Respiratory health, lung function, and airway responsiveness in school-age survivors of very-low-birth-weight.

Abstract

The purpose of this study was to determine the respiratory symptoms, pulmonary function, and airway reactivity in school-age survivors of very-low-birth-weight and to describe the influence of birth weight and perinatal illness on their pulmonary function. Thirty (of 39) 10- to 11-year-old survivors of very-low-birth-weight (VLBW) recruited at birth into a prospective longitudinal study of development; 30 (of 32) normal-birth-weight peers recruited from the same school or census tract as the VLBW group at age 5; and 15 normal-birth-weight siblings of the VLBW group participated in the study. Outcome measures were mother's reports of respiratory health; forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1); FEV1/FVC; forced expiratory flow, midexpiratory phase (FEF25-75); peak expiratory flow rate (PEFR); and tolerance to methacholine. There were no differences between groups in mothers' reports of current respiratory health. Pulmonary function values were lower for the VLBW survivors but significant only for FEF25-75 (F = 4.13; P = 0.02). Number of days in the intensive care nursery correlated significantly with decreased FEV1 (r = -.40, df = 28, P = 0.03), FEV1/FVC (r = -.37, df = 28, P = 0.04, and FEF25-75 (r = -.39, df = 28, P = 0.03). Only the relationship between length of nursery stay and FEV1/FVC was independent of birth weight. Number of days on mechanical ventilation was significantly correlated with decreased FEV1 (-.44, df = 28, P = 0.01), FEV1/FVC (r = -.38, df = 28, P = 0.04), FEF25-75 (r = -.44, df = 28, P = 0.01, and PEFR (r = -.40, df = 28, P = 0.03). All of these relationships were independent of birth weight. There were no significant associations between perinatal risk factors and methacholine responsiveness. Differences between VLBW children and normal-birth-weight children in pulmonary function are modest even when statistically significant. Severity of perinatal illness influences pulmonary function parameters into late childhood.