Radiologic diagnosis of ventilator-associated pneumonia.

D espite the pivotal role of abnormal chest radiographic findings in alerting clinicians to the possibility of ventilator-associated pneumonia (VAP), the accuracy of radiographic interpretation has received little research interest. Autopsy and clinical data have documented many other causes of abnormal findings, adversely affecting specificity.8,18,83 In addition, sensitivity may be overestimated. Studies of Pneumocystis carinii pneumonia in immunocompromised hosts with normal findings on radiographs have demonstrated evidence of infection. No study has investigated the possibility that this situation may occur in patients with VAP. A concomitant presence of other major clinical characteristics of pneumonia (ie, fever, leukocytosis, and purulent secretions) can occur in patients without radiographic changes, and the condition is often diagnosed as purulent tracheobronchitis. The autopsy study of Rouby et al84 suggests that this may be a valid entity. Whether these cases represent pneumonia with a false-negative chest radiographic interpretation has not been studied. The reviewed studies attempt to distinguish between a variety of disorders that mimic pneumonia in overall clinical impression, specific radiographic signs, or both. Only six studies were available for analysis (Tables 5– 6).8 –10,39,41,85