Pediatric Pulmonary Hypoplasia - Causes, Symptoms, Diagnosis & Treatment

Pediatric Pulmonary Hypoplasia

Dr.Bharat Parmar profile Authored by Dr.Bharat Parmar on 20 Jan 2015 - 12:02.

Pulmonary hypoplasia refers to an incomplete or partial development of the lung tissues, resulting in a variety of symptoms, specifically respiratory distress soon after the birth. It is characterized by reduced lung size and weight due to reduced lung tissues. Pulmonary hypoplasia can either affect one side of lung or both, unilateral or bilateral, respectively.

The severity of the symptoms may vary with the stage of lung development with respect to the pseudo glandular stage (6 to 16 weeks of pregnancy). Normally, lung growth is regulated by a wide range of factors including volume and pressure in the lung, composition of lung fluid, function of kidneys, thoracic space, normal breathing movement and so on.

Alteration or abnormality in any of these factors may result in pulmonary hypoplasia. It is usually caused as a consequence of altered in-utero developments or due to congenital (birth defect), which is rare but life-threatening. Congenital pulmonary hypoplasia is reported to affect almost 10 of 10,000 live births around the world. Mortality rate varies somewhere around 71-95%, while the fetus with pulmonary hypoplasia is in the womb. 

As discussed, pulmonary hypoplasia can be either primary (due to familial autosomal recessive inheritance or idiopathic- with an unknown cause) or may be secondary due to congenital disease or condition and some other conditions causing deficiency of factors responsible for the lung development:

  • Malformation of the chest cavity / diaphragm (congenital diaphragmatic hernia) that pushes stomach into the chest cavity and alters the lung formation (congenital diaphragmatic hernia).
  • Altered breathing of the fetus may be due to neuromuscular conditions or lesions in the central nervous system.
  • Deficiency of amniotic fluid (Oligohydramnios), which may be caused due to undeveloped kidneys, blockage in urine tubes, and so on.
  • Altered lung fluid and lung fluid pressure in the fetus, the cause of this is often remains unknown.
  • Other congenital diseases, including multiple pterygium syndrome, scimitar syndrome, congenital heart disease, etc.

Other underlying conditions that may cause pulmonary hypoplasia may include:

  • Having nonfunctional parenchymal lung tissues (extralobar sequestration)
  • A tumour in the cavity that separates the lungs from the chest (medicinal tumour)
  • Reduced pulmonary vascular perfusion
  • Narrowing of the thorax due to skeletal dysplasiasis
  • Excessive pressure on the thorax e.g. Due to large intra-abdominal mass
  • Fryns syndrome (multiple congenital diseases)
  • Meckel syndrome, causing multiple renal cysts
  • The Pena Shokeir syndrome (PSS)

Symptoms and its severity may vary depending on the patient’s overall clinical profile, part of lung remained undeveloped and underlying other abnormalities. However, some children may remain asymptomatic while others may present with the following symptoms:

  • Immediate respiratory distress that often demands ventilatory support
  • Shortness of breath that may be accompanied by blue discoloration of the skin (cyanosis), especially in older children.
  • Frequent respiratory infections
  • Increased acidity
  • Deprived oxygen supply to the body or body parts (hypoxia)
  • Increased level of carbon dioxide in the blood (hypercarbia)
  • Symptoms of other neonatal disorders like skeletal dysplasia
  • Other birth defects like congenital heart diseases

Diagnosis of pulmonary hypoplasia may be prenatal or postnatal (after the birth). Diagnosis may involve several tests and examinations, as listed below.

Prenatal diagnostic tests may include:

  • Antenatal ultrasound- To identify amniotic fluid deficiency and ancillary signs that may indicate pulmonary hypoplasia.
  • Fetal ultrasound - To measure the lung size and circumference of the head, ratio less than 1 increases the mortality rate.
  • Doppler velocimetry - To detect severe forms of pulmonary hypoplasia by looking at increased peripheral pulmonary arterial resistance.
  • Nuchal scan - To look for increased nuchal translucency that often indicates the presence of congenital diaphragmatic hernia.
  • Fetal MRI - To calculate the lung volumes more accurately to avoid misdiagnosis.

Diagnostic tests after birth (postnatal) may include:

  • Blood and other laboratory tests – To look for altered levels of serum creatinine, blood urea and electrolytes that may indicate impaired renal functions causing pulmonary hypoplasia.
  • Examining lung weight and ratio of lung weight to body weight
  • Tests to look for mean radial alveolar count

Most of the above mentioned causes serve as risk factors that later turn as an underlying cause. However, the following factors may increase the risk of mortality:

  • Early membrane ruptures, usually before 25 weeks of pregnancy
  • Severely deficient amniotic fluid for longer than 2 weeks (typically when fluid index is less than 4)
  • Early birth (before the complete gestation)

Factors associated with poor outcomes may include:

  • Accumulation of the fluid in fetus compartments
  • Type and extent of cystic adenomatoid malformation

Treatment of pulmonary hypoplasia aims to increase the lung volume and improve overall lung development (in the fetus before birth). Suitable treatment intervention may be selected based on the lesion.

  • Treating early rupture of membrane – Preterm labor is effectively treated with medicines like tocolytics (e.g.Magnesium sulphate and nifedipine), antibiotics, and steroids, either as a monotherapy or in various combinations.
  • Amnioinfusions – It is a procedure of instilling the fluid in the amniotic sac. A series of amnioinfusions may be performed to treat the preterm rupture of membranes at less than 32 weeks of pregnancy.
  • Improving fetal lung development – Usually, corticosteroids are preferred while the fetus is in the womb and detected with lung anomalies.
  • Extra corporeal membrane oxygenation (ECMO) – To improve the oxygen supply with the aid of special machines. It is often accompanied by anti-coagulant medicines. It is especially indicated in those with congenital diaphragmatic hernia and persistent pulmonary hypertension associated with pulmonary hypoplasia.
  • Inhaled nitric oxide therapy (iNO) –To treat the shortness of breath causing pulmonary hypertension and deficiency of oxygen to the body (anoxemia). However, it is not effective pulmonary hypoplasia is caused due to congenital diaphragmatic hernia. Fetoscopic tracheal occlusion -To treat severe congenital diaphragmatic hernia that is causing pulmonary hypoplasia.
  • Dialysis – To restore the kidney functions when there is a chronic renal impairment.
  • Surgery – To correct the congenital defects like cystic lung abnormalities, congenital heart defects and many more that affects lung development and its function.

Complications:

Pulmonary hypoplasia is associated with following complications:

  • Chronic lung disease
  • Risk of severe upper respiratory tract infections (URTIs) and lower respiratory tract infections (LRTIs)
  • Increased risk of respiratory syncytial virus (RSV) prophylaxis, especially infants (<2 years) who had been treated for chronic lung disease

General tips:

  • Use the prescribed medications as directed.
  • Prefer to use inhalers (bronchodilator or corticosteroids) to treat the obstruction in the air passages or wheezing episodes.
  • Vaccinate your child against influenza, preferably before the high risk season begins.
  • Get your child administered with complete doses and booster doses of 13-valent pneumococcal conjugate vaccine (PCV13).
  • Give ventilation, whenever needed
  • Feed healthy food (consult the specialist before you make any choices)

 

 

 

*Disclaimer This is not medical advice. The content is for educational purposes only. Please contact your doctor for any health care issues.