Basics

Persistent Pulmonary Hypertension In the Newborn

Persistent Pulmonary Hypertension of the Newborn (PPHN) is a rare and a serious life-threatening condition which occurs usually in post-term or full-term babies. PPHN is greatly characterized by the non-presence of cyanotic congenital disease of the heart, relentless post-birth hypoxemia and marked pulmonary hypertension. It is also found to occur in cases where the child is not able to receive sufficient amount of oxygen during the time of delivery.

Causes
Usually, at the time of birth of the baby, the circulatory system rapidly adapts itself to the outside conditions when the baby starts breathing. This leads to changes in the lungs pressure which cause the lungs to inflate and as a result, there is a permanent closure of the ductus arteriosus.

The circulating blood in the heart then is ready to be pumped into lungs for an exchange of carbon dioxide and oxygen. However, in a PPHN-affected baby, the ductus arteriosus remains open and the blood flow in the body of the child persists on bypassing the lungs. As a result, the breather air’s oxygen content is not allowed to reach the bloodstream normally.

This leads to a state where the blood returns to the heart in an oxygen-poor condition. This is medically termed as PFC (Persistent Fetal Circulation).
 
Several conditions may develop during, antenatally or soon after the child’s birth, resulting in breakdown of pulmonary vascular resistance to reduce at the time of evolving of the circulation from a fetal state to a post-natal one. This condition then results in cyanosis due to the shunting of blood (right-to-left) across to the existing cardiovascular channels of the body to high systemic versus pulmonary pressure.

Diagnosis
Infant suffering from PPHN may be provided with supplemental oxygen to correct the state of arterial hypoxemia. The physician may note the oxygen tension gradient that is between the pre-ductal and post-ductal arterial circulation. The oxygen tension gradient may not be there in case of substantial shunting which is at the foramen ovale level. The diagnosis of PPHN is thereafter confirmed echocardiographically.

The management of PPHN includes the treatment of fundamental causes, analgesia and sedation. It also involves measures adapted for raising tissue and blood oxygenation levels, reducing the pulmonary vascular resistance and normalizing blood pH. Nowadays, inhaled nitric oxide is successfully used for the purpose of decreasing the need for the extracorporeal membrane oxygenation and also for the treatment of PPHN.