This paper examines the evidence base for preventing central venous catheter-associated bloodstream infections, with a focus on the relative merits of sterile versus clean techniques. It opens by establishing the prevalence of central venous catheter use and the documented risks of catheter-related complications, including infection, hemorrhage, and thrombosis. A review of three key clinical studies — covering antimicrobial-coated catheters, antibiotic-lock techniques, and large-scale prospective surveillance — demonstrates that sterile techniques consistently outperform less rigorous approaches. The paper then describes evidence-based practice guidelines for catheter insertion and maintenance before concluding that sterile technique represents the superior standard of care.
Central line infections can be serious and even life-threatening, but the threat is largely preventable when proper cleaning techniques are used. Central line-associated bloodstream infections are well-documented risks associated with central venous catheter use (Doran, Ivy, Barst, Hill & Murali, 2011). Chronic intravenous therapy introduces a number of significant challenges for patients and caregivers alike, who are required to become proficient with the sterile preparation of medication, operation of the pump, and care of the central venous catheter in order to prevent catheter-related bloodstream infections (Doran et al., 2011).
Lorente, Henry, and Martin (2005) emphasize that central venous catheters are commonly used in critically ill patients for the administration of fluids, medications, blood products, and parenteral nutrition, for the insertion of a transvenous pacing electrode, and to monitor hemodynamic status (p. 631). Although precise figures are not universally available, some indication of the prevalence of central venous catheter use can be discerned from the results of a clinical study by EPIC, which found that more than three-quarters (78%) of critically ill patients had some form of central venous catheter inserted (Lorente et al., 2005).
Central venous catheterization can result in a number of adverse outcomes, including infection, hemorrhage, and thrombosis (Lorente et al., 2005). The growing attention being paid to catheter-related infections concerns their inordinately high mortality rates and the high costs associated with the intervention (Lorente et al., 2005). Current estimates indicate that between 1% and 13% of central venous catheterizations develop a catheter-associated bloodstream infection (Lorente et al., 2005). Despite the growing body of evidence concerning these infections, there remains a dearth of studies that have investigated the problem in detail (Lorente et al., 2005).
Because the risk is well documented, all clinicians, patients, and caregivers should follow effective methods for preventing central venous catheter-associated bloodstream infections (Kovner & Knickman, 2005). Even with the best precautions in place, however, central venous catheter-associated bloodstream infections can still occur (Lorente et al., 2005).
A study of 281 hospitalized patients requiring 298 triple-lumen polyurethane venous catheters in five university-based medical centers was conducted by Raad, Darouiche, and Dupuis (1997). The researchers used 147 catheters pretreated with tridodecylmethyl-ammonium chloride and coated with minocycline and rifampin, with 151 untreated, uncoated catheters used as controls. Quantitative catheter cultures, blood cultures, and molecular typing of organisms were used to determine catheter-related colonization and bloodstream infections and to evaluate the efficacy of the intervention.
The results of this randomized, double-blind study showed that the experimental and control groups were comparable in terms of age, gender, preexisting diseases, degree of immunosuppression, therapeutic interventions, and risk factors for catheter infections (Raad et al., 1997). According to these researchers, "Colonization occurred in 36 (26%) uncoated catheters and 11 (8%) coated catheters (P < 0.001). Catheter-related bloodstream infection developed in 7 patients (5%) with uncoated catheters and no patients with coated catheters (P < 0.01)" (Raad et al., 1997, p. 273). The statistical analysis indicated that coating catheters with minocycline and rifampin provided an independent protective factor against catheter-related colonization, with no adverse effects related to the coated catheters or antimicrobial resistance being identified (Raad et al., 1997). These researchers concluded that sterile catheters can save both money and lives (Raad et al., 1997).
A study by Carratala, Niubo, and Fernandez-Sevilla (1999) evaluated the efficacy of an antibiotic-lock technique for the prevention of catheter-related infections caused by gram-positive bacteria in neutropenic patients with hematologic malignancies. Patients with nontunneled, multilumen central venous catheters were assigned in a randomized, double-blinded manner to receive either 10 U of heparin per ml (57 patients) or 10 U of heparin per ml and 25 μg of vancomycin per ml (60 patients), which were instilled in the catheter lumen and allowed to dwell for one hour every two days (Carratala et al., 1999).
The randomized, double-blind study by Carratala and his associates used the following protocols:
Insertion-site and hub swabs were taken twice weekly. The primary and secondary end points of the trial were significant colonization of the catheter hub and catheter-related bacteremia, respectively.
The key findings of this study included the following:
Significant colonization of the catheter hub occurred in nine (15.8%) patients receiving heparin — seven patients were colonized with Staphylococcus epidermidis, one with Staphylococcus capitis, and one with Corynebacterium sp. None of the catheter hubs of patients receiving heparin and vancomycin were colonized (P = 0.001). Catheter-related bacteremia developed in four (7%) patients receiving heparin — three had S. epidermidis bacteremia and one had S. capitis bacteremia — while none of the patients in the heparin and vancomycin group developed catheter-related bacteremia (P = 0.05). The times to catheter hub colonization and to catheter-related bacteremia by the Kaplan-Meier method were longer in patients receiving heparin and vancomycin than in those receiving heparin alone (P = 0.004 and P = 0.06, respectively). These results indicate that sterile techniques were more effective in reducing the incidence of catheter-related infections (Carratala et al., 1999).
Finally, a prospective observational study conducted by Lorente and his associates in a 24-bed medical surgical intensive care unit of a 650-bed university hospital included all consecutive patients admitted to the ICU during the three-year period from 1 May 2000 to 30 April 2003, for a total of 2,018 patients. The number of central venous catheterizations and the number of catheter-days were as follows:
Global: 2,595 catheterizations and 18,999 catheter-days; Subclavian: 917 and 8,239; Jugular: 1,390 and 8,361; Femoral: 288 and 2,399.
The catheters used in the Lorente et al. study were radiopaque polyurethane catheters rather than antimicrobial-coated catheters. Catheter placement and maintenance were performed using the following protocol:
1. Catheters were inserted by physicians using the following sterile-barrier precautions: large sterile drapes around the insertion site, surgical antiseptic hand washing, and sterile gown, gloves, mask, and cap.
2. The skin insertion site was first disinfected with 10% povidone-iodine and anesthetized with 2% mepivacaine.
3. Catheters were percutaneously inserted using the Seldinger technique and fixed to the skin with 2-0 silk suture.
4. After line insertion, the area surrounding the catheter was cleaned with sterile gauze soaked with povidone-iodine, and a dry sterile gauze occlusive dressing covered the site.
5. No topical antimicrobial ointment was applied to insertion sites (Lorente et al., 2005).
The results of the study showed that the incidence of catheter-related local infections was statistically higher for femoral versus jugular access (15.83 versus 7.65, p < 0.001) and femoral versus subclavian access (15.83 versus 1.57, p < 0.001). In addition, the incidence of catheter-related local infections was also higher for jugular versus subclavian access (7.65 versus 1.57, p < 0.001). The incidence of catheter-related bloodstream infection density was statistically higher for femoral versus jugular (8.34 versus 2.99, p = 0.002) and femoral versus subclavian (8.34 versus 0.97, p < 0.001) accesses, and higher for jugular than for subclavian access (2.99 versus 0.97, p = 0.005) (Lorente et al., 2005). One of the key findings that emerged from the Lorente et al. (2005) study was that "in order to minimize catheter-related infection, it is necessary to monitor its incidence and to implement preventive measures" (p. 635).
"Evidence-based guidelines for catheter insertion and maintenance"
The research showed that central venous catheterization can result in a number of different complications, including infection, hemorrhage, and thrombosis. The research also showed that even with the most aggressive infection-control protocols in place, central venous catheter-associated bloodstream infections can still occur. Nevertheless, evidence-based guidelines are available that can help reduce the risk of infection, including the consistent use of sterile techniques. In sum, when it comes to central venous catheterization, clean is better than dirty — and sterile is better than clean.
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