Diagnosis and differential diagnosis of ventilator-associated pneumonia.

Clinical criteria, radiographic findings, and analysis of a tracheal aspirate are inaccurate for diagnosing ventilator-associated pneumonia (VAP). This article reviews both invasive and noninvasive diagnostic techniques, discusses microbiologic and microscopic analysis of lower airway secretions, and considers factors influencing the results of these tests. The differential diagnosis of fever and pulmonary densities in ventilated patients is discussed, and a systematic diagnostic approach for the evaluation of patients with suspected VAP is presented.