Pathophysiology of COPD Flashcards
What does COPD stand for?
Chronic obstructive pulmonary disease
What is COPD?
COPD is an umbrella term for a mixture of chronic bronchitis and emphysema
Encompasses a long term, progressive and accelerated decline in the respiratory system
What are the major factors contributing to COPD?
90% COPD due to long term tobacco smoke exposure
30% long term smokers develop COPD
Genetic (𝝰-1 antitrypsin deficiency) Environmental hazards (pollution)
How does smoking effect the respiratory system?
Harmful constituents of tobacco smoke cause acute damage to respiratory tissue, generating an inflammatory response
With repeated exposure, the inflammation becomes pathological and generates chronic and irreversible dysfunction
Which pathological features are present in COPD patients?
Chronic bronchitis
- impaired mucociliary clearance
- increased risk of infection; recurrent infection
- sensory neurons irritation; cough
- decreased luminal area; increased resistance +
obstruction
Emphysema
Describe the effects on airway vessels (bronchioles) of Chronic bronchitis
- Damage to cilia
- Mucus hyper-secretion; more goblet cells and more
mucus gland activation - Inflamed / swollen airway tissue and oedema
- Weakened airway structure (loss of elastin)
- loss of airway patency causing collapse
What are the effects of emphysema on respiratory system?
Decreased SA and perfusion -> less gas exchange
Loss of elastin fibres = more compliance, decreased recoil
- can cause barrel chest
What are the effects of airway obstruction and trapping?
- Decreased ventilation = alveolar hypoxia
- Decreased lung recoil increases expiratory effort
required
=> Overall causes hypoxaemia
Describe how alveolar structure aids gas exchange in normal healthy individuals
Elastin present in surrounding alveoli, provides radial traction to splint bronchioles against positive Palv
How does alveolar structure differ in patients with COPD?
Without radial traction due to loss of elastin, bronchioles collapse causing obstruction
How does COPD effect lung function?
COPD exacerbation temporarily, dramatically reduces lung function and contribute to respiratory system decline
How does chronic respiratory failure cause heart failure?
- Hypoxic vasoconstriction + inc. pulmonary vascular
resistance
=> pulmonary hypertension - Inc. RV afterload = RV hypertrophy
- Right heart failure
Explain the effects of chronic respiratory failure on quality of life?
Causes
- hypoxaemia
- hypercapnia
- academia
decreased exercise tolerance = fatigue
decreased quality of life
How can you prevent COPD?
Smoking cessation is most effective
Lung function doesn’t regenerate and decline continues just not as rapidly
How can we assess respiratory failure in the lab?
Resistance compliance testing
- evaluating model induced functional changes to airway
tone and airway hyper-responsiveness (AHR)
Broncho-alveolar Lavage
- used to sample cytokines + cells present in airways and
lungs following disease model
