Procedure-related infections and preventive measures

Abstract

Medical and surgical advances in the care of critically ill patients relyincreasingly on indwelling devices of various kinds. The prevention of nosocomial infections remains problematic in critical care patients because prosthetic devices represent an increasing risk of infection, impairing the natural defence mechanisms of the patients. Catheter-related urinary tract infection is the most common nosocomial infection and accounts for about 40% of all nosocomial infections. The diagnosis of urinary tract infection is simple in the majority of symptomatic infections, but becomes a problem in infections associated with low-count bacteriuria. In asymptomatic patients it is difficult to distinguish colonization from true bladder bacteriuria. The most common risk factors for the development of catheter-associated urinary tract infections are duration of catheterization, and microbial colonization of the catheter-drainage tube junction and the urethral and periurethral region. The most important measures for prevention of urinary tract infection are strict indications for urinary catheters, with suprapubic drainage being preferred; aseptic nursing techniques; closed sterile drainage systems; and early removal of the catheter. Nosocomial pneumonia represents 10–20% of all nosocomial infectionsand is often the final complication in hospitalized patients. The diagnosis of nosocomial pneumonia may be difficult, although a number of important technical advances have been developed (the use of protected brush techniques and bronchoalveolar lavage) to obtain optimal specimens for culture. Main risk factors for development of nosocomial pneumonia are intubation, nasogastric tube, enteral nutrition, colonization of the oropharynx, aspiration of potential pathogens and bacterial colonization of the gastric juices. Efforts to prevent nosocomial pneumonia include both oral decontamination regimens and specific stress ulcer prophylaxis. The most important hygienic measures for preventing ventilator-associated pneumonia are changing of masks and oxygen tubes after each patient, and hand washing before and after contact with respiratory secretions. The use of intravenous catheters is associated with the risk of iatrogenic infection, with a higher rate in patients undergoing central rather than peripheral venous catheterization. The diagnosis of catheter-related infection is established by isolation of the same organism from the catheter and the blood. Predisposing factors for intravascular device-related infections are duration of catheterization, catheter material, local infection, and presence of bacteria on the skin surrounding the insertion site, on the hub or in the infusate. Useful hygienic measures for prevention of intravascular infection are hand and skin disinfection before inserting cannulas, and changing dressings, administration sets and peripheral cannulas every 48–72 hours. To reduce the amount of infection related to invasive devices, new diagnostic and preventive methods should be evaluated. Incorporation of non-toxic antiseptics into the catheter and the development of new catheter materials may be the most promising approaches to reducing the incidence of device-related infection.