Evolution and Determinants of Lung Function until Late Infancy among Infants Born Preterm

Abstract

to investigate the evolution of lung function in preterm infants with and without bronchopulmonary dysplasia (BpD) and to determine the perinatal characteristics associated with indexes of lung function in later infancy. Longitudinal lung function assessments were performed at approximately 6, 12, 18, and 24 months of corrected age in preterm infants. Perinatal characteristics were further analyzed to ascertain the determinants of lung function indexes. Although all preterm infants (n = 121; 61 without BPD and 60 with BPD) exhibited decreased lung function in early infancy (6 months of age), after body length was adjusted for, only infants with BPD exhibited poor performance. Furthermore, the lung function of infants with mild to moderate BPD caught up gradually, but the generally poor lung function performance of infants with severe BPD, especially in forced expiratory flow, persisted until later age (24 months). Regarding perinatal characteristics, the z-score of body length at the time of examination and total number of days on positive-pressure ventilation are the major determinants of lung function in later infancy.Bronchopulmonary dysplasia (BPD) is a chronic lung disease that develops in preterm infants, namely less than 37 weeks' gestational age, who were exposed to mechanical ventilation and oxygen supplementation. Dysplasia of microvessels, airways, and alveoli have been observed in lungs of such premature infants 1 . The "new" form of BPD, deemed a developmental disorder, differs pathologically and clinically from the "old" form 2 . Before the period of antenatal steroid and intratracheal surfactant, the "old" BPD occurred in preterm infants (usually late preterm) who suffered from surfactant deficiency. These infants required high-ratio oxygen and ventilatory support, which trigger a heterogenous lung injury and remodeling. The sequels of lung damage marks with regions of atelectasis and hyperinflation, hyperplasia of airway smooth muscle, lung fibrosis, and pulmonary vascular hypertensive changes 3 . After the period of prenatal steroid and postnatal surfactant intervention, the mortality of BPD significantly decreased, and shifted the demographics of BPD to more extreme preterm infants. "New" BPD then occurred and being characterized by arrested alveolar-capillary development, namely fewer and larger alveoli develop, reducing the overall surface available for gas exchange 4 . The airways are relatively less affected, and inflammation is usually less prominent than in the old form of BPD 1 .Although previous studies have showed that infants with BPD have significant decline in lung function till third decade of life 5 , it's uncertain whether this defect is a consequence of prematurity and/or BPD. Long-term studies on the lung function of survivors of old BPD have reported that abnormalities in forced expiratory flow persisted over time [6][7][8] . However, the results from these studies may differ from children with new BPD, which usually develops in more preterm infants, who might have received mar...

Distinct lung function and bronchodilator responses between term and preterm young children with recurrent wheezing

“…Because the majority of the preterm group in this study had moderate-to-severe BPD (14 out of 23 children), children in this group still demonstrated poorer-than-average baseline lung function. 24 Interestingly, our results showed no differences in Crs between three groups. Since the symptom of wheezing originated from obstruction of small airway, the pulmonary elasticity of these children with recurrent wheezing will be comprehensible.…”

“…Studies have shown that young children with preterm birth have significant airway obstruction. 24,25 Respiratory dysfunction was shown to be even more pronounced in + MODEL children with BPD. 24 Some researchers have speculated that airway obstruction results from inflammatory insults affecting the conducting bronchioles during the late canalicular or early saccular stage of lung development.…”

“…24,25 Respiratory dysfunction was shown to be even more pronounced in + MODEL children with BPD. 24 Some researchers have speculated that airway obstruction results from inflammatory insults affecting the conducting bronchioles during the late canalicular or early saccular stage of lung development. 26 Furthermore, high risks of wheezing and asthma have been observed in young children with preterm birth.…”

Pulmonary Outcomes in Children Born Extremely and Very Preterm at 11 Years of Age

“…These recent findings suggest that ex-preterm children with early reduced lung function compared to term controls could improve lung function over time, especially in absence of BPD ( 15 , 25 , 27 ). According to these findings, we speculate that the lung function was normal in our study population at 11 years of age probably because their lung function improved over time.…”

“…Few longitudinal studies were performed. A recent longitudinal study assessing lung function at different time points (6, 12, 18, and 24 months) found that lung function in preterm infants with mild to moderate BPD improved gradually ( 25 ).…”