Pathophysiology of COPD

Question 1

Definition of COPD

Answer 1

A disease state characterised by the presence of chronic bronchitis and or emphysema associated with airflow obstruction; often accompanied by airway hyperreactivity and may be partially reversible

Question 2

Prevalence

Answer 2

Accounts for 1 in 4 deaths
COPD is the third largest cause of death
Prevalence has risen 14% in the last decade

Question 3

Epidemiology

Answer 3

Approximately 90% of COPD patients are smokers, but only 15% of smokers will develop the disease
Global problem increasing as developing countries adopt Western lifestyle

Question 4

Other causative factors (not smoking)

Answer 4

Passive smoking, pollutants, inhalation of other toxins, developmental lung changes

Question 5

Pathology- inflammation, mucus, airway

Answer 5

Inflammation dominated by neutrophil invasion of the lung tissue and predominantly in the peripheral lung
Mucous hypersecretion but less viscous than asthmatics
Bronchoconstriction including a high parasympathetic tone

Question 6

Obstructive vs restrictive lung diseases

Answer 6

Obstructive diseases have air flow problems, which decrease the airway diameter
Restrictive diseases decrease the lung volume

Question 7

More pathology

Answer 7

Epithelial shedding and damage to cilia
Oedema
Damage to the alveolar extracellular matrix due to elastase leading to irreversible loss of lung elasticity

Question 8

Mechanism of action

Answer 8

Th1 type T cell activates neutrophils, which has differential sensitivity to steroids (not affected by them)

Question 9

Treatment

Answer 9

Corticosteroids (little benefit)
Long acting B agonists (not as effective as in asthma)
Anticholinergics e.g. ipratropium, tiotropium
Oxygen
Avoid respiratory infections (immunisation)
Smoking cessation- the only measure that reduces rate of decline of airway function

Question 10

Treatment efficacy of inhaled corticosteroids

Side effects

Answer 10

Very effective in asthma but may only reduce exacerbations with COPD
Side effects include adrenocortical suppression, reduction in bone mineral density, candidiasis of mouth and throat, resistance in certain individuals

Question 11

Future in Treatment

Answer 11

Phosphodiesterase type 4 inhibitors
Cilomilast Ariflo in phase II clinical trial
Main adverse effects are nausea and vomiting