John: Hello, I'm John Hilton, editor of the Cochrane Editorial unit. One of the most widely used devices in medicine is the central venous catheter, allowing direct access to a patient’s blood stream. However, it can cause infections and the use of antiseptics on the skin is one way to minimise this risk. Nai Ming Lai from the School of Medicine in Taylor's University in Malaysia has worked with colleagues to examine the relevant evidence and led the Cochrane Review, published in July 2016.

Nai Ming: The central venous catheter, or CVC, is an important device for administering fluids, blood products, medications and parenteral nutrition directly into a person’s blood. However, by providing a way for micro-organisms to colonise and spread inside the body it can increase mortality, morbidities and the costs of health care. In order to try to reduce these catheter-related infections, healthcare staff often use antiseptic solutions to clean the skin around the catheter insertion site, both prior to insertion and whilst the catheter is in place.
Our review assesses the effects of skin antisepsis as part of CVC care and has shown that it is not clear whether this cleaning of the skin around CVC insertion sites reduces catheter related blood stream infection compared with no skin cleansing.
We included 13 studies, with a total of nearly 3500 CVCs. The studies were from 8 countries across America, Europe and Asia, and were mostly done with adults in intensive care units or other specialist hospital units. Most studies assessed skin antisepsis before insertion and while the CVC was in place, but the quality was mixed, with blinding of the participants and carers being a major problem.
The studies had made several different comparisons. The first of which was skin antisepsis against no skin antisepsis, and the three studies found no evidence of clear differences in catheter related blood stream infections, colonisation of the catheter and need for antibiotics.
There were also several head-to-head comparisons between different skin antiseptic agents. The most common comparison was chlorhexidine solution versus povidone-iodine solution as active substances. These studies showed that chlorhexidine solution may modestly reduce catheter related blood stream infections as well as catheter colonisation compared with povidone-iodine solution. However, it is unclear whether there was an effect on mortality rates as only one study reported this, and although similar death rates were observed with chlorhexidine and povidone iodine, the small numbers mean that a difference cannot be ruled out.
Evaluations of other skin antiseptic agents were generally made in single, small studies, many of which did not report our primary outcome of catheter-related blood stream infection, or other important outcomes such as skin infections and adverse events.
In summary, it is unclear whether skin antisepsis reduces catheter related blood stream infection compared with no skin antisepsis. Skin antisepsis using chlorhexidine solution may reduce rates of catheter related blood stream infection and colonisation compared with antisepsis using povidone iodine. However, these findings are based on very low quality evidence, which means the true effects may be very different; and the results may be influenced by the nature of the antiseptic base solution, namely, whether an aqueous or alcohol-based solution is used. Further trials are needed to assess the effectiveness and safety of different skin antisepsis regimens and these should measure critical clinical outcomes such as sepsis, catheter-related blood stream infections and mortality.

John: If you would like to read more about the current evidence, or to watch for future updates of this review should these trials be done, you can find the full version online in the Cochrane Library. Got to Cochrane library dot com and search ‘skin antisepsis’.