Lung Volume and Ventilation Inhomogeneity in Preterm Infants at 15-18 Months Corrected Age

Objective

To assess whether lung volume and ventilation inhomogeneity in preterm infants at 15-18 months corrected age, and the change in these outcomes from the newborn period to 15-18 months corrected age, depend on gestational age (GA) at birth and the severity of neonatal lung disease.

Study design

Preterm (GA range, 23-32 weeks) and term healthy control infants were studied in quiet sedated sleep at 15-18 months corrected age by multiple breath washout with 5% sulfur hexafluoride using an ultrasonic flowmeter. Valid measurements were obtained from 58 infants. Multivariate and multilevel regression was used to analyze outcomes.

Results

Functional residual capacity (FRC), lung clearance index, and first and second to zeroeth moment ratios were calculated. After accounting for body size at test, FRC at follow-up, and the increase in FRC from the newborn period to 15-18 months corrected age were positively associated with GA and negatively associated with the duration of endotracheal ventilation. Indices of ventilation inhomogeneity were unaltered by GA and the duration of endotracheal ventilation.

Conclusions

In very preterm infants, GA and the duration of endotracheal ventilation are independently associated with reduced lung volume and lung growth during infancy, although the effect size of these findings is small.

BMI, Body mass index, BPD, Bronchopulmonary dysplasia, FRC, Functional residual capacity, GA, Gestational age, LCI, Lung clearance index, M₁/M₀, First to zeroeth moment ratio, M₂/M₀, Second to zeroeth moment ratio, MV, Minute volume, NLD, Neonatal lung disease, PMA, Postmenstrual age, RDS, Respiratory distress syndrome, RR, Respiratory rate, V_T, Tidal volume