Bronchiectasis : Causes, Pathophysiology

Bronchiectasis is the destruction and dilatation of proximal and medium-sized bronchi. The bronchi size becomes more than 2mm. The most important characteristic features of Bronchiectasis are bronchorrhea and mucopurulent sputum. The most commonly involved areas of the lung are the lower lobes, right middle lobe, and lingula.

Causes of Bronchiectasis

• Focal Bronchiectasis
  • Tumor- It leads to compression or obstruction of the bronchi and that leads to this stasis of the secretion.
  • Foreign Body Aspiration- It is very common in the pediatric age group.
  • Lymph node enlargement
• Diffuse Bronchiectasis
  • The most common reason for diffuse Bronchiectasis is infection.
  • The bacteria responsible for infection and Bronchiectasis are Pseudomonas, mycoplasma pneumonia, Bordetella pertussis, and Burkholderia cepacia.
  • A decrease in immunity can lead to the progression of different organisms. HIV and hypogammaglobulinemia are the common causes of a decrease in immunity and can lead to Bronchiectasis.
• Recurrent Micro Aspirations- In patients with Scleroderma and bulbar palsy there is a risk of chronic minute aspirations, however in ICU and comatose patients aspirations can cause lung Abscess.
  • The rheumatological causes are Rheumatoid arthritis, Sjogren syndrome, Inflammatory bowel disease, and Idiopathic pulmonary fibrosis.
  • In idiopathic pulmonary fibrosis, the fibrosis can cause airway distortion that causes abnormality in ventilation and also decreases lung clearance. This leads to traction Bronchiectasis.
  • The other causes of traction Bronchiectasis are radiation exposure to the chest and sarcoidosis.
• The Autoimmune Causes Are:

1. Allergic Bronchopulmonary Aspergilloma- The hypersensitivity reaction against aspergillus fumigatus can lead to Bronchiectasis. It usually occurs in asthma patients.
2. Serum IG E levels of the patient will be high and on sputum examination fungal hyphae can be observed.
3. On HRCT, central Bronchiectasis can be diagnosed.

• Genetic causes are A1 antitrypsin deficiency, cystic fibrosis, and Kartagner syndrome.
• The miscellaneous causes are yellow nail syndrome. 
•  In 25 to 50% of patients, it can occur idiopathically.

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Pathophysiology in Some Important Diseases

• A1 antitrypsin deficiency
  • The role of A1 antitrypsin is to neutralize the elastase enzyme in the alveolar macrophages.
  • A1 antitrypsin is produced by hepatocytes.
  • In most cases of A1 antitrypsin deficiency, the production is normal but A1 antitrypsin is not released out and starts accumulating in hepatocytes.

The Manifestations Of A1 Antitrypsin Deficiency Are

• Panacinar emphysema
• Bronchiectasis
• Cirrhosis
• Cystic fibrosis
• It is an Autosomal Recessive Disease.
• It occurs due to F508 mutation and the defective chromosome is chromosome #7.
• The mucus becomes thick which leads to stasis of mucus and alteration of bronchi.
• Colonization of Airways by Pseudomonas aeruginosa forms biofilm in the bronchi.
• It causes infertility in both males and females.
• Infertility in males is due to agenesis of vas deferens and in females, infertility is due to the presence of thick cervical mucus.
• Kartagener Syndrome
  • It is also called immotile cilia syndrome. It is due to a dynein arm defect but these secretions are normal.
  • It occurs with a triad of:
• Recurrent sinusitis
  • Bronchiectasis
  • Situs inversus 
  • The cause of infertility in males is due to a defect in sperm motility.
  • In females, infertility is not seen because the movement of ova depends on both peristalsis and cilia motility, so even if the cilia motility is affected, ova can move into the fallopian tube. Therefore infertility is not included in this triad.

Also read: Cardiopulmonary Resuscitation (CPR): Procedure, Steps and Types

Clinical features of Bronchiectasis

• Productive cough
• Broncorrhea
• Dyspnea on exertion
• Crepts more than Rhonchi will be present.
• Clubbing is not seen in chronic bronchitis but it is seen in Bronchiectasis.
• Weakness 
• Weight loss
• Cyanosis may or may not be present.
• Cor pulmonale

Diagnosis and management of Bronchiectasis

• The patient will present with features of Bronchiectasis. X-rays will be normal in the early stages but few cases can present with a tram-track appearance on the lower lobe.
  • HRCT scan is the investigation of choice
  • Tram-track appearance
  • Signet ring-like appearance

• The diameter of the airway should be more than 1.5 times the diameter of the blood vessel.
• Pulmonary function test obstructive pattern FEV1/FVC less than 0.7.
• No improvement with bronchodilators.
• On Sputum culture, Dittrich plugs will be developed. These are yellow concentrations colonies of the bacteria.
• Fungal hyphae will be seen.
• In HIV patient, 4^th generation ElISA is done.
• Autoimmune panel should be done
• Genetic testing for the diagnosis of A1 antitrypsin deficiency.
• Cystic fibrosis should be diagnosed with Pilocarpine iontophoresis.
• Nasal lung biopsy or video microscopic analysis is done to diagnose the Kartegener syndrome.
• Quantitative immunoglobulin level should be checked.

Also Read:  Platelet Disorders

Treatment of Bronchiectasis

• Mucolytics is given for purulent bronchorrhea. DORNase/DNAase can be infused in cystic fibrosis patient.
• For inspissated secretion, 3% saline nebulization with bronchodilators is prescribed.
• Percussion device that is high frequency chest oscillatory device helps in dislodgement of mucus.
• Respirometer is used.
• Physiotherapy and incentive spirometry.
• Vaccines
• Gamma globulins in hypogammaglobulinemia.
• Antibiotics like ciprofloxacin, macrolides, and tobramycin nebulization can be given in cystic fibrosis patient to prevent colonization of Airways.
• Steroids in ABPA exacerbation.

Also Read: Primary Biliary Cholangitis : Pathophysiology, Clinical Features

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