-
CLABSI, which is associated with the use of
CVCs, is a type of catheter-related bloodstream infection defined as the
presence of bacteremia originating from an IV catheter. CLABSI -- the
most common cause of nosocomial bacteremia -- is frequent, lethal, and
costly. Although the use of CVCs is increasing, there is evidence that
the incidence and rate of CLABSIs can be reduced. Central lines are
required for adequate volume replacement in patients who are severely
dehydrated or intravascularly volume depleted for any reason. Although
necessary in such situations, use of central lines puts patients at risk
for a number of complications, including CLABSIs.
Defining CLABSI
A CLABSI is defined by the US Centers for Disease Control and Prevention (CDC) National Nosocomial Infections Surveillance System (NNIS) and the National Healthcare Safety Network (NHSN) as a primary bloodstream infection in a patient who had a central line within the 48-hour period before the development of the bloodstream infection.[1,2] According to the NNIS, diagnosis of CLABSI requires that at least 1 of the criteria in the box below be met.
Criterion 1: Patient has a recognized pathogen cultured from 1 or more blood cultures, and the organism cultured from the blood is not related to infection at another site.
Criterion 2: Patient has at least 1 of the following signs or symptoms:
Fever (temperature, > 38°C)
Chills
Hypotension
and signs and symptoms and positive blood culture results are not related to infection at another site
and common skin contaminant (eg, diphtheroids, Bacillus species, Propionibacterium species, coagulase-negative staphylococci, or micrococci) cultured from 2 or more blood samples drawn on separate occasions (Figure 1).
Criterion 3: Patient < 1 year of age has at least 1 of the following signs or symptoms: fever (> 38°C core), hypothermia (< 36°C core), apnea, or bradycardia
and signs and symptoms and positive laboratory results are not related to an infection at another site
and common skin contaminant (ie, diphtheroids [Corynebacterium species], Bacillus [not Bacillus anthracis] species, Propionibacterium species, coagulase-negative staphylococci [including Staphylococcus epidermidis], viridans group streptococci, Aerococcus species, Micrococcus species) is cultured from 2 or more blood cultures drawn on separate occasions.
Figure 1. Normal flora colonies from skin.
- Central lines are intravascular infusion devices that terminate at or close to the heart or in 1 of the great vessels. Pacemaker wires are not considered central lines because they are not used to infuse or withdraw fluids.
Table 1. Types of Intravenous Devices Used for Infusion of Fluids and/or Hemodynamic Monitoring
| Type of Catheter | Length | Description |
| Peripheral | ||
| Peripheral venous catheter | < 7.6 cm | Usually inserted into a forearm or hand vein; most commonly used short-term intravascular device; rarely associated with bloodstream infection |
| Midline catheter | 7.6-20.3 cm | Peripheral catheter is inserted via the antecubital fossa into the proximal basilic or cephalic veins; does not enter central veins; associated with lower rates of phlebitis and infection than CVCs |
| Central | ||
| Nontunneled CVC | ≥ 8 cm | Inserted percutaneously into central veins (subclavian, jugular, femoral); most commonly used CVC; accounts for about 90% of all catheter-related bloodstream infections |
| Percutaneously inserted central catheter (PICC) | ≥ 20 cm | Inserted via basilic, cephalic, or brachial veins into the superior vena cava; easier to maintain and associated with fewer mechanical complications (eg, hemothorax) than nontunneled CVCs |
| Tunneled CVC | ≥ 8 cm | Surgically implanted into subclavian, internal jugular, or femoral veins; the tunneled portion exits the skin; a Dacron cuff just inside the exit site inhibits migration of organisms into the catheter tract by stimulating growth of surrounding tissue, thus sealing the catheter tract |
| Totally implantable device | ≥ 8 cm | Subcutaneous port or reservoir with self-sealing septum that is tunneled beneath the skin; implanted in subclavian or internal jugular vein; accessed by a needle through intact skin; low rates of infection |
Data from Mermel LA, et al. Clin Infect Dis. 2001;32:1249-1272.
Pathogenesis of CLABSI
CVCs become colonized with microbes from the skin surrounding the insertion site or from the catheter hub.[3] The pathogenesis of a CLABSI depends on the type of catheter. A CLABSI related to a catheter of short-term use is usually secondary to extraluminal colonization. Long-term use of tunneled catheters usually causes infection via intraluminal colonization, most commonly from contamination of the catheter hub.Certain catheter materials are thrombogenic, which may also predispose to catheter colonization and CLABSI.[4] Other factors that may contribute to microbial colonization are depicted in Figure 2.[3] The adherence properties of a microorganism may also play a role in the pathogenesis of a CLABSI. For example, Candida species may produce adherence factors in the presence of glucose-containing IV fluids, which may explain why patients receiving parenteral nutrition have an increased incidence of fungal bloodstream infections. Therefore, prevention strategies should target ways to minimize colonization of the catheter.
Figure 2. Pathogenesis of vascular access-related infections. Potential sources of infection include the contiguous skin flora, contaminated catheter hub and lumen, contaminated infusate, and hematogenous colonization of the device from distant, unrelated sites of infection.
HCW = healthcare worker
From Crnich CJ, et al. Clin Infect Dis. 2002;34:1232-1242.
Epidemiology
Bloodstream infections are a common nosocomial infection and are responsible for 30%-40% of all nosocomial infections in the ICU.[5] A national surveillance study reported the incidence of nosocomial bloodstream infection as 60 cases/10,000 hospital admissions; approximately 50% of the cases occurred in the ICU.[1] Central lines are the most frequent cause of catheter-related infections.[4]It is important to note that the CLABSI rate (not incidence) is calculated by dividing the number of CLABSIs by the number of central line-days and multiplying the result by 1000. For example, if an ICU had 5 central line infections and 100 central line-days, the CLABSI rate would be calculated as follows: 5/100 x 1000 = 50 central line infections/1000 central line-days. In the United States, the CLABSI rate is 80,000 central line-days per year.[6,7]
CLABSIs are associated with significant morbidity and mortality, and excessive hospital costs. The associated mortality rate and excess hospital length of stay are 0%-15% and 9-12 days, respectively.[5,8] Until recently, the association between CLABSI and mortality in critically ill patients was unclear, but a meta-analysis by Siempos and colleagues that evaluated the mortality of ICU patients with and without catheter-related bloodstream infections found that catheter-related bloodstream infection was associated with higher all-cause mortality (odds ratio, 1.81).[9]
Microbiology
The pathogens most commonly associated with nosocomial bloodstream infections are listed in Table 2.[10] Since the 1980s, gram-positive organisms have been the predominant organisms associated with nosocomial bloodstream infections, but gram-negative and Candida species are also problematic. Yeasts colonizing the endolumen of a CVC are shown in Figure 3.Table 2. Pathogens Associated With Nosocomial Intravascular Catheter-Related Bloodstream Infections
| Class of Pathogen | Specific Pathogens |
| Gram-positive organisms | Coagulase-negative staphylococci Staphylococcus aureus Enterococci |
| Gram-negative organisms | Pseudomonas species Enterobacter species Serratia species Klebsiella species Escherichia coli Acinetobacter baumannii |
| Fungal organisms | Candida species C albicans, C glabrata |
Figure 3. Electron micrograph of yeasts colonizing the endolumen of a central venous catheter.
Image courtesy of Dr. P. Kite, Department of Medical Microbiology, Leeds Teaching Hospitals).
Using surveillance data from the CDC, Burton and colleagues examined trends in the rate of methicillin-resistant Staphylococcus aureus (MRSA)-related CLABSIs in ICUs in the United States from 1997 to 2007. They found that the overall incidence of MRSA-related and methicillin-sensitive S aureus-related CLABSIs decreased during this period in adult ICUs.[11] Specifically, a 50% decline in MRSA-related CLABSIs since 2001 was observed among the ICUs that reported data to the CDC, suggesting that efforts at prevention are succeeding.
Additional host factors that increase susceptibility include age, comorbid conditions, severity of underlying illness, loss of skin integrity, and immune deficiency states. Of note, female sex is associated with a reduced risk for CLABSI.
Patient Profile, Continued
Upon transfer to the ICU, MW was resuscitated with IV fluids and vasopressors, and she was started on empirical antibiotic therapy. While performing an initial assessment, MW's nurse notices that the femoral CVC dressing is loose and there is erythema around the insertion site. CLABSI is the suspected source of sepsis. The femoral CVC is removed, and a new CVC is inserted into her right subclavian vein for hemodynamic monitoring and administration of IV fluids, vasopressors, and antibiotics. A transparent dressing is applied.Prevention of CLABSI
The Society for Healthcare Epidemiology of America (SHEA) and the Infectious Diseases Society of America (IDSA) jointly published a guideline, Strategies to Prevent Central Line-Associated Bloodstream Infections in Acute Care Hospitals, which highlights practical recommendations for implementing and prioritizing CLABSI prevention efforts before, during, and after central line insertion in acute care hospitals.[6] Although the compendium is an evidence-based guideline, the evidence base for many interventions comes from nonrandomized clinical trials, case-control studies, and expert opinion, and the quality of evidence varies.CVC Insertion: Before, During, and After
Prevention of CLABSI is a multidisciplinary approach that begins with education of clinicians involved in insertion, care, and maintenance of vascular catheters. Education should include the standard of care (clinical practice guidelines), including infection prevention and control measures, selection of the type of catheter and insertion site, use of ultrasound guidance for catheter insertion,[12] tools to facilitate the standard of care, and the potential consequences of breaching the standard of care. Zingg and colleagues conducted a prospective interventional cohort study of clinicians working in medical and surgical ICUs.[13] The intervention was an educational program on hand hygiene, standards of catheter care, and preparation of IV drugs. The study showed that a multimodal educational program focused on evidence-based catheter care techniques can effectively reduce the rate of CLABSIs.The standard of care for CVC insertion and maintenance can be summarized as follows:
- Explanation of procedure to patient and informed consent;
- Selection of insertion site;
- Selection of catheter type;
- Central line catheter cart;
- Hand hygiene;
- Barrier precautions;
- Skin antisepsis;
- Sterile dressing application;
- Care of administrations system; and
- Catheter removal.
Potential sources of infection during and after catheter insertion include the contiguous skin flora, contaminated catheter hub and lumen, contaminated stopcocks, contaminated infusate, and hematogenous colonization of the device from distant, unrelated sites of infection (Figure 2). Catheter hub manipulation increases the likelihood of catheter contamination and as a result increases the risk for CLABSI.[14] Frequent access allows contamination via the skin or the skin flora of clinicians.
Figure 2. Pathogenesis of vascular access-related infections. Potential sources of infection include the contiguous skin flora, contaminated catheter hub and lumen, contaminated infusate, and hematogenous colonization of the device from distant, unrelated sites of infection.
HCW = healthcare worker
From Crnich CJ, et al. Clin Infect Dis. 2002;34:1232-1242.
Catheter hubs, needleless connectors, and injection ports of stopcocks should be disinfected with an alcoholic chlorhexidine preparation or 70% alcohol before accessing the catheter or tubing.[6] Antimicrobial catheter lock solutions may also help decrease CLABSI.[15] The lumen of a catheter hub is filled with an antimicrobial solution that is left in place until the catheter is reaccessed. There is concern about the emergence of resistance in exposed organisms; therefore, these locks should only be used for prophylaxis in patients with limited venous access and a history of CLABSI, or patients who are at high risk for severe complications from a CLABSI (ie, patients with recently implanted intravascular devices).[6] Administration sets that are not used for infusing blood, blood products, or lipids should be changed at more frequent intervals (eg, every 96 hours). Administration sets that are used for infusing blood, blood products, or lipids should be changed at regular intervals (eg, every 24 hours).
Catheters coated with chlorhexidine/silver sulfadiazine have been shown to reduce the risk for CLABSI compared with noncoated catheters,[4] and are recommended if it is anticipated that the catheter will remain in place more than 5 days.[16] Minocycline/rifampin-coated catheters have been shown to reduce the risk for CLABSI,[15,17] and have been shown to be superior to first-generation chlorhexidine/silver sulfadiazine-impregnated catheters for preventing CLABSI after 6 days of use.[18]
The safety of changing semitransparent dressings every 7 days vs the standard practice of every 3 days was recently reaffirmed in a multicenter, randomized controlled trial comparing the application of a chlorhexidine gluconate-impregnated sponge with standard dressings at the catheter-skin insertion site of patients with central lines or arterial catheters.[20] This study also compared a strategy of changing unsoiled adherent dressings every 7 days vs the standard practice of every 3 days. The safety of changing dressings every 7 days was demonstrated in both the control and intervention (chlorhexidine gluconate-impregnated sponge) groups. However, the use of chlorhexidine gluconate-impregnated sponges is more expensive.[15] The SHEA/IDSA guidelines recommended considering sponge dressings for CVCs in units with high CLABSI rates and in certain high-risk patients.[6]
There is no evidence that the following reduce the CLABSI rate:
- Routine, scheduled replacement of CVCs;
- Routine, scheduled guidewire replacement[21-23];
- Culturing of CVC catheter tip; and
- Application of antibiotic ointment to the catheter insertion site.
Documentation and Surveillance
Recording the details of the CVC insertion in a standardized way is important for documenting and monitoring adherence to the standard of care. Information that should be routinely documented in the medical record includes:- Informed consent;
- Indication for CVC;
- Name of person who inserted the CVC;
- Insertion site;
- Date and time of insertion;
- Insertion technique (ie, sterile skin preparation, use of local anesthetic);
- Amount and character of fluid withdrawn during insertion;
- Estimated blood loss;
- Complications;
- Laboratory and other diagnostic tests ordered; and
- Type of dressing applied over catheter insertion site.
Bringing It All Together: The Central Line Bundle
A strategy for reducing the risk for CLABSI is the use of predetermined bundles of interventions that focus on a few specific, high-yield measures to simplify and focus measures for prevention of infection. The central line bundle consists of a group of evidence-based interventions for patients with central lines that, when implemented together, have been shown to result in better outcomes than when implemented individually.[24] The bundle includes measures that prevent extraluminal and intraluminal contamination, migration, adhesion, and colonization. The 5 components of the central line bundle are described in Table 4.
Table 4. Implementing the Central Line Bundle
| Components of Bundle | Rationale |
|---|---|
| Hand hygiene | Proper hand hygiene reduces the
likelihood of central line infections. Washing hands or using an
alcohol-based waterless hand cleaner can help to prevent contamination
of central line sites and bloodstream infections.[4]
Clinicians who insert or manipulate vascular catheters should perform hand hygiene with an alcohol-based hand rub or antiseptic soap and water, regardless of whether examination or surgical gloves are worn. |
| Maximal barrier precautions | Maximal barrier precautions clearly reduce the odds of developing catheter-related bloodstream infections.[25,26] This approach has been shown not only to decrease the rate of CLABSIs,[25] but also to reduce cost.[26]
For the operator placing the central line and for those assisting in the procedure, maximal barrier precautions mean strict compliance with handwashing and wearing a cap, mask, sterile gown, and gloves. The cap should cover all hair and the mask should cover the nose and mouth tightly. These precautions are the same as for any other surgical procedure that carries a risk for infection. For the patient, maximal barrier precautions means covering the patient from head to toe with a sterile drape with a small opening for the site of insertion. |
| Chlorhexidine skin antisepsis | Chlorhexidine skin antisepsis has been proven to provide better skin antisepsis than other antiseptic agents, such as povidone-iodine solutions.[24] Chlorhexidine-based antiseptic skin preparation should be used for patients older than 2 months of age, and should be allowed to air-dry for approximately 2 minutes before beginning insertion of the catheter.[24] |
| Optimal catheter insertion site selection, with avoidance of the femoral vein for central venous access in adults | The catheter insertion site
influences the risk for an infectious complication, partly due to the
risk for phlebitis and the density of local skin flora. Lower-extremity
insertion sites are associated with a higher risk for infection. A
higher risk for infection is associated with internal jugular vs
subclavian catheter insertion.[27-29]
Whenever possible, the femoral site should be avoided and the subclavian site should be preferred over the jugular and femoral sites for nontunneled catheters in adult patients. This recommendation is based solely on the likelihood of reducing infectious complications.[24] Subclavian placement may have other associated risks. The Central Line Bundle requirement for optimal site selection suggests that other factors (eg, the potential for mechanical complications, the risk for subclavian vein stenosis, and catheter-operator skill) should be considered when deciding where to place the catheter. In these instances, teams are considered compliant with the bundle element as long as they use a rationale construct to choose the site. The core aspect of site selection is the risk-benefit analysis by a physician as to whether the subclavian vein is most appropriate for the patient. There will be occasions when the physician determines that the risks of using the subclavian vein outweigh the benefits, and a different vessel is selected. For the purposes of bundle compliance, if there is dialogue between the clinical team members as to the selection site and rationale, and there is documentation as to the reasons for selecting a specific different vessel, this aspect of the bundle should be considered as in compliance.[24] |
| Daily review of the necessity for all central lines and prompt removal of unnecessary lines | Daily review of the necessity of central lines will prevent unnecessary delays in removing lines that are no longer clearly necessary in the care of the patient. Many times, central lines remain in place simply because of their reliable access and because personnel have not considered removing them. The risk for infection increases over time as the line remains in place, and that risk is decreased if the line is removed. |
The use of a central line bundle was tested in a large statewide collaborative initiative.[2] The Michigan "Keystone Project" assessed a CLABSI prevention bundle similar to the one described above. To this bundle, the Keystone project team added a catheter insertion checklist to ensure that healthcare workers were observing the essential prevention measures and a catheter insertion cart to ensure that necessary supplies were always available for each insertion.[2] The Keystone project also empowered ICU nurses to halt insertion efforts when the checklist was not fully implemented or when asepsis was violated. The use of this checklist and nurse-overseen prevention bundle was implemented in 108 ICUs in Michigan. The results were dramatic. CLABSI rates were reduced by up to 66% and sustained over the 18-month study period. The proven success of the central line bundle, such as the one used in the Keystone project, demonstrates that focusing on a few high-yield prevention measures can markedly reduce CLABSI rates. Whether similar results can be achieved with the use of bundles with fewer components (ie, simply daily cleansing of ICU patients with chlorhexidine) remains to be tested.
Best Practice
Routine surveillance should be done to monitor for CLABSIs. CLABSI rates should be measured at baseline and monitored over time to evaluate unit-specific performance improvement efforts and to benchmark against national CLABSI rates (Figure 4).
Figure 4. Catheter-related bloodstream infection rates in a surgical ICU compared with National Nosocomial Infections Surveillance System rates.
From Earsing KA, et al. Nurs Manage. 2005;36:18-24.
Patient Profile, Continued
MW was weaned off of vasopressor support within 24 hours. Blood cultures grew MRSA and IV vancomycin was initiated. A transesophageal echocardiogram ruled out endocarditis. Once she was hemodynamically stable and clinically improved, a peripheral IV catheter was inserted and the CVC was removed.Summary
CLABSIs are associated with the use of CVCs, and are defined as the presence of bacteremia originating from an IV catheter in a patient who had a central line within the 48-hour period before the development of the bloodstream infection. Worldwide, CLABSIs are the most common cause of nosocomial bacteremia and are frequent, lethal, and costly. CLABSIs are common in all hospital settings, but CLABSI rates are higher in non-ICU settings, such as hematology/oncology wards, bone marrow and solid organ transplant units, inpatient dialysis units, and long-term acute care areas.Risk factors for CLABSIs include emergent CVC insertion, repeated CVC access, the site of CVC insertion, prolonged use of CVCs, and the physical properties of the CVC as well as host factors, such as age, sex, comorbidities, severity of illness, loss of skin integrity, and immune deficiency.
CLABSIs are a largely preventable complication of medical care. Prevention of CLABSI requires a multidisciplinary approach, including education of clinicians on the consequences of CLABSIs, and clinical practice guideline recommendations and best practices, such as the central line bundle for prevention. Continuous quality monitoring is critical to reducing variance in standards of care and improving outcomes.
References
Additional Reading found at-http://en.wikipedia.org/wiki/Nosocomial_infection
Source -Borrowed from MedScape-http://www.medscape.org/viewarticle/708524
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