Complications of BPD
Heart and Circulation (Cardiovascular) Complications
A Quick Review of The Circulation
The purpose of the lungs is to allow oxygen to be delivered to the blood, and to remove carbon dioxide, or waste gas, from the blood. Blood travels to the right side of the heart through veins, from all over the body. The right side of the heart then pumps the blood into the lungs through the pulmonary arteries. After blood has travelled through the lungs, picking up oxygen, it travels through the pulmonary veins to the left side of the heart. The chambers that make up the left side of the heart then pump the blood through arteries, to all parts of the body.
What Is Pulmonary Hypertension?
When a part of the lungs doesn't contain enough oxygen (for example, if there is a lobar pneumonia there), the pulmonary arteries that carry blood to that section of the lungs constrict, so that blood travels, instead, to healthier parts of the lung, that contain more oxygen. Unfortunately, if all parts of the lung don't contain enough oxygen, this normal process becomes harmful, because it results in every pulmonary artery constricting. This is called Pulmonary Hypertension.
When Pulmonary Hypertension happens, the right side of the heart is forced to try to pump blood through very-narrowed arteries, which is much harder work. Eventually, the right side of the heart can "tire out," which is known as heart failure (or cor pulmonale). Pulmonary Hypertension and Cor pulmonale is the most serious complication of BPD, because it can lead to permanent narrowing of the pulmonary arteries, and permanent, sometimes severe, damage to the heart. Cor pulmonale can usually be prevented, by ensuring that the oxygen saturation of babies with BPD stays above 92%. This requires regular monitoring of the oxygen saturation by your doctor or respiratory therapist, and may mean giving your baby supplemental oxygen.
Some babies with very severe BPD and severe lung scarring have scars that narrow or destroy pulmonary arteries, which sometimes causes (or worsens) Pulmonary Hypertension. When Pulmonary Hypertension occurs, your doctor may recommend increasing the amount of oxygen your baby is getting. Some babies require water pills, or Digitalis (Digoxin, or Lanoxin®), a medicine which stregthens the heart.
High Blood Pressure (Your baby's — not yours!)
Another cardiac complication of BPD is high blood pressure, or hypertension. High blood pressure is believed to be due to the physical stress that ill babies with BPD must deal with. Some medications may increase the blood pressure, as well. High blood pressure is treated with blood pressure medications. Babies with BPD should have their blood pressures checked regularly.
Breathing (Respiratory) Complications
Infections
The most common respiratory complication of BPD is difficulty handling respiratory infections, such as colds, "the flu", and pneumonia. Respiratory infections are the commonest cause of severe attacks of difficulty breathing in BPD. All respiratory infections increase the amount of mucous in the lungs, which can make it more difficult for air to travel through the bronchial tubes, or into the airsacs. This can lead to lower oxygen saturations, and increase the work of breathing. Babies with BPD have fewer airsacs than normal, so they have difficulty tolerating having airsacs blocked by a pneumonia or even by a plug of mucous. Respiratory infections can also worsen inflammation in the lungs, leading to more fluid in the lungs and/or bronchospasm. If your child develops a respiratory infection, you should contact your doctor.
Two viruses can can cause particularly severe respiratory distress, wheezing, and/or pneumonia are Respiratory Syncitial Virus (or RSV) and Influenza Virus. RSV is a common cause of severe inflammation, mucous plugging, and bronchospasm of the very tiny airways (or bronchioles). This infection is called bronchiolitis. Other viruses than can cause similar infections include Parainfluenza Virus and Adenovirus. Because infections can be so serious in BPD, it's important to try to prevent infections as much as possible.
Excessive Fluid in the Lungs (Pulmonary Edema)
Particularly during periods of respiratory distress, the breathing muscles work harder to pull air into the lungs. This "pull" also tends to pull water out of the tiny blood vessels in the lungs and into the lung tissue. Inflammation also makes it easier for fluid to travel from the blood vessels into the lung tissue. This water tends to accumulate in the walls of the airsacs, making it more difficult for oxygen to travel from inside the airsacs to the blood vessels around the airsacs. Fluid in the air sacs also makes the air sacs, and therefore the lungs, more stiff. Fluid can also accumulate in the walls of the bronchial tubes, making the bronchial tubes narrower. The increased lung stiffness and narrowing of the bronchial tubes makes breathing even more difficult, perpetuating the problem. Narrowing of the bronchial tubes can also cause wheezing. Fluid accumulation in the lungs can occur when babies with BPD are given too much fluid to drink (or, in hospital, by an intravenous). It also can occur during infections, which increase inflammation and which cause respiratory distress.
Apnea Spells (Apnea)
A less common respiratory complication of BPD is apnea. Apnea means stopping breathing for a brief (10 seconds or longer) or prolonged period of time. You can tell when a baby is not breathing because the chest (or rib cage) is not moving at all. During apnea, babies may become blue, and the heart rate may slow.
Apnea is common in premature babies while they remain in the Neonatal Intensive Care Unit. Nearly all affected babies have "outgrown" their problem with apnea before leaving the nursery.
A few babies with BPD have persisting problems with apnea, and may need to go home on an apnea monitor for a number of months. Parents who have a home apnea monitor are taught Cardio-pulmonary resuscitation (or CPR).
In general, it is believed that babies at home with BPD have apnea about as often as other babies. Some studies suggest that the incidence of Sudden Infant Death Syndrome (SIDS, or "Crib Death") is slightly more common in babies with BPD, but this is controversial, and most doctors do not believe that the risk is high enough to justify sending all babies with BPD home on apnea monitors. You may wish to discuss this with your doctor.
During severe respiratory infections, a baby with BPD who is struggling to breathe may tire out and have apnea; for this reason, babies with BPD and severe respiratory distress should be seen by a doctor (see BPD Emergencies). Apnea spells can also be caused by Gastro-esophageal Reflux.
"Large Airway" Complications — Subglottic Stenosis and Treacheomalacia
During the early phases of treatment of Respiratory Distress Syndrome and BPD, a ventilator is used to deliver oxygen to the lungs of a premature baby. The oxygen travels from the ventilator, into a tube that runs from just outside the baby's mouth or nose, through the voicebox (or larynx) and into the windpipe (or trachea). This tube is used to deliver fresh oxygen from the ventilator directly into the baby's lungs. The tube is called an endotracheal tube.
Occasionally, prolonged use of the endotracheal tube can lead to damage to the windpipe (or trachea). This can lead to narrowing of the windpipe (known as Subglottic Stenosis or Tracheal Stenosis) or softening of the windpipe (known as Tracheomalacia). These conditions lead to constant "wheezing" breathing in and/or breathing out, which may worsen with activity or crying. Tracheomalacia often improves as the baby grows, but severe damage to the trachea may require surgery or tracheostomy. 
A tracheostomy is a hole created at the base of the neck which allows a inverted-"L"-shaped tube to be inserted directly into the windpipe. This is sometimes needed to bypass a severe obstruction involving the upper part of the windpipe.
Asthma and Reactive Airways Disease
Asthma is a disease in which their is episodic narrowing of the bronchial walls, triggered by exposure to various substances in the environment. Because the bronchial walls react following exposure to these substances, asthma (particularly in the setting of another lung disease, like BPD) is sometimes termed "Reactive Airways Disease." Reactive Airways Disease, or "asthma" is another common complication of BPD. About 1/2 of children with BPD will have "asthma" or "Reactive Airways Disease," and sophisticated lung tests can pick up asthma-like changes in 80-90% of children and young adults with a history of BPD.
Asthma-like symptoms in children with BPD is believed to be due to persisting inflammation of the airways. This is due to an increased number of cells (known as inflammatory cells) in the airways, where they release certain chemicals. These chemicals cause the airways' walls to become swollen and narrowed. The chemicals alo cause excessive mucous production by the airways, and bronchospasm.
Symptoms of asthma include episodic wheezing, cough, difficulty breathing, and chest tightness, which may be more pronounced during colds, at night, or with exercise. These symptoms respond to a bronchodilator medication. "Asthma" is probably commmoner in children where allergic-type diseases (such as allergies, hay fever, asthma, and eczema) run in the family.
"Asthma" may require treatment with bronchodilators or anti-inflammatory medications.
Gastro-Intestinal Complications
Gastro-esophageal Reflux and Aspiration
Gastro-Esophageal Reflux
When narrowing of the bronchial tubes is present, air often has more trouble leaving the lungs than entering the lungs. This causes the lungs of many babies with BPD to be over-inflated. Overinflated lungs push down on the stomach. When the stomach is squeezed, stomach contents, such as stomach acid and partly- digested milk, sometimes flow back up the feeding tube (or esophagus) to the mouth. This is called Gastro-Esophageal Reflux. Once these liquids have reached the mouth, they can be inhaled into the lungs. This is called Aspiration.
Clearly, the stomach contains acid, which, when aspirated, can burn the lining of the lungs (just like strong acid can burn your skin). Aspiration can lead to inflammation of the bronchial tubes and bronchospasm. Repeated aspiration can lead to worsened lung scarring or delay the healing process in BPD. Aspiration can also cause lung infection or pneumonia. For these reasons, it is important to diagnose Gastro-Esophageal Reflux.
The symptoms of Gastro-Esophageal Reflux are excessive spitting up after meals, sometimes associated with coughing or choking. Gastro-Esophageal Reflux can lead to persistent coughing, wheezing, or difficulty breathing, or apnea spells. Large feeds and naso-gastric tube feeds can over-fill the stomach and worsen Gastro-Esophageal Reflux.
Gastro-Esophageal Reflux may be diagnosed using several different tests. Babies may be given Barium or milk containing a tiny amount of radioactive dye. X-rays are then taken to see if the barium or dyed-milk travel back up the feeding tube. These tests are known as a Barium Swallow and Milk Scan, respectively. Another test involves putting a tiny pH meter into the feeding tube, using a naso-gastric tube. The pH meter checks for the presence of stomach acid in the feeding tube, for 24 hours. This is known as a pH probe study.
There are several different treatments for Gastro-Esophageal Reflux. The simplest involves raising the head of the bed (with some blocks or books) to an angle of about 15°, and placing the baby in the bed, on his stomach, after feeds. This helps keep the feed in the stomach. Feeding the baby small amounts at a time, on a frequent basis, often helps as well. Some babies improve when their formula is thickened with infant cereal. In more severe cases, medications such as Metoclopramide (Maxeran®), or Domperidone (Motilium®) can be used to prevent Gastro-Esophageal Reflux.
These medications are often used with an antacid, or a medicine which reduces stomach acid, such as Ranitidine (Zantac®) or Cimetidine (Tagamet®). When these medications are unsuccessful, surgery may be needed to strength the valve at the bottom of the feeding tube (which normally prevents Gastro-Esophageal Reflux).
Aspiration due to Swallowing Difficulties
Aspiration can also occur when a baby chokes while drinking or eating solids or liquids, with the food travelling into the windpipe and lungs, rather than into the esophagus. Any food breathed into the lungs can cause lung damage, blockage in the lungs, and infections. Choking is more common in infants who also have developmental delays. If you have concerns about your child's ability to swallow, or if you notice that your child coughs, chokes, sputters, or wheezes during feeds, you should discuss this with your doctor.Your doctor may order a Barium X-ray to check the swallowing, or have your child seen by a swallowing specialist (an Occupational Therapist or Speech Therapist). In many cases, a swallowing specialist can provide advice on how to prevent choking during feeds. In a few very severe cases, tube-feeding may be required. You may click on Naso-gastric tube feeding or gastrostomy tube feeding for more information about these techniques.
Complications due to Medications
The most common medication causing serious side effects is a water pill, or diuretic, called Lasix® (or furosemide). Lasix® can cause kidney stones, hearing problems, and low calcium levels, which can lead to softening of the bones (or rickets). For these reasons, doctors try to use Lasix® for as short a time as possible. When a baby has been on Lasix® for a long period of time, the doctor will often order an ultrasound of the kidneys and a hearing test. Your doctor will also look for signs of rickets.