Bronchiectasis-Revisited Essays - Respiratory System, Medicine

Bronchiectasis-Revisited Essays - Respiratory System, Medicine Bronchiectasis-Revisited K. Neelakantan Viswanathan Introduction: Bronchiectasis is a common chronic lung disease characterized by a "vicious cycle" of infection, inflammation and irreversible destruction in the airway (4). Laennec in 1819 defined bronchiectasis based on the findings in an infant who died of whooping cough."Bronemon" in Greek means the windpipe and "ektasis" means stretched out or extension (9).Bronchiectasis is a pathological, irreversible dilatation of the proximal, medium sized and terminal airways more than 2 mm in size, the 4th to the 10th generations being involved (10). Pathology: The normal bronchial wall consisting of cartilage, muscle and elastic tissue gets destroyed and is replaced by fibrous tissue. There is chronic,recurrent infection of secretions that pool within the airways. The organisms produce pigments, proteases and other toxins impairing mucociliary clearance. Epithelial injury is induced by the host inflammatory response, largely due to neutrophil-released mediators and protection against infection is compromised. There is also bronchial and peribronchial inflammation and fibrosis, bronchial wall ulceration, squamous metaplasia and mucous gland hyperplasia. The pulmonary parenchyma supplied by. The abnormal airways contain areas of fibrosis,emphysema,bronchopneumonia and atelectasis in varying combinations (1). The bronchiectatic cavities may be lined by granulation tissue,squamous epithelium or normal ciliated epithelium(6).Bronchiectasis may be accompanied by massive collapse in which all the airways and alveoli distal to the site of collapse are deflated resulting in an airless lobe (13).Reid's Classification (1950) divides this entity into saccular (cystic), fusiform (cylindrical) and varicose types (7). In addition there are follicular, nodular and traction types. There is transmural inflammation and mucosal oedema in cylindrical types, cratering and ulceration in cystic types with bronchial arteriole neo-vascularisation and distortion due to scarring or obstruction from repeated infections in the varicose types (4). In traction types there is extensive volume loss of lung bringing the upper and lower parts of the spine together with concavity to the affected side. Bronchiectasis commonly affects lower lobes, the left more frequently than the right. Next in frequency are the right middle lobe and the lingual (8). The apical segment is spared (12).Aspiration commonly affects the right lung and the lower lobes or the posterior segment of the upper lobes (4).Bronchiectasis sicca involves the upper lobes and is characterized by haemoptysis instead of sputum production, the aetiology, most often, being tuberculosis. Cystic fibrosis and allergic bronchopulmonary aspergillosis (ABPA) also affect the upper lobes.ABPA produces proximal or central (perihilar) bronchiectasis involving 4th-7th generations. Nodular bronchiectasis occurs in Mycobacterium avium infections. It is common in white women aged 55 and above with chronic cough with middle lobe or lingular involvement (4). Pseudo bronchiectasis occurs in expansion of a collapsed lung, usually after pneumonia. Aetiology: The causes of bronchiectasis may be easily remembered as follows: Bordetella pertussis infections Respiratory syncitial virus, Rheumatoid arthritis,Riley -Day syndrome,Relapsing polychondritis Obstruction by foreign body Neoplastic / Nodal compression Chagas disease Hypogammaglobulinaemia (especially selective deficiency of IgG2), HIV infection,Herpes simplex,Histoplasmosis Influenza,Inflammatory bowel diseases,Interstitial lung disease (fibrosing alveolitis) Exanthems-measles, mumps Cystic fibrosis, Congenital sequestrated lung. Coeliac disease, Ciliary dyskinesia (primary), in which the respiratory mucosal biopsy shows broken or missing ciliary spokes Tuberculosis,Toxins- ammonia, paraquat Aspiration of gastric contents,Alcoholism,Adenovirus infections,Alpha-1- antitrypsin deficiency,Atypical Mycobacteria (avium),Atypical pneumonia( Mycoplasma), Allergic bronchopulmonary aspergillosis (ABPA) Systemic complement deficiencies, Sjogren's syndrome,Sarcoidosis Idiopathic (commonest) Syndromes associated with bronchiectasis Kartagener's syndrome: an autosomal recessive' disorder, described in 1933 by a pediatrician, characterized by situs inversus, frontal sinusitis or agenesis of frontal sinuses and bronchiectasis. It is also associated with immotile cilia, due to an abnormal protein involved in the modified ciliary motility causing absence or aberrance of dynein arms, and hence persons with Kartagener's syndrome are infertile. The situs inversus is the chance result of embryonic migration of viscera rather than the normal cilia- dependent placement of internal organs (12). . Young's syndrome: characterized by obstructive azoospermia as a result of enlarged, palpable and obstructed epididymal head and obstruction by inspissated secretions (2). Williams Campbell syndrome: characterized by expiratory collapse of proximal airways on bronchoscopy. There is generalized bronchial cartilage deficiency leading to bronchomalacia. Mounier-Kuhn syndrome: characterised by congenital deficiency of bronchial cartilage associated with tracheobronchomegaly. Enlargement of the airways and deep corrugations produced by the redundant musculo-membranous tissues between the cartilaginous rings gives roentgenographic appearance of multiple diverticulae on CT (lO). Brock's syndrome: characterized by right middle lobe collapse, the bronchiectasis being caused by a foreign body or enlarged lymph node, usually tuberculous. Chandra- Khetarpal syndrome:characterized by levocardia, bronchiectasis and frontal sinusitis. Ciliary dysfunction is not a feature of this syndrome (3). MacLeod's (Swyer-James)syndrome: in which the disease is associated with a unilateral hyperluscent lung and characterized by brochiolitis obliterans (4). Yellow nail syndrome: associated with lymphedema and pleural effusion due to hypoplastic lymphatics. Childhood pentad of bronchiectasis:Whooping cough, measles, mumps, influenza, and primary complex are considered to be childhood infections that predispose to bronchiectasis in adult life. Clinical Features: Persons with bronchiectasis bring out copious foul smelling khaki-coloured sputum