PULMONARY-FUNCTION IN INFANTS WITH NEONATAL CHRONIC LUNG-DISEASE WITHOR WITHOUT HYALINE-MEMBRANE DISEASE AT BIRTH

We studied whether neonatal chronic lung disease (NCLD), hyaline membr ane disease (HMD) and differences in ventilatory support affected pulm onary function during the first year of life, in 65 infants born prema turely, The relationship between body weight and oxygen consumption (V 'O-2) was also analysed, The study comprised 14 infants without cardio respiratory disease, 19 infants with HMD but without NCLD, 9 infants w ith NCLD without prior HMD, and 23 infants with NCLD following HMD, At 6 and 12 months corrected postnatal age, static respiratory system co mpliance (Crs) was measured by weighted spirometry and the functional residual capacity by closed circuit helium dilution (FRCHe) combined w ith assessment of ventilation distribution from the mixing index (MI), Ventilatory support during the first 5 days of therapy was quantified from peak inspiratory pressure (PIP), mean airway pressure (MAP) and fractional inspiratory concentration of oxygen (FI,O-2). Infants with NCLD had a shorter duration of gestation and lower birth weight than t hose without NCLD (Wilcoxon, p=0,002 and p=0,001, respectively), Pulmo nary function at 6 and 12 months corrected age was not different betwe en NCLD infants with or without HMD at birth, Infants with NCLD had lo wer Crs and MI than those without NCLD (analysis of variance (ANOVA), p<0,011), but their FRCHe was not different, V'O-2 adjusted for body w eight was comparable in the four groups, PIP and FI,O-2 were higher (W ilcoxon, p<0,01) in the NCLD infants than in those with HMD alone, but MAP was not different, Except for FI,O-2, these indices were not diff erent among the infants with NCLD, We conclude that birth weight is th e major determinant of the development of neonatal chronic lung diseas e, At 6 and 12 months corrected age, the abnormal pulmonary function i s not associated with prior hyaline membrane disease.