Diagnosis and treatment of pulmonary infections in adult respiratory distress syndrome.

Nosocomial bacterial pneumonia, or the recently introduced term, "ventilator-associated pneumonia," is a common cause of infection in adult respiratory distress syndrome (ARDS). The presence of ventilator-associated pneumonia in ARDS patients is associated with prolonged ventilatory support and increased mortality rates. Unfortunately, clinical and radiographic diagnoses of pneumonia are sensitive but nonspecific and, at best, select a patient population for which further diagnostic evaluation is warranted. The empiric use of broad-spectrum antibiotics in mechanically ventilated patients without pneumonia may be harmful by facilitating colonization and superinfection with virulent organisms. Recent techniques for sampling lower respiratory tract secretions (protected specimen brushing, bronchoalveolar lavage), via fiberoptic bronchoscopic and nonbronchoscopic guidance have been used to establish improved accuracy in the diagnosis of pneumonia. Although these methodologies are not in widespread use in the ICU setting, the results obtained, when properly performed and with carefully processed specimens, may direct the clinician to the appropriate antibiotic therapy and provide a method of assessing its effectiveness. Moreover, if pneumonia is not confirmed, then an aggressive reevaluation of fever and pulmonary infiltrates in the patient with ARDS is indicated.