Preventing Intravenous Catheter-Associated Infections: An Update
By Marlene Wellman Schmid, RN, PhD, CIC
Nosocomial or hospital-acquired infections cost several billion dollars and cause more deaths annually per year than road accidents.1,2 The Fatality Analysis Reporting System (FARS01 reported 37,043 fatal crashes in 1999 in the US compared to the estimated 88,000 deaths in the two million patients who developed hospital-acquired infections, as reported by the Centers for Disease Control and Prevention (CDC).1,3 The Institute of Medicine (IOM) estimates the range to be 44,000 to 98,000.4 This equates to a 4.4 case fatality rate (88,000/2 million) for those patients who develop hospital-acquired infections.3
When compared to the crash fatality data, hospitalized patients are 2.4 times more likely to die from a hospital-acquired infection than they are from a road accident. In the 21st century, expenses incurred for nosocomial infections continue to skyrocket, costing the healthcare industry approximately $4.6 billion annually.3,6 Adding to these healthcare costs are similar infections occurring in nursing homes, outpatient clinics, dialysis centers, infusion therapy centers, and other sites of healthcare delivery.
Of the estimated two million nosocomial infections, approximately 850,000 are classified as catheter-associated infections (CAIs), with 50,000 categorized by CDC surveillance criteria as catheter-associated bacteremias (CABs)5-7 The majority of these infections are associated with central intravenous catheters. The case fatality rate for CABs is more than 20% (10,000 deaths/50,000 cases) and the attributable mortality 35%.7 Attributable mortality essentially means that of those patients who undergo intravenous therapy and develop complications and subsequently die, 35% of the cause of his/her death can be attributed to the presence of the intravenous catheter. This percentage is derived from hospitalized patient data comparing those who have intravenous catheters that complicate and die compared to similar patients who do not have intravenous catheters but complicate and die.8
Central Line Infections and Intensive Care Units
The CDC's National Nosocomial Infections Surveillance (NNIS) program for the 285 participating US hospitals reported a significant decline in bloodstream infections from 1990 to 1999.3,6 The greatest decline was reported in medical (nonsurgical) intensive care units (ICUs) followed by coronary ICUs, pediatric ICUs, and surgical ICUs.3,6 During this same time period, patient acuity has increased sharply. Patients admitted to hospitals today are sicker and experience shorter lengths of stay. Those admitted to intensive care units (ICUs) are five to ten times more likely to acquire nosocomial infections than other hospital patients.9-11 While ICU patients are at increased risk, their frequency of infections at the different anatomic sites and their risk of developing the infection vary by the type of ICU where they are admitted.
Sources of Organisms in Catheter-Associated Infections
Epidemics are defined as rates of disease or events significantly higher than the usual frequency while endemic rates reflect the usual frequency of disease or events.12 Maki's criteria of >15 colony forming units (CFUs) continues as the gold standard for discriminating between catheter-related infections versus catheter colonization.13,14 Infection means the invasion of the body (or a site if localized into one area) by pathogenic microorganisms that reproduce and multiple (>15 CFUs on culture), causing disease and tissue damage.13-15 The primary sources for most pathogens causing endemic catheter-associated bloodstream infections are the catheter insertion site or the catheter hub.16 Contamination may result from the patients' own flora or from healthcare workers' hands during insertion or manipulation, or both.
Colonization occurs when microorganisms are present and multiplying but are not invading the tissue or causing damage.13-15 When aseptic technique is used during catheter placement, then colonization typically results from the patient's own endogenous flora (originating from the patient).16 These organisms migrate along the outside or inside lumen of the intravenous catheter and seed the intravenous site causing colonization, or it may progress to a localized or systemic infection.16 Marik reported that approximately 25% of the central venous catheters become colonized and 20% to 30% of these colonized catheters become infected.10,18-22
ICUs as High-Risk Areas
Complicating hospitalized patients' risks for catheter-associated infections, Pelletier reported that patients with coexisting infections are more likely to have catheter-related infections or bacteremia than patients without coexisting infections even when no differences were found in APACHE II scores, white blood counts (WBC), length of hospital stay, time from admission to fever, time from fever to treatment, normalization of WBC, days of antibiotics, defervescence (diminishing or disappearance of a fever), gender, presence of comorbidities, colonization while in the ICU, or mortality rate.9
It also has been reported that an increased risk for catheter-associated infections occurs in patients who have pneumonia and urinary tract coexisting infections.9,23 These authors reported that 37.3% of the intensive care unit patients with pneumonia and 28.8% with urinary tract infections also developed catheter associated infections.9 Brown and Warren reported pneumonia occurring in 25-50% of the ICU patients they studied but less than 3% developed urinary tract infections.23 These authors also reported that catheter-associated infections with bacteremias were connected to an increased proportion of gram-negative organisms compared to those catheter infections without bacteremia.9
Although the CDC only recognizes catheter-related bloodstream infections with bacteremia and labels those infections without bactermia as colonization, Pelletier indicated that perhaps the definition of catheter-associated infections should be expanded to include those bloodstream infections that are without the presence of systemic illness and not explained as a result of another infectious source.9
Most intravenous catheter infections result from either catheter seeding occurring during catheter placement (extraluminal) or during manipulation of hubs or catheter junctions during use (intraluminal).14 All patients who receive intravenous therapy are at risk for catheter-related infections, although the degree of risk varies by type of device and access site. Catheter-related infections account for approximately 30% of all hospital-acquired infections. For critically ill patients bacteremia is the leading cause of nosocomial infections.24 Although diagnosis of these infections may be difficult, catheter-associated infections should be suspected in patients who have these devices and develop fever, chills, and leukocytosis with no other apparent site of infection.24
Contributing to the seriousness of nosocomial infections, especially in ICUs, is the increasing incidence of infections caused by antibiotic-resistant pathogens and specifically Staphylococcus aureus and Enterococcus. For example, more than half of the catheter-associated bloodstream infections in the US are caused by the gram-positive organism staphylococci.10
Air, Skin, and Blood as a Source of Infection
Weinstein29 identified three main sources of bacteria responsible for IV-associated infections: the air, the skin, and the blood. Although the number of microbes per cubic foot of air varies, depending on the particular area of the hospital involved, contamination can occur when infection is present and bacteria escape in the form of bodily discharge onto clothing, bedding, and dressings.29 The type of organism isolated from an intravenous site and/or blood can offer insight into its source. Gram-negative rods suggest water or the human digestive tract as the contamination source while gram-positive bacteria is more common in soil and could be potentially be traced back to the healthcare workers', the patients', and/or significant others' hands.29,40
Infections by Air
Airborne contaminates settle on injection ports. Intravenous tubing may be inadvertently contaminated when allowed to drape onto the floor or placed next to the patient in a bed where urine and fecal incontinence could contaminate access ports or tubing exterior. Healthcare workers' (HCWs) hands may become contaminated while bathing or cleaning the patient or during manipulation of dressings or devices. Subsequent manipulation of intravenous tubing and access ports without prior hand washing may inadvertently contaminate access sites along the intravenous system, on the IV drip rate regulator, or on IV sites during dressing changes.36
Airborne contamination occurs during activities such as bed making, when one coughs or sneezes, or during suctioning, sending bacteria flying into the air on particles of lint, pus, dried epithelium, and/or droplet nuclei.29,30,32 Increased activity triggers a rise in the number of airborne particles and creates an environment that interferes with aseptic technique and potentially contributes to contamination. Airborne microorganisms in patient areas and utility rooms may find their way to IV fluids and equipment via breaches in aseptic technique.
A particle 100 microns in size is equivalent to 0.004 inches or 25 microns = 0.001 inches.29 Therefore, housekeeping departments play a pivotal role in maintaining a clean patient care environment by decreasing the environmental bioburden.
To prevent intravenous tubing contamination, the HCW should cover and contain drainage from infected wounds, avoid excessive movement of linens, and keep all intravenous tubing off the floor.23 They should decontaminate access ports by scrubbing injection ports for at least one minute with 70% alcohol or 30 seconds with an antiseptic microbial solution such as providone-iodine.25,35,43The solution should then be allowed to dry for maximum antimicrobial effect.25,35,43 All intravenous-tubing sets should be replaced when they leak at injection sites, connections, or vents, or when they become contaminated.25,35,43
Capping intravenous sites for intermittent infusion preserves IV access when patients no longer need continuous infusions but still need intermittent IV access.11,36 These caps should be changed after multiple punctures with large bore needles and/or needleless access devices, because frequent punctures into IV caps may compromise the integrity of the cap material and increase the risk for the IV to leak or become contaminated. New caps should be used each time a new IV catheter is inserted.11,36
Although no textbooks or articles were found that cited exactly how many punctures an IV cap can tolerate safely before the integrity is impaired and should be changed, the safest guideline is to check with the manufacturer of the product for guidance and incorporate the information into the agency IV policy for your specific equipment. Intuitively, the larger the needle or needleless access device and the more frequently accessed, the more likely the integrity of the cap will become impaired.11 The Occupational Safety and Health Administration (OSHA) requires hospitals to use needleless systems; however, if needles must be used current recommendations state #20 to #25 gauge needles that are one inch or less in length cause the least amount of damage and allow for the cap material to reseal after puncture.33,37,43
Infections on the Skin
Although several studies are dated, they are and continue to form the rationale used by the Intravenous Nurses Society (INS) to support the gold standard of intravenous skin prepping prior to IV catheter insertion. Alcohol 70% is frequently used to prepare the skin site prior to venipuncture, and when applied with friction for one minute, results in 75% reduction in the minimum organism count on skin, ie., 10,000 organisms/cm2 (0.155 square inches) on normal skin to 2,500.39,42 These organisms, or resident flora, are not simply ones that adhere to dirty skin but live deep within the epithelial structures of the skin and are shed in large numbers with hand washing or scrubbing.39 Furthermore, patients will become colonized with organisms from the hospital environment. Colonization rapidly increases with duration of hospital stay. Staphylococcus epidermidis, Staphylococcus aureus, and gram-negative bacilli such as Klebsiella, Enterobacter, Serratia and enterococci (intestinal flora) are ubiquitous on the skin of hospitalized patients.40,41
Abrams reported that anaerobic bacteria occurs 1000:1 aerobic in the bowel.39 Fecal incontinence increases environmental contamination and the risk of access devices including IVs becoming contaminated subsequently increases. While antibiotic resistant organisms such as vancomycin-resistant enterococcus (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) can be spread by direct contact, effective handwashing by healthcare workers has been proven to be successful in interrupting transmission.36,44, Saliva, which contains as many as 100 million organisms per milliliter, can also cause contamination when a worker or patient speaks during a procedure including during IV site placement or IV dressing changes.39 Establish the sterile field and equipment needed for the procedure and limit conversation to eliminate droplet contamination of the site and equipment.36
Failure to properly prep the skin prior to catheter insertion increases a patient's risk for colonization and/or infection via the IV site. Most organisms are not visible to the human eye. When properly applied (friction rubbing for one full minute), the effect of alcohol 70% in reducing the bacterial count on normal skin at an IV insertion site has been reported to be nearly equivalent to a 12-minute hand scrub.42 INS continues to support the use of alcohol 70% as an effective IV skin prep.43
In addition to alcohol 70%, other products currently available include iodine, iodine-containing disinfectants, and chlorhexidine.45 The iodine and iodine-containing disinfectants continue to be reliable in preparing the skin for venipuncture because they provide bactericidal, fungicidal, and sporicidal activity when applied with friction and allowed to dry to activate the antimicrobial properties. Like alcohol, tincture of iodine (2% iodine in 70% alcohol) is inexpensive and also should be applied working from the center of the insertion site to the periphery.43 When left on the skin, iodine products provide a sustained antimicrobial effect up to 6 hours after application.43 However, patients should be screened for allergies. Iodophor preparations require at least a minimum 30-second contact time and INS standard recommends two-minute drying time in order for the agent's properties to become activated.43
In 1991, Maki reported that the use of chlorhexidine in skin preparation and IV dressing changes was associated with the lowest incidence of catheter-related infections and catheter related bacteremia.41 The greatest challenge has been for manufacturer's to produce chlorhexidine in easy to use skin prep packages or swab sticks.
Intravenous sites can become seeded when organisms from distant infection sites are transported to the access port or adhere to the catheters, as discussed above.9 When attempting to determine if the patient has a catheter-associated infection, Phillips.35 recommends HCWs be suspicious of an IV catheter-related infection if the blood drawn from the IV cannula has five times the organism growth compared to blood obtained from a peripheral vein. Removal is recommended when catheters are implicated in catheter-associated infections.43
Preventing Central IV Catheter-Associated Infections
Routine intravenous solutions such as normal saline, lactated ringers, and/or dextrose solutions are good for only 24 hours once the hermetically sealed wrapper is removed.29,36,43 All intravenous solution containers must be carefully inspected before hanging.29,36,43 Glass bottles may become cracked or damaged and plastic bags punctured, allowing bacteria and fungi to invade the solutions contaminating the container.25,29,36,43 Healthcare workers should be aware that Pseudomonas cepacia, Acinetobacter, and Serratia are the most common organisms that grow in 5% dextrose in water.14 Most bacteria will grow in normal saline (0.9% sodium chloride solutions [USP] normal saline) except Candida species, which grow easily in amino acids and 25% dextrose solutions.14,29
Healthcare workers must inspect each container of intravenous solution carefully, holding it against a light and dark background examining for cracks, defects, turbidity, and particulate matter.29,36,43 Never use any glass container lacking a vacuum when opened. Always label infusates with the date, time, and your initials when hung.36,43
The pH of intravenous solutions and medications can irritate IV access sites and forms the rationale for having multiple types of devices (peripheral, midline, PICC, and CVC) available to HCWs. For example, dextrose is slightly acidic (pH 4.5 to 5.5) while sodium chloride solutions have pHs ranging from 6.8 to 8.5.35 In general, dextrose solutions should be used as a base for acidic drugs and sodium chloride solutions should be used for alkaline medication dilution. Intravenous medications that are widely dissimilar in pH values are unlikely to be compatible in solution.35 Multiple antibiotics have an acidic pH that is stable in dextrose, but alkaline antibiotics such as carbenicill, are unstable when mixed with dextrose.35 The HCW should follow manufacturers' guidelines and check intravenous and medication compatibility charts prior to administration.35
New technology currently being tested for catheter-related infections include antibiotic and antiseptic-coated catheters, antiseptic hubs, disinfecting caps, and flushing solutions.38 Risk for developing catheter-associated infection varies by device. Marik (2000) reported that approximately 5% of all patients with uncoated, indwelling central intravenous catheters would develop a blood stream infection yielding 10-infections/1,000 catheter days.10,18-22
Each organization should have established policies and procedures for the placement of intravenous catheters. At a minimum, healthcare professionals should have a comprehensive understanding of anatomy and physiology, vascular assessment techniques, and insertion techniques appropriate to the specific device. The catheter should always be inspected for product integrity prior to insertion. Precautions to consider when stylets, needles, and/or wires are used to facilitate catheter placement include a) stylets that are part of the product should never be reinserted due to the potential for severing and/or puncturing the catheter and b) catheters must never be withdrawn through a needle.43
Intravenous Policy Issues
A maximum of two attempts at cannulation by any one healthcare worker should be made in order to avoid multiple unsuccessful attempts, causing unnecessary trauma to the patient and limiting future vascular access. Catheters placed in an emergency situation where aseptic technique potentially has been compromised should be replaced as quickly as possible and definitely within 24 hours.36,43 Current INS43standards recommend that HCWs should always follow manufacturers' guidelines for all intravenous catheters and document the catheter placement, gauge, length and number of attempts, anatomical location, and patient's response to the procedure in the patient's medical record. PICC and CVC Central catheters should be radiopaque and placement radiologically confirmed.43 Radiological confirmation should also be obtained when there is difficulty with catheter advancement, pain or discomfort after catheter advancement, inability to obtain positive aspiration of blood, inability to flush the catheter easily, difficulty in removing guidewire, or guidewire noted to be bent upon removal.43
IV catheter and skin junction sites should be assessed for potential complications (redness, tenderness, pus, warmth, and edema) at established intervals by hospital policy.3 The HCW should change gauze dressings routinely every 48 hours on peripheral and central catheter sites and immediately if the integrity of the dressing is compromised.43 If gauze is used in combination with a transparent dressing, it is considered a gauze dressing and should be changed every 48 hours.43 If transparent semi-permeable dressings are used on peripheral IV sites and as long as the integrity of the dressing is maintained, then the dressing is changed at the same time as the 72-hour catheter site rotation is done.43 If a central catheter-related infection is suspected, the HCW should change over the guidewire and culture the distal segment.43,47 Single-lumen central catheters should be used unless clear indication for a multi-lumen catheter exists.43,47 If catheter segments are culture positive, the catheter should be removed.43,47 After PICC and central venous catheters are removed, the site dressing should be changed every 24 hours and the site assessed until epitheliazed.43 Once a central catheter has been inserted, the HCW should never readvance if it becomes dislodged.43
According to INS standards, hospitals are expected to maintain an intravenous phlebitis rate of less than or equal to 5% with the 72-hour continuous primary and secondary tubing administration set changes.43 Tubing continuous primary and secondary administration sets should be changed every 48 hours if there is an increase in the incidence of phlebitis above recommended levels and/or if an increase in catheter-associated infections is noted.43 Primary intermittent or intermittent secondary tubing continues to be changed every 24 hours.43 Add-on devices, such as tubing extensions, filters, stop-cocks, and needleless devices, should be changed when the administration sets are changed.43 Some solutions, ie., total parenteral nutrition (TPN), lipids, blood and/or blood components) should dictate whether the administration set is changed more frequently.43 Typically, administration sets used for TPN and lipids are changed every 24 hours while blood sets are changed every four hours or with each unit of blood, whichever comes first.43
Intravenous therapy continues to be the most frequent medical procedure hospitalized patients will experience. Scrupulous aseptic and sterile technique during placement and maintenance of these sites will prevent catheter-associated complications. Patients who are in intensive care units and who develop pneumonia and urinary tract infections, are at increased risk for intravenous catheter-associated infections. Furthermore, the increased use of antibiotics creates a patient care environment where antibiotic resistance emerges. Following INS standards for intravenous therapy will decrease the risk of catheter-associated infections and will improve patient outcomes.
Marlene Schmid, RN, PhD, CIC, is an associate professor at the University of Wisconsin School of Nursing.