obstructive and restrictive Flashcards
Obstructive lung diseases
Characterized by increase in resistance to airflow
• FEV1/FVC ratio of less than 0.7 – Reduced FEV1
Restrictive diseases
Characterised by reduced expansion of lung parenchyma and decreased total lung capacity (TLC)
• FEV1/FVC ratio remains normal – Both FEV1 and FVC reduced
four major types of emphysema
Centriacinar
• Panacinar
• Paraseptal
• Irregular
Emphysema
• Definition:
Irreversible enlargement of the airspaces distal to the terminal bronchiole
• accompanied by destruction of their walls.
Centriacinar
Most common form
Pronounced in the upper lobes - apical segments
• Involves proximal parts of the acini (Respiratory bronchioles) and spares distal
parts (Alveoli)
• Both normal and emphysematous air spaces exist in same acinus
• Severe disease involve distal parts (alveoli) and resemble Panacinar emphysema
Paraseptal –
volves distal part of acinus (Alveoli), proximal portion is normal (Terminal bronchiole)
• Severe in the upper half of the lungs
• More striking adjacent to pleura, septa, and margins of lobules
• Complication
• Occurs adjacent to areas of fibrosis, scarring, atelectasis
• Cause of pneumothorax in young adults
Panacinar
α1-antitrypsin deficiency
• Acini are uniformly enlarged from respiratory bronchiole to terminal blind alveoli
• Affects lower zones and anterior margins of lung
Emphysema
• Pathogenesis
Toxic injury and inflammation
Protease-antiprotease imbalance
Oxidative stress
Infection
Emphysema
• Gross morphology
Voluminous lungs that overlap heart in the chest cavity
• Usually, the upper 2/3 are more involved
• Apical bullae may be present.
• Cut surface
• Large alveolar spaces are seen
Emphysema
• Microscopy
Abnormally large alveoli separated by thin septa with focal Centriacinar fibrosis.
• Dilated pores of Kohn
• Club shaped septa
• Small airway inflammation
• Inflammatory infiltrates in bronchial walls
Emphysema
• Clinical features
Barrel-chest
• Dyspnoea
• Impaired expiratory airflow is the key to diagnosis
• Prolonged expiration
• Often referred to as “Pink puffers”
• Patients sits forward in hunched-over position and breathes through pursed lips - Puffer
• Blood-gas values relatively normal at rest as the patient over-ventilate to remain oxygenated - Pink
Emphysema
• Treatment
Smoking cessation
- Oxygen therapy
- Long-acting bronchodilators
- Inhaled corticosteroids
- Physical therapy
- Bullectomy
- Lung volume reduction surgery
- Lung transplantation
Chronic Bronchitis
• Definition
Persistent, productive cough ≥ 3 months ≥ 2 consecutive years in the absence of any other
identifiable cause
Chronic Bronchitis
• Pathogenesis
- Mucus hypersecretion
- Acquired (CFTR) dysfunction
- Inflammation
- Infection
Chronic Bronchitis
• Gross morphology
Hyperemia, swelling and oedema of mucous membranes
• Associated mucinous or mucopurulent secretions
• May see casts of mucus and exudate in airways
Chronic Bronchitis
• Microscopy
Characteristic microscopic features • Chronic inflammation of the airways • Thickened bronchiolar wall • smooth muscle hypertrophy • Deposition of extracellular matrix in the muscle layer • Peri-bronchial fibrosis
Chronic Bronchitis
• Cardinal symptoms:
Persistent cough • Productive of sputum • Dyspnoea on exertion • Hypercapnia, hypoxemia, mild cyanosis • “Blue bloaters
Asthma
• Definition
Heterogenous disorder of the conducting airways usually caused by an immunological process marked by
episodic bronchoconstriction, inflammation of the bronchial walls; and increased mucus secretion
Asthma Classification
Atopic • IgE-mediated (type I) hypersensitivity reaction • Onset - childhood • Triggered by environmental allergens • Non-atopic • No evidence of allergen sensitization • Drug induced • Aspirin-sensitive asthma • Occupational
Asthma
• Pathogenesis
Th2 Responses, IgE, and Inflammation
• Presentation of antigen to naïve CD4+ helper T cells
• IL-4
• Stimulates class switching to IgE and promotes the development of additional Th2 cells
• IL-5
• Development and activation of eosinophils
• IL-13
• Enhances IgE production
• Stimulate mucus secretion by epithelial cells
Sensitization and activation of Mast Cells
• Activated by high-affinity IgE Fc receptors
• Release of mediators by mast cell (degranulation)
• Vasoactive amines. – histamine
» Smooth muscle contraction
» Increases vascular permeability
» Mucus secretion.
• Enzymes – Proteases (Chymase/Tryptase)
» tissue damage
• Proteoglycans – heparin and chondroitin sulphate
» package and store the amines
Status asthmaticus
Unremitting asthmatic attack
• Lungs are distended by over inflation
• Small areas of atelectasis
• Most striking: occlusion of bronchi and bronchioles by thick mucus plugs
Asthma
• Sputum
Curschmann spirals
Numerous eosinophils
Charcot-Leyden crystals
Asthma
• Clinical features
Chest tightness, dyspnea, wheezing, coughing (+/- sputum)
• Classic attack - several hours
• Status asthmaticus – days or even weeks
• Between the attacks, patients may be virtually asymptomatic
Bronchiectasis
• Definition
disorder in which destruction of smooth muscle and elastic tissue by chronic
necrotising infections leads to permanent dilation of bronchi and bronchioles
