Flat chest in chronic bronchopulmonary dysplasia.

In patients with chronic bronchopulmonary dysplasia, the anteroposterior dimension of the chest on the lateral radiograph is often relatively narrow compared with the chest width on the frontal radiograph. A prospective comparison was made of pediatric clinic outpatients who had chest radiography during a 1-month period. Chest widths and thicknesses were measured from the anteroposterior and lateral radiographs, respectively, and a dimensionless ratio of width to thickness was calculated. The chest thus measured was significantly flatter (p less than 10(-6] in 18 patients with chronic bronchopulmonary dysplasia than it was in 128 unaffected patients and in 18 unaffected age-matched patients; there was, however, considerable overlap in chest dimensions between patients with and without bronchopulmonary dysplasia. We speculate that the abnormality results from a combination of demineralized bones, prolonged recumbent positioning, and chronic sternal retraction. It is plausible, but remains to be proved, that this chest wall deformity may be clinically deleterious because it interferes with respiratory mechanics. This prospective comparison of patients with and without bronchopulmonary dysplasia shows that despite considerable overlap in chest dimensions, patients with bronchopulmonary dysplasia tend to have a distinctive chest deformity whose measured difference from control patients is statistically significant.