Innovations in healthcare have led to survival of a higher proportion of critically-ill, elderlyudand immuno-compromised patients. Intravascular devices (IVDs) are indispensable inudproviding safe, reliable vascular access and continuous haemodynamic monitoring of theseudpatients in the intensive care unit. Unfortunately, many healthcare-acquired or nosocomialudinfections in severely ill patients can be caused by the very medical devices that areudimplanted to provide life-sustaining care.udIVDs comprising peripheral arterial catheters (ACs), non-tunnelled short-term central venousudcatheters (CVCs) and peripherally-inserted central catheters (PICCs) breach the skin andudprovide a potential avenue for external micro-organisms to invade the tissue or bloodstream.udAll IVDs are associated with a risk of both local and systemic catheter-related bloodstreamudinfection (CRBSI).udFew studies have been conducted on colonization rates of ACs and their potential to causeudCRBSI. Therefore, in a preliminary study, we compared the colonization rates of ACs withudCVCs which were concurrently managed in a defined cohort of patients. This study revealedudthat both AC colonization and CRBSI rates were comparable to those in concurrently-sitedudand identically managed CVCs. Therefore, ACs should be accorded the same degree ofudimportance as CVCs as a potential source of sepsis. This observation led to the developmentudof 3 studies to critically examine a number of aspects of this problem.udStudy 1: To determine the predominant mechanism of ACs colonization by comparing ACsudaccessing frequency to colonization rateudStudy 2: To determine the degree of microbial colonization on the external and internaludsurfaces of concurrently-sited IVDs and to establish if microbial growth is greater on audparticular segment of the IVDs at the time of removal. Study 3: To determine the degrees of concordance of nursing care and management of IVDsudwith Centers for Disease Control and Prevention (CDC) guidelines and institutionaludprotocols, and how the deficit in adherence to these protocols may impact on IVDudcolonization.udThere are currently three explanations for the process of microbial colonization in IVDs. Theudfirst suggests colonization by micro-organisms occurs on the outside of the catheter, eitherudvia downward colonization of micro-organisms from the patient’s skin surface on the outsideudsurface of the catheter, or via upward colonization where the micro-organisms are inoculatedudon the tip of the IVD at the time of insertion. The second suggests micro-organisms areudintroduced via the inside surface of the IVD, either via a contaminated infusate, or viaudcontamination of the port or hub connected to the IVD. The third suggests that microorganismsudare disseminated from some other part of the patient’s body, and carried via theudbloodstream to both the inside and outside surfaces of the catheter.udA common assumption is that the more frequently an IVD is accessed, the greater theudlikelihood of contamination and colonization. My first study sought to determine if accessingudfrequency had an influence on the rate of colonization in ACs, thereby testing the influence ofudthe second mechanism (i.e. contamination of hub or infusate) on IVD colonization. In thisudstudy we used some of the data from the prior surveillance cohort with additional dataudcollection. No significant differences were found between the rates of accessing the ACs andudtheir colonization when adjusted for confounding, continuous variables. Accessing frequencyudof an AC did not appear to be a major predisposing factor for the likelihood of colonization,udsuggesting that the second mechanism of IVD colonization via the intra-luminal route wasudless common in the context of reasonable application of aseptic practices.My next study focused on determining the degree of microbial colonization on the externaludand internal surfaces of concurrently-sited IVDs, and to establish if a relative difference inudmicrobial growth existed on a particular segment of the IVD at the time of removal. Thisudinvolved determining the colony count at six different sites on each individual IVD, allowingudrepeated-measures comparison of each IVD with itself. Degree of colonization was greatestudat the proximal, external surface of the intravascular segment of all IVD types compared toudthe middle or distal segments. Overall degree of colonization on the IVDs’ internal surfacesudwas also less than on the external surfaces. This suggests that the wound site created by IVDudinsertion may be a significant source of colonization and CRBSI. This finding raised theudquestion if IVD wound-site care practices might contribute to the likelihood of colonization.udIt is apparent that IVD colonization is caused by multiple factors, one being the environmentudin which these IVDs are managed and cared for on a daily basis. Practice guidelines andudinstitutional infection control protocols provide a reference point for nurses involved with theudcare and management of IVDs to implement best practice. However, little is known aboutudhow closely nurses adhered to the guidelines and protocols when caring and managing IVDs,udand if any variations in practice contributes to increased microbial colonization in IVDs.udTherefore, the final study sought to determine the degree of concordance of current nursingudpractice to evidence-based practice guidelines, as a proxy for actual adherence to protocols,udand how partial or non-adherence to protocols may impact on colonization. This studyudshowed that there was less than ideal adherence to practice protocols, and that for someudaspects of practice, adherence to protocol by intensive care unit nurses (who manage IVDudcare daily), was less than those who had less experience of IVD care. Clearly, nurses haduddifferent preferences for sourcing advice and information about IVD care practices. Futureudresearch would be required to determine whether this differential adherence to protocols andudguidelines was associated with poorer outcomes, better outcomes, or no outcome differences.In summary, the major findings of this work are:ud1) Establishing that AC colonization rates and CRBSI rates were similar to CVCs,udreiterating the need to accord the same degree of importance to ACs as CVCs as audpotential source of sepsis.ud2) Dispelling the notion that the more frequently an IVD is accessed, the greater theudlikelihood of contamination and colonization.ud3) IVD colonization via the intra-luminal route was less common when compared to theudmechanism of microbial colonization on the external surface of the IVD.ud4) Microbial colonization is heaviest on the external surface of the proximal segment ofudall IVD types compared to the middle or distal segments, and that overall degree ofudcolonization on the IVDs’ internal surfaces was also less than on the external surfaces.ud5) Discrepancies in concordance between the CDC guidelines and current nursingudpractice existud6) A knowledge-practice gap exists because the access to evidence-based protocolsudintended to provide vital information and guide nursing practice may be hindered byudthe choice of end-users who may not use these protocols.
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