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Introduction
The progress of modern medicine has been advanced, in part, by
the wide use of invasive medical devices, including IV catheters.
However, IV catheters are often associated with serious infectious
complications, such as catheter-related bloodstream infection (CRBSI).[1] In
fact, CRBSI is considered to be the most common type of nosocomial
bloodstream infection, a finding that has been attributed to the
wide use of intravascular catheters in hospitalized patients.[2,3]
It is estimated that 7 million central venous catheters (CVCs)
will be inserted annually in the
United States
. Even with the best available aseptic techniques being used during
insertion and maintenance of the catheter, 1 of every 20 CVCs inserted
will be associated with at least 1 episode of bloodstream infection. [4]
Therefore, it is estimated that more than 300,000 episodes of
CVC-related bloodstream infections will occur annually in the United
States over the next few years.[5] Pittet and colleagues[6] recently
estimated the attributable mortality rate of such infections in
critically ill patients to be 25%. Each episode of CRBSI will cost
$30,000-56,000 per survivor and result in an additional average
stay of 6.5 days in the ICU.
The high morbidity, mortality, and cost
attributed to CRBSI are the driving forces underlying the search
for new preventive approaches to reduce BSI’s.
Catheter-related
bloodstream infections (CRBSI) resulting from bacterial colonization
of an central venous catheter are a significant clinical problem,
magnified in recent years by the increasing use of central
venous catheters in intensive care, chemotherapy and total
parental nutrition (TPN). In particular, central venous catheter-related
infections are a common cause of bacteraemia and sepsis.
There
are three routes by which infection can occur:
- Intraluminal : situated
within, occurring within, or introduced from internal lumen (catheter)
- Extraluminal:
situated outside, occurring from outside,
tracked down outside of catheter
- Hematogenous: occurring from blood
Diagnosis of CRBSI
Clinical
The symptoms and signs of catheter-related infection
may be localized to the insertion site or track of a tunneled
device. Alternatively, manifestations may be systemic and possibly
complicated by bacterium.
Local
infection |
Systemic
infection |
- Local inflammation
- Discharge around the line
- Erythematic
- Pain
|
- Fever
- Rigors when the line is used
- Tachycardia
- Metastatic infection
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Pathogenesis
Several factors pertaining to the pathogenesis of CRBSI have been
identified during the last decade. These are:
Skin and Hub
The skin and the hub are the most common sources of colonization
of percutaneous vascular catheters (Figure). For short-term, nontunneled,
noncuffed catheters, the organisms migrate from the skin insertion
site along the intercutaneous segment, eventually reaching the
intravascular segment or the tip. [7, 8]
For long-term catheters (particularly those that are cuffed or
surgically implanted), the hub is a major source of colonization
of the catheter lumen, which ultimately leads to bloodstream infections
through luminal colonization of the intravascular segment. [9-11]
The skin and the hub are the most common sites for bacterial migration
resulting in infection.
Catheter Surface
Organisms that adhere to the catheter surface
maintain themselves by producing an "extracellular slime," a
substance rich in exopolysaccharides, often referred to as fibrous
glycocalyx or microbial biofilm.[12,13] The organisms embed themselves
in the biofilm layer, becoming more resistant to the antimicrobial
activity of glycopeptide antibiotics.[14,15]
Thrombin Sheath
Following insertion, a thrombin sheath rich in host proteins covers
the internal and external surface of the intravascular segment
of the catheter. The proteins in the thrombin sheath -- such as
fibrin, fibrinogen, fibronectin, laminin, thrombospondin, and collagen
-- act as adhesins. Organisms, such as coagulase-negative staphylococci,
bind to fibronectin. Staphylococcus aureus binds strongly
to both fibronectin and fibrinogen,[16,17] while Candida
albicans binds well to fibrin.[18] This process,
observed at the molecular level, is translated into a correlation
at the clinical level between thrombogenesis and infection.[19] As
such, reduction in thrombus formation in the catheter will reduce
the formation of a thrombin sheath and reduce the formation of
biofilm.
Colonization of CVCs
The colonization of CVCs is almost universal. Electron microscopy
studies show that all catheters eventually become colonized after
insertion.[7] However, the risk of infection is directly
proportional to the quantitative level of organisms multiplying
on the surface of the intravascular segment of the catheter. Therefore,
factors that would potentiate the multiplication and spread of
organisms from the biofilm environment would increase the risk
of bloodstream infections.
Skin Organisms
The skin is the major source of catheter colonization and infection,
followed by the hub; the latter is often contaminated by the hands
of medical personnel. Such skin organisms as coagulase-negative
staphylococci and S aureus are the leading pathogens that
cause vascular catheter-related infections.[1,20]C
albicans and Candida parapsilosis have been shown to
colonize the hands of medical personnel.[21]
In addition, C parapsilosis has been associated with total
parenteral nutrition and glucose-containing infusions.[22] Both C
albicans and C parapsilosis are emerging as important
pathogens that cause catheter-related infections.[1,2] It
should be noted that coagulase-negative staphylococci and C
parapsilosis produce extracellular slime.[12,13,15]
Approaches to Prevention
Since skin flora, such as staphylococci,
are the predominant organisms that cause CRBSI, antimicrobial agents
that are highly active against such organisms should be employed.
Antimicrobial agents used in the prevention of CRBSI should have
broad-spectrum activity against gram-positive organisms, gram-negative
organisms, and Candida species.
The
complexity of catheter colonization and the infection process are
caused by the formation of biofilm. Microorganisms bind to the
surface of host proteins, such as fibrin and fibronectin, to produce
biofilm; together they act as binding factors. Therefore, practices should be in place that reduce the formation and contamination of biofilm, such as effective flushing and swabbing techniques.
The following sections describe approaches
for preventing CRBSI.
Prevention of CRBSI
Several factors affect the risk of CRBSI including:
- Site of insertion
- Type of devices and Hygiene and Aseptic Technique
- Insertion and Maintenance Technique
- Duration of Placement
Site of Catheter Insertion
The site at which the catheter is placed influences the subsequent
risk for catheter related infection and phlebitis. This is directly
related to the density of local skin flora. Catheters inserted
into an internal jugular vein have been associated with higher
risk for infection than those inserted into the subclavian or femoral
vein.
Type of Device
| Type of intravascular device |
Comments |
| Peripheral venous catheter |
Usually inserted into the veins of the forearm
or the hand; most commonly used short-term intravascular device;
rarely associated with bloodstream infection |
| Peripheral arterial catheter |
For short-term use; commonly used to monitor
hemodynamic status and to determine blood gas levels of critically
ill patients; risk of bloodstream infection may approach that
of CVCs |
| Midline catheter Peripheral catheter |
(size, 7.6–20.3 cm) is inserted via the
antecubital fossa into the proximalbasilic or cephalic veins,
but it does not enter central veins; is associated with lower
rates of phlebitis and infection than are CVCs |
| Nontunneled CVC |
Most commonly used CVC; accounts for an estimated
90% of all catheter-related bloodstream infections; increased
risk of infection with internal jugular vein site ofinsertion |
| Pulmonary artery catheter |
Inserted through a Teflon introducer and typically
remains in place for an average duration of only 3 days; most
catheters are heparin bonded to reduce catheter thrombosis
and microbial adherence to the catheter |
| Pressure-monitoring system |
Used in conjunction with arterial catheter; associated
with both epidemic and endemic nosocomial bloodstream infections;
source is often the fluid column in the tubing between the
patient’s intravascular catheter and the pressure-monitoring
apparatus, contaminated infusate,or nondisposable transducers |
| Peripherally inserted centra lCatheter |
Provides an alternative to subclavian or jugular
vein catheterization; is inserted via the peripheral vein into
the superior vena cava, usually by way of cephalic and basilar
veins; is easier to maintain and is associated with fewer mechanical
complications (e.g., hemothorax) than are nontunneled CVCs |
| Tunneled CVC |
Surgically implanted CVC (e.g., Hickman, Broviac,
Groshong, or Quinton catheter) with the tunneled portion exiting
the skin and a Dacron cuff just inside the exit site; the cuff
inhibits migration of organisms into the catheter tract by
stimulating growth of surrounding tissue, thus the sealing
catheter tract; used to provide vascular access to patients
who require prolonged iv chemotherapy, home-infusion therapy,
or hemodialysis |
| Totally implantable device |
A subcutaneous port or reservoir with self-sealing
septum is tunneled beneath the skin and is accessed by a needle
through intact skin; low rates of infection |
| |
NOTE. CVC, central venous catheter. |
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Table 3. Types of
intravascular devices and comments on their use.
The type of catheter placed directly
affects the patients risk of catheter related bloodstream infections. Central
Venous Catheters are most commonly associated with increased risk
of infection.
Other devices that are available to assist in the prevention
of Catheter Related Bloodstream Infections include:
Sutureless devices
Catheter Securement devices
Aseptic Hubs
Luer Activated Access ports that can be conpletely disinfected or that feature novel caps to automatically disinfect
the hub.
Antimicrobial Catheters
Cook and Arrow feature Central Venous
Catheters with Antimicrobial properties.
Hand Hygiene and Aspetic Technique
Surveys have revealed that near 30% of nurses do not follow appropriate
hand hygiene regimen prior to catheter placement or maintenance.
The
primary sources of most pathogens causing endemic catheter associated
bloodstream infection are the catheter insertion site or the catheter
hub. Contamination may result from the patient’s
own flora or from the healthcare worker’s hands during insertion,
manipulation, or both. Following proper hand hygiene
and aseptic technique is a key to prevention.
Insertion and Maintenance Technique
Catheters which are inserted
and managed by specialized nursing teams assist in the prevention
of catheter related infections. These teams follow the “Central-Line Bundle”,
where each team member is trained on the proper insertion and care
of the catheter, all components for maximal barrier sterile insertion
are provided in one kit or cart for easy access, and a check list
is provided and followed. By assuring that all prevention strategies
are utilized appropriately during placement and care, the risk
of infection has been shown to decrease.
Main factors for success
with insertion and maintenance include:
Use of Chlorhexidine for disinfection
of site before insertion and in follow up care
PICC Teams or IV Teams
Re-Education on the importance of Hand Hygiene
and “Scrub
the Hub” campaigns|
Catheter Site Dressing Regimens, Catheter
Securement
Maximal Barrier Precaution Line Insertion Kits or Line
Insertion Carts
These factors are so important that the Association
for Vascular Access (AVA) has initiated a program called SAVE THAT
LINE!
Scrupulous hand hygiene before and after
contact with all vascular access devices and prior to insertion.
Aspetic technique during catheter insertion
and care
Vigorous friction to hubs. Vigorous friction
with alcohol wherever you make or break a connection to give medications,
flush, change tubing or access injection port or add on device.
Ensure Patency- flush all lumens with adequate
amount of saline or heparinized saline to maintain patency per
institution policy.
Why are access ports so important?
Luer activated needleless access ports provide access
to the intravascular system with a standard male luer from a syringe
or IV tubing set. These ports act as entry points for potential
bacteria ingress if they are not disinfected properly or if by
design they can not be disinfected properly.
Air, Skin, Blood, and
other bodily discharge can settle on injection ports. Airborne
contaminants from a cough, sneeze, saliva, etc can settle on injection
ports. Bodily discharge from the patient can contaminate clothing,
bedding, dressings, and the floor. Intravenous tubing that is allowed
to drape on the floor or next to the patient may inadvertently
be contaminated where fecal mass or urine could contaminate the
injection port or tubing exterior. The healthcare workers hands
may become contaminated while bathing or cleaning the patient or
during manipulation of dressing or devices. Subsequent manipulation
of the intravenous tubing and access port without prior hand washing
can lead to infection (20). The access port is the access site to the
intravascular system. Anything that comes in contact with the port
can subsequently be delivered directly into the intravascular system
of the patient. The ability to disinfect the access port is of
utmost importance.
Recently, press and presentations have concluded
that some luer activated needleless access ports have been shown
to increase the risk of catheter related bloodstream infections.
Dr. Jarvis, previously a specialist for the CDC on the topic of
Hospital Acquired Infections, has presented data at several conferences
during 2005 - 2007 on this topic. He suggests that
mechanical valves and positive pressure mechanical valves increase
the risk of catheter related bloodstream infection due to the design
of the product. The table lists the risk factors Dr. Jarvis presents
related to mechanical valves:
| Difficulty cleaning access surface |
HCW’s may not adequately
clean the intricate surface details, leading to fluid path
contamination. |
| Gap around plunger harbors bacteria |
Gap cannot be accessed for disinfection
and can lead to fluid path contamination especially with
repeated access such as SAS or SASH method. |
| Opaque housing hides incomplete
flushing of media based fluids |
During the course of normal manipulation
of the catheter small amounts of media like fluid contaminate
the valve. If these organisms proliferate, then they can
be infused with subsequent manipulations. |
| Internal mechanisms obscure fluid
path |
Impossible to visually confirm
complete flushing. |
|
Obviously, the luer activated access port is extremely important
and must be designed to allow appropriate disinfection and flushing
of blood components from the device. With out complete flushing
of the device and catheter, thrombus formation may occur. Multiple
studies have shown that a decrease in blood accumulation in the
line reduces the formation of biofilm and CRBSI’s. Devices should feature access ports that can be disinfected during normal swabbing. Devices should be clear to promote effective flushing.
Duration of Placement
The longer the catheter is indwelling the greater the risk of
infection. Longer placement results in more chances for microbial
ingress due to more contact, manipulation, etc.
Today, measures to prevent bloodstream infections are top priority
for infection control practitioners and other health care workers.
The Institute for Healthcare Improvement has a new program titled
Save 5 Million lives.
The 5 Million Lives Campaign is an initiative to engage
U.S.
hospitals in a commitment to implement changes in care proven to
improve patient care and prevent avoidable deaths. The
Campaign is the first national effort to promote saving a specified
number of lives by a certain date.
The program has a campaign
to prevent central line associated bloodstream infections. You
can review the details of this campaign by accessing the How to
Guide for Central Line Infections at www.ihi.org/IHI/Programs/Campaign/.
The
Center for Disease Control, CDC, also has a MMWR guideline which
promotes proper technique for preventing Catheter Related Bloodstream
Infections. This document titled
Guidelines for
the Prevention of Intravascular Catheter-Related Infections is
in this manual under the section titled guidelines.
Most hospitals
track their bloodstream infection rate per 1000 catheter days and
are actively pursuing methods to assist in reduction of bloodstream
infections. We feel MaxPlus and MaxPlus Clear are both excellent devices to implement to assist in the reduction of bloodstream infections.
References:
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catheters. Clin Infect Dis. 1992;15:197-210.
- Maki DG. Infections due to infusion therapy. In: Bennett JV,
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- Jarvis WR, Edwards JR, Culver DH, et al. Nosocomial infection
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- Maki DG, Cobb L, Garman JK, et al. An attachable silver impregnated
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- Schmid, M. RN PHD CIC Preventing Intravenous Cather Associated Infections; An Update
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