Healthcare-associated infection is a major patient safety concern that causes morbidity, mortality and increased healthcare costs. The prevention, or at least significant reduction, of catheter-related bloodstream infections (CRBSIs) requires a multimodal approach, with adherence to rigorous application of standardised infection prevention and control behaviours (Loveday et al, 2014). Vascular access remains the most frequent invasive procedure undertaken in healthcare, with 60% of patients in the UK and 80% in the US requiring intravenous (IV) access (Lavery and Ingram, 2005; Hadaway, 2012; Wallis et al, 2014). However, the lack of compliance to best practice by many health professionals continues to create a high risk of infection and other complications.
In 2016, Pronovost et al published research on the progress of the first version of the Michigan Keystone project research data, which had been initiated in 2009. The results demonstrated a significant reduction in central venous catheter-related infection following implementation of simple infection-control practices such as standardised skin decontamination before catheter insertion; use of sterile drapes, gowns and gloves; and use of ultrasound to cannulate the vessel. (By reducing multiple needlesticks, ultrasound will not only increase vessel health but also reduce the number of breaches in the skin, and thus the risk of contamination and infection.)
Since then, healthcare providers have understood that the process for reducing vascular access device (VAD)-related infection is multidimensional, and that, with the right interventions, a near zero CRBSI rate is possible (Hakko et al, 2015).
In recent years, there have been many advances in techniques related to the insertion, care and maintenance of VADs, but there is still more to do. Many devices and systems are currently available, with more innovations expected. Despite these advances, the risk of complications persists, so the priority remains to focus on the basics. This article focuses on the risk of complications associated with the improper care and maintenance of needlefree connectors (NFCs) and IV lines. It explores how these complications occur and outlines the evidence on how to avoid them.
Implications of poor practice on infection
Woller et al (2016) stated that patients require IV therapy interventions earlier and for longer periods, and that long-term central venous access is now common in all areas of acute hospital and community settings. The care and maintenance of these VADs play a vital role in reducing the risk of CRBSIs. Routine practice in all healthcare organisations should comprise consistent implementation of a standardised approach; the best way of achieving this is to use care bundles (Stevens and Schulman 2012; Hugill, 2017). Care bundles provide a structured framework for delivering evidence-based care: they generally comprise a set of three to five clinical practices, some of which may relate to the use of devices, that when performed collectively and reliably, have been proven to improve patient outcomes (Institute for Healthcare Improvement, 2019).
Knowledge about how CRBSI and exit site infections occur can help avoid their occurrence; understanding the differences between intraluminal and extraluminal infection can inform healthcare providers about which measures will maintain the catheter (Kallen et al, 2010) and keep it free from complications. There is a significant risk that microorganisms can enter the exit site, form a biofilm on the outside of the indwelling catheter and then find their way into the bloodstream (Taylor and Palagiri, 2007; Han et al, 2010). This can result in colonisation, which, if left untreated, can lead to systemic infection.
Frasca et al (2010) and, more recently, Moreau et al (2019) stated that the most effective way to reduce the risk of exit site infection is to regularly decontaminate the skin surrounding the catheter exit site and then cover the device with a semipermeable, vapour permeable dressing, ensuring that the area of decontaminated skin is larger than the film dressing. The dressing should be left in place for 7 days, during which time it should not be disturbed unless debris is visible under the dressing or the dressing starts to lift (Royal College of Nursing (RCN), 2016).
Exit site extraluminal infections are easier to recognise and treat in the initial stages of infection as the site will show signs of phlebitis; the first sign is usually redness of the skin around the catheter, along with localised pain and swelling (Brooks, 2016).
In contrast, intraluminal CRBSI remains the most significant infection complication but, unlike extraluminal infections, it might not be visible. Studies, such as Curran (2016), have shown that colonisation of the NFC or the presence of intraluminal biofilm can result in pathogens finding a way into the internal lumen of the IV catheter and then into the bloodstream. Both can result from poor practice during the manipulation of the NFC and injection of IV therapy. Central venous IV line infections are associated with increased physical and psychological morbidity, mortality, length of hospital stay and costs (Ferroni et al, 2014). The severity of an infection and its outcome will depend on many things including how quickly it is identified and treated, and the type of device used.
Burden of vascular access device-related bloodstream infections
To standardise clinical practice, it is essential to understand the definitions of CRBSI, which applies to all indwelling VADs, and central line-associated bloodstream infection (CLABSI). In 2017, a round table was held in which a group of experts discussed these two different classifications, with a view to identifying possible approaches for standardising best practice for reporting and reducing these infection rates (Fronzo, 2017). Although the term CRBSI is the more valid infection-rate indicator as it is based on blood and catheter-tip culture results from samples taken from the actual catheter and in different locations of the venous circulation, making it arguably more scientific than CLABSI, it is typically used for clinical research rather than surveillance purposes. In contrast, the term CLABSI is used for surveillance only. It is widely used in health care in the UK, particularly in critical care, to monitor acute central venous catheter infection rates, as they can be reported to the Department of Health (Fronzo, 2017).
Like Madni and Eastman (2018), the experts attend the round table were trying to devise an umbrella term to cover both classifications. Unfortunately, they were unable to come to a consensus, and this was ultimately defined by Holzmann-Pazgal (2019) as the presence of bacteraemia originating from an intravenous (IV) catheter.
VAD-associated infections account for up to 20% of hospital-acquired infections in the UK, and are associated with an increased length of hospital stay, mortality and treatment costs (Health Protection Agency, 2012). In the UK, it is estimated that the cost of treating a single CRBSI is approximately £9900 (Thokala et al, 2016).
Role of care bundles
Simple interventions in the care and maintenance of VADs can help to significantly reduce the incidence of infections and other complications. In the author's experience, this can make organisations feel safer and well-led, which will reassure their users and increase confidence in care.
Care bundles have been shown to reduce infection rates (Choi et al, 2013) and the risk of complications associated with VADs (Sichieri et al, 2018). They are available in a variety of formats and their adoption will depend on the healthcare organisation and its needs. Some trusts that advocate the use of disinfecting caps, based on the evidence, might include them in their care bundles to standardise and document this practice: it will make this practice auditable and remind staff when the cap was applied. Nevertheless, the use of disinfecting caps can be just as effective when introduced into routine IV practice (Holzmann-Pazgal, 2019).
Care bundles can also enable early detection of complications such as CRBSI and exit site infection as they prompt health professionals to observe the exit-site for signs of phlebitis, discharge or tracking of the vein. Unfortunately, care bundles alone will not achieve a reduction in CRBSI rates (Harnage, 2012) as the health professional needs to know what action to take when a complication is observed. In addition, care bundles also, of course, rely on compliance (Chopra and Shojania, 2013; McGuire, 2015; Simon et al, 2016). Sadly, non-compliance with the care and maintenance of VADs is often a catalyst for more serious complications, such as CRBSI. To prevent the occurrence of basic complications, it is essential that devices have safeguards such as long-term subcutaneous fixation devices (to prevent catheter migration), impregnated film dressings (to reduce the risk of exit site infection), passive or positive pressure NFCs (to prevent blood reflux into the distal catheter tip) and disinfecting caps (to mitigate the effects of non-compliance with the care and maintenance of VAD and thus reduce the risk of CRBSIs).
Disinfection of needlefree connectors
NFCs can protect against contamination and infection of the distal hub of the IV catheter, which is a primary entry point for microorganisms into the catheter lumen and the bloodstream. NFCs can also reduce the risk of other complications, such as occlusion, air embolism and thrombosis, and extend the life of the VAD (Kelly et al, 2017). However, if they are not maintained and used correctly, they can also increase the risk of intraluminal contamination (Hanchett, 2019).
Any exposed part of a catheter can harbour bacteria. NFCs are handled regularly when a catheter is in use, which is one reason why they need to be disinfected before use (Curran, 2016). Disinfection relies on adherence to guidance on scrub-the-hub practice. If NFCs have been insufficiently cleaned or are touched after disinfection, there is a risk that bacteria could be injected into the vascular system when they are next used (Percival et al, 2014).
The scrub-the-hub concept is not a new practice, and there is much evidence to support it. However, it is well documented that compliance with this technique is low (Moureau and Flynn, 2015), creating a significant safety issue. A systematic review found that colonisation of NFC hubs is considered to cause 50% of post-insertion catheter-related infections (Moureau and Flynn, 2015).
This safety risk was highlighted in a study by Casey et al (2018), which investigated the differences in microbial ingress between six different NFCs. Assessments included how long it took to manually disinfect them (including drying time). The study concluded that different types of NFCs might be associated with different risks of internal microbial contamination. It showed that even 15 seconds of decontamination may not fully eradicate microorganisms from the injection ports of some devices. It seems that the small crevices in the top of some NFCs can create dead space in which bacteria can multiply.
The manual disinfection of NFC requires a multi-step approach, but the technique and length of time required for manual disinfection are open to interpretation. In a survey of 1237 UK hospital departments, it was reported that 77% of IV hubs were being cleaned for ≤25 seconds, 54% for ≤10 seconds and 30% for ≤5 seconds; all of these timings sit outside national guidance (Rawlinson, 2014).
Most healthcare organisations use a wipe impregnated with 2% chlorhexidine and 70% alcohol, which has been proven to decontaminate NFCs if applied for 30 seconds, as recommended by evidence-based guidelines such as Epic3 (Loveday et al, 2014; Infusion Therapy Society (INS) standards, 2016; RCN, 2016). Manufacturers and suppliers of the most commonly used NFC advise that the disinfected area should be left to dry for 30 seconds or until ‘visibly dry’ (Clinell, 2015). However, it seems that the amount of time required to disinfect a NFC is often overlooked by health professionals.
Benefits of passive disinfecting caps
The above evidence demonstrates that CRBSI rates can be significantly reduced with a high level of adherence to guidance on NFC disinfection. However, manual disinfection of NFCs is significantly affected by human factors such as workload, stress, competency and training (Van Cott, 1994).
One way of mitigating this is to use passive disinfecting caps. Also known as port protectors, these are devices that are impregnated with an antiseptic agent and connected to the luer fitting of a NFC when it is used with a central or peripheral line. They act as a physical barrier between line accesses.
Recent evidence demonstrates that passive disinfecting caps are effective in maintaining a low rate of CLABSI. A systematic review and meta-analysis found that passive disinfecting caps significantly reduced the incidence of CLABSI when compared with manual disinfection. Of the nine UK and US studies included in the review, five described cost savings ranging from US$39 050 to US$3 268 990 (Voor et al, 2017). The authors concluded that passive disinfecting caps should be considered for inclusion in central-line maintenance care bundles.
Cameron-Watson (2016) examined the effect of implementing the use of a passive disinfecting cap on compliance and the incidence of VAD-related bacteraemia within one hospital trust. Before the audit, staff at the trust had scrubbed the hub with a wipe impregnated with 2% chlorhexidine and 70% alcohol. During the 6-month audit period, when the trust switched to the passive disinfecting cap, CRBSI rates reduced from 26 to eight cases (69%); staff compliance with the disinfection procedure increased to ≥80%. Cameron-Watson concluded that passive disinfecting caps facilitate a consistent technique for the decontamination of NFCs, ensuring they are disinfected and dried (the ‘kill time’) for the correct time period.
In their systematic review, Moureau and Flynn (2015) concluded that, despite educational initiatives and the availability of more effective disinfection agents, there is still non-adherence to best practice for disinfecting access ports, both before and after access. Alonso et al (2019) also undertook a systematic review on disinfection times for NFCs, in which they identified that <15 seconds was substandard and that ≥30 seconds decreased the line contamination, suggesting that it should be incorporated into clinical practice.
In 2015, Kamboj et al examined the impact of routine use of passive disinfecting caps on catheter hub decontamination in a group of haematology-oncology patients in a US centre. They found that use of the caps was associated with a 34% decrease in CLABSI rates in these high-risk patients. This reduction equated to an estimated annual saving of US$3.2 million.
Nicolás et al (2015) compared rates of colonisation inside the hub, assessed using cultures, and phlebitis in standard care (scrub-the-hub) versus a passive disinfection system that combined a luer disinfecting cap with a 70% isopropyl alcohol-impregnated sponge. This study, which was conducted over a 1-month period in a Spanish healthcare setting and involved 29 patients, found that bacterial growth was detected in 43.7% of the standard care samples compared with none in the passive disinfecting cap ones. No differences in the degree of contamination were found between NFCs used on central venous and peripheral VADs and there were no cases of phlebitis.
Wright et al (2013), DeVries et al (2014), Merrill et al (2014) and Stango et al (2014) all demonstrated similar results where passive disinfecting caps improved patient outcomes by reducing CRBSI rates and increasing adherence to catheter care and maintenance. Ramirez et al (2012) and Sweet et al (2012) both showed a significant reduction in CLABSI rates using disinfecting caps and an increase in adherence to care and maintenance bundles in a critical care setting and an oncology department, respectively.
BD PureHub™ Disinfecting Cap
There is a body of evidence indicating that use of disinfecting caps represents good clinical practice. BD has therefore developed a cap designed to enable rapid and powerful disinfection of NFCs. The device, called the BD PureHub uses a sterilised 70% isopropyl alcohol solution to disinfect NFCs, providing a >4-log (99.99%) reduction in bacteria within 1 minute of application (BD White Paper, 2018). Log reduction is a mathematical term used to show the relative number of live microorganisms eliminated from a surface as a result of disinfection or cleansing. A 4-log reduction means the number of germs is 10 000 times smaller than it was previously. Furthermore, when used in combination with the BD MaxZero™ and BD MaxPlus™ NFC, the BD PureHub can reduce the time required for passive disinfection from 60 to 15 seconds (BD White Paper, 2018).
The manufacturer states that the BD PureHub cap maintains a physical barrier against contamination for up to 7 days if not removed, indicating that its use facilitates adherence to disinfection protocols. The cap is compatible with the existing luer NFCs available on the market. The actual cap has finger grips to ease application and removal (Figure 1).
The evidence summarised above clearly indicates that the use of passive disinfecting caps on NFCs can significantly reduce CLABSI rates. Relying on the manual scrub-the-hub technique seems flawed as it relies on the health professional cleaning the NFC effectively for the required time every time it is used. BD PureHub is designed to ensure that the NFC is fully disinfected and acts as a barrier against the ingress of bacteria, protecting the NFC when the catheter is not in use.
All VADs with out-of-the-body dwelling lumens, such as peripherally inserted central catheters (PICCs) and tunnelled catheters, should be flushed every 7 days if not removed, regardless of whether or not they are in use (RCN, 2016). The BD PureHub should be changed when this flushing takes place.
Use of the BD PureHub should reassure patients and healthcare organisations that catheters in situ are being protected. The cap has a distinctive colour, and so it can be easily identified that the attached hub has been disinfected. It also serves as a visual reminder that the VAD is being used and protected. This can be important for patients with a tunnelled renal catheter, which should only be used for dialysis. Health professionals are more likely to pay attention to a catheter lumen if there is a brightly coloured cap protecting the hub from clinical misuse. In catheters being used to administer parenteral nutrition, the cap can be used to protect the NFC and lumen of catheters from transient bacteria; these can colonise and rapidly multiply in areas around the connector, where the parenteral nutrition liquid can lay dormant when the catheter is not in use (RCN, 2016).
The BD PureHub is part of an approach to vascular access management that aims to improve efficiency, standardise practice and, ultimately, improve patient outcomes.
Conclusion
The evidence indicates that use of passive disinfecting caps is good practice for protecting lumens of central venous catheters. The literature on the use of these disinfecting caps has focused exclusively on short non-tunnelled, cuffed and non-cuffed central catheters, PICCs and midlines. However, it could easily be applied to peripheral cannula, especially in light of the guidance from Epic3 (Loveday et al, 2014) about extending the indwell time for peripheral cannulae to as long as the device is required. Further research and evidence on the use of disinfecting caps on peripheral cannulae would be justified.
The evidence supports the routine use of BD PureHub passive disinfecting caps, as part of a care bundle, for the prevention of CRBSI in units where infection rates are high. The cap serves as a barrier to intraluminal infection and its bright colour provides a visual prompt to health professionals to undertake VAD care and maintenance. Its use will help protect patients and reduce costs.