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Bronchopulmonary dysplasia: improvement in lung function between 7 and 10 years of age
1Neonatology, Division, Hospital for Sick Children, Toronto, Ontario, Canada.
Insights
Children with bronchopulmonary dysplasia show improved lung function and continued growth during school years. Those with normal lung function at age 7 maintained it, while others experienced repair or growth.
Area of Science:
- Pediatrics
- Pulmonology
- Neonatology
Background:
- Bronchopulmonary dysplasia (BPD) is a chronic lung disease affecting premature infants.
- Long-term respiratory outcomes and lung growth in BPD survivors are not fully understood.
Purpose of the Study:
- To evaluate the natural history and lung function changes in patients with BPD from age 7 to 10 years.
- To assess somatic growth and pulmonary function development in school-aged children with a history of BPD.
Main Methods:
- Longitudinal study of 32 patients with BPD at mean ages of 7 and 10 years.
- Assessment of somatic growth, lung volumes (total lung capacity, functional residual capacity, residual volume), forced expiratory volume in 1 second (FEV1), and diffusing capacity for carbon monoxide.
- Methacholine challenge tests were performed to assess airway hyperresponsiveness.
Main Results:
- Patients maintained normal height and weight percentiles, growing along their established curves.
- Mean total lung capacity and functional residual capacity remained normal, but residual volume/total lung capacity ratios were elevated.
- Patients with FEV1 < 80% at age 7 showed significant improvement by age 10 (p < 0.05); those with normal FEV1 at age 7 maintained normal function.
- Resting diffusing capacity for carbon monoxide was normal at age 10; most patients had positive methacholine challenge tests.
Conclusions:
- Children with BPD and normal lung function at age 7 demonstrate normal lung growth.
- Those with mild to moderate BPD show continued lung growth or repair during school years.
- Despite persistent airway hyperresponsiveness in many, clinically diagnosed asthma was infrequent.
Abstract:
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.