What is pulmonary interstitial emphysema (PIE)?

Pulmonary interstitial emphysema (PIE) is when air gets trapped in the tissue outside of tiny air sacs (alveoli) in the lungs. It affects newborn babies. PIE is fairly common in neonatal intensive care units (NICUs).

When you breathe, air travels in through your mouth and nose to your lungs. The air goes into the alveoli. This is where gases get exchanged. Here, the lungs send oxygen to the blood. And they release carbon dioxide, a waste product. The oxygen then travels through the blood to all the organs of your body.

Normally, air in the lungs stays in the alveoli. But in some cases, air can escape into the nearby tissue around the tiny sacs. This tissue is called the interstitium. This can happen if the wall of an air sac breaks open. If enough air leaks out, this can cause problems with breathing and blood flow.

PIE usually affects low-weight infants who need a device (ventilator) that helps with breathing. These infants often have a lung problem that is caused by preterm birth. PIE often affects infants in the first few days of life. It may affect one or both lungs.

PIE is classified by how long it lasts. Acute PIE lasts for less than a week. If it lasts longer, it is called persistent PIE. PIE may also be called diffuse or localized. Diffuse means it occurs in multiple places in the lungs. Localized means it occurs in a single spot.

What causes pulmonary interstitial emphysema?

PIE most often happens in preterm infants. It occurs when their lungs don't make enough of a substance called surfactant. Surfactant allows alveoli to be more flexible and less likely to break open.

Being on a ventilator may cause PIE. During artificial ventilation, a ventilator applies air pressure to the air sacs of your child’s lungs. This helps your child breathe by opening closed-off lung sacs. But in some cases, this extra pressure can create a leak in an air sac.

Who is at risk for pulmonary interstitial emphysema?

Babies with a greater risk of PIE are those with the following conditions:

• Preterm birth, which often leads to respiratory disease

• The lungs don't develop correctly (pulmonary hypoplasia)

• Breathing in the first intestinal discharge (meconium) at birth

• A lung infection (pneumonia)

• Very fast breathing right after birth (transient tachypnea of the newborn)

What are the symptoms of pulmonary interstitial emphysema?

Signs of PIE often appear within 4 days of birth. Mild PIE may have no signs. More severe PIE may cause signs of breathing trouble, such as:

• Grunting

• Fast breathing

• Pale appearance

• Parts of the body tinted blue (cyanosis) due to low oxygen in the blood

How is pulmonary interstitial emphysema diagnosed?

You may be asked about you and your child’s health history. This may include information before, during, and after birth. Your child will have a physical exam. Their heart and lungs may be checked. Blood tests may be done to look for signs of low levels of oxygen and high levels of carbon dioxide.

Your child may likely have an imaging test, such as a chest X-ray or a chest CT scan. Leaked air will often appear on both of these imaging tests.

How is pulmonary interstitial emphysema treated?

PIE is a serious condition. It can cause death if not correctly treated. For this reason, treatment is done inside a neonatal intensive care unit (NICU).

Treatment is done to make sure your child gets enough oxygen. It also aims to prevent more air leaks. Treatment may include:

• Lying your baby on the side with the air leak, which helps move more air into the lung that is working well

• Lowering ventilator pressure if possible, to help prevent more air leaks

• Using high-frequency oscillatory ventilation, which may lower pressure in the air sacs

• Giving extra oxygen

Your child’s vital signs and levels of oxygen in the blood are checked during the treatment. Your child may also need X-rays to check on the status of the air leaks as they heal.

In most cases, PIE gets better with these treatments, and the leaked air goes away.

If your child has a severe localized case of PIE, the healthcare team may collapse the lung with the air leak for a short time. This is so the air sac can heal. This is done by placing a breathing tube into the lung without the air leak. Or air flow may be blocked for a short time to the lung with the air leak. Your child might need a breathing tube and ventilator support during this time.

In rare cases, a child might need to have part of a lung removed to treat PIE that does not go away.

Your child may also need treatment for other lung problems that may be causing the PIE.

What are possible complications of pulmonary interstitial emphysema?

PIE can sometimes cause pneumothorax. This is air in the space between the outer lungs and the chest wall. This can make breathing problems worse. Your child may need ventilator support or a chest tube for a large pneumothorax.

How can I prevent pulmonary interstitial emphysema?

Preventing preterm birth may help prevent PIE. You can decrease the chance of preterm birth by:

• Not smoking during pregnancy

• Not using alcohol or drugs during pregnancy

• Getting early and regular prenatal care throughout your pregnancy

• Getting medical attention at the first signs of preterm labor

Key points about pulmonary interstitial emphysema

• Pulmonary interstitial emphysema (PIE) is when air gets trapped in the tissue outside air sacs in the lungs.

• It affects some newborn babies who are placed on ventilators, or breathing machines. PIE is fairly common in NICUs.

• Lung disease caused by preterm birth increases a child’s risk of PIE.

• PIE can cause trouble breathing and low oxygen levels in the blood.

• In most cases of PIE, the air leaks go away on their own with supportive care.

• In rare cases, your child might need a lung deflated for a short time to help treat PIE. Surgery may be needed in rare cases.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your healthcare provider if you have questions, especially after office hours and on weekends and holidays.