Pulmonary function outcomes in bronchopulmonary dysplasia through childhood and adulthood

Bronchopulmonary dysplasia (BPD) results from prematurity and surfactant deficiency with contributing factors such as barotrauma, volutrauma, and oxygen toxicity determined by supportive mechanical ventilation care and infection. Taken together, these factors result in chronic inflammation with recurring cycles of lung damage and repair that impair alveolarisation and vascularisation in developing lungs. Typically, BPD patients develop long-term pulmonary complications as a result of structural changes in the airways that persist into adulthood. As BPD patients age, primary care physicians need to understand the impact of this disease on pulmonary function. In this review, data are presented on pulmonary function outcomes resulting from BPD through later childhood and young adulthood.
Several studies show that pulmonary complications continues to exist in early to late childhood. For instance, chronic airway obstruction typically persists in former premature infants with 'classic' BPD during early childhood and can be associated to air trapping in infants with "new BPD". The airway obstruction is typically fixed (i.e. unresponsive to ß2-agonists). The mechanism of development of fixed airway obstruction is most likely related to early life structural changes in the airways. Preterm children with a history of BPD more commonly have abnormal pulmonary function (i.e., significant reduction in FVC, FEV1, and FEF25-75) along with bronchodilator responsiveness as compared to preterm children without BPD and children born term. Several studies have evaluated the physiological response to exercise in late childhood and overall showed a reduction in performance and a worsening in respiratory parameters in children with a history of BPD. In addition, a study showed that exercise-induced bronchospasm occurred in 50% of the BPD group. The reduction in exercise capacity results from a reduction in ventilatory reserve and gas transfer.
Only few studies have assessed pulmonary function of BPD survivors reaching the adult years, Those individuals who have participated in studies continue to show different degrees of pulmonary function changes, primarily due to airway obstruction. These complications include chronic pulmonary function impairment, reduced exercise capacity, and more rapid deterioration of lung function than in normal subjects as adolescents and young adults. In addition, the diagnosis of asthma and use of asthma inhalers is significantly more prevalent among patients born prematurely than controls. Screening by computer tomography of adult patients (age 17-33) showed that 84% of survivors of moderate and severe BPD had emphysema.
Follow-up studies of preterm infants with BPD shows that long-term pulmonary complications resulting from airway structural changes persist into adulthood. Given the advances in therapy and management, BPD is an evolving disease. The "new BPD" in post-surfactant era has different pathophysiological changes and different radiological and clinical presentations. These differences between "classic" and 'new" BPD may also influence long-term pulmonary outcomes, with possible less impairment in the latter case. This is an important issue for primary care physicians who will be involved with the care of these patients.

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