Bronchopulmonary dysplasia: improvement in lung function between 7 and 10 years of age.

To evaluate the natural history of bronchopulmonary dysplasia, we studied the same 32 patients at a mean age of 7 and 10 years. The group as a whole had normal height and weight percentiles, and each child grew along his or her established somatic growth curve. Although some children had abnormal values, the group maintained a normal mean total lung capacity and functional residual capacity. The mean residual volume and the residual volume/total lung capacity ratios were elevated at both ages. At age 7 years the 19 patients (59%) who had a forced expiratory volume in 1 second (FEV1) of less than 80% had "catch up" improvement by 10 years of age (65 +/- 11% to 72 +/- 16% of predicted value; p less than 0.05). All the children who had a normal FEV1 at 7 years of age continued to have a normal FEV1 at age 10 years. Resting single-breath carbon monoxide uptake by the lung was normal when measured at age 10 years. The majority of patients had a positive methacholine challenge test result at both ages, although there was a low incidence of clinically diagnosed asthma. This study demonstrates that patients with bronchopulmonary dysplasia who have normal lung function at age 7 have had normal lung growth and that those with evidence of mild to moderate lung disease have continued lung growth or repair, or both, during their school years.