Persistent Pulmonary Hypertension of the Newborn (PPHN) is a serious condition where a newborn’s circulatory system does not adapt to breathing air after birth. The blood vessels in the baby’s lungs remain constricted, keeping blood pressure in these arteries dangerously high. This elevated pressure prevents adequate blood flow to the lungs, meaning the baby’s body and organs do not receive sufficient oxygen.
The Circulatory Transition at Birth
Before birth, a fetus relies entirely on the placenta for oxygen and nutrient exchange. Blood largely bypasses the lungs through two shunts: the foramen ovale, an opening between the heart’s upper chambers, and the ductus arteriosus, a vessel connecting the pulmonary artery directly to the aorta. This fetal circulatory pattern ensures oxygenated blood from the placenta is efficiently directed to the developing body, while only a small amount flows to the fluid-filled lungs.
Upon birth, the newborn takes its first breath, causing the lungs to expand and fill with air. This expansion triggers a rapid decrease in pressure within the pulmonary arteries, allowing blood to flow freely into the lungs to pick up oxygen. The change in pressure and oxygen levels causes the foramen ovale and ductus arteriosus to begin closing, redirecting all blood flow through the lungs. This transforms the circulatory system from a fetal bypass to an independent, adult-like circulation.
Causes and Associated Conditions
Persistent Pulmonary Hypertension of the Newborn (PPHN) arises when this normal circulatory transition fails. Lung problems are common contributors, including meconium aspiration syndrome, where a baby inhales its first stool into the lungs, or pneumonia, a lung infection. Respiratory distress syndrome (RDS), often seen in premature infants with underdeveloped lungs, can lead to PPHN.
Events around the time of birth, such as birth asphyxia, a lack of oxygen before or during delivery, can interfere with circulatory adaptation. Infections like sepsis, a bloodstream infection, or other systemic infections increase the risk of PPHN. Congenital anomalies, such as a diaphragmatic hernia where abdominal organs protrude into the chest and impede lung development, are associated with PPHN.
Maternal factors can also play a role. Conditions like maternal diabetes or the use of certain medications late in pregnancy, such as nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or aspirin, or selective serotonin reuptake inhibitors (SSRIs), have been linked to PPHN. These medications can sometimes cause premature constriction of the ductus arteriosus in the womb.
Symptoms and Diagnostic Confirmation
Affected infants often exhibit rapid breathing (tachypnea), along with visible retractions where the skin between or beneath the ribs pulls inward with each breath. Grunting sounds during breathing and a bluish tint to the skin and lips (cyanosis) are common signs. A rapid heart rate and low blood pressure may also be present.
For a definitive diagnosis, medical professionals rely primarily on an echocardiogram, an ultrasound of the heart. This test allows doctors to visualize the heart, observe high pressures in the pulmonary artery, and detect abnormal blood flow patterns, such as right-to-left shunting through the foramen ovale or ductus arteriosus. The echocardiogram confirms PPHN and rules out structural heart defects.
Other tests help identify underlying causes. A chest X-ray assesses lung condition, looking for pneumonia or meconium aspiration syndrome. Arterial blood gas tests measure oxygen and carbon dioxide levels, providing information about the baby’s oxygenation. Pulse oximetry, which measures oxygen saturation, may show persistently low levels despite oxygen administration, often with a significant difference between oxygen levels in the right arm and a leg.
Treatment Approaches in the NICU
Treatment for PPHN begins with supportive care in the Neonatal Intensive Care Unit (NICU). This includes maintaining a stable body temperature, providing intravenous fluids and nutrition, and minimizing external stimulation.
Oxygen therapy helps relax constricted pulmonary blood vessels and improve blood flow to the lungs. Oxygen can be delivered through nasal prongs or an incubator to achieve adequate oxygen saturation. If the baby’s breathing remains challenged, a mechanical ventilator may be used to assist breathing.
Inhaled nitric oxide (iNO) is an effective treatment for PPHN. This gas is administered directly into the baby’s breathing circuit, acting as a selective vasodilator that relaxes lung blood vessels. iNO allows more blood to flow to the lungs, improving oxygen uptake and reducing pulmonary artery pressure.
If a baby does not respond to inhaled nitric oxide and conventional ventilation, more advanced interventions may be considered. High-frequency oscillatory ventilation, a specialized mechanical ventilation, improves oxygenation. In severe cases, Extracorporeal Membrane Oxygenation (ECMO) may be employed. ECMO acts as a temporary heart-lung bypass machine, oxygenating the baby’s blood outside the body and allowing the heart and lungs to rest.
Long-Term Outlook and Follow-Up
Advancements in medical care, including inhaled nitric oxide and ECMO, have improved outcomes for affected infants. The prognosis for a newborn with PPHN depends on the severity of the illness, underlying cause, and associated conditions. Despite improved survival rates, some survivors may face long-term health challenges.
Up to 25% of infants who survive PPHN may experience lasting effects, often related to the initial lack of oxygen reaching the brain. These issues include neurodevelopmental delays, affecting cognitive abilities or motor skills. Hearing loss, ranging from mild impairment to deafness, is another recognized complication.
Survivors may also develop chronic lung problems or decreased physical activity. Regular follow-up appointments with pediatric specialists, such as developmental pediatricians, audiologists, and pulmonologists, are recommended. This care helps track development, identify lingering issues early, and provide appropriate interventions.