Computed tomography in established adult respiratory distress syndrome. Correlation with lung injury score.

STUDY OBJECTIVES

To identify serial changes in the appearances of the lungs on computed tomography (CT) in patients with established adult respiratory distress syndrome (ARDS). Second, to evaluate any relationship between the extent of morphologic abnormalities on CT anatomic and physiologic derangement using a numeric score of the severity of lung injury.

DESIGN

Retrospective, descriptive.

SETTING

Adult intensive care unit, Department of Radiology, and outpatient department of a national tertiary referral center.

PATIENTS

Eight patients meeting diagnostic criteria for ARDS able to tolerate CT scanning during the acute phase of their illness and who survived to be reevaluated during convalescence.

INTERVENTIONS

Mechanical ventilatory support. Conventional intensive care support of other failed systems a appropriate.

MEASUREMENTS AND RESULTS

Thin-section CT scans of the lungs categorized as to extent (calculated percent volume of abnormal lung), distribution, and dominant disease pattern. Concurrent lung injury score (LIS) was recorded at the time of the CT during the acute phase of illness (mean, 26 days; range, 3 to 48 days after precipitating event) and at follow-up (96; 17 to 187 days). On initial CT scans, disease patterns included ground-glass opacification (8/8), parenchymal distortion (8/8), multifocal areas of consolidation (6/8), reticular opacities (6/8), and linear opacities (5/8). On follow-up scans, there was clearing of consolidation in all patients, but ground-glass opacification persisted in four of eight patients. The reticular pattern persisted unchanged in five of eight patients, became more extensive in two of eight, and developed in one. A reticular pattern was most pronounced in areas that had been densely consolidated previously. Evidence of parenchymal distortion, present on the initial scan in all patients, persisted in six of eight patients. Computed tomographic features suggestive of emphysema developed in one patient. The LIS revealed moderate to severe ARDS in all patients initially; this decreased to a mild or zero LIS at follow-up. Overall, there was 76.9% +/- 5.3% abnormal lung on the initial CT scan and 34.5 +/- 9.3% on the follow-up CT scan. There was a significant correlation between the extent of abnormalities on CT and LIS (r = 0.75, p < 0.01).

CONCLUSIONS

The CT appearances of patients with ARDS who survive are variable and relate to the pattern of disease in the acute phase. Furthermore, the extent of CT abnormalities correlates strongly with LIS in both the acute phase and at follow-up.