Reduced Lung Function at Preschool Age in Survivors of Very Low Birth Weight Preterm Infants

Abstract

Background: Survivors of preterm birth are at risk of long-term respiratory consequences. The objective of this prospective study was to assess pulmonary function at preschool age of former very low birth weight (VLBW) preterm children. Methods: Lung function of children born preterm and term controls aged 5–6 years were assessed by spirometry. The results were converted to z-scores. A questionnaire regarding respiratory symptoms was completed. Associations to gestational age (GA), birth weight (BW), bronchopulmonary dysplasia (BPD), and perinatal factors were assessed. Results: In total, 85 VLBW preterm children and 29 term controls were studied. Of the preterm children, the mean GA was 28.6 ± 2.6 weeks and the mean BW was 1,047 ± 273 gm. Preterm children had significantly lower z-scores of forced expiratory volume in 1 s (FEV 1 ), FEV 1 /forced vital capacity (FVC) ratio, and forced expiratory flow rate between 25–75% of FVC (FEF 25−75 ), compared with term controls (−0.73 vs. 0.04, p = 0.002; −0.22 vs. 0.39, p = 0.003; −0.93 vs. 0.0, p < 0.001; respectively). Further segregation of the preterm group revealed significantly impaired FEV 1 , FEF 25−75 in children at earlier gestation (≤ 28 weeks, n = 45), lighter at birth (≤ 1,000 g, n = 38), or with BPD ( n = 55) compared with term controls ( p < 0.05). There were significant negative relationships between the severity of BPD with FEV 1 , FVC, and FEF 25−75 ( p < 0.05). However, no correlation between lung function measurements and respiratory symptoms was found. Conclusions: VLBW preterm infants have reduced lung function at preschool age, especially among those with younger GA, lower BW, and BPD. Additional long-term follow-up of respiratory outcomes are needed for this vulnerable population.

The Consensus Definition of Bronchopulmonary Dysplasia Is an Adequate Predictor of Lung Function at Preschool Age

“…Reduced small airway patency, as assessed by FEF 25−75 , has been reported during different stages of infancy (26,(28)(29)(30)(31). In our study, all groups showed a reduction of FEF 25−75 relative to the reference population.…”

“…this technique in preschool age children (26). The results of a previous study (15) that analyzed the suitability of this technique for assessment of lung function in healthy preschoolers support widespread application of the GLI-2012 reference equations.…”

“…definition of BPD of the requirement of 28 days of oxygen therapy before 36 weeks PMA. Recently, Chang et al (26)…”

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

“…Kitchen et al ( 24 ) found that lung function was similar in very low birth weight children compared to normal weight birth ones at 8 years of age, despite very low birth weight children suffered more frequently from wheezing in the first 2 years of life. In a recent study performed in preschool aged children, a similar lung function in mild BPD ex-preterm subjects compared to ex-preterm ones without BPD and term controls has been shown, suggesting that mild BPD might not lead to long-term respiratory consequences ( 21 ). The available conflicting findings might be partially explained by the small study sample size, the heterogeneity in the definition of BPD and in the lung function methods utilized, and the different age in which lung function was assessed in cross-sectional studies.…”

“…Scientific evidence is still conflicting regarding the persistence of impaired lung function in expreterm children. On one hand, a lot of studies showed lung function impairment in preterm children (19)(20)(21). On the other hand, several studies observed inconsistent association between birth weight and FEV1/FVC (22,23).…”