B-type Natriuretic Peptide and Occult Pulmonary Hypertension in Premature Infants

Infants born at < 28 weeks gestation have an underdeveloped cardiorespiratory system. Premature birth disrupts the development of the lungs and lung vasculature. Many infants are able to recover from this with supportive intensive care and time allowing fro growth and development. However there is increasing evidence from animal and human studies that a subgroup are at risk of abnormal pulmonary vascular development leading to a prolonged need for respiratory support and increased risk of death in the first two years of life. At present we lack good screening tools to identify infants at risk of abnormal pulmonary vascular development. There is evidence from studies on animals, adults, children and term-born infants that B-type Natriuretic Peptide is elevated in the presence of pulmonary hypertension. Our hypothesis is that NTpBNP levels in extremely low gestational age neonates increase with increasing severity of lung disease and that those with the highest NTpBNP levels have the highest risk of recurrent hypoxemia (low oxygen levels). We also hypothesise that those with the highest late NTpBNP levels will demonstrate more cardiac dysfunction with evidence of raised pulmonary artery pressures in the most severely affected. NTpBNP levels may help doctors to stratify premature infants into low, intermediate or high risk categories for the development of pulmonary hypertension and allow clinicians to identify those infants in need of further investigation. NTpBNP levels may also help identify which infants may benefit from medications that lower pulmonary pressures.