Persistent pulmonary hypertension of the newborn is a serious disorder in which the small arteries in the lungs remain narrowed (constricted) after delivery, thus limiting the amount of blood flow to the lungs and therefore the amount of oxygen in the bloodstream.
This disorder causes severe trouble breathing (respiratory distress) in full-term or postterm newborns.
Breathing is rapid, and the skin and/or lips may be bluish or may be pale and grayish.
The diagnosis is confirmed by an echocardiogram.
Treatment involves opening (dilating) the small arteries in the lungs by giving high concentrations of oxygen, sometimes while supporting the newborn’s breathing with a ventilator.
To help dilate the arteries in the lungs, sometimes nitric oxide is added to the gas that the newborn is breathing.
Extracorporeal membrane oxygenation (a type of heart-lung bypass machine) is sometimes used in the most severe cases.
(See also Overview of General Problems in Newborns.)
Normally, the small blood vessels in the fetus's lungs are tightly constricted before birth. The lungs do not need much blood flow before birth because the placenta rather than the lungs eliminates carbon dioxide and transports oxygen to the fetus. However, immediately after birth, the umbilical cord is cut and the newborn’s lungs must take over the role of oxygenating the blood and removing carbon dioxide. To achieve this process, it is necessary for the fluid filling the air sacs (alveoli) in the lungs to be replaced by air and for the pulmonary arteries, which circulate blood through the lungs, to widen (dilate) so that an adequate amount of blood flows through the lungs to be oxygenated. (See also Normal Fetal Circulation.)
Persistent pulmonary hypertension of the newborn is more common among newborns who are full term (delivered between 37 weeks and 42 weeks of gestation) or postterm (delivered after 42 weeks of gestation).
Causes of PPHN
Sometimes the blood vessels in the lungs do not widen (dilate) after birth as they normally should. When the blood vessels in the lungs do not widen, blood pressure in the pulmonary arteries is too high (pulmonary hypertension), and blood flow to the lungs is insufficient. Because of this insufficient blood flow, not enough oxygen reaches the newborn's blood (hypoxia).
There are many reasons why the blood vessels may not widen, including:
Severe distress during delivery (such as from meconium aspiration syndrome)
Any other circumstance that causes a low level of oxygen in the fetus before, during, or after delivery, such as birth asphyxia, infection in the mother or the fetus (sepsis in the newborn or pneumonia in the newborn), problems with the placenta, congenital diaphragmatic hernia, collapsed lung, or underdeveloped lungs
Heart problems that may be caused by the mother's use of certain medications during pregnancy (such as large doses of aspirin or other nonsteroidal anti-inflammatory drugs [NSAIDs] such as ibuprofen)
Symptoms of PPHN
Sometimes persistent pulmonary hypertension is present at birth. Other times, it develops over the first day or two.
Breathing is usually rapid, and newborns may have severe trouble breathing if they have an underlying lung disorder (such as respiratory distress syndrome).
The skin and/or lips may have a bluish discoloration (cyanosis) due to low blood oxygen levels. In newborns with dark skin, the skin may appear blue, gray, or whitish, and these changes may be more easily seen in the mucous membranes lining the inside of the mouth, nose, and eyelids. Sometimes, the lower half of the body has a lower oxygen level and more cyanosis than the upper half.
Sometimes newborns with persistent pulmonary hypertension have low blood pressure (hypotension) that causes weak pulses and a pale, grayish hue to the skin. Newborns with dark skin who have low blood pressure or poor blood flow to the body may also have a pale, grayish hue or mottled appearance to the skin.
Diagnosis of PPHN
Oxygen levels that are lower in the legs than the arms, or low oxygen levels that do not increase when the infant is given oxygen
Echocardiogram
Chest x-ray
Doctors may suspect persistent pulmonary hypertension if the newborn has severe trouble breathing, cyanosis, and/or low oxygen levels in the blood that do not increase when oxygen is given, especially if the symptoms vary with the newborn's level of agitation or activity. They also may suspect this disorder in newborns who have meconium aspiration syndrome, who may have an infection, who need more oxygen or breathing support than expected, and in those whose mother took high doses of aspirin or ibuprofen during pregnancy or had a stressful delivery.
To confirm the diagnosis of persistent pulmonary hypertension of the newborn, doctors do an echocardiogram to see how blood flows through the newborn's heart and to the lungs.
A chest x-ray may be normal or may show changes caused by an underlying disorder (such as diaphragmatic hernia or pneumonia).
Cultures of the blood may be done to look for certain kinds of bacteria. Other tests may be done to determine whether the newborn has sepsis.
Treatment of PPHN
Oxygen
Often nitric oxide gas or other medications
Sometimes a ventilator
Sometimes extracorporeal membrane oxygenation
Treatment of persistent pulmonary hypertension of the newborn involves placing newborns in a quiet environment and giving them oxygen. Oxygen is typically given through prongs placed in the newborn’s nostrils or through a face mask. In severe cases, a ventilator (a machine that helps air get in and out of the lungs) may be needed and may be used to provide 100% oxygen. A high percentage of oxygen in the blood helps widen the arteries in the lungs.
A small concentration of the gas nitric oxide may be added to the oxygen that the newborn is breathing. Inhaled nitric oxide widens the arteries in the newborn’s lungs and reduces pulmonary hypertension. This treatment may be needed for several days. The newborn may also be given other medications that widen the arteries, either by vein (intravenously) or by mouth.
Rarely, if all other treatments do not work, extracorporeal membrane oxygenation (ECMO) can be used. In this procedure, blood from the newborn is circulated through a machine that adds oxygen and removes carbon dioxide and then returns the blood to the newborn. The machine acts as an artificial set of lungs for the newborn. As the machine does the work of getting oxygen into the newborn's body, the newborn's lungs have time to rest and the blood vessels slowly widen. ECMO has been lifesaving, allowing some newborns with pulmonary hypertension who do not respond to other treatments to survive until the pulmonary hypertension resolves.
Fluids and other treatments, such as sedatives, muscle relaxants, antibiotics for infection, and heart failure medications, are given as needed.
Prognosis for PPHN
Persistent pulmonary hypertension of the newborn is fatal in a few infants depending on the cause of the persistent pulmonary hypertension.
Some children develop developmental delays, hearing problems, or chronic lung disease.
