Enteral nutrition as a risk factor for nosocomial pneumonia.

Nutritional support of critically ill patients in the intensive care unit is important, since adverse effects of malnutrition are multiple and common. Nutrition via the enteral or gastrointestinal tract is often preferred over central venous or total parenteral nutrition as the initial choice of nutritional therapy due to its relative ease of administration, lower cost and infrequent association with severe complications. Recent data suggest that nosocomial pneumonia, a severe and ominous complication of critical illness, is related to gastric colonization secondary to alkalinization of stomach contents by antacids and H2-antagonists. Nosocomial pneumonia may also be related to enteral nutrition. Gastric microbial growth increases after the onset of enteral nutrition. Gastric organisms can be transmitted to the trachea and result in tracheal colonization and nosocomial pneumonia. Gastric to tracheal transmission of organisms is probably related to pulmonary aspiration. Several factors are important in pulmonary aspiration, including nasogastric tube size, method of nutrient delivery, patient position, and gastric and intestinal motility. Enteral nutrition must be considered in both the evaluation of mechanisms of nosocomial pneumonia and the strategies of prophylaxis.