COPD Flashcards
What is COPD?
- A lung disease characterised by airflow limitation, not fully reversible
- FEV1/FVC ratio less than 70%
- Chronic bronchitis
- Emphysema
What is chronic bronchitis?
- Disease of mucus blocking the airways
- Productive cough for 3 months in 2 successive years
What is emphysema?
- Disease of loss of elastic tissue around acini and terminal bronchioles
- Airspaces are enlarged
What are the risk factors of COPD?
- Smoking
- Age
- Urban environment
- Occupation
- Low birth weight
What is the pathogenesis of chronic bronchitis?
Irritants induce:
- hypersecretion of mucus + hypertrophy of mucus glands
- metaplasia of ciliated epithelium → squamous epithelium
- CD8+ T-cells, macrophages and neutrophils
What is the gross appearance of CB?
- Swollen + erythmatous airways
- Covered in layer of mucin
What are the hallmarks of CB?
- Mucus gland hypertrophy
- Increase in goblet cells
- Loss of ciliated cells
- +/- squamous metaplasia
What are the complications of CB?
- Severe airway obstruction: hypercapnia, hypoxemia, cyanosis
- pulmonary hypertension → right HF
- recurrent infections
What is the respiratory acinus?
- Portion of lung tissue formed by branching of a single terminal bronchiole
- Includes respiratory bronchiole, alveolar ducts and alveoli
What is a lung lobule?
- Hexagonal area of lung parenchyma, consisits of 3-5 respiratory acini
What is centriacinar emphysema?
- Central/proximal part of acinus affected
- Seen mostly in apical lobes
What is panacinar?
- Acini uniformly enlarged
- More common in lower lobes
- Occurs in A1AT deficiency
What is distal acinar?
- Predominantly affects the distal part of acinus
- Mostly associated with pneumothorax
What is the pathogenesis of emphysema?
- Elastase: protease present in macrophages + neutrophils, released during inflammatory response
- Antiproteases: Alpha 1 antitrypsin (A1AT) counteract elastase effect
- People with deficiency of A1AT have higher incidence of emphysema
How does tobbaco affect capillaries?
- Nicotine
- IL-8, LTB4, TNF
- Stimulate neutrophils to release elastase
How does tobbaco affect alveoli directly?
- Reactive O2 species → inactive A1AT
- Increased neutrophil elastase
- Tissue damage and macrophage elastase
What is the main factor in emphysema pathogenesis?
- Elastin degradation by macrophages and neutrophils
- Imperfect repair of elastin
What is Bullous emphysema?
- Large subpleural spaces, bullae >1cm
- Near apex, if ruptured → pneumothorax
look like bubbles
What is A1AT deficiency characterized by?
- Inhibits neutrophil elastase
- Common in Europe
- Autosomal recessive normal : PiMM
- Abnormal: PiZZ
What is associated with lower lobe emphysema?
- A1AT deficiency
What are the consequences of emphysema?
- Severe dyspnoea
- Weight loss (lack of oxygen to peripheries)
What is blue bloater seen in?
- Chronic bronchitis
What is pink puffer seen in?
- Emphysema
What is the clinical presentation of COPD?
- SOB, wheeze
- Productive cough
- Recurrent chest infections
- Pleuritic chest pain
- Right HF
- Hyperinflation of lungs
- Barrel chest on CXR
What are the clinical signs of COPD?
- Accessory muscle use
- Hyperinflation
- Pursed lip breathing
- Wheeze and ronchi on auscultation
- Features of right HF (peripheral oedema, right heart enlarged)
What is the gold standard for diagnosing COPD?
- Spirometry
- FEV1/FVC ratio < 70%
What is the gold initiative for COPD?
- Staging system for COPD
- Mild to severe, 1-4
What causes death due to COPD?
- Respiratory acidosis + coma
- Cor pumonale
- Pneumothorax
Which two principles relate to airflow restriction?
- Bernoulli’s principle (constriction)
- Poiseuille’s Law (radius increases flow)
What is Bernoulli’s principle?
- With increased airflow, pressure decreases
- So airways constrict more
What prevents airflow restriction?
- Elastic tissue keeps airways open
- Opposes Bernoulli’s principle
