Prediction of respiratory failure in late-preterm infants with respiratory distress at birth

The aim of this study was to evaluate indices of respiratory failure in terms of their ability to predict respiratory impairment and need for ventilatory support in late-preterm neonates with respiratory distress. Arterial blood gas data during the first 12 postnatal hours or until intubation were recorded in 155 neonates with gestational age 34^0/7–36^6/7 weeks admitted in the NICU with respiratory distress between January 2006 and June 2008. Alveolar-arterial oxygen tension difference (A-aDO₂), arterial to alveolar oxygen tension ratio (a/A ratio), and partial arterial oxygen tension to inspired oxygen fraction ratio (PaO₂/FiO₂) were calculated. Considering the worst single value of each parameter, receiver operating characteristic curve analyses and area under the curve (AUC) comparisons were used to evaluate their predictive performance. Fifty-five neonates (35.5%) required mechanical ventilation. The predictive performances of the maximum A-aDO₂ (AUC 0.97), minimum a/A ratio (AUC 0.95), and minimum PaO₂/FiO₂ (AUC 0.95) were similar. The A-aDO₂ at a threshold of >200 mmHg proved to be more effective than the other parameters, having excellent positive and negative likelihood ratios of 24.5 and 0.02, respectively. This threshold was achieved by 98.25% of the neonates who developed respiratory failure at a median of 3 h before the ventilatory support to be definitely decided. Composite indices, such as A-aDO₂, a/A ratio, and PaO₂/FiO₂, can reasonably predict respiratory failure in late-preterm neonates with respiratory distress, allowing for closer monitoring, early medical intervention, or transfer to a level III neonatal unit.