Bronchopulmonary Dysplasia or Respiratory Insufficiency

What is Bronchopulmonary Dysplasia?

Bronchopulmonary dysplasia or chronic lung disease of neonates predominantly affects preterm babies (born before 37 weeks), especially those born before 28 weeks gestation (7 months gestation). These infants are born with underdeveloped lungs and usually need ventilator support and prolonged oxygen therapy. Unfortunately, in some cases these machines damage the infants’ delicate airways. The airway and lung damage can lead to or aggravate respiratory distress syndrome (RDS).

Bronchopulmonary dysplasia (BPD) is defined as the condition that occurs when symptoms of RDS persist for more than one month after birth. It is marked by scarring and inflammation of the lungs.

BPD was first described in 1967 by Northway et al who noticed the development of a new chronic lung disease in a set of premature infants who suffered from respiratory distress syndrome (RDS) and received ventilation with high levels of oxygen. Although typically associated with premature birth, it can also affect full term infants who need aggressive ventilator support for acute lung disease.

Epidemiology of Bronchopulmonary Dysplasia

According to the American Lung Association, about 10,000 new cases of infants are diagnosed with BPD annually in the US. Most infants outgrow BPD and get better, though they may have some persistent symptoms. Rarely, BPD can be fatal. BPD ranks as the most common chronic lung disease of infancy in the United States.

What are the Causes and Risk Factors of Bronchopulmonary Dysplasia?

BPD occurs most often due to respiratory distress syndrome (RDS), common complication in preterm infants. Lungs in preterm babies lack surfactant, a naturally produced substance that prevents the air spaces in the lungs from collapsing. These infants therefore have difficulty breathing at birth which is made worse by infections, inflammation and fluid build-up damaging the fragile lungs and airways even further.

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In addition, babies with RDS need treatments such as oxygen therapy and a ventilator to survive. Although lifesaving, these treatments may also hurt the lungs, limiting normal growth and increase the risk of BPD.

Risk Factors of BPD

• Degree of prematurity – infants born at less than 28 weeks gestation. Lungs are more underdeveloped. BPD is rare in infants born after 32 weeks gestation
• Low birth weight – less than 4.5 pounds
• Prolonged mechanical ventilation (can damage the air sacs or alveoli of lungs by overstretching)
• High concentrations of oxygen and prolonged oxygen therapy – levels less than 60 percent are considered safe

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• Male gender
• Genetic factors
• Maternal factors – smoking, drug abuse, infections, malnutrition (may result in preterm labor with consequent increased risk of BPD)
• Miscellaneous –Intrauterine growth retardation (impaired development of the baby in the womb)

What are the Symptoms and Signs of Bronchopulmonary Dysplasia?

• Rapid shallow breathing (tachypnea)
• Labored breathing (indrawing of ribs while breathing)
• Nasal flaring during inhalation
• Coughing
• Wheezing (a soft whistling sound as the baby breathes out)
• Bluish discoloration of the skin around the lips and nails due to low oxygen levels in the blood
• Impaired growth
• Repeated lung infections that may require hospitalization

How do you Diagnose Bronchopulmonary Dysplasia?

History and Clinical features

Typically, BPD is considered if symptoms of RDS in a preterm infant last longer than normal. Doctors often use a specific time frame, such as 28 days, as a marker. BPD may also be diagnosed if respiratory problems persist beyond the premature baby’s actual due date.

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Investigations

• Chest x-ray - Chest x-ray is useful to make a diagnosis as well as to see if the condition is becoming progressively worse. The x-ray appearances may vary greatly in different cases.
• Blood tests - Analysis of arterial blood may show hypercapnia (increased CO2 concentration) and relative hypoxia (low oxygen concentration) with decreased blood pH (acidosis).

How is Bronchopulmonary Dysplasia Treated?

Several treatment modalities are used to manage BPD. Infants with BPD are usually in an incubator in the neonatal intensive care unit (NICU) to reduce chances of infection

Respiratory support – A ventilator or a nasal continuous positive airway pressure (NCPAP) machine will provide oxygen. This has to be carefully monitored to reduce risk of further lung damage as prolonged ventilator use can damage the baby’s lungs.

Oxygen therapy – High concentrations can damage lungs and eyes and should be carefully monitored

Antibiotics – To reduce risk of infection

Diuretics - These drugs help to reduce the amount of fluid in and around the air spaces and given by mouth

Corticosteroids - Reduce and/or prevent lung inflammation. They also decrease swelling within the walls of the windpipes and decrease mucus production. Mothers at risk of preterm labor may be given prophylactic steroids to decrease chances of infant RDS

Bronchodilators - Help to relax the muscles around the air passages, widening the diameter of the airway tubes and making breathing easier. They are usually administered as a mist by a mask over the infant’s face and using an inhaler or nebulizer with a spacer.

Recent studies have shown that babies treated early on with surfactant replacement tend to have a better outcome and do not need to be on prolonged ventilator support but can be instead maintained on continuous and steady oxygen flow to lungs through the nose, reducing risk of further lung damage.

Viral immunization - Babies with BPD are at increased risk of respiratory tract infections, especially respiratory syncytial virus (RSV). They should get monthly injections with a medication that helps prevent infections during the RSV season.

Heart medications – Occasionally infants with BPD may require special drugs to relax the muscles around the blood vessels in the lung, and reduce the strain on the heart.

General Guidelines for Care of Infants with Bronchopulmonary Dysplasia

• Infants with mild BPD – May not need any treatment. Some may need medicines given orally or as a spray when the babies have breathing difficulties or other problems.
• Premature infants with mild BPD – May be discharged with monitors that continuously monitor their heart rate and breathing, as well as devices that check the oxygen levels in the blood (pulse oximeters).
• Moderate to severe disease – Infants with moderate to severe disease may need nasal prongs to supply oxygen for several months. They may need respiratory support with machines that provide continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP). Rarely in severe disease, a tracheostomy procedure with a breathing tube introduced in the front of the neck may become necessary. If feeding difficulties are present a permanent feeding tube may be needed
• Frequent follow up - By pediatric lung specialist for the first few years of life