Persistent pulmonary hypertension of the newborn is a serious disorder in which the arteries to 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 arteries to the lungs by giving high concentrations of oxygen, often 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 is sometimes used in the most severe cases.
(See also Overview of General Problems in Newborns.)
Normally, the blood vessels to 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 bring blood to the lungs, to widen (dilate) so that an adequate amount of blood flows through the lungs to be oxygenated.
Causes
Sometimes the blood vessels to the lungs do not widen (dilate) after birth as they normally should. When the blood vessels to 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 blood.
There are many reasons 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 infection in the mother or the fetus (sepsis in the newborn), problems with the placenta, diaphragmatic hernia, collapsed lung, underdeveloped lungs, or pneumonia in the newborn
Certain changes in the newborn's circulation, including those resulting from taking certain medications during pregnancy (such as large doses of aspirin or other nonsteroidal anti-inflammatory drugs such as ibuprofen)
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).
Symptoms
Sometimes persistent pulmonary hypertension is present from birth. Other times, it develops over the first day or two.
Breathing is usually rapid, and the newborn may have severe trouble breathing if it has 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. Sometimes newborns with persistent pulmonary hypertension have low blood pressure (hypotension) that causes weak pulses and a pale, grayish hue to the skin.
In newborns of color, the skin may change to colors such as yellow-gray, gray, or white. Newborns of color who have low blood pressure may also have a pale, grayish hue to the skin. These changes may be more easily seen in the mucous membranes lining the inside of the mouth, nose, and eyelids.
Diagnosis
Bluish or gray discoloration even though the newborn is receiving oxygen
Echocardiogram
Chest x-ray
Doctors may suspect persistent pulmonary hypertension if the mother took high doses of aspirin or ibuprofen during pregnancy or had a stressful delivery. They also suspect persistent pulmonary hypertension if the newborn has severe trouble breathing, bluish or gray discoloration that does not go away when high concentrations of supplemental oxygen are given, and unexpectedly low oxygen levels in the blood. Doctors may also suspect persistent pulmonary hypertension in newborns who have meconium aspiration syndrome, who may have an infection, or who need more oxygen or breathing support than expected.
To confirm the diagnosis of persistent pulmonary hypertension of the newborn, doctors do an echocardiogram to see how blood flows through the 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 meconium aspiration syndrome).
Cultures of the blood may be done to look for certain kinds of bacteria.
Treatment
Supplemental oxygen
Sometimes a ventilator
Sometimes nitric oxide gas
Sometimes extracorporeal membrane oxygenation
Treatment of persistent pulmonary hypertension of the newborn involves placing newborns in an environment with 100% oxygen. 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 going to the lungs.
A very 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.
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 antibiotics for an infection, are given as needed.
Prognosis
About 10 to 60% of affected newborns die depending on the cause of the persistent pulmonary hypertension.
About 25% of survivors have developmental delays, hearing problems, functional disabilities (meaning a decreased ability to do physical activities), or a combination.
