The CDC 2011 Guidelines for the Prevention of Intravascular Catheter-Related Infections
CDC Recommendations
Background
The optimal interval for routine replacement of IV administration sets has been examined in a number of well-controlled studies and meta-analyses. Data from these studies reveal that replacing administration sets no more frequently than 72–96 hours after initiation of use is safe and cost-effective [141, 177, 179–181]. More recent studies suggest that administration sets may be used safely for up to 7 days if used in conjunction with antiseptic catheters or if fluids that enhance microbial growth (e.g., parenteral nutrition or blood) have not been used [216, 345]. When a fluid that enhances microbial growth is infused (e.g., fat emulsions and blood products), more frequent changes of administration sets are indicated as these products have been identified as independent risk factors for CRBSI [182, 216, 346–350]. Little data exist regarding the length of time a needle used to access implanted ports can remain in place and the risk of CRBSI. While some centers have left them in place for several weeks without CRBSI, [351], this practice has not been adequately studied.
Needle-less Intravascular Catheter Systems
Recommendations
Background
Stopcocks used for injection of medications, administration of IV infusions, and collection of blood samples represent a potential portal of entry for microorganisms into vascular access catheters and IV fluids. Whether such contamination is a substantial entry point of microorganisms that cause CRBSI has not been demonstrated. Nonetheless, stopcocks should be capped when not being used. In general, closed catheter access systems are associated with fewer CRBSIs than open systems and should be used preferentially [352].
"Piggyback" systems (secondary intermittent infusions delivered through a port on a primary infusion set) are used as an alternative to stopcocks. However, they also pose a risk for contamination of the intravascular fluid if the device entering the rubber membrane of an injection port is exposed to air or if it comes into direct contact with nonsterile tape used to fix the needle to the port. Modified piggyback systems have the potential to prevent contamination at these sites [353].
Attempts to reduce the incidence of sharps injuries and the resultant risk for transmission of bloodborne infections to healthcare personnel have led to the introduction and mandating of needleless infusion systems. There are several types of needleless connectors on the market.
The first type of needleless system connectors consisted of a split septum connector, which is accessed with a blunt cannula instead of a needle (external cannulae activated split septums). Because of the large amount of space in the connector to accommodate the cannula, when the cannula is removed it may result in the creation of negative pressure which may cause blood to be aspirated into the distal lumen, possibly increasing the risk of catheter occlusion or thrombosis. A luer-activated device, which incorporates a valve preventing the outflow of fluid through the connector, was designed to eliminate this problem. Some luer devices require a cap to be attached to the valve when not in use, which can be difficult to maintain aseptically, and therefore they may be prone to contamination.
Another type of second-generation needleless system addressed the occlusion issue by incorporating positive or neutral fluid displacement to either flush out aspirated blood or prevent its aspiration into infusion catheters.
Use of needleless connectors or mechanical valves appear to be effective in reducing connector colonization in some [196, 354, 355], but not all studies [356] when compared with stopcocks and caps. In one study [354], the incidence of CRBSI was reduced when the needleless connector was compared with standard stopcocks. Appropriate disinfectants must be used to prevent transmission of microbes through connectors [357]. Some studies have shown that disinfection of the devices with chlorhexidine/alcohol solutions appears to be most effective in reducing colonization [195, 196]. In addition, the time spent applying the disinfectant may be important. One study found that swiping the luer-activated device with 70% alcohol for only 3 to 5 seconds did not adequately disinfect the septal surface [358]. However, a number of outbreak investigations have reported increases in CRBSIs associated with a switch from external cannulae activated split septum needleless devices to mechanical valve devices [197, 198, 200, 359]. The reasons for these associations are not known and it is also not known if this is a device-specific or class association, particularly as physical and mechanical properties of needleless connectors vary from device to device. In addition, one investigation found CRBSIs increased with the switch from a luer-activated negative displacement mechanical valve to a luer-activated positive fluid displacement mechanical valve [199]. However in an observational study, a switch from a luer-activated negative displacement mechanical valve to a different luer-activated positive displacement mechanical valve as part of a bundled intervention resulted in a significant decrease in CRBSIs [201]. Potential explanations for outbreaks associated with these devices include difficulty encountered in adequate disinfection of the surface of the connector due to physical characteristics of the plastic housing diaphragm interface, fluid flow properties (laminar vs. turbulent), internal surface area, potential fluid dead space, inadequate flushing of the device due to poor visualization of the fluid flow pathway in opaque devices, and the presence of internal corrugations that could harbor organisms, particularly if the catheters are used to withdraw blood [199]. Some studies have shown that the increase in CRBSIs with the change to lueractivated devices may be related to improper cleaning and infection control practices such as infrequently changing the devices [192, 194]. Additionally, silver-coated connector valves have been FDA approved; however, there are no published randomized trials with this device and no recommendation can be made regarding its use. Likewise, an antiseptic-barrier cap for needleless connectors has been studied in a laboratory setting and appears to be effective in preventing the entry of microorganisms [360], but has not yet been studied in a clinical trial.