Emphysema of Lung

1. Etiology of Localized Emphysema

Localized emphysema (hyperinflation) results from a "ball-valve" mechanism where air enters on inspiration but is trapped during expiration.

• Congenital Causes:
  1. Congenital Lobar Emphysema (CLE): Cartilage deficiency or dysplasia.
  2. Bronchogenic Cyst: Extrinsic compression of a bronchus.
  3. Congenital Pulmonary Airway Malformation (CPAM): Type II or III.
  4. Vascular Rings/Slings: e.g., Double aortic arch or Pulmonary artery sling.
• Acquired Causes:
  1. Foreign Body Aspiration: Most common cause of sudden localized hyperinflation.
  2. Mucus Plugging: Common in Asthma, Cystic Fibrosis, or Bronchiolitis.
  3. Endobronchial Tumors: e.g., Bronchial carcinoid (rare in children).
  4. Post-infectious: Lymph node enlargement (TB) or bronchial stenosis.

2. Congenital Lobar Emphysema (CLE): Pathophysiology

• Characterized by overdistension of one or more pulmonary lobes.
• Mechanism: 50% are idiopathic; 25% due to bronchial cartilage deficiency (bronchomalacia) leading to expiratory collapse.
• Distribution: Left Upper Lobe (43%) > Right Middle Lobe (32%) > Right Upper Lobe (20%).

3. Clinical Presentation

The presentation depends on the severity of air trapping and mediastinal shift.

• Neonatal Period (80%): Presents in the first month with acute respiratory distress, cyanosis, and difficulty feeding.
• Infancy: Recurrent wheezing, persistent cough, and repeated lower respiratory tract infections (LRTI).
• Physical Examination:
  • Inspection: Asymmetric chest expansion, tachypnea, accessory muscle use.
  • Percussion: Hyper-resonant note over the affected lobe.
  • Auscultation: Markedly diminished breath sounds on the affected side; mediastinal shift (displaced apex beat).

4. Investigations

• Chest X-ray (CXR): Hyperlucent lobe with loss of bronchovascular markings. Shows depression of the ipsilateral diaphragm and herniation of the lung across the midline.
• Antenatal Ultrasound/MRI: May detect fetal lung masses (hyperechoic lung).
• CT Chest (High Resolution): Gold standard to confirm the affected lobe, assess the lung parenchyma, and rule out extrinsic vascular compression.
• Echocardiography: Mandatory, as 10-15% of CLE cases are associated with Congenital Heart Disease (VSD, PDA).

5. Management

• Emergency Stabilization: Oxygen supplementation; avoid Positive Pressure Ventilation (PPV) if possible, as it may worsen air trapping and cause tension pneumothorax-like physiology.
• Surgical Management:
  • Therapeutic Gold Standard: Lobectomy of the involved lobe.
  • Indications: Severe respiratory distress or failing to thrive.
  • Approach: Open thoracotomy or Video-Assisted Thoracoscopic Surgery (VATS).
• Conservative Management:
  • Indicated for asymptomatic or mild cases discovered incidentally.
  • Requires close clinical and radiological follow-up.

6. Prognosis

• Post-operative prognosis is excellent.
• Compensatory lung growth occurs in the remaining lobes, usually resulting in normal pulmonary function tests (PFTs) in later childhood.