Description of the condition
Central venous catheters (CVCs) play an important role in the management of patients, serving as reliable vascular access and the site of venous pressure monitoring. They are inserted when a patient requires venous access over an extended period of time, and allow the intravenous administration of complex drug treatments, blood products and nutritional support without the trauma associated with repeated needle insertions (Webster 2011). Although mostly used in intensive-care units and oncology settings, CVCs are increasingly being used in other wards and outpatient settings.
There are multiple types of CVCs in use throughout clinical practice. A CVC can be designated by: its intended life span (e.g. temporary or short-term versus permanent or long-term); its site of insertion (e.g. subclavian, femoral, internal jugular or peripherally inserted central catheter (PICC)); its pathway from skin to vessel (e.g. tunnelled versus nominee); its physical length (e.g. long versus short) or some other special characteristic(s) (e.g. impregnation with heparin or number of lumens) (O'Grady 2011). More information regarding the variety of catheters used in clinical practice is included in Appendix 1.
Owing to the invasive procedure necessary for placing a CVC and the resulting break in the skin (integument), complications such as exit-site infections and bloodstream infections can develop (Han 2010). A serious complication of CVCs is catheter-related blood stream infections (CR-BSI), also known as 'catheter sepsis'. CR-BSI rates are influenced by patient-related factors, such as severity and type of illness (e.g. full-thickness burns versus post-cardiac surgery), by catheter-related factors (such as the condition under which the catheter was placed and catheter type), and by institutional factors (e.g. bed size, academic affiliation) (O'Grady 2011). Many studies have estimated the incidence of CR-BSI, generally reporting a range between 1 and 3.1 per 1000 patient days (Pronovost 2006; Schwebel 2012), but rates have been shown to decrease to zero after interventions (Han 2010). The attributable cost of CR-BSI varies between USD 3124 and USD60,536 per event (Raad 2007; Schwebel 2012), and is associated with an attributable mortality of 0% to 11.5% (Timsit 2011).
CVCs are foreign objects, and, as such, require their external component both to be protected adequately from microbial contamination from the surrounding environment and secured to the skin. Dressings and securements must ensure CVCs do not dislodge or fall out (or both), or move within or out of the great veins. This can occur via movement or pressure on the external component of the device, through forced removal, or ‘drag’ from infusion tubing or ‘catching’ on environmental structures (Naimer 2004). Movement of the CVC to a location outside the target placement can result in line failure or cardiovascular instability. In critical situations line failure (e.g. the interruption of inotropic support during cardiogenic shock) can have catastrophic consequences for the patient's morbidity and mortality.
Description of the intervention
There is a plethora of CVC dressings and securements from which clinicians may select. The earliest securement approach was simple tape or gauze-tape, with plastic film dressings becoming prominent in the 1980s. First-generation occlusive standard polyurethane (SPU) dressings were later developed to become semi-permeable to oxygen, carbon dioxide and water vapour (e.g. OpSite IV 3000®, Smith and Nephew; Tegaderm Plus®, 3M), as occlusive dressings trap moisture on the skin and provide an ideal environment for quick growth of local microflora (Frasca 2010). Each dressing is transparent, permitting continuous visual inspection of the catheter site. A recent approach to CVC securement is the bordered polyurethane (BPU) dressing that retains the central polyurethane component of SPU dressings with an added external adhesive border of foam or cloth fabric to maximise catheter security (e.g. Tegaderm Advanced®, 3M).
The majority of CR-BSI are caused by micro-organisms found in the patient's own commensal skin flora, such as Staphylococcus epidermidis and Staphylococcus aureus (Timsit 2011); consequently, we have seen the arrival of medication-impregnated dressings in recent years. The most common of these are the chlorhexidine gluconate-impregnated (CGI) dressings. These CGI dressings release chlorhexidine-gluconate on the cutaneous underlying surface when placed over the catheter insertion site (Arvaniti 2012). Chlorhexidine gluconate is a cationic biquanide that provides rapid antisepsis because of its broad spectrum of germicidal activity against most CR-BSI-causing pathogens (Garland 2001). The chlorhexidine gluconate impregnates the whole dressing, or is applied using an impregnated sponge (e.g. Biopatch®) and covered by a transparent polyurethane dressing. Other medication-impregnated dressings discussed in the literature include silver-impregnated and iodine-impregnated dressings (Wille 1989). The iodine-impregnated dressings release free iodine when exposed to wound exudate, while the silver-impregnated dressings expose the entrance site to silver ions, which are thought to have antimicrobial properties. Some researchers recommend the use of hydrocolloidal dressings for the dressing of CVCs. This type is traditionally used on open wound sites to promote moist healing as, as the hydrocolloid matrix absorbs excess moisture away from the skin surface, it reduces the likelihood of microbial growth (Nikoletti 1999).
Securement of the CVC is also facilitated by mechanisms other than dressings. Traditionally, CVCs were routinely sutured in place, prior to a dressing being applied (O'Grady 2011). In addition to this option, clinicians frequently reinforced the device security using non-commercial options including sterile strips or non-sterile tape. Recently, sutureless securement devices (SSD) have become available commercially. These are used in addition to transparent dressings, and use a large adhesive footplate and an underlying pad with an device-locking clasp (e.g. Statlock®, Bard). These, theoretically, reduce movement, kinking and flow impedance, maximising catheter stabilisation (Yamamoto 2002).
Each of these CVC dressing and securement types has different therapeutic goals and is readily available for clinicians and patients to purchase from numerous suppliers. The diversity of dressings and securements available to clinicians (including variation within each of the types discussed above) makes evidence-based decision-making difficult in this area. With the availability of increasingly sophisticated and expensive CVC dressings and securements, practitioners need to know how effective these dressings are compared with more traditional dressings.
How the intervention might work
The ideal CVC dressing should:
provide a barrier protection from colonisation and infection, preventing CR-BSI;
provide adequate securement to prevent accidental removal, partial dislodgement and micro-motion, preventing CVC failure;
be comfortable and non-irritating for the patient;
be easy to use; and
Several studies have reported the effectiveness of interventions to reduce CR-BSI rates, including maximal sterile precautions during insertion, skin antisepsis, securement devices and antimicrobial coatings (Levy 2005; Han 2010; Timsit 2011). The role of the CVC dressing in preventing CR-BSI is to provide a barrier protection, thereby preventing migration of skin organisms at the insertion site into the cutaneous catheter tract - and subsequent colonisation of the catheter tip - and preventing direct contamination of the catheter by contact with hands and other materials (O'Grady 2011).
Why it is important to do this review
Decreasing the incidence of CR-BSI and preventing CVC failure are important objectives with a significant impact on patient morbidity and mortality, yet there is no consensus on the optimal dressing type to use with CVCs, despite more than two decades of research and debate. The recent Cochrane review "Gauze and tape and polyurethane dressings for CVC" focused on only two product types (Webster 2011), and, therefore, does not adequately address the variety of products now available in the clinical environment. A large variety of dressings and types of securement are currently available for use with CVCs, as well as reports from many research studies that used different outcomes and comparisons.