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Relationship between infant lung mechanics and childhood lung function in children of very low birthweight
K N Chan1, Y C Wong, M Silverman
1Department of Paediatrics and Neonatal Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London, England.
Insights
Neonatal mechanical ventilation in very low birthweight infants may impact early lung function. However, airway conductance later in infancy is a stronger predictor of lung function at 9 years old.
Area of Science:
- Pediatric Pulmonology
- Neonatal Respiratory Medicine
Background:
- Very low birthweight infants often require respiratory support.
- Neonatal respiratory interventions can influence lung development.
Purpose of the Study:
- To investigate the long-term effects of neonatal respiratory therapy on lung function in very low birthweight children.
- To identify predictors of childhood lung function in this vulnerable population.
Main Methods:
- Longitudinal study of 27 very low birthweight children (birthweight ≤ 1,500 g).
- Repeated lung function measurements in infancy and assessment at ~9 years of age.
- Comparison between mechanically ventilated and non-ventilated infants, correlating with neonatal respiratory support intensity.
Main Results:
- Mechanically ventilated infants showed reduced early lung compliance and increased thoracic gas volume.
- Early lung compliance correlated with forced expiratory volume at 1 second at 9 years.
- Late infant airway conductance strongly predicted 9-year lung function, independent of ventilation.
Conclusions:
- Perinatal factors influencing early lung mechanics are weak predictors of childhood lung function.
- Airway conductance in late infancy is a significant predictor of lung function at 9 years.
- Factors like prematurity and constitutional elements influence later airway function.
Abstract:
Twenty-seven children of very low birthweight (less than or equal to 1,500 g) whose lung function had been measured on several occasions during the first year were studied at the age of about 9 years. Fifteen of the children had received neonatal intermittent positive pressure ventilation, mostly for respiratory distress syndrome. Ten of the ventilated children were still oxygen dependent at 30 days of age. Compared to the remainder of the group, mechanically ventilated children had reduced lung compliance in early infancy and increased thoracic gas volume in the middle of their first year. These changes correlated with the level of neonatal respiratory therapy as indicated by the oxygen score. Lung compliance in early infancy, but not thoracic gas volume, correlated with forced expiratory volume at 1 second recorded at 9 years. On the other hand, reduced airway conductance showed no significant correlation with the neonatal oxygen score, but there was a strong correlation between airway conductance late in infancy and lung function at 9 years. This relationship was independent of neonatal mechanical ventilation. We conclude that perinatal factors, which may be associated with disturbed lung mechanics early in infancy, are only weak and indirect predictors of childhood lung function. Airway conductance late in infancy, determined by constitutional factors, prematurity itself or other undetermined factors, is a good predictor of airway function at 9 years.