Evidence-based measures to prevent central line-associated bloodstream infections: a systematic review 1

ABSTRACT Objective: to identify evidence-based care to prevent CLABSI among adult patients hospitalized in ICUs. Method: systematic review conducted in the following databases: PubMed, Scopus, Cinahl, Web of Science, Lilacs, Bdenf and Cochrane Studies addressing care and maintenance of central venous catheters, published from January 2011 to July 2014 were searched. The 34 studies identified were organized in an instrument and assessed by using the classification provided by the Joanna Briggs Institute. Results: the studies presented care bundles including elements such as hand hygiene and maximal barrier precautions; multidimensional programs and strategies such as impregnated catheters and bandages and the involvement of facilities in and commitment of staff to preventing infections. Conclusions: care bundles coupled with education and the commitment of both staff and institutions is a strategy that can contribute to decreased rates of central line-associated bloodstream infections among adult patients hospitalized in intensive care units.


Introduction
Central Venous Catheters (CVC) play an important role in the treatment of hospitalized patients, especially critically ill patients (1) . Intensive Care Units (ICU) employ measures such as diagnostic procedures and invasive devices that may trigger complications such as healthcare-associated infections (HAI) (2) . The challenges imposed to the prevention of nosocomial infections are even greater in an ICU due to the variety of microorganisms, often multiresistant, which require the use of broad-spectrum antibiotics. ICUs are characterized by performing invasive procedures intended for diagnostic purposes or to enable the cure of patients, but which complicate the control of infections (3) .
Note that central line-associated bloodstream infection (CLABSI) is the primary complication of central venous catheters (4) .
In the United States, from 250,000 to 500,000 CLABSIs are estimated to occur every year, which result in a rate from 10% to 30% of mortality (5) . A study was conducted in Brazil with 33 patients hospitalized in an adult ICU using a total of 50 CVCs. Of these, 18 were diagnosed with CLABSI. In regard to clinical outcome, 20% of the patients who presented CLABSI died.
The incidence of primary bloodstream infection was 1.52/1,000 catheters-day and the CVC utilization rate 0.80 (6) . Critical care workers should be aware of CLABSI rates in the ICUs in which they work and devise quality control programs to attain rates not higher than 0.5-1/1,000 CVC/day (7) .
In this sense, there is a concern over the risk of infections to which patients are exposed, the prevalence of CLABSI, the need to improve care concerning the implantation and maintenance of CVCs, and the adoption of evidence-based measures to ground the care provided by the health staff. Therefore, systematized care defined by evidence-based guidelines confers safety and quality onto the care provided by the intensive care team and can effectively reflect decreased HAI rates.
Seeking to contribute to safer care provided to critically ill patients, this study's aim was to identify evidence-based care to prevent central line-associated bloodstream infection among adult patients hospitalized in intensive care units.

Method
A systematic review was conducted in accordance with the protocol proposed by the Federal University of São Paulo (UNIFESP), together with Cochrane Brazil, namely: establishing the research question (using the PICO strategy); identifying and selecting studies; critically assessing studies; collecting data; analyzing and presenting data; and interpreting results (8) .
The colonization of insertion sites was not affected by the use of medical grade honey (p=0.98).
1.c (the Figure 2 (20) Bathing with 2% chlorhexidineimpregnated washcloths to reduce the risk of colonization by MRSA.
CLABSI incidence decreased in the period post intervention (p < 0.05).

2.d
Girard R et al./2012 (22) Comparison of effectiveness, ease of use, and costs of alcohol-based chlorhexidine antiseptic and povidone-iodine solutions.
Significant decrease in the incidence of colonization with the chlorhexidine solution (p=0.041). No significant difference in the incidence of CLABSI (p=0.426).

2.d
Hocking C et al./2013 (23) Implementation of insertion and maintenance bundles recommended by the Institute for Healthcare Improvement (IHI); bundles for high-risk patients; maintenance and insertion checklist; performance feedback to the team.  (40) Priority of the subclavian site even in the presence of tracheostomy rather than the femoral site.
Infection rates remained low after intervention (0.5 in 2008 and 0.2 in 2009).

3.e
Ellger B et al./ 2011 (42) Non-return valves designed to prevent backflow of fluid when more than one infusion is delivered through venous access.
Non-return valves did not protect against bacterial contamination nor prevented backflow; in 30% of cases, bacteria were detected proximal to the valve.

5.c
Richards GA et al./2014 (43) Use of Certofix ® protect CVC to prevent biofilm formation through a surface charged by chemical structures positively charged in the inner and outer surfaces.
The charge seemed to significantly inhibit biofilm formation, as well as diminish the number of isolated bacteria. However, due to limitations, we suggest a controlled clinical trial be conducted in the future.   (39) . Level of evidence: 3.e.

5.c
Three studies (8.8%) presented multidimensional programs that resulted in reduced rates of infections (13,25,33) . after the intervention. The study emphasized that the role of the nurse as a leader of the multi-professional team was key for the success of interventions (13) . Level of evidence: 1.c Four studies (11.7%) addressed educational strategies as the study's main focus, among which two also assessed the cost-effectiveness of this type of intervention (11,19,21,31) . Two studies presented a training program based on the simulation of sterile techniques during CVC insertion and showed that the program decreased infection rates from 3.6 to 1/1,000 cathetersday after the intervention in the first study (11) (1.c) and the second study reported a decrease of 3.82 to 1.29/1,000 catheters-day (31) . Level of evidence: 3.c.
One study assessed the cost-effectiveness of the strategy previously mentioned, associated with a care bundle, a catheter insertion cart and a verification list as mandatory in the program in which a nurse had the power to interrupt the procedure if the items contained in the list were not complied with. The simulation training was mandatory for all the hospital's physicians and included a pre-course, self-guided reading of papers and instructional books, a 4-hour simulation course supervised by assistant physicians and intensive care workers. The educational strategy resulted in a decrease of 58% in the incidence of CLABSI (21) . Level of evidence: 2.d. One study assessed the efficacy and costeffectiveness of educational interventions and suggested that a variety of educational approaches could be cost effective and decrease the facility's costs (19) . Level of evidence of economic analysis: 2.
Institutional strategies are considered important when seeking compliance with measures concerning the implantation and maintenance of central catheters. One study focused on external audits to assess compliance Perin DC, Erdmann AL, Higashi GDC, Sasso GTM.
with CVC insertion and maintenance practices, presenting monthly feedback to the team. Compliance with care practices increased during the intervention period, showing a significant decrease in the global incidence of infections, though the incidence rate either increased or remained stable after the intervention. The study emphasized the value of auditing-and feedbackbased interventions, though reports of lack of leadership and the staff's high turnover represent weaknesses, indicating the need for studies focused on behavioral change strategies (16) . Level of evidence: 2.c.
Due to the association of CVC with parenteral nutrition (PN), which incurs an increased risk of CLABSI occurring, and seeking to clarify the impact of the infusion system on infection rates, a multi-center study compared sterile multichamber bags for parenteral nutrition (PN). This is considered to be a closed infusion system, with compounded parenteral nutrition (two compounds). The rate of CLABSI was 35.3% greater among patients who received compounded PN in comparison to those who received PN through the closed system (14) . Level of evidence: 1.c.
In regard to bandages impregnated with antiseptic and antibiotics intended to reduce the colonization of bacteria on the catheter insertion site, one study assessed the potential of a bandage containing chlorhexidine to decrease infection. The facility where the study was conducted had already implemented care concerning the insertion and maintenance of catheters, surveillance and education. CLABSI rates were significantly lower among patients using bandages with chlorhexidine, 1.51/1,000 CVS days in comparison to 5.87/1,000 CVC days in patients with conventional bandages (27) . Level of evidence: 2.d.
The influence of different types of catheters on CLABSI prevention and decreasing biofilm formation was addressed in 3 studies (34)(35)(36) . there was a tendency for the incidence of CLABSI in the "subclavian + tracheostomy" group to be lower, 3.9 vs. 11.2I CLABSI/1,000 catheters-days (40) . Level of evidence: 3.e.
Studies tested some interventions that did not obtain significant results in reducing infections rates and colonization (10,12,15,18,20,22,(42)(43) . A study investigated whether non-return valves, designed to prevent the backflow of fluids, would be efficacious in reducing infections. The conclusion, however, was that nonreturn valves do not prevent backflow nor serve as a bacterial filter (42) . Level of evidence: 5.c. One CVC impregnated with silver nanoparticles was assessed, but no significant effect was found and for this reason it cannot be recommended (10) , nor can the use of CVC Certofix ® Protect (B Braun), which promised to prevent biofilm formation through a charged surface (43)