Persistent Pulmonary Hypertension In Newborns

Persistent pulmonary hypertension in newborns is a life threatening condition, which occurs when the pulmonary arteries carrying blood to the lungs remain constricted in the infant, reducing blood flow to the lungs and resulting in poor oxygenation of the blood.

  • Persistent pulmonary hypertension is the result of extreme respiratory distress occurring in infants born at full term as well as in post-term babies. It may be caused if the mother uses some NSAID drugs during pregnancy too.
  • Rapid breathing and bluish color of the skin termed cyanosis are the usual symptoms.
  • The typical symptoms indicate the disorder, but an echocardiogram helps in confirming the diagnosis.
  • Dilating the pulmonary arteries which lead to the lungs by providing supplementary oxygen, while the infant is hooked onto a ventilator, is the usual treatment procedure.
  • Nitric oxide in small amounts is introduced into the oxygen supply provided to the infant to facilitate the opening up of pulmonary arteries.
  • A technique called extracorporeal membrane oxygenation, or ECMO, may be necessary in severe cases of persistent pulmonary hypertension.

The circulatory pattern of the fetus is different from that of the newborn. The placenta is supplying oxygenated blood to the fetus, so the blood flow from the fetal heart is directed away from the lungs as long as the infant is connected to the placenta. The pulmonary arteries which carry the blood from the heart into the lungs remain constricted during this time. When the infant is born, and the umbilical cord is severed, the lungs begin functioning. The air sacs which were previously filled with fluid become dry and get filled with the air inhaled by the infant. In the meantime, the blood flow to the lungs through the pulmonary artery should begin too, so that the oxygenation of blood can take place in the lungs. The opening up of the pulmonary artery normally facilitates the blood flow to the lungs. In some cases, the pulmonary arteries remain constricted even after the lungs start functioning, resulting in the condition called persistent pulmonary hypertension. The infant may be breathing, but the oxygenation of blood fails to take place as the blood does not reach the lungs. Poor oxygenation precipitates the typical symptom cyanosis, wherein the skin of the infant appears bluish.

Prolonged labor and complications during delivery causing fetal distress, is thought to be a risk factor for developing persistent pulmonary hypertension. Other causes include extreme respiratory distress resulting from other disorders of the lungs present in the infant, or due to meconium aspiration. Certain NSAIDs like aspirin as well as indomethacin taken during pregnancy also can cause pulmonary hypertension.

Causes

Pulmonary hypertension in newborns is prevalent in post term infants as well as in babies born at term. Excessive use of aspirin and another non steroidal anti-inflammatory drug named indometacin during pregnancy is known to cause this condition in infants. Respiratory distress present in the newborn due to meconium aspiration syndrome or any other disorders of the lung such as pneumothorax, lung infections and pneumonia can initiate pulmonary hypertension. However, in rare cases, persistent pulmonary hypertension develops without any lung disorders too.

Symptoms and Diagnosis

Rapid breathing, cyanosis or bluish tinge to the skin, and if lung disorders are present, respiratory distress due to them, are the usual symptoms. If the infant develops low blood pressure, characteristic symptoms of hypotension such as rapid heartbeat, weak pulse and pale, clammy skin also may be present. Some infants show symptoms of persistent pulmonary hypertension right from the time of birth. It may develop later also, but usually within the first two days of birth.

Diagnosis of persistent pulmonary hypertension is based on the symptoms as well as the presence of risk factors such as difficult delivery, meconium aspiration syndrome, other lung disorders resulting in respiratory distress, and the medical history of the mother taking aspirin or indometacin excessively in pregnancy. An x-ray of the chest may not show any abnormality, unless lung disorders are present. An echocardiogram, showing high pressure persisting in the arteries leading to the lungs (pulmonary arteries), confirms the diagnosis.

Treatment

Persistent pulmonary hypertension in newborns is treated by keeping them in a special environment saturated with oxygen. High oxygen content in the infant’s blood can help open up the arteries leading to the lungs. When persistent pulmonary hypertension is severe, ventilator support is necessary to provide 100% oxygen to the baby.

Occasionally, a small amount of nitric oxide gas is introduced into the oxygen supply provided to the infant. Nitric oxide has the property of opening up arteries. When used in the infants, it helps in reducing the constriction of the pulmonary artery and relieving pulmonary hypertension. The treatment with nitric oxide may have to be continued for many days. Another treatment option called extracorporeal membrane oxygenation, or ECMO for short, is considered when the other treatments fail. The blood of the infant is taken out of the body and fed into a machine that purifies the blood by removing carbon dioxide and enriching it with oxygen. In short, ECMO takes over the function of the lungs temporarily. ECMO is the only option in many cases when infants with pulmonary hypertension are not helped by other available treatments. This procedure has helped save many lives by keeping the infant alive till pulmonary hypertension is resolved and normal circulation is restored.

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Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery
Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

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