CONTENT:
- Definition
- Causes
- Symptoms
- Pathogenesis
Definition/What is Bronchiectasis?
It is basically a disorder in which the bronchi and bronchioles undergo irreversible (permanent) dilation, this dilation is caused mainly by infections. Bronchiectasis can either be localised or generalised process.
What causes Bronchiectasis?
Bronchiectasis is caused by destruction of the muscle and elastic tissue of bronchial wall. It is uncommon these days due to better control over lung infections but it may be developed in association with few other conditions. It may be divided into Nonobstructive Bronchiectasis and Obstructive Bronchiectasis.
Nonobstructive Bronchiectasis:
It is usually of generalised type characterised by dilation throughout the lung.
It may be the result of chronic necrotizing infections caused by
- Bacteria like Mycobacterium tuberculosis, Staphylococcus aureus, Haemophilia influenza, Pseudomonas
- Viruses like adenovirus, influenza virus, HIV (human immunodeficiency virus)
- Fungi like Aspergillus species
There are genetic causes as well like:
- Young’s syndrome: Here the patients develop bronchiectasis, sinusitis and obstructive azoospermia. The cause is not known.
- Kartagener or immobile cilia syndrome: It is an autosomal recessive syndrome with lack of ciliary function and causes retention of secretions and recurrent infections. It comprises of sinusitis, dextrocardia, bronchiectasis and male infertility (sperm dysmotility).
- Other dyskinetic ciliary syndromes: These have deficient cilia throughout the body. ( *cilia are eyelash like filaments that are numerous on animal cells and are involved in locomotion of water i.e., move water relative to the cell in a regular movement of cilia)
Immunodeficiency also leads to Bronchiectasis. Patients suffering from hypogammaglobulinemia (having low levels of antibodies called immunoglobulin in your immune system), HIV infection, bronchiolitis obliterans after lung transplantation have increased susceptibility to infections which in turn lead to Bronchiectasis.
Certain autoimmune diseases like rheumatoid arthritis and immune mediated diseases like allergic bronchopulmonary aspergillus also lead to bronchiectasis.
Obstructive Bronchiectasis:
It is localized to the obstructed segment of the lung and not the whole lung.
Partial or total obstruction of the bronchial lumen is the major cause. It results from tumor, foreign body aspiration and mucus plugs. Patients with atopic asthma and chronic bronchitis are also prone to this.
Symptoms associated with Bronchiectasis:
- Severe persistent productive cough: It is the most common clinical feature. Productive cough is when you have a cough that produces mucus or phlegm (sputum).
- Sputum is foul smelling, sometimes blood tinged. Patients also complain of dyspnea (a sensation of running out of air or not able to breathe efficiently) and orthopnea (shortness of breath when your lying at your back)
- A sudden attack or outburst of cough occurs when the patient rises in the morning, this is because of the changes in position leading to drainage of collections of pus and secretions into the bronchi.
Pathogenesis:
It involves two major factors i.e., obstruction and chronic persistent infection that are necessary for the development of bronchiectasis.
- Obstruction: Partial or total obstruction of the bronchial lumen by tumor, mucus plugs and foreign body aspiration impairs clearing mechanism of the lung causing accumulation of secretions distal to the obstruction resulting in secondary infection leading to inflammation, this causes weakening and dilation of airways.
- Chronic persistent necrotizing infection in the bronchi or bronchioles lead to increased bronchial secretion, this secretion causes obstruction of the airways leading to inflammation and fibrosis of the airway walls, finally resulting in weakening and dilation of airway.