This is the second part of the epic2 guidelines on preventing catheter-related bloodstream infection (CR-BSIs) associated with central venous access devices (CVADs). It presents general principles of catheter management, as well as key audit criteria related to CVADs.
Aseptic technique is important when accessing the system
HICPAC considered evidence demonstrating that contamination of the catheter hub is an important contributor to intraluminal microbial colonisation of catheters, particularly long-term catheters (Salzman et al, 1993a; Raad et al, 1993; Capell et al, 1986; Linares et al, 1985; Sitges-Serra et al, 1985; De Cicco et al, 1982; Peters et al, 1982).
In an overview of catheter management (Mermel, 2000), additional evidence from a prospective cohort study suggested that frequent catheter hub manipulation increases the risk for microbial contamination Weist et al, 1997).
During prolonged catherisation, catheter hubs are accessed more frequently, increasing the likelihood of a CR-BSI emanating from a colonised catheter hub rather than the insertion site (Raad et al, 1993).
Consequently, Mermel (2000) commented that hubs and sampling ports should be disinfected before they are accessed (Maki et al, 1997) and noted that both povidone-iodine and chlorhexidine are effective (Salzman et al, 1993b; Rushman and Fulton, 1993).
Systematic review evidence
A recent randomised prospective clinical trial (Casey et al, 2003) compared the microbial contamination rate of luers of CVAD with either PosiFlow needleless connectors or standard caps attached. The efficacy of chlorhexidine gluconate 0.5% w/v in industrial methylated spirit (IMS) BP 70% w/w spray (Hydrex DS); sterile isopropyl alcohol (IPA) 70% w/w spray (Spiriclens); and 10% (w/v) aqueous povidone-iodine (Betadine) for the disinfection of intravenous connections.
Patients were designated to receive chlorhexidine/alcohol, isopropyl alcohol or povidone-iodine for pre-CVAD insertion skin preparation and disinfection of the connections. After 72 hours in situ the internal surfaces 18% of luers with standard caps were contaminated with microorganisms, while only 6.6% of those with needleless connectors were contaminated.
Of those needleless connectors disinfected with isopropyl alcohol, 69.2% were externally contaminated with microorganisms compared with 30.8% disinfected with chlorhexidine/alcohol and 41.6% with povidone-iodine. These results suggest that the use of needleless connectors may reduce the microbial contamination rate of CVAD luers compared with the standard cap.
Furthermore, disinfection of needleless connectors with either chlorhexidine/alcohol or povidone-iodine significantly reduced external microbial contamination. Both these strategies may reduce the risk of catheter-related infections acquired via the intraluminal route.
Although now generally alcohol-resistant, some CVAD and catheter hub materials may be chemically incompatible with alcohol or iodine and the manufacturer's recommendations must be complied with.
A single patient-use application of alcoholic chlorhexidine gluconate solution (preferably 2% chlorhexidine gluconate in 70% isopropyl alcohol) should be used and allowed to dry when decontaminating the injection port or catheter hub before and after it has been used to access the system, unless contraindicated by the manufacturer's recommendations, in which case either aqueous chlorhexidine gluconate or aqueous povidone iodine should be used.
Inline filters do not help prevent infections
Although in-line filters reduce the incidence of infusion-related phlebitis, HICPAC could find no reliable evidence to support their efficacy in preventing infections associated with intravascular catheters and infusion systems.
Infusate-related BSI is rare and HICPAC concluded that filtration of medication or infusate in the pharmacy is a more practical and less costly way to remove particulates. Furthermore, in-line filters might become blocked, thereby increasing the number of line manipulations and decreasing the availability of administered drugs (CDC, 2002).
We found no additional good quality evidence to support their use for preventing infusate-related CR-BSI.
In-line filters should not be used routinely for infection prevention purposes.
Antibiotic lock solutions have limited uses in preventing infection
Antibiotic lock prophylaxis - flushing and then filling the lumen of the CVAD with an antibiotic solution and leaving it to dwell in the catheter - is sometimes used in special circumstances to prevent CR-BSI, for example in treating patients with a long-term cuffed or tunnelled catheter or port with a history of multiple CR-BSI despite optimal maximal adherence to aseptic technique.
Evidence reviewed by HICPAC (CDC, 2002) demonstrated the effectiveness of this type of prophylaxis in neutropenic patients with long-term CVAD. However, the committee found no evidence that routinely using this procedure in all patients with CVAD reduced the risk of CR-BSI and may lead to an increase in antimicrobial resistant microorganisms.
Antibiotic lock solutions should not be used routinely to prevent catheter-related bloodstream infections.
Systemic antibiotic prophylaxis does not reliably prevent CR-BSI
No studies appraised by HICPAC demonstrated that oral or parenteral antibacterial or antifungal drugs might reduce the incidence of CR-BSI among adults.
However, among low birthweight infants, two studies reviewed by HICPAC had assessed vancomycin prophylaxis; both demonstrated a reduction in CR-BSI but no reduction in mortality.
Because the prophylactic use of vancomycin is an independent risk factor for the acquisition of vancomycin-resistant Enterococcus (VRE), the risk for acquiring VRE probably outweighs the benefit of using prophylactic vancomycin (CDC, 2002).
Systematic review evidence
A Cochrane Review (van de Wetering and van Woensel, 2003) concluded that prophylactic antibiotics or catheter flushing with vancomycin and heparin may help cancer patients at high risk of catheter-related infections.
Patients with cancer often need to receive drugs and other treatments intravenously, so are frequently fitted with long-term tunnelled CVADs. Infections sometimes occur. Clinical trial evidence shows it may be useful to give prophylactic antibiotics prior to inserting a tunnelled CVAD or to flush the catheter with combined vancomycin and heparin, but microbial resistance may occur unless this practice is limited to high-risk patients.
Do not routinely administer intranasal or systemic antimicrobials before insertion or during the use of a central venous catheter to prevent catheter colonisation or bloodstream infection.
A dedicated catheter lumen is needed for parenteral nutrition
HICPAC reviewed evidence from a prospective epidemiologic study examining the risk for CR-BSI in patients receiving total parenteral nutrition (TPN). it concluded that either using a single lumen CVAD or a dedicated port in a multilumen catheter for TPN would reduce the risk of infection (CDC, 2002).
Preferably, a single-lumen catheter should be used to administer parenteral nutrition. If a multilumen catheter is used, one port must be exclusively dedicated for hyperalimentation and all lumens must be handled with the same meticulous attention to aseptic technique.
Maintaining catheter patency and preventing catheter thrombosis may help prevent infections
Indwelling central venous and pulmonary artery catheters are thrombogenic. Thrombus forms on these catheters in the first few hours following placement (Hoar et al, 1981) and may serve as a nidus for microbial colonisation of intravascular catheters (Raad et al, 1981).
Thrombosis of large vessels occurs after long-term catheterisation in 35 to 65% of patients (Andrew et al, 1995; Krafte-Jacobs et al, 1995; Talbott et al, 1995; Chastre et al, 1982; Valerio et al, 1981).Prophylactic heparin and warfarin have been widely used to prevent catheter thrombus formation and catheter related complications, such as deep venous thrombosis (DVT) (CDC, 2002; Randolph et al, 1998a).
Two types of heparin can be used: unfractionated (standard) and low molecular weight. Although more expensive, low molecular weight heparin has a longer duration of action and is generally administered by subcutaneous injection once daily.
The standard prophylactic regimen of low molecular weight heparin is at least as effective and as safe as unfractionated heparin in preventing venous thrombo-embolism and does not require laboratory monitoring (Mehta, 2006).
A meta-analysis of RCTs (Randolph et al, 1998a) evaluated the benefit of infused prophylactic heparin through the catheter, given subcutaneously or bonded to the catheter in patients with CVADs. It found that prophylactic heparin:
- Was associated with a strong trend for reducing catheter;
- Significantly decreased central venous catheter-related venous thrombosis;
- Significantly decreased bacterial colonisation of the catheter;
- Showed a strong trend for a reduction in CR-BSI.
The authors of this meta-analysis concluded that heparin administration effectively reduces thrombus formation and may reduce catheter-related infections in patients who have central venous and pulmonary artery catheters in place.
They suggest that various doses of heparin and new methods of heparin bonding need further comparison to determine the most cost-effective strategy for reducing catheter-related thrombus and thrombosis.
There are many preparations and routes of administration of heparin, and as yet no definite evidence that heparin reduces the incidence of CR-BSI, but this may reflect the heterogeneity of heparin and its administration. Warfarin has also been evaluated as a means for reducing catheter-related thrombosis.
In a controlled trial of 82 patients with solid tumours randomised to receive or not to receive low-dose warfarin (1mg daily) beginning three days prior to catheter insertion and continuing for 90 days, warfarin was shown to be effective in reducing catheter-related thrombosis (Bern et al,1990).
The rates of venogram-proved thrombosis were four of 42 in the treatment group versus 15 of 40 in the control group, with 15 having symptomatic thromboses. In this study, warfarin was discontinued in 10% of patients due to prolongation of the prothrombin time.
Heparin versus normal saline intermittent flushes
Although many clinicians use low-dose intermittent heparin flushes to fill the lumens of CVAD locked between use in an attempt to prevent thrombus formation and prolong catheter patency, the efficacy of this practice is unproven.
Despite its beneficial antithrombotic effects, decreasing unnecessary exposure to heparin is important to minimise adverse effects associated with heparin use, such as heparin-induced thrombocytopenia (Passannante and Macik, 1998). The risks of these adverse effects can be avoided by using 0.9% sodium chloride injection instead of heparin flushes.
A systematic review and meta-analysis of RCTs evaluating the effect of heparin on duration of catheter patency and prevention of complications associated with the use of peripheral venous and arterial catheters concluded that heparin at doses of 10U/ml for intermittent flushing is no more beneficial than flushing with normal saline alone (Randolph et al, 1998b).
This finding was in agreement with two other meta-analyses (Goode et al, 1991; Peterson and Kirchoff, 1991). Manufacturers of implanted ports or opened-ended catheter lumens may recommend heparin flushes for maintaining patency and many clinicians feel that heparin flushes are appropriate for flushing CVAD that are infrequently accessed.
HICPAC reviewed all of the evidence for intermittent heparin flushes and systemic heparin and warfarin prophylaxis and concluded that no data demonstrated that their use reduces the incidence of CR-BSI and did not recommend them for infection prevention purposes (CDC, 2002).
Although their use for preventing CR-BSI remains controversial, patients with CVADs may also have risk factors for DVT and systemic anticoagulants may be prescribed for DVT prophylaxis. In addition, heparin flush solutions may help to maintain patency in catheter lumens that are infrequently accessed and may also be recommended by manufacturers of implantable ports and for CVAD used for blood processing such as haemodialysis or apheresis.
Preferably, sterile 0.9% sodium chloride for injection should be used to flush and lock catheter lumens that are in frequent use.
When recommended by the manufacturer, implanted ports or opened-ended catheter lumens should be flushed and locked with heparin sodium flush solutions.
Systemic anticoagulants should not be used routinely to prevent CR-BSI.
Needleless devices require vigilance
Needleless infusion systems have been widely introduced into clinical practice to reduce the incidence of sharp injuries and the potential for the transmission of bloodborne pathogens to healthcare workers.
HICPAC examined evidence that these devices may increase the risk for CR-BSI and concluded that when they are used according to the manufacturers' recommendations, they do not substantially affect the incidence of CR-BSI (CDC, 2002).
Some are more expensive than standard devices, may not be compatible with existing equipment and may be associated with an increase in bloodstream infection rates (CDC, 1997).
The introduction of new needleless intravascular devices should be monitored for an increase in the occurrence of device associated infection.
If needleless devices are used, the manufacturer's recommendations for changing the needleless components should be followed.
When needleless devices are used, healthcare workers should ensure that all components of the system are compatible and secured, to minimise leaks and breaks.
When needleless devices are used, the risk of contamination should be minimised by decontaminating the access port before and after use with a single patient-use application of alcoholic chlorhexidine gluconate solution (preferably 2% chlorhexidine gluconate in 70% isopropyl alcohol)unless contraindicated by the manufacturer's recommendations, in which case aqueous povidone iodine should be used.
Change intravenous administration sets appropriately
The optimal interval for the routine replacement of intravenous solution administration sets has been examined in three well-controlled studies reviewed by HICPAC (CDC, 2002). Data from each of these studies reveals that replacing administration sets no more frequently than 72 hours after initiation of use is safe and cost-effective.
When a fluid that enhances microbial growth is infused, such as lipid emulsions, blood products, more frequent changes of administration sets are indicated as these products have been identified as independent risk factors for CR-BSI.
In general, solution administration sets in continuous use need not be replaced more frequently than at 72 hour intervals unless they become disconnected or a CVAD is replaced.
Administration sets for blood and blood components should be changed when the transfusion episode is complete or every 12 hours (whichever is sooner), or according to the manufacturer's recommendations.
Administration sets used for total parenteral nutrition (TPN) infusions should generally be changed every 24 hours. If the solution contains only glucose and amino acids, administration sets in continuous use do not need to be replaced more frequently than every 72 hours.
Key audit criteria
Apart from providing practice advice, guidelines can also be used as audit criteria to measure adherence. Below are some examples of how these guidelines can be used.
Identify all patients with central venous catheters.
All patients should have a patient record that documents the reason for CVAD placement, type of catheter, catheter insertion site, catheter replacements and care.
Data collection: Review of patient notes
Ensure all healthcare workers are trained to implement these guidelines and assessed as competent.
Support healthcare workers to consistently adhere to guideline recommendations.
All healthcare worker involved in the care of people with CVADs receive training and updates in the management of CVADs.
Data collection: Review of staff education records/direct observation/self-audit
Assess the need for continuing venous access on a regular basis and remove a CVAD as soon as clinically possible in order to reduce the risk for infection.
Evidence of regular and frequent assessment of the need for CVAD and catheter discontinuation rates when the catheter is no longer essential for medical management.
Data collection: Review of patient notes
Ensure that patients and carers are informed and educated about the management of their CVAD.
All patients and carers are aware of the need to:
- Decontaminate their hands when manipulating the system;
-Use aseptic technique when manipulating or accessing the system.
Data collection: direct patient questioning of patients and carers.
Andrew, M. et al (1995) A cross-sectional study of catheter-related thrombosis in children receiving total parenteral nutrition at home. Journal of Pediatrics; 126: 358-363.
Bern, M.M. et al (1990) Very low doses of warfarin can prevent thrombosis in central venous catheters. A randomized prospective trial. Annals of Internal Medicine;112: 423-428.
Capell, S. et al (1986) Catheter sepsis due to coagulase-negative staphylococci in patients on total parenteral nutrition. European Journal of Clinical Microbiology and Infectious Diseases;5: 40-42.
Casey, A.L. et al (2003) A randomized, prospective clinical trial to assess the potential infection risk associated with the PosiFlow® needleless connector. Journal of Hospital Infection; 54: 288-293.
Centers for Disease Control and Prevention (2002) Guidelines for the Prevention of intravascular-catheter-related Infections. Morbidity and Mortality Weekly Report; 51 (No.RR-10): 1-29. Available from www.cdc.gov/mmwr/PDF/rr/rr5110.pdf
Centers for Disease Control and Prevention (1997) Evaluation of safety devices for preventing percutaneous injuries among health care workers during phlebotomy procedures: Minneapolis-St Paul, New York City, and San Francisco, 1993-1995. Morbidity and Mortality Weekly; 46: 2, 21-25.
Chastre, J. et al (1982) Thrombosis as a complication of pulmonary-artery catheterisation within the internal jugular vein. New England Journal of Medicine; 306: 278-281.
deCicco, M. et al (1982) Source and route of microbial colonization of parenteral nutrition catheters. Lancet; 2: 1258-1261.
Goode, C.J. et al (1991) A meta-analysis of effects of heparin flush and saline flush: quality and cost implications. Nursing Research; 40: 324-330.
Hoar, P.F. et al (1981) Heparin bonding reduces thrombogenicity of pulmonary-artery catheters. New England Journal of Medicine; 305: 993-995.
Krafte-Jacobs, B. et al (1995) Catheter-related thrombosis in critically ill children: comparison of catheters with and without heparin bonding. Journal of Pediatrics; 126: 50-54.
Linares, J. et al (1985) Pathogenesis of catheter sepsis: a prospective study with quantitative and semiquantitative cultures of catheter hub and segments. Journal of Clinical Microbiology; 21: 357-360.
Maki, D.G. et al (1997) Prevention of central venous catheter-related bloodstream infection by use of an antiseptic-impregnated catheter. A randomized controlled trial. Annals of Internal Medicine; 127: 257-266.
Mehta, D.K. (ed) British National Formulary No. 51. London: British Medical Association and the Royal Pharmaceutical Society of Great Britain; March 2006.
Mermel, L.A. (2000) Prevention of intravascular catheter-related infections. Annals of Internal Medicine;132: 5, 391-402.
Passannante, A., Macik, B.G. (1998) Case report: the heparin flush syndrome: a cause of iatrogenic hemorrhage. American Journal of Medical Science; 296: 71-73.
Peters, G. et al (1982) Adherence and growth of coagulase-negative staphylococci on surfaces of intravenous catheters. Journal of Infectious Diseases; 146: 479-482.
Peterson, F.Y., Kirchoff, K.T. (1991) Analysis of the research about heparinized versus nonheparinized intravascular lines. Heart and Lung; 20: 631-640.
Raad, M.L. II et al (1994) The relationship between the thrombotic and infectious complications of central venous catheters. Journal of the American Medical Association; 271: 1014-1016.
Raad, I. et al (1993) Ultrastructural analysis of indwelling vascular catheters: a quantitative relationship between luminal colonization and duration of placement. Journal of Infectious Diseases; 168: 400-407.
Randolph, A.G. et al (1998a) Benefit of heparin in central venous and pulmonary artery catheters: a meta-analysis of randomized controlled trials. Chest; 113: 1, 165-171.
Randolph, A.G. et al (1998b) Benefit of heparin in peripheral venous and arterial catheters: systematic review and meta-analysis of randomised controlled trials. British Medical Journal; 316: 969-975.
Rushman, K.L., Fulton, J.S. (1993) Effectiveness of disinfectant techniques on intravenous tubing latex injection ports. Journal of Intravenous Nursing; 16: 304-308.
Salzman, M.B. et al (1993a) Use of disinfectants to reduce microbial contamination of hubs of vascular catheters. Journal of Clinical Microbiology; 31: 475-479.
Salzman, M.B. et al (1993b) A prospective study of the catheter hub as the portal of entry for microorganisms causing catheter-related sepsis in neonates. Journal of Infectious Diseases 1993;167:487-490.
Sitges-Serra, A. et al (1985) A randomized trial on the effect of tubing changes on hub contamination and catheter sepsis during parenteral nutrition. Journal of Parenteral and Enteral Nutrition; 9: 322-325.
Talbott, G.A. et al (1995) A prospective study of femoral catheter-related thrombosis in children. Archives of Pediatric and Adolescent Medicine; 149: 288-289.
Valerio, D. et al (1981) Central venous thrombosis associated with intravenous feeding: a prospective study. Journal of Parenteral and Enteral Nutrition; 5: 240-242.
Van de Wetering, M.D., van Woensel, J.B.M.(2003) Prophylactic antibiotics for preventing early central venous catheter Gram positive infections in oncology patients (Review). The Cochrane Database of Systematic Reviews; Issue 1: 1-16.
Weist, K. et al (1997) Contamination of stopcocks mounted in administration sets for central venous catheters with replacement at 24 hrs versus 72 hrs: a prospective cohort study. Infection Control and Hospital Epidemiology; 18: 5, part 2, 24.