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The intravenous catheter has become an indispensable tool for providing treatment in the intensive care unit (ICU). In the United States, 15 million central venous catheters days occur in ICUs each year.1 Critical care professionals must be knowledgeable and proactive to prevent patients from developing catheter-related bloodstream infections (CRBSI).
The density of skin flora at the insertion site is a major risk for (CRBSI).2 Catheters can become colonized by organisms from the skin, the hub and lumen, the bloodstream, and, less frequently, from the infusates. Bacterial adhesion to the catheter is dependent on the surface characteristics of the catheter, bacterial-biomaterial surface interactions, and protein adhesion on the surface biomaterial. Host proteins such as fibronectin, fibrinogen, fibrin and collagen can promote adhesion. Persistence of the bacterial adherence to the catheter surface and biofilm for¬mation is critical in the development of CRBSI.3
CRBSI rates range from 5.0 per 1,000 central-line days in medical/surgical ICUs to 8.5 per 1,000 central-line days in burn units.4 A calculation based on Centers for Disease Control and Prevention (CDC) and National Nosocomial Infections Surveillance System (NNIS) data using 5.3 central-line infections per 1,000 catheter days in the ICU estimates that 80,000 central-line infections occur each year in ICUs in the United States.5 Catheter-related infection is one of the most common healthcare-associated infections. It is a true patient safety issue, leading to increased morbidity, mortality and healthcare costs. In ICUs within the United States, anywhere from 2,400 to 20,000 patients die annually from CRBSIs. The estimated annual cost of caring for patients with CRBSIs ranges from $296 million to $2.3 billion.5
It’s All in the Definition
The lack of a clear, unified definition for CRBSI has led to difficulties comparing trial results.6 A distinction is made between a surveillance definition, which includes all bloodstream infections (BSI) in patients with a central-venous catheter when other sites of infection have been ruled out, and a clinical definition, which includes only BSIs where, after examination of the patient record, other sources were excluded and cultures of the catheter tip and bloodstream demonstrated substantial colonies of an identical organism.7 Often, making a definitive diagnosis of CRBSI is not possible until culture results are available. CRBSI is suspected more often than it is actually confirmed. In the absence of other explana¬tions, it is often presumed.8
Definite catheter-related sepsis is defined as at least one peripheral positive blood culture and either (1) a positive semiquantitative (> 15 colony-forming units [cfu]/catheter segment) or quantitative (> 103 cfu/catheter segment) catheter tip culture with the same microorganism and antibiogram isolated from the catheter segment and peripheral blood, (2) a positive hub or site culture growing the same microorganism as the peripheral blood, or (3) positive paired central and peripheral blood cultures growing the same organism where the central blood culture is positive less than two hours earlier than the peripheral blood culture or has five more times the growth of the peripheral blood culture.9 In a study of differential time to positivity, catheter-related bacteremia could be diagnosed in patients who had a positive culture result from catheter blood at least two hours earlier than the positive peripheral blood culture.10
Does the Insertion Site Matter? Insertion in a femoral site is related to a higher risk of CRBSI in adults.11-13 In comparison with subclavian access, jugular venous access was associated with higher infection rate.14 In CDC guidelines, the subclavian site is recommended over femoral or jugular accesses for central venous access.7
What About Antimicrobial-impregnated Catheters? The literature contains much discussion regarding the body of evidence comparing antimicrobial-impregnated central venous catheters to standard catheters.15-19 CDC guidelines comment that the decision to use an antimicrobial-impregnated catheter should be based on the need to enhance prevention of CRBSI after standard procedures have been implemented.7
How Can We Make It Safer? Given the risk of infection with a central venous line, a higher level of barrier precautions is necessary with insertion. Recommendations have been made for full-barrier precautions using a large sterile drape, cap, mask and sterile gown and gloves.7 These do not obviate proper hand hygiene. Skin preparation with 2% aqueous chlorhexidine gluconate has been shown to result in lower infection rates compared to 10% povidine-iodine or 70% alcohol.20,21
Is it Possible to Reduce Central-line Infections? Evidence-based interventions exist that individually have been shown to decrease CRBSI rates. However, there is difficulty in translating that research into true patient benefits. An education-based intervention directed toward ICU nurses and physicians highlighting correct practices for preventing CRBSI resulted in a reduction of CRBSI rates in medical and surgical ICUs.22-23
The Pittsburgh Regional Health Care Initiative, in collaboration with the CDC, successfully reduced CRBSI rates in ICU patients by 68% over a four-year period.24 They implemented evidence-based catheter insertion practices, including maximum barrier precautions, chlorhexidine skin disinfection, avoidance of femoral insertion site, and specific dressing practices. An education module reviewed prevention strategies. Standardized tools recorded insertion practices and a kit included supplies required to adhere to standardized insertion practices. CRBSI rates were measured and feedback was provided. The approaches for change were not new, and the results demonstrated that it is possible to reduce CRBSI rates when evidence-based preventive practices are followed.24
By implementing five interventions, physicians and nurses from Johns Hopkins University saw a substantial decrease in CRBSI and significant savings in lives and costs.25 An educational intervention was used to increase awareness of evidence-based infection control practices. A line insertion cart centralized equipment needed to comply with evidence-based guidelines. The continued need for a catheter was assessed daily and incorporated into the daily goals form, which outlined the care plan for each patient. A checklist of evidence-based strategies was completed at the bedside during the insertion procedure by the nurse, who was empowered to stop the procedure if the guidelines were not met. These successes can be translated to other ICUs. A collaborative project among Michigan ICUs, the Michigan Health and Hospital Association, and Johns Hopkins University Quality and Safety Research Group demonstrated similarly significant results in reducing CRBSI rates. One hundred twenty ICUs from 70 hospitals demonstrated significant decreases in infection rates and healthcare dollars as well as a significant number of saved lives.26
These improvements indicate that catheter-related bloodstream infections are a preventable cause of morbidity and mortality. With continued education on best practices, infection rates can be decreased. Facilitating best practices with checklists, an equipment cart, maximum barrier precautions, careful insertion site selection, and attention to infection control by the entire care team can create a safer environment, save lives, reduce healthcare costs and lead to better outcomes.
Watch the iCritical Care Podcasts for an audio companion to this article. Visit www.sccm.org/podcast for more information.
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