Pulmonary infection in intensive care units.

Since the earliest days of organized intensive care, pulmonary infection has been a problem in patients undergoing artificial ventilation of the lungs [43]. Hospital-acquired pneumonia is an important cause of morbidity and mortality among Intensive Care Unit (ICU) patients, and its incidence has not been reduced by developments in medical technology. Pneumonia in artificially ventilated patients can be clinically indistinguishable from non-infective conditions commonly encountered in intensive care, such as atelectasis and pulmonary oedema, and the patient's condition may fail to improve even when antimicrobial therapy is commenced early in the course of the condition. The practical difficulties of diagnosing and treating pneumonia in patients undergoing artificial ventilation have encouraged a more detailed investigation of the determinants of nosocomial pneumonia in the hope of developing more successful preventive strategies. The outcome of this research has been the recognition of the importance of bacterial colonization of the ventilated lung, which in turn has become the basis for preventive strategies, including selective decontamination and preservation of the "gastric acid barrier".