Persistent pulmonary hypertension of the newborn (PPHN)

How does this happen?

Before birth, a baby's lungs are full of fluid and do no breathing. The blood vessels in them are deliberately tight, so blood is diverted past the lungs through two shortcuts: an opening between the top chambers of the heart, and a vessel connecting the two main arteries.

At birth, the first breaths inflate the lungs and oxygen reaches the lung tissue. The blood vessels relax, the shortcuts close over hours to days, and blood begins flowing through the lungs.

In PPHN that switch does not happen. The vessels stay tight, pressure in the lung circulation stays high, and blood continues to take the shortcuts. Because that blood has not passed through the lungs, it carries little oxygen. ¹

This creates a cycle that is important to understand. Low oxygen makes the lung vessels constrict further, which sends more blood around the lungs, which lowers oxygen further. Breaking that cycle is the whole point of treatment.

It also explains the characteristic bedside sign. The vessel connecting the two main arteries joins the circulation after the branch to the right arm. So blood going to the right hand has come through the lungs, and blood going to the feet may include blood that skipped them. A saturation difference between the right hand and a foot points to PPHN. ¹

What causes it?

Two different questions get mixed together here. The first is what leads to this injury in the body. The second is whether anyone could have prevented it. They are not the same question, and the answer to the first does not settle the second.

Happens even with perfect care

• Meconium aspiration syndrome, one of the most common causes. ¹
• Respiratory distress syndrome and other lung disease.
• sepsis, particularly Group B strep infection. ²
• hypoxic-ischemic encephalopathy and low oxygen around birth. ³
• Congenital diaphragmatic hernia and lung underdevelopment, which are structural and not preventable at birth. ⁴
• Idiopathic PPHN, where the lungs look normal and no cause is found.
• Cesarean birth without labor, which is associated with a slower transition.

Associated with gaps in care

These are situations where published standards say what the care team should watch for and do. A gap here does not prove anyone caused your child's injury. It points to where the medical records will have an answer.

PPHN is usually a complication of something else, so the questions point back to that.

• Infection not recognized and treated, where standards for evaluating and treating a possibly infected newborn exist. ²
• A loss of oxygen during labor not acted on. ⁵
• The saturation difference between hand and foot not checked, which is a simple bedside test that points to the diagnosis. ¹
• Escalation delayed, including delay in starting inhaled nitric oxide or in referring for ECMO where indicated. ¹
• Delivery or care at a hospital without the level of newborn care required, where levels are formally defined and where ECMO is available only at certain centers. ⁶
• Excessive handling in a baby known to have PPHN.

Whether any of this amounts to a departure from the standard of care takes a physician expert reading the whole record.

What are the signs, by age?

Signs change as a child grows. A newborn cannot show you a walking problem. Some children look fine at first and show differences months later.

At birth and the first hours

• Blue color that does not improve with oxygen.
• Fast breathing, grunting, flaring nostrils, drawing in between the ribs.
• Low Apgar score scores in some babies. ⁷
• A heart murmur.
• A baby who looks worse than the chest X-ray suggests, which is a classic feature.

The first week

• Oxygen levels that swing widely, particularly with handling.
• A difference between right hand and foot saturations. ¹
• Need for a ventilator, inhaled nitric oxide or ECMO.
• Low blood pressure.
• Seizures if there was a period of very low oxygen. ⁸

Around 3 months

• Most survivors have recovered lung function.
• Some need oxygen at home.
• Feeding difficulty in babies who were very unwell.
• Hearing loss, which is a recognized issue after PPHN and after ECMO and can appear later. ⁹

Around 6 months

• Developmental follow-up, judged at corrected age where the baby was preterm. ¹⁰
• Repeat hearing assessment, because hearing loss after PPHN can be late in onset. ¹¹

Around 12 months

• Most children have no ongoing respiratory issues.
• Developmental differences where there was significant low oxygen. ³

Toddler years

• Increased wheezing with viral illness in some children.
• Hearing and developmental follow-up continuing.

School age

• Most children have no lasting effects.
• Where there was brain injury or hearing loss, the picture follows those.

How is it diagnosed?

Pre- and post-ductal saturations. Oxygen levels measured on the right hand and on a foot. A significant difference points to blood bypassing the lungs. It costs nothing and it should be done in any newborn with unexplained low oxygen. ¹

Echocardiogram is the key test. It shows the pressure in the lung circulation, shows blood flowing the wrong way through the fetal shortcuts, and rules out a heart defect, which is the main alternative explanation and which would be made worse by some PPHN treatments.

Chest X-ray, which may show a cause such as meconium aspiration syndrome or respiratory distress syndrome, or may look surprisingly clear in idiopathic PPHN.

Blood gases and continuous monitoring.

Infection screen, because sepsis is a common cause. ²

Assessment for brain injury where there was significant low oxygen, including whether cooling criteria are met. ¹²

Getting the echocardiogram matters because heart disease and PPHN can look identical from the bedside and need opposite treatments.

What is the treatment?

Treat the cause, whether that is infection, meconium or surfactant deficiency.

Oxygen and ventilation, carefully. Both too little and too much oxygen are harmful, so targets are set and followed. High-frequency ventilation is often used.

Keep everything else stable. Blood pressure, temperature, blood sugar, calcium and pain control all affect lung vessel tone.

Minimal handling. Babies with PPHN can drop their oxygen sharply when disturbed. Care is clustered, lights are dimmed and the room is kept quiet. This is treatment, not preference. ¹

Inhaled nitric oxide, the specific treatment, which relaxes lung blood vessels without dropping blood pressure elsewhere. ¹

surfactant, where there is underlying lung disease.

ECMO, for babies who do not respond. This requires transfer to a center that provides it, and the decision to refer is time-sensitive. ^{1 6}

Follow-up hearing assessment, because hearing loss after PPHN and ECMO is recognized and can be late in onset. ⁹

What is the long-term outlook?

Most babies with PPHN survive and recover normal lung function, and outcomes have improved substantially since inhaled nitric oxide and ECMO became available. ¹

The main determinants are the underlying cause, how severe the low oxygen was, and how long it lasted.

Two follow-up issues are specific to this group and are sometimes missed.

Hearing loss, which is recognized after PPHN and after ECMO, and which can appear later rather than at the newborn screen. Repeat testing is appropriate. ^{9 11}

Developmental follow-up, where there was significant low oxygen. ¹⁰

What does daily life look like?

In the NICU, this is one of the conditions where parents are asked not to touch their baby much. That is genuinely hard, and it is genuinely treatment. Ask the nurse when the next handling window is and what you can do during it, such as steady hand containment rather than stroking.

After discharge, ordinary life for most families, sometimes with home oxygen for a period.

Keep the hearing appointments even if the newborn screen passed. That is the one thing families most often let slide, and it is the one with the clearest reason to attend.

What does care cost over a lifetime?

No agency publishes a lifetime cost estimate for PPHN.

For a baby who recovers, cost is the intensive care stay, which is high and time-limited, and ECMO substantially increases it.

Where there is brain injury or hearing loss, the published anchors are CDC's estimates of about $921,000 for cerebral palsy and about $417,000 for hearing loss, both in 2003 dollars, which are separate population estimates that cannot be added together. ¹³ See the cost of care estimator.

What can you do this week?

1. Ask whether an echocardiogram has been done and whether heart disease has been ruled out.
2. Ask what the right hand and foot saturations are.
3. Ask whether inhaled nitric oxide is being used and whether it is helping.
4. Ask what the plan is if things get worse, and whether ECMO would mean transfer.
5. Ask when you can hold your baby and what handling is safe now.
6. Ask for hearing assessment before discharge and a repeat later.
7. Ask for developmental follow-up to be arranged.

What should you ask each specialist?

Take these with you. Write the answers down in the moment, because you will not remember them later.

For the neonatologist

• What is causing the PPHN?
• What did the echocardiogram show, and has heart disease been excluded?
• Is nitric oxide working, and what is the next step if it is not?
• Would ECMO mean transfer, and at what point would you refer?
• Was there a period of low oxygen that affects the brain?

For the nurse

• When is the next handling window?
• What can I do that helps rather than disturbs?
• What are the numbers you are watching, and what do they mean?

You can also build a printable list with the question generator.