Imaging strategies in the detection and evaluation of ARDS

Considerable evidence has accumulated indicating that the chest radiograph is the most reliable imaging technique to evaluate the severity of lung edema in patients with established ARDS. Recently, the radiographic approach has been validated by direct comparison of an x-ray score of edema with the densitometric analysis of lung CT scan images. CT scanning may prove useful in quantitating the amount of residual healthy lung and in evaluating the effectiveness of PEEP in patients with acute respiratory failure. The application of CT scanning in these patients should be further expanded. Special effort should be made to evaluate unanesthetized, spontaneously breathing patients and to correlate CT quantitative data with the simultaneous analysis of portable chest radiographs in order to enhance the physician's ability to extract valuable, physiologic information from the chest film in critically ill patients. In order to improve the survival rate of patients with ARDS, methods are needed which detect ARDS at its earliest clinical stage. A number of radioisotopic techniques have been developed, based on the evaluation of the leakiness of the alveolar-capillary barrier either from the vascular or from the airspace side. Clearance of aerosolized DTPA from airspaces, although extremely sensitive, is not specific for ARDS in as much as factors other than lung injury may equally affect the rate of DTPA clearance from the lung. External detection of transvascular protein flux may serve as noninvasive means to assess the integrity of the lung microvascular endothelial barrier.(ABSTRACT TRUNCATED AT 250 WORDS)