Respiratory infection in the chronically critically ill patient - Ventilator-associated pneumonia and tracheobronchitis

Nosocomial pneumonia and tracheobronchitis are common in mechanically ventilated patients, but the chronically ventilated patient presents unique management problems. Although many chronically ventilated patients develop pneumonia, the daily risk is lower than for short-term ventilated patients, reflecting a "survivor effect" and an inherently better ability to resist infection compared with the acutely ill ventilated patient. Chronically ventilated patients have many reservoirs for exposure to large numbers of bacteria, including respiratory therapy devices and the hospital environment. Exposure to bacteria can lead to tracheobronchial colonization with gram-negative bacteria, a common harbinger of pneumonia. Colonization does not always lead to infection, especially if host defenses are adequate. Colonization may be eliminated when host defenses improve, as can occur with nutritional support. Respiratory infection can involve highly resistant bacteria, and therapy must be prompt and accurate. For organisms that are resistant to available antibiotics, adjunctive inhaled antibiotics may be beneficial.