New approaches in the diagnosis of pneumonia in ICU patients

The following clinical criteria can be used for the diagnosis of pneumonia in ventilated patients: 1. New infiltrates on chest X-ray. 2. Purulent tracheal secretions (TS). 3. Positive bacteriological finding in TS. 4. Temperature over 38.5 degrees C. 5. Leucocyte count over 12,000/mm 3. 6. Characteristic auscultatory findings. 7. Impaired gas exchange. When the first three criteria are fulfilled and a further two criteria are positive, a respiratory tract infection is highly probable and therapy with antibiotics justified. When fewer criteria are fulfilled, or in cases in which specific criteria cannot be applied, for example, patients with the acute respiratory distress syndrome (ARDS), a lung contusion, or an infection located elsewhere, invasive bronchoscopic diagnosis by protected specimen brush (PSB) or bronchoalveolar lavage (BAL) is indicated. The PSB method is characterised by very good specificity, though a not so high sensitivity. Compared to the PSB method, the BAL method has a lower specificity but is more sensitive. Pre-conditions for the successful application of both methods include correct technical handling as well as close co-operation between the intensive care physician and the microbiology laboratory.