Investigation of choice for diagnosis of bronchiectasis:
Correct Answer: HRCT
Description: Ans. a. HRCT (Ref: Harrison 19/e p1694, 18/e p2143)HRCT is investigation of choice for diagnosis of bronchiectasis.High Resolution Computed tomography (HRCT)HRCT uses very thin 1-2 mm thin slicesQ.HRCT is used primarily to diagnose:BronchiectasisQInterstitial lung diseaseQ (Fibrosing alveolitis, asbestosis)BronchiectasisAbnormal and permanent dilatation of bronchiQ.The bronchial dilatation of bronchiectasis of is associated with destructive and inflammatory changes in the walls of medium sized airways, often at the level of segmental or subsegmental bronchi.Types of bronchiectasisCylindricalVaricoseSaccular (cystic)* Bronchi appears as uniformly dilated tubes that ends abruptly at the point that smaller airways are obstructed by secretionsQ* Affected bronchi have an irregular or beaded pattern of dilatation resembling varicose veinsQ.* Bronchi have a ballooned appearance at the periphery, ending in blind sacs without recognizable bronchial structures distal to the sacsQ.Etiology and pathogenesis:Bronchiectasis is a consequence of inflammation and destruction of the structural components of the bronchial wall. InfectionQ is the usual cause of inflammation.1. Infectious causes:Adenovirus and influenza virusQ are the main viruses that cause bronchiectasis in association with lower respiratory tract involvement.Impaired host defense mechanisms are often involved in the predisposition to recurrent infections.The major cause of localized impairment of host defenses is endobronchial obstruction, like Carcinoid tumors or foreign body aspirationQ.Primary ciliary dyskinesia, Kartagener's syndrome and cystic fibrosis are also associated with bronchiectasis.2. Non-infectious causes:Exposure to toxic substances like inhalation of toxic gases such as ammonia or aspiration of acidic gastric contentsQ.Clinical Manifestations:Patient typically presents with persistent or recurrent cough and purulent sputum productionQ.HemoptysisQ occurs in 50-70% of cases and can be due to bleeding from friable, inflamed airway mucosa.More significant, even massive bleedingQ is consequence of bleeding from hypertrophied bronchial arteries.Physical examination includes crackles, rhonchi, and w heeze may be heard, all of which reflect the damaged airway containing significant secretionsQ.Radiographic findings:HRCT is investigation of choiceQ.When seen longitudinally, the airways appears as 'tram tracks'Q; when seen in cross section, they produce 'ring shadows'Q; Inspissated secretions (e.g., the 'tree-in-bud' pattern)Bronchiectasis of relatively proximal airways suggests ABPA, whereas the presence of multiple small nodules (nodular bronchiectasis) suggests infection with M. avium complexQ.
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