[Diagnostic criteria for respiratory infection in intensive care patients]

The optimal technique for diagnosing nosocomial bacterial pneumonia in critically ill patients cared for in an Intensive Care Unit remains unclear. Firstly, fever, purulent secretions and new pulmonary infiltrates can be associated with a variety of other common pathological processes. Secondly, microscopic and culture of tracheal secretions are frequently unrewarding since the upper respiratory tract of most ventilated patients is colonized with potential pulmonary pathogens, wether or not deep pulmonary infection is present. Thus, the results of studies evaluating the clinical diagnosis of nosocomial pneumonia in this setting have been very disappointing. An important advance has been the development of the protected specimen brush technique. We and others have demonstrated that the secretions obtained using this technique and evaluated by quantitative cultures are useful in distinguishing patients with and without pneumonia. However, this procedure has important limitations in that results are not available immediately and in that a few false negative or false positive results may be observed. Recently, the use of bronchoalveolar lavage has been suggested to be of value in establishing the diagnosis of pneumonia since the cells recovered by lavage may provide a sensitive and specific means for early and rapid diagnosis of pneumonia in this setting and that the lavage technique can be conveniently incorporated into a protocol along with the quantitative culture of samples obtained using the protected specimen brush.