-
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.
Several types of intravascular devices are commonly used (Table 1). A
central line is an intravascular device that terminates close to the
heart or near a great vessel that is used for infusion, withdrawal of
blood, or hemodynamic monitoring. The aorta, pulmonary artery, superior
vena cava, inferior vena cava, brachiocephalic veins, internal jugular
veins, subclavian veins, external iliac veins, and common femoral veins
are considered 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 |
CVCs = central venous catheters
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.
The reader is also referred to a Video in Clinical Medicine in
The
New England Journal of Medicine illustrating placement of a central venous line.
[12]
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.
-
In fact, scheduled routine exchanges of
catheters over a guidewire are associated with a trend toward an
increasing rate of catheter-related infections,
[21]
and the application of antibiotic ointment to catheter insertion sites
increases the rate of catheter colonization by fungi and promotes the
emergence of antibiotic-resistant bacteria.
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
