[The shielded bronchial brush and transcutaneous tracheal puncture].

Specific bacteriological diagnosis is the first condition for optimal treatment in bacterial pneumonias. Despite many attempts to improve its reliability, bacteriological examination of the sputum is a non-sensitive and non-specific examination. Transtracheal aspiration (TTA) and bronchoscopic protected brush (BPB) are more reliable examinations but their practice is limited because of their invasive characteristic. Then treatment of non-critical pneumonia is often based on the probable organism. BPB is carried out using a protected brush with a double catheter which is introduced into the bronchial tree under fiberscopic control. Although easy, such a technique must be accurate in its performance. Even if good reliability of this method is well establish in in vitro and in vivo studies, it remains that false positive results have been described in clinical studies, so that quantitative cultures are needed. Results are evident in non-intubated patients without bronchial disease in which identifying the responsive germ is the only purpose. But in intubated ventilated patients two problems are faced: firstly on establishing a positive diagnosis of bacterial pneumonia and secondly on identifying the responsive germ. TTA technique prevents pollution of the specimen with oropharyngeal flora: bronchial secretions are aspirated by a catheter introduced into the trachea via percutaneous route through crico-thyroid membrane. Its performance is easy, quick and severe complications are very rare when usual contraindications are taken into account (severe hypoxia, hemostatic disorders). Being of good sensitivity, the TTA shows false positive results in patients with chronic bronchial diseases. On a bacteriological point of view, these protected techniques have to be used only when pyogenic bacteria are suspected. Invasive techniques are needed when there are factors of specific severity or other risk factors. The choice (TTA or PBP) depends mostly on medical habits and material availability.