Antenatal corticosteroids for fetal lung maturation in threatened preterm delivery: indications and administration.

INTRODUCTION: Antenatal maternal administration of corticosteroids has been shown to reduce morbidity and mortality rates in preterm delivery. Threatened spontaneous or medically indicated preterm delivery for maternal or fetal indications between 24 and 34 weeks of gestation with unknown fetal lung maturity status are indications for antenatal corticosteroid administration. Recent studies have challenged current practice of antenatal glucocorticoid use. The goal of this expert letter is to provide recommendations based for the clinical use of antenatal glucocorticoids based on the current evidence from published studies. METHODS: The published literature (PubMed search), as well as the recommendations of other national societies, has been searched and taken into consideration for these recommendations. RESULTS/CONCLUSIONS: The standard regimen of antenatal corticosteroids involves a single course of 2 × 12 mg betamethasone administered intramuscularly within 24 h. The administration of corticosteroids usually is performed between 24 and 34 weeks gestation. However, under particular circumstances it may be beneficial even at 23 weeks and at 35-36 weeks of gestation. The evidence to date is clearly against the routine administration of multiple antenatal steroid courses. In special clinical situations, a second course of betamethasone ("rescue course") may be justifiable. Tocolysis during administration of steroids is not routinely indicated in the absence of contractions, cervical shortening or rupture of membranes.

Lung volume, breathing pattern and ventilation inhomogeneity in preterm and term infants.

BACKGROUND: Morphological changes in preterm infants with bronchopulmonary dysplasia (BPD) have functional consequences on lung volume, ventilation inhomogeneity and respiratory mechanics. Although some studies have shown lower lung volumes and increased ventilation inhomogeneity in BPD infants, conflicting results exist possibly due to differences in sedation and measurement techniques. METHODOLOGY/PRINCIPAL FINDINGS: We studied 127 infants with BPD, 58 preterm infants without BPD and 239 healthy term-born infants, at a matched post-conceptional age of 44 weeks during quiet natural sleep according to ATS/ERS standards. Lung function parameters measured were functional residual capacity (FRC) and ventilation inhomogeneity by multiple breath washout as well as tidal breathing parameters. Preterm infants with BPD had only marginally lower FRC (21.4 mL/kg) than preterm infants without BPD (23.4 mL/kg) and term-born infants (22.6 mL/kg), though there was no trend with disease severity. They also showed higher respiratory rates and lower ratios of time to peak expiratory flow and expiratory time (t(PTEF)/t(E)) than healthy preterm and term controls. These changes were related to disease severity. No differences were found for ventilation inhomogeneity. CONCLUSIONS: Our results suggest that preterm infants with BPD have a high capacity to maintain functional lung volume during natural sleep. The alterations in breathing pattern with disease severity may reflect presence of adaptive mechanisms to cope with the disease process.