Total parenteral nutrition and infections associated with use of central venous catheters.

The article in this issue by Dimick et al 1 about total parenteral nutrition (TPN) and infections associated with use of central venous catheters addresses a major concern in critical care medicine. In day-to-day practice, certain intervention-related complications are inevitable. As our understanding in general improves, we find many other factors that contribute to complications. Dimick et al indicate that with proper care, infection related to central venous catheters used for TPN is avoidable. As critical care medicine continues to advance, outcomes improve and interventions previously considered high risk become safer. Two vital components of critical care are the use of central venous catheters and TPN. The most severely ill patients often require both for survival and recovery. In the intensive care unit, gastrointestinal dysfunction associated with multiorgan failure and shock or with abdominal surgery is not uncommon. Nutrition cannot be compromised. However, when TPN is suggested for a patient, the risk of infectious complications, especially infection related to use of central venous catheters, is often thought greater than potential benefits. Why is this risk so often weighed with greater importance than are other clinical factors? Does this concern have merit, or is it simply an overreaction? Catheter-related infection is potentially devastating. Such infections greatly increase morbidity, mortality, and length of stay. Pittet and Wenzel reported an odds ratio for death of 20.45 (95% CI, 18.9-22.1) for patients with catheter-related infection. Thus, the concern is understandable because of the potential consequences. A decade ago, Kudsk et al compared the prevalence of septic complications in a group of severely ill trauma patients who received either TPN or enteral feeding. The group given TPN had significantly higher prevalences of pneumonia (31% vs 11.8%; P¬<¬.02), intra-abdominal abscess (13.3% vs 1.9%; P¬<¬.04) and catheter sepsis (13.3% vs 1.9%; P¬<¬.04). Other investigators reported similar data. The large difference in rates between patients given TPN and those given enteral feedings makes it difficult to argue a lack of association between TPN and infectious complications. The question yet to be answered about TPN is, despite the inherent infectious risks, can infectious complications be avoided? Dimick et al have begun to answer this question. Now that a decade has passed, the research of Dimick et al and that of other investigators has improved safety for interventions commonly used in critically ill patients. The earlier studies on TPN were performed without glucose control. Recently, van den Berghe et al reported that tight glucose control decreased mortality significantly (8.0% with conventional treatment vs 4.6% with tight glucose control, P¬<¬.04). Were the increases in infectious complications in the earlier reports a direct result of poorly controlled hyperglycemia? If euglycemia had been achieved, would the differences in infectious rates found by Kudsk et al and Moore et al have been smaller or nonexistent? Of all the potentially devastating infectious complications, catheter-related infection remains the major concern associated with use of TPN. Because of the wide use of central catheters and the potential for devastating outcomes, the concerns are not surprising. However, because early provision of nutritional support improves outcomes in critically ill patients, avoiding or delaying administration of TPN solutions is potentially harmful. Having guidelines to use TPN and yet avoid catheter-related infection may markedly improve outcome. The findings of Dimick et al have begun to dispel myths about catheter-related infection associated with use of TPN and give clinicians proper directions on how to use TPN safely.