Clinical diagnosis of ventilator associated pneumonia revisited: comparative validation using immediate post-mortem lung biopsies

Abstract

Background-A study was undertaken to assess the diagnostic value of diVerent clinical criteria and the impact of microbiological testing on the accuracy of clinical diagnosis of suspected ventilator associated pneumonia (VAP). Methods-Twenty five deceased mechanically ventilated patients were studied prospectively. Immediately after death, multiple bilateral lung biopsy specimens (16 specimens/patient) were obtained for histological examination and quantitative lung cultures. The presence of both histological pneumonia and positive lung cultures was used as a reference test. Results-The presence of infiltrates on the chest radiograph and two of three clinical criteria (leucocytosis, purulent secretions, fever) had a sensitivity of 69% and a specificity of 75%; the corresponding numbers for the clinical pulmonary infection score (CPIS) were 77% and 42%. Non-invasive as well as invasive sampling techniques had comparable values. The combination of all techniques achieved a sensitivity of 85% and a specificity of 50%, and these values remained virtually unchanged despite the presence of previous treatment with antibiotics. When microbiological results were added to clinical criteria, adequate diagnoses originating from microbiological results which might have corrected false positive and false negative clinical judgements (n = 5) were countered by a similar proportion of inadequate diagnoses (n = 6). Conclusions-Clinical

The Vexing Problem of Ventilator-Associated Pneumonia: Observations on Pathophysiology, Public Policy, and Clinical Science

“…22 In some reports, negative sputum cultures missed between 15 and 56% of pneumonias discovered at autopsy. 23,24 Moreover, VAP can be confused with ventilator-associated tracheobronchitis, which is a nosocomial infection of the tracheobronchial tree, but not the lung tissue itself. 10 Ventilator-associated tracheobronchitis has the same clinical and microbiological signs as VAP, but without deteriorating oxygenation and chest radiographic findings.…”

Ventilator-Associated Pneumonia: Diagnosis, Treatment, and Prevention

“…Unfortunately, and unlike for community-acquired pneumonia, accepted clinical criteria for pneumonia are of limited diagnostic value in definitively establishing the presence of VAP. In a postmortem study by Fabregas et al, when findings on histologic analysis and cultures of lung samples obtained immediately after death were used as references, a new and persistent (Ͼ48-h) infiltrate on chest radiograph plus two or more of the three criteria (i) fever of Ͼ38.3°C, (ii) leukocytosis of Ͼ12 ϫ 10 9 /ml, and/or (iii) purulent tracheobronchial secretions had a sensitivity of 69% and a specificity of 75% for establishing the diagnosis of VAP (60). When all three clinical variables were required for the diagnosis, the sensitivity declined further (23%); the use of a single variable resulted in a decrease in specificity (33%).…”

“…The "bacterial index" is the sum of the logarithm of the number of bacteria cultured per milliliter of bronchoalveolar lavage (BAL) fluid. Two subsequent studies evaluated the accuracy of the CPIS by using both histology and lung tissue cultures as the reference tests (60,162). In these investigations, the sensitivity was 72% to 77%, and the specificity was 42% to 85%.…”

Early-onset pneumonia after liver transplantation: Microbiological findings and therapeutic consequences

“…12,[16][17][18] All chest radiographs were analyzed prospectively by 2 of the investigators (S.J. and C.P.-B.).…”