Consultant Nurse, Critical Care,
Imperial College Healthcare NHS Trust,
Charing Cross Hospital,
Catheter-related bloodstream infection (CRBSI) describes a systemic infection that is directly attributable to an intravascular catheter.(1) CRBSI contributes to morbidity and mortality and increase length of stay and hospital costs.(2)
Routes of infection
It is widely accepted that there are four main ways in which an intravascular catheter can become infected:
- Intraluminal contamination: contamination of the internal lumen of the intravascular catheter. The catheter or catheter hub becomes contaminated by organisms from the patient’s skin or from the hands of healthcare workers.
- Extraluminal contamination: contamination of the external surface of the intravascular catheter. Organisms from the patient’s skin or from the hands of healthcare workers migrate from the insertion site along the catheter tract and colonise the external surface of the catheter.
- Haematogenous seeding: the intravascular catheter becomes colonised by a blood-borne organism that has seeded from a focus of infection elsewhere within the body.
- Contaminated infusates: the administration of contaminated intravenous fluids or drugs, now a relatively rare phenomenon.
The majority of CRBSIs are caused by intraluminal and extraluminal contamination of intravascular catheters. These two routes of infection can be specifically targeted by the implementation of evidence-based guidelines for the reduction of CRBSI.
The term intravascular catheter is used to describe a catheter that is inserted into the bloodstream. This term covers catheters that are placed within the arterial or venous system and includes both peripheral and central devices. The device that is associated with the greatest risk of CRBSI is the central venous catheter (CVC).(3) This article will focus on infection prevention associated with CVCs.
Guidelines and audit
The CDC guidelines(3) and the epic(2) guidelines(1) remain the most comprehensive evidence-based guidelines for the prevention of CRBSI. These guidelines can be supplemented by European guidelines for the care of haemodialysis catheters(4) and catheters used for parenteral nutrition.(5) There is now a wealth of evidence demonstrating that CRBSI can be reduced by the implementation of, and adherence to, evidence-based guidelines. The use of audit is recommended to assess knowledge of, and adherence to, evidence-based guidelines. Audit should be used to review practice standards for the insertion and care of venous access devices.(3)
Education and training
Education of healthcare professionals is a key strategy in the prevention of CRBSI. Evidence consistently demonstrates that CRBSI declines when infection prevention strategies are standardised. Education should focus on knowledge of, and adherence to, the infection prevention strategies outlined in the evidence-based guidelines.(1,3) When vascular access devices are used in secondary care, patients or carers should also be educated on the safe care and management of their devices.(1)
Evidence has shown that staffing levels directly influence the development of CRBSI in intensive care units (ICU).(6) Adequate staffing levels should be maintained in the ICU to reduce the risk of CRBSI.(3)
Hand hygiene and glove usage
Hand hygiene remains a cornerstone of infection prevention. Effective hand hygiene significantly reduces the number of pathogenic organisms carried by healthcare workers and directly influences the likelihood of developing CRBSI through intraluminal or extraluminal contamination of an intravascular catheter. Hands should be decontaminated by washing or by using an alcohol hand rub before performing any aspect of CVC care.(1,3,5) Careful hand hygiene is also required before and after glove use.
Sterile gloves should be worn for the insertion of CVCs.(1,3–5) An aseptic non-touch technique (ANTT) and a new pair of non-sterile gloves should be used when handling CVCs, administering medications and changing dressings.(1,3,5) To perform an ANTT the key parts of the infusion system must not be touched, that is, the sterile end of the fluid administration set and the open end of the catheter hub. If it is not possible to maintain an ANTT, sterile gloves should be worn for CVC care.(1,3)
Maximal sterile barrier precautions
The use of a sterile gown, sterile gloves and a large sterile drape are universally agreed to be the minimum standard of practice during the insertion of CVCs.(1,3–5) However the CDC guidelines also recommend the use of a mask and cap during CVC insertion.(3)
The patient’s own skin can contribute to the development of CRBSI. Fredericks(7) reported that up to 10 million aerobic bacteria can be present on 1cm2 of skin. Effective skin decontamination before CVC insertion is essential for the prevention of intraluminal and extraluminal contamination. Evidence strongly supports the use of 2% chlorhexidine gluconate in 70% isopropyl alcohol as the antiseptic of choice prior to CVC insertion(8) and this is now recommended by all the major guideline groups for skin antisepsis before catheter insertion and during dressing changes.(1,3–5,9,10)
A single patient application of antiseptic solution is preferable to a multidose container.(1,9,10) Aqueous chlorhexidine gluconate should be used if alcohol is prohibited by the CVC manufacturer.(1,3,5) Alcoholic povidone iodine should be used if the patient is known to be sensitive to chlorhexidine.(1,3,5) The antiseptic solution should be applied for at least 30 seconds using a side-to-side, back-and-forth motion, which will disrupt the skin cells and exposes the microorganisms to the antiseptic solution. The antiseptic should be allowed to dry naturally for at least 30 seconds.
- There are four broad classifications of CVC:
- Non-tunnelled catheters
- Tunnelled catheters
- Peripherally inserted central catheters (PICCs)
- Implanted ports.
Non-tunnelled catheters are associated with a high risk of CRBSI. They are the devices of choice for short-term use in acute and critical care; they are not appropriate for use within the community. These devices are available with single or multiple lumens; however, to reduce the risk of CRBSI the catheter should have the minimum number of lumens required for the management of the patient.(1,3,5)
Tunnelled catheters and PICCs are appropriate for medium- to long-term use in the hospital and the community. A port is a long-term device, fully implanted under the skin, and associated with a lower rate of CRBSI. The correct device should be selected for the correct therapy.(1,5,9,10)
Antimicrobial catheters have been developed in an attempt to reduce the high risk of CRBSI associated with non-tunnelled CVCs. The use of antimicrobial catheters is only recommended if hospitals or departments are unable to reduce their incidence of CRBSI through education programmes, the use of maximum sterile barrier precautions and the use of 2% chlorhexidine gluconate in 70% isopropyl alcohol for skin antisepsis.(1,3,5)
Catheter site selection
The site of catheter insertion has been shown to influence the development of CRBSI. The subclavian site is associated with the lowest risk of CRBSI but carries a high risk of mechanical complications, including pneumothorax and subclavian artery puncture. The benefits and risks must be evaluated prior to catheter site selection.(1,3,5) The subclavian site is the site of choice for non-tunnelled CVCs.(1,3) However, the subclavian site should not be selected for haemodialysis catheters because it is associated with an increased risk of subclavian vein stenosis.(3,4) The internal jugular vein is the recommended site for the placement of haemodialysis catheters.(4) The femoral site should not be used for CVC insertion because it carries the highest risk of CRBSI.(1,3–5)
Ultrasound for CVC insertion
The use of ultrasound is recommended for the placement of all CVCs, elective and emergency, because it is associated with a lower rate of complications, including CRBSI.(3,5)
The traditional use of sutures to secure CVCs is being challenged by increasing evidence that suggests they can be associated with an increased risk of CRBSI. Stabilisation devices, such as Statlock and Grip-Lok, now provide an alternative to sutures and are recommended as a strategy to reduce CRBSI.(3,5,9,10)
The ideal catheter dressing allows inspection of the catheter entry site while protecting the entry site from microbial contamination. Many guidelines recommend the use of a sterile, transparent, semi-permeable dressing but also recognise that gauze dressings are useful.(1,3,5) Gauze is suitable when patients are diaphoretic or when there is bleeding from the insertion site; once this has resolved the transparent dressing then becomes the dressing of choice.(1,3,5) Transparent dressings should be replaced every seven days or earlier if they become loose or soiled.(3–5,9,10) The catheter entry site should be monitored for signs of infection.(3,10)
Topical antimicrobial ointments are not recommended at CVC insertion sites as they are associated with an increased risk of fungal infection and microbial resistance.(1,3,5)
Catheter replacement and catheter removal
There is no evidence that the routine replacement of CVCs reduces the incidence of CRBSI.(1,3,5) CVCs should not be changed over a guide wire when catheter infection is suspected; a new site should be selected.(1,3,5) CVCs should be removed when they are no longer required.(1,3,5,9,10)
Administration sets and infusion equipment
Administration sets should be labelled with the date and time to ensure that they are changed appropriately. Administration sets for clear fluids should be changed every 72 hours but administration sets containing lipid should be changed every 24 hours.(1,3,5,9,10) Administration sets for blood and blood products should be changed when the transfusion is completed, or every 12 hours, whichever is sooner.(1,10) All changes should be performed using an aseptic technique.
Stopcocks (three-way taps) should be considered part of the administration set and changed when the set is changed. Needle-free devices should be changed in line with the manufacturer’s recommendations.
Stopcocks, catheter hubs, connections and needle-free devices should be thoroughly decontaminated with 2% chlorhexidine in 70% isopropyl alcohol before use, unless contraindicated by manufacturer’s instructions.(1,3,5,9,10)
Each individual evidence-based recommendation can contribute to a reduction in CRBSI. ‘Bundling’ all the recommendations together (care bundles) has an even greater impact on reducing CRBSI. The use of care bundles to consistently deliver a high standard of evidence-based care is effective in reducing CRBSI and maintaining low levels of CRBSI. Documenting and reporting compliance with the elements of the care bundle provides quality assurance and helps to set appropriate targets for performance improvement.(3)
- Pratt RJ et al. epic2: National evidence-based guidelines for preventing healthcare-associated infections in NHS hospitals in England. J Hosp Infect 2007;65S:S1–S64.
- Dimick JB et al. Increased resource use associated with catheter-related bloodstream infection in the surgical intensive care unit. Arch Surg 2001;136:229–34.
- O’Grady NP et al. Guidelines for the prevention of intravascular catheter-related infections, 2011. CDC and HICPAC. www.cdc.gov/hicpac/pdf/guidelines/bsi-guidelines-2011.pdf (accessed 5 January 2012)
- Vanholder R et al. (2010) Diagnosis, prevention and treatment of haemodialysis catheter-related bloodstream infections (CRBSI): a position statement of European Renal Best Practice (ERBP) www.ndtplus.oxfordjournals.org/content/3/3/234.full.pdf.
- Pittiruti M et al. ESPEN Guidelines on parenteral nutrition: central venous catheters (access, care, diagnosis and therapy of complications). Clinical Nutrition 2009;28:365–77. www.espen.org/documents/0909/Central%20Venous%20Catheters.pdf (accessed 5 January 2012).
- Robert J et al. The influence of the composition of the nursing staff on primary bloodstream infection rates in a surgical intensive care unit. Infect Control Hosp Epidemiol 2000;21:12–17.
- Fredericks DN (2001) Microbial ecology of human skin in health and disease. J Investig Dermatol Symp Proc 2001;6:167–69.
- Chaiyakunapruk N et al. Chlorhexidine compared with povidone-iodine solution for vascular catheter-site care: A meta-analysis. Ann Intern Med 2002;136:792–801.
- Infusion Nurses Society. Infusion Nursing Standards of Practice. J Infusion Nursing 2011;34:11.
- Royal College of Nursing. Standards for infusion therapy, 2010. Royal College of Nursing, London, UK.