Structural and Functional Lung Impairment in Adult Survivors of Bronchopulmonary Dysplasia

Rationale: As more preterm infants recover from severe bronchopulmonary dysplasia (BPD), it is critical to understand the clinical consequences of this condition on the lung health of adult survivors.

Objectives: To assess structural and functional lung parameters in young adult BPD survivors and preterm and term control subjects.

Methods: Young adult survivors of BPD (mean age, 24 yr) underwent spirometry, lung volume assessment, transfer factor, lung clearance index, and fractional exhaled nitric oxide measurements, together with high-resolution chest computed tomography and cardiopulmonary exercise testing.

Measurements and main results: Twenty-five adult BPD survivors (mean ± SD gestational age, 26.8 ± 2.3 wk; birth weight, 866 ± 255 g), 24 adult prematurely born non-BPD control subjects (gestational age, 30.6 ± 1.9 wk; birth weight, 1,234 ± 207 g), and 25 adult term-birth control subjects (gestational age, 38.5 ± 0.9 wk; birth weight, 3,569 ± 2,979 g) were studied. Subjects with BPD were more likely to be wakened by cough (odds ratio, 9.7; 95% confidence interval, 1.8-52.6; P < 0.01) or wheeze and breathlessness (odds ratio, 12.2; 95% confidence interval; 1.3-112; P < 0.05) than term control subjects after adjusting for sex and current smoking. Preterm subjects had greater airway obstruction than term subjects. Subjects with BPD had significantly lower values for FEV1 and forced expiratory flow, midexpiratory phase (percent predicted and z-scores), than term control subjects (both P < 0.001). Although non-BPD subjects also had lower spirometric values than term control subjects, none of the differences reached statistical significance. More subjects with BPD (25%) had fixed airflow obstruction than non-BPD (12.5%) and term (0%) subjects (P = 0.004). Both BPD and non-BPD subjects had significantly greater impairment in gas transfer (Kco percent predicted) than term subjects (both P < 0.05). Eighteen (37%) preterm participants were classified as small for gestational age (birth weight below the 10th percentile for gestational age). These subjects had significantly greater impairment in FEV1 (percent predicted values and z-scores) than those born appropriate for gestational age. BPD survivors had significantly more severe radiographic structural lung impairment than non-BPD subjects. Both preterm groups had impaired exercise capacity compared with term control subjects. There was a trend for greater limitation and leg discomfort in BPD survivors.

Conclusions: Adult preterm birth survivors, especially those who developed BPD, continue to experience respiratory symptoms and exhibit clinically important levels of pulmonary impairment.