Evaluation of the Prevalence of Persistent Pulmonary Hypertension in Neonates (PRE-HIFREQ)

Respiratory failure after birth is still a severe problem. Risk factors include premature labor and delivery by cesarean section. Despite the improvement of the quality of perinatal care in Poland, almost a constant percentage of premature babies has been born in Poland. The number of births by cesarean section is also rising - both planned and preceded by the attempt to vaginal delivery. TTN - Transient Tachypnea of the Newborn is one of the most common causes of respiratory failure in newborns. TTN occurs in approximately 10% of newborns born between 33 and 34 weeks of gestation, in about 5% of newborns born between 35 and 36 weeks and less than 1% of neonates.

At baseline of transient tachypnea of the newborn (TTN), there are disorders of absorption of pulmonary fluid. In the flow of water, epithelial sodium channels and Na+ / K+ -ATPase play an essential role. Their stimulation increases the absorption of water from the lung airspace and increases its transport both inside and outside the cell. In the subsequent stages of removal of interstitial pulmonary fluid, the vascular system and the lymphatic system are involved.

TTN is usually a self-limiting process, and treatments are not defined. There are also reports of "malignant TTN" in which infants develop persistent pulmonary hypertension of newborns (PPHN) (3). TTN infants typically require non-invasive respiratory support (CPAP, for example) and may need higher oxygen concentrations in the respiratory mixture to maintain proper oxygenation. Some experts suggest that the early use of expanding pressure (nasal CPAP) may relieve severe forms of TTN and prevent using of mechanical ventilation, and also may eventually prevent the development of persistent pulmonary hypertension.

Persistent pulmonary hypertension of newborns (PPHN) is a disorder arising at the stage of a physiological passage of fetal circulation into the neonatal circulation in the perinatal period. It is associated with a lack of decreasing pulmonary vascular resistance, which is influenced by increasing levels of oxygen in the blood and numerous biochemical and hormonal factors. From own observations and data from the literature, it is estimated that PPHN occurs in approximately 0.1-0.2% of newborns born term or near the term. Treatment of persistent pulmonary hypertension is difficult. Despite the use of mechanical ventilation, inhaled nitric oxide (iNO) or extracorporeal oxygenation (ECMO), the risk of death is still around 10-15%. This percentage has declined in recent years, but it is believed that persistent pulmonary hypertension of newborns is one of the most challenging situations in intensive care of newborns. In addition, infants who have undergone PPHN are exposed to long-term effects in the form of neurological complications or neurodevelopmental disorders.

Before initiating a clinical trial (intervention) with the experimental therapy, an initial follow-up study was conducted to assess the incidence of failure in respiratory insufficiency and the rate of PPHN in neonates born between 32 and 41 weeks of gestation. The failure of treatment will be defined as the need for invasive ventilation (intubation and mechanical ventilation). To accurately determine the degree of respiratory failure, a scale was developed that was an adaptation of the Silverman scale. PPHN will be defined by parameters measured in echocardiography and on changes in blood gases. Also, a comparison of parameters of acid-base balance and the type of treatment of respiratory failure after birth will be performed in the follow-up study. Based on the collected data, validation of the modified Silverman scale and evaluation of its clinical utility will be presented.