الفهرس 
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Abstract
Persistent pulmonary hypertension of the newborn (PPHN) results from the failure of relaxation of the pulmonary vasculature at birth, leading to shunting of non oxygenated blood from the pulmonary to the systemic circulation. More often, full term and near term infants are affected.
The diagnosis of PPHN should be suspected when the level of hypoxemia is disproportionate to the degree of respiratory distress and pulmonary parenchymal radiological findings. Echocardiography should always be performed upon suspicion of PPHN. It provides an estimate of pulmonary artery pressure by determining the peak velocity of tricuspid regurgitation. It is often difficult to diagnose PPHN early especially when echocardiographic evaluation is not available. Brain type natriuretic peptide (BNP) was recently proposed as a biomarker for diagnosis of PPHN.
Natriuretic peptides are ring shaped amino acid sequences with various actions and constitutes a family of four members ANP, BNP, CNP, and DNP. BNP is an endogenous peptide hormone of 32 amino acid that is secreted by the cardiac ventricles in response to increased wall stress. It induce diuresis, natriuresis and relaxation of human arteries. It has been used in diagnosis of many cardiovascular diseases in adult population however, few studies are available on its role in neonatal illnesses.
The present study showed that maladaptation is the most common type of PPHN (70%) with meconium aspiration syndrome (MAS) the commonest cause (40%). BNP levels were significantly elevated in neonates with PPHN (P<0.001) relative to infants with non-cardiac causes of respiratory distress and infants breathing room air. Underdevelopment type had the highest BNP level among different types of PPHN though this level was statistically insignificant.
Also BNP levels correlate significantly with echocardiographic estimates of pulmonary artery pressure (P= 0.023) and tricuspid regurgitation jet gradient (P= 0.018). As a marker of severity for respiratory distress, oxygenation index was correlated to BNP level but this was statistically insignificant.
Initial BNP levels were higher in died cases though not reaching a significant level. This study found that elevated BNP levels at study entry were significantly declined after recovery of PPHN cases.
At last BNP is rapid, easily available and inexpensive tool that help in diagnosis of PPHN in term and near term newborns and monitor the response to treatment.