Parents often have questions about pulmonary hypertension in the newborn period. Please see below to see the answers to some of the most frequently asked questions. Click to see the answers.
Having high pressure in your lungs is called pulmonary (= lung) hypertension (= high pressure). Pulmonary hypertension (sometimes also called persistent pulmonary hypertension of the newborn, PPHN) is usually diagnosed by an ultrasound scan of the heart performed at the cot side called an echocardiogram.
About one in every 500 babies develop pulmonary hypertension and it can happen for lots of different reasons. The lung blood vessels can be underdeveloped or fail to open properly after birth because of complications during pregnancy and labour, infections, and lung malformations. It is also common in babies born prematurely, especially those who need extra support with their breathing for a long time.
There are many different reasons that a baby may develop pulmonary hypertension, some being extremely rare. The situations that neonatal teams encounter most commonly in babies are described below.
Persistent pulmonary hypertension of the newborn (PPHN): Failure of normal transition of blood flow in the heart-lungs-and body from fetal life to newborn life which results in pulmonary hypertension and a need for high oxygen supplementation. Sometimes chorioamnionitis (infection in the mums’ waters before birth), oligohydramnios (not enough water during pregnancy) or infection at time of birth or immediately after, can contribute to babies having PPHN.
Prematurity: Premature lungs can be underdeveloped. Sometimes there is a delay or failure to fully open blood vessels in the lungs that normally open after birth. Premature babies can also fail to close connections between lung vessels and vessels supplying the rest of the body which are no longer needed after birth and normally close spontaneously in the first couple of hours to days. These factors can all contribute to pulmonary hypertension.
Infection: Infections contracted by the mother during pregnancy or the baby after birth can lead to inflammation in the lungs.
Meconium aspiration syndrome: occurs when during delivery amniotic fluid containing meconium (baby’s first stool) is inhaled into a babies lungs and can obstruct their airways. This causes a process of inflammation in the lungs which in turn can aggravate the lung vessels causing them to tighten and increase the resistance to blood flow through them, resulting in pulmonary hypertension.
Congenital diaphragmatic hernia (CDH): is a defect in a baby’s diaphragm resulting in abdominal organs being displaced, herniated, into the chest cavity. As a result of this when babies are born, they struggle to ventilate with their own lungs and require ventilation and ultimately surgery to repair the defect. In the majorities of babies who undergo surgery the pulmonary hypertension resolves, however in a very small number of babies it may persist, and they may require life-long treatment under a specialist pulmonary hypertension team.
Pulmonary hypertension associated with chronic lung disease (CLD): is a form of chronic pulmonary hypertension that occurs in extremely preterm babies and is associated with high risk of death under the age of two years. However, after the age of two years the long-term outcome in these children is more optimistic and the pulmonary hypertension may even resolve.
PDA: The ductus arteriosus is an extra blood vessel which all babies have in the womb. It connects the two main blood vessels leaving the heart. These are called the aorta (= body artery) and pulmonary (= lung) artery. Before a baby is born, the ductus arteriosus diverts blood from the lungs to the rest of the body. After your baby is born, their lungs fill with air, and blood will flow to their lungs. The ductus arteriosus is then not needed, and usually closes over the first few days of life.
In some babies, particularly babies born premature, the ductus arteriosus may not close properly, this is called a patent ductus arteriosus or PDA. Although PDAs are more common in babies born premature, they can also occur in babies born at term. In some babies the PDA may require treatment due to too much blood bypassing the body and going to the lungs. This can cause pressure in the lung vessels to increase. Over time this may cause the blood vessels themselves to tighten being more resistant to blood flow and chronic pulmonary hypertension can occur. Therefore, in some babies the PDA may need to be treated to close to stop pulmonary hypertension developing. Treatment options in some babies’ include medication, if this fails then some babies may need either surgery or a cardiac catheter (passing a long thin tube called a catheter, through a vein or artery in the heart) to close the PDA.
Genetics: In extremely rare cases there may be a genetic association with pulmonary hypertension. Everyone has a code, called the genome, made of their DNA. This code tells proteins in the cells to turn on/off functions in cells to allow our bodies to work. Everyone has mutations or spelling mistakes in their genome and most of these spelling mistakes do not result in any problem. However, if the spelling mistake, or mutation, can result in a disease process it is called pathogenic. In practical terms most babies do not need to undergo genetic testing for pulmonary hypertension if the cause is known. However, if the cause for pulmonary hypertension is not clear and it persists beyond the newborn period, they may have their genetics tested to look for known mutations. Often this happens when the baby is a bit older. The spelling mistake, or mutation, can rarely be inherited from either parent even if they are not affected by the disease, or it can occur randomly called a “de novo” mutation that is not inherited. The most common pathogenic mutation causing pulmonary hypertension in newborns is in the TBX4 gene. More information can be found here TBX4.org.
Symptoms vary from baby to baby and often can be due to other conditions such as infection, pneumonia and chronic lung disease. Babies may need high levels of respiratory support and supplementary oxygen. Other signs may include fast breathing, pulling in of their chest and having blue lips, hands or feet.
Your baby’s healthcare provider will check his or her health and delivery history. They will examine your baby. If your baby is unwell, breathing fast, has low levels of oxygen in their blood or needing help to breathe they will perform additional tests to diagnose pulmonary hypertension, including:
Oxygen level checks. Your baby’s oxygen levels will be checked at different spots on his or her body. Your child’s healthcare provider will compare these levels to check if blood is being circulated to your baby’s lungs.
Chest X-ray: This can show certain problems with the lungs or heart.
Echocardiogram. This is an ultrasound picture of the heart and blood vessels. The healthcare provider uses this to look at different body structures and to measure the blood pressure in different areas.
Blood tests to look for possible causes for pulmonary hypertension such as infection.
Treatment focuses on the underlying cause of the pulmonary hypertension and varies dependent on this. Your baby’s doctor will be able to explain the treatment that is best suited for your baby’s type of pulmonary hypertension.
If the pulmonary hypertension occurs immediately after birth, called persistent pulmonary hypertension of the newborn (PPHN) the treatment is supportive which often means supporting the lungs through ventilation and oxygenation and treating any possible infections. The use of an inhaled gas, nitric oxide, which is a very potent vasodilator acts to relax specifically the pulmonary arteries and hence reduce pulmonary vascular resistance. Nitric oxide is also typically used in cases of transient pulmonary hypertension.
For pulmonary hypertension that is not transient there are few treatments approved for the treatment of pulmonary hypertension in newborns and more research needs to be done to find medicines that can be used to treat these babies. However, there have been many studies looking at safety and tolerability of medications in babies, most commonly sildenafil, which acts along a similar way to nitric oxide, and as such has become common practice internationally to use in babies with pulmonary hypertension that persists. Other classes of medication for treating pulmonary hypertension are available in older children, however their use must be guided by the expertise of specialist centres managing children with pulmonary hypertension and is beyond common practice on the neonatal unit.
Supplemental oxygen: Your baby gets additional oxygen through a mask, prongs in the nose, plastic hood, or endotracheal tube.
Endotracheal (ET) tube: This is the best way to give the most oxygen possible. A tube is put into your baby’s windpipe (trachea). It helps him or her breathe.
Nitric oxide: This is the most used treatment world-wide for babies unwell in hospital with pulmonary hypertension. It is a colourless gas that can be administered through apparatus used to support a baby’s breathing. It works by dilating the blood vessels in the lungs.
Milrinone: is a medication given continuously through a drip that acts to help the heart muscle squeeze more effectively and is often used in babies with pulmonary hypertension when the heart has to work harder to pump blood around the body. Babies need to be very closely monitored on the intensive care unit with this medication.
Diuretics: these are water tablets that act on the kidneys to remove water from other parts of the body by increasing the amount of urine passed. They can be helpful when the heart is under extra strain.
Sildenafil: is a medication that in certain cases of babies with pulmonary hypertension can be given as a liquid or through a drip to relax and open-up the vessels in the lungs.
Extracorporeal membrane oxygenation (ECMO): this procedure is done if a baby does not respond to conventional care. Blood from the babies’ veins is pumped through an artificial lung, oxygen is added, and carbon dioxide is removed from the blood. The blood is then returned to the baby. This procedure is only done in certain neonatal intensive care units.
When your baby is ready to leave the neonatal unit, either home or to a paediatric ward, their care will be taken over by a paediatric team. If they have ongoing pulmonary hypertension, it is common that they will require ongoing specialist care, which may include respiratory specialist, cardiologist, or specialist in pulmonary hypertension.