Pulmonary Hypertension in Preterm Children Born at Gestational Age <30 Weeks: Prevalence, Risk Factors and Outcome

Background:

The development is not complete in premature born children. For example, the lungs are not fully developed. This is associated with shortness of breath and an increased oxygen need. Some of these children will need ventilation support and develop the condition Bronchopulmonary dysplasia (BPD). BPD is considered with lung injury and more than 28 days of ventilation support. These children have more need for oxygen and are extra sensitive for infections. In the present era, BPD most often occurs in extremely premature infants born at 24-28 weeks' post menstrual age, who have showed less severe acute respiratory symptoms and require less respiratory support than BPD patients have traditionally had in the past. Histological examination of these 'new BPD' patients suggests that the extreme preterm birth in combination with perinatal lung injury affects the normal growth of the lung development, resulting in disrupted vascular growth and impaired alveolarization, which could result in PH, a high blood pressure in the lungs. The causal relation among prenatal factors, prematurity, BPD and PH are not fully known yet. In premature newborns, < 30 weeks, the prevalence of BPD has been estimated to be 30-60% , while the prevalence of occurrence of PH received significantly less attention and estimates vary from 18% in the total group and up to 30% in the BPD-group and 50% in the severe BPD-group. The development of PH complicates the postnatal course of extreme premature infants. Both early and late PH are associated with poor outcomes among preterm infants, with and without BPD. Recent reports suggests that morbidity and late mortality of PH in the 'new BPD' is high, with up to 48% mortality 2 years after diagnosis of PH. The pathogenesis of BPD is complex and known risk factors for the development of severe BPD includes maternal and neonatal factors, such as childbearing history, male gender, smoking mother during pregnancy, chorioamnionitis, low-birth-weight, gestational age, cholestasis and acute lung injury by high ventilator settings. Risk factors for the development of PH in extreme preterm infants are not well defined. Knowledge of prevalence and risk factors of PH in extreme premature infants will allow evidence-based screening guidelines for the infants. Also potentially leading to prevention of this complicating condition in the future, since an earlier intervention will be possible under guidance of known risk factors. Early detection will lead to early and thus potentially better treatment of PH in preterm born infants.

Objective of the study:

Primary:

To identify the incidence and prevalence of PH in premature born infants with and without BPD in the first year of life.