catheter are removed with a No. 11 disposable scalpel.

5 The operator then exchanges sterile surgical gloves, and the entire area is widely draped with six sterile cloth surgical towels or other large commercially available sterile barriers, with the distal catheter hubs being carefully and sterilely removed from the previous paper or cloth towel barrier to the new widely draped sterile barrier.

6 A sterile guidewire is carefully inserted through the distal port of the catheter after removal of the cap, with care taken that the wire does not touch the external portion of the hub.

7 The old catheter is carefully removed, with care taken to avoid contact with the surrounding skin.

8 Appropriate culture specimens are then obtained by amputating the 5-cm intracutaneous segment and the 5-cm distal tip of the removed catheter. This can be done with a sterile disposable suture removal kit (containing disposable forceps and scissors). The segments are placed into two separate culturettes following removal of the cotton-tipped swab, and the tip of the culturette is manually crushed to release the inner preservative. The two culturettes are labeled appropriately and transported immediately to the microbiology laboratory for semiquantitative or quantitative cultures.

9 The portion of the guidewire protruding from the skin is then cleaned with 4% chlorhexidine. Before handling the new catheter, it is best to change to a third pair of sterile gloves. A new catheter is then placed over the guidewire into the proper anatomic position.

10 The catheter is sutured into place after the guidewire is removed.

A chest radiograph is generally not required after guidewire exchange.

For CVCs (16–30 cm in length), both the tip and the intracutaneous 5-cm segments from the removed catheter are sent for semiquantitative or quantitative culture. For PA catheters and introducers, the 5-cm tip of the PA catheter and the 5-cm intracutaneous segment of the catheter introducer are sent in separate culturettes for semiquantitative or quantitative culture.

Whereas strategies aimed at reducing CRBSI are traditionally focused on isolated technical interventions, there is accumulating evidence that systems-based interventions are also very effective in improving patient outcomes. Common themes in the various systems-based strategies are education of nursing and physician staff in evidence-based practices of hand hygiene and catheter site preparation. Additionally, these interventions should employ ongoing compliance and CRBSI surveillance and feedback to the teams with observed compliance and CRBSI event rates. By utilizing evidence-based practices, monitoring compliance and CRBSI rates, and updating the care teams concerning their progress, an environment of conscientious quality improvement and patient safety is created. Several investigators have studied this type of intervention and realized 50% to greater than 70% reductions in CRBSI rates across various critical care settings.⁴⁷^–⁴⁹ It is clear that individual technical innovations offer the means to decrease CRBSI rates. However, initiating a multimodal approach that incorporates evidence-based practices, team education, results tracking, and feedback may offer the most robust and sustainable improvements in patient outcomes.

Infection Risks of Specific Catheters

Previously we have discussed CRBSI as a uniform phenomenon without distinguishing the specific burden of risk associated with specific catheters. Each type of catheter carries an associated degree of risk for CRBSI. Many investigators have focused on individual catheter types when reporting these risks. Maki et al. conducted a meta-analysis of 200 published prospective studies encompassing 65,105 intravascular catheters ranging from peripheral IV catheters to left ventricular assist devices. The pooled mean CRBSI rates vary from 0.1/1000 catheter-days observed in subcutaneous venous ports to 9.0/1000 catheter-days reported for venous cutdowns.⁴ In the following sections, we will discuss the most commonly used catheters and their associated CRBSI infection risks.

Multiple-Lumen Central Venous Catheters

Zürcher et al. conducted a meta-analysis of five published reports from randomized controlled trials to test whether the number of catheter lumens influenced catheter colonization and CRBSI. The authors observed a statistically significant difference in the CRBSI rate between single and multiple-lumen catheters. The multiple-lumen catheters were associated with an 8.4% rate of CRBSI, while single-lumen catheter rates were 3.1%.⁵⁰ The report is limited because the number of infections per 1000 catheter-days is not reported. Lorente et al. conducted a prospective study of all patients admitted to a 24-bed ICU in Spain. They observed an overall CRBSI rate of 2.79/1000 catheter-days. Data were analyzed by anatomic site. Femoral, jugular, and subclavian sites were analyzed, with the CRBSI risk decreasing in that order.⁵¹ Maki et al. observed a range of CRBSI for short-term, noncuffed central venous catheters from 1.2 to 4.8/1000 catheter-days.⁴

Arterial Catheters

Arterial catheterization for hemodynamic monitoring is a common procedure in the ICU. The anatomic sites used for arterial access include the radial artery (the site most commonly used), brachial, dorsalis pedis, axillary, and femoral arteries. Lorente et al. prospectively observed 2018 ICU patients over 3 years to analyze the incidence of CRBSI according to different access sites. The overall incidence of CRBSI for arterial catheters in their study was 0.59/1000 catheter-days. They observed no infections in the brachial and dorsalis pedis sites, although these sites combined accounted for less than 10% of the total number of catheters included in the study. The incidence of CRBSI was 0.25/1000 catheter-days for the radial site and 1.92/1000 catheter-days for the femoral site. They concluded that using the femoral site increases the risk of arterial catheter-related infection.³ The incidence rates for arterial CRBSI noted by Lorente was lower than the pooled mean of 1.7/1000 catheter-days published in the meta-analysis by Maki et al.⁴ Of note, the study by Lorente was published in 2006, the same year as the review by Maki, and was not included in Maki’s report.

Long-Term Central Venous Catheters

Although seldom used in the acute critical care setting, catheters for long-term central venous access in both the inpatient and outpatient setting are frequently employed for total parenteral nutrition and chemotherapy. In cancer patients, the catheters most frequently used have been long-dwelling tunneled devices (Hickman, Broviac, Groshong).⁵² These catheters allow for long-term IV therapy without the need for frequent catheter exchanges. Darouiche et al. conducted a randomized controlled trial comparing antimicrobial-impregnated, non-tunneled, long-term central venous catheters to nonimpregnated tunneled catheters in terms of rates of catheter colonization and CRBSI. Their study included 312 catheters. They observed no significant difference in CRBSI rates between the two types of catheters.⁵³ The tunneled catheters were associated with 1.43/1000 catheter-days, whereas the impregnated catheters had a rate of 0.36/1000 catheter-days, P = 0.13.⁵³ In the meta-analysis by Maki et al. the CRBSI rate for long-term cuffed and tunneled central venous and hemodialysis catheters was 1.6/1000 catheter-days. The rate for subcutaneous ports was 0.1/1000 catheter-days.⁴

The rates of colonization per 1000 catheter-days observed in Darouiche’s study were 7.9 for antimicrobial-impregnated catheters and 6.3 for tunneled catheters. These rates were not significantly different, P=0.46.⁵³

Peripherally Inserted Central Venous Catheters

Peripherally inserted central venous catheters (PICCs) have become a standard approach to securing long-term IV access for patients in both the inpatient and outpatient settings. PICCs are regarded as durable and associated with easier insertion and removal compared to long-term central venous catheters. Despite the ease of placement and removal, PICCs are no less vulnerable to CRBSI than other forms of vascular access. Safdar and Maki prospectively studied patients from two randomized trials assessing the efficacy of chlorhexidine-impregnated sponge dressings and chlorhexidine for cutaneous antisepsis. In total, 115 patients had 251 PICCs placed for a mean duration of catheterization of 11.3 days. A CRBSI rate of 3.5/1000 catheter-days was observed in this cohort. It is important to note that the CRBSI rate was calculated from the pooled control groups of both trials.⁵⁴ A lower rate of CRBSI was observed by Walshe et al., who prospectively followed 351 patients with PICC lines over a 1-year period. A CRBSI rate of 2.46/1000 catheter-days including 19 primary and 7 secondary bloodstream infections were found in this cohort.⁵⁵

Table 128-1 from Maki et al.⁴ lists rates of intravascular device–related bloodstream infection caused by various types of devices used for vascular access.

TABLE 128-1 Rates of Intravascular Device–Related Bloodstream Infection Caused by Various Types of Devices Used for Vascular Access

Adjuncts To Prevent CRBSI

Central venous catheters should be removed as soon as possible and when no longer medically necessary. Hand hygiene, use of the subclavian vein site when possible, preparation with chlorhexidine-based solutions, and maximal sterile barrier precautions during catheter insertion are all important in reducing CRBSI risk. In addition to these recommendations, a number of other technological advances may be indicated.

Antiseptic-Impregnated and Antibiotic-Impregnated Catheters

Central venous catheters impregnated with various antiseptic and antibiotic agents are now commonly used to reduce the frequency of CRBSI. There are conflicting studies in the literature concerning whether or not such catheters are cost-effective.⁵⁶^–⁵⁹ Among the most commonly used antiseptic impregnated catheters is one in which both the inner and outer lumens are bonded with silver sulfadiazine and chlorhexidine antiseptics. Both silver sulfadiazine and chlorhexidine possess broad-spectrum antimicrobial properties, and the two agents exhibit a synergistic activity, reducing the risk of the emergence of resistant strains of bacteria.^56,⁶⁰ Reports of hypersensitivity to chlorhexidine have emerged as its use has become more commonplace.⁶¹

In the late 1990s, polyurethane CVCs impregnated with minocycline and rifampin on both the internal and external surfaces were developed.⁶² Initial concerns that widespread use of surface antibiotics for preventing CRBSI may contribute to the emergence of antibiotic-resistant organisms have not been identified.^63,⁶⁴

Recommendations

The following recommendations are based on the studies reviewed in this chapter and published CDC guidelines.^24,²⁵ These guidelines are currently in revision, and the reader is encouraged to refer to the CDC website for any updates.

Physicians in critical care units are encouraged to study their own patient populations to determine the incidence of significant catheter colonization and CRBSI and to develop appropriate guidelines for catheter exchange and site maintenance. On the basis of currently available information, peripheral arterial catheters, CVCs, and PA catheters do not require “routine” exchange either to a different site or over a guidewire. Although the risk of colonization and bacteremia increases with time, the optimal time for catheter removal is not known for peripheral arterial catheters, central venous catheters, and pulmonary artery catheters. Routine catheter exchange in critically ill patients does not alter infection risks.

Recommendations for short-term catheter placement are outlined in Table 128-2. Any catheter (peripheral or central) that is placed under less than ideal conditions should be treated as a potential source of infection. Generally, such a catheter should be removed and a new catheter inserted at a different site if catheterization is needed for longer than 48 hours. Ideal conditions for catheter insertion include:

• Use of sterile disposable surgical gowns, masks, hats, and gloves

• Careful preparation of the skin site with a chlorhexidine solution

• Wide draping of the area to create an adequate sterile field

TABLE 128-2 Recommendations for Short-Term Catheter Placement