Pathophysiology and Pharmacology of COPD

Question 1

What is COPD ?

Answer 1

progressive development of airflow obstruction that is irreversible

COPD destroys the alveoli

Question 2

Symptoms of COPD

Answer 2

• wheezing
• breathlessness
• cough
• sputum production
• infective exacerbations

Question 3

Common causes of COPD

Answer 3

• smoking
• air pollution
• exposure to fumes and dust
• chest infection during the first year of life
• early nutrition
• genetic factors

Question 4

Chronic bronchitis ( a mucus problem )

Answer 4

hypertrophy and hyperplasia of submucosal glands - increased mucus production - increase in goblet cell - increased mucus production - mucociliary dysfunction - builds up mucus in the airways

Reduces amount of CO2 excretion and 02 inhalation
Natural narrowing of airways that occurs during exhalation plus presence of mucus plugs leads to air trapping in alveoli . This leads to decrease in partial pressure of O2 and increase partial pressure of CO2.

Accumulation of mucus also makes an ideal environment for bacteria to grow and cause infections which poses an increased risk of pneumonia

Question 5

Emphysema ( an inflammatory and structural problem )

Answer 5

• destruction of elastic leads to narrowing and collapse of airways and alveoli.
• this air trapping inside the alveoli
• this is turn leads to decrease partial pressure of O2 and an increase in partial pressure of CO2

LOW VENTILATION CAN LEAD TO HYPOXEMIC VASOCONSTRICTION - PULMONARY HYPERTENSION - RIGHT VENTRICULAR FAILURE

Question 6

Natural course of COPD

Answer 6

• breathlessness initially on exercise and also on rest.
• cough and scutum production initially in morning but later all day.
• acute respiratory infections with increasing frequency especially in winter.
• hypoxia initially on exercise but later during sleep and even at rest by day leading to pulmonary hypertension
• chronic respiratory failure
• terminal acute respiratory failure

Question 7

STOP SMOKING

Answer 7

• nicotine replacement therapy
• psychological counselling, group therapy

Question 8

COPD THERAPY

Answer 8

1. Bronchodilators
   - short acting bronchodilators initially such as salbutamol or terbutaline.
   - then long acting B2 agonists such as salmeterol
   - M3 muscarinic antagonists more effective EG. long active tiotropium
2. Anti-inflammatory therapy
   - modest effect of corticosteroids such as inhaled beclomethasone
   - PDE4 inhibitors
3. Oxygen therapy

Question 9

Bronchodilator therapy

Answer 9

1. B2 AGONISTS = acts on B2 receptors on bronchial smooth muscle to produce relaxation and dilation of airways. Also, improve mucociliary clearance and inhibit neutrophil recruitment and activation
2. Anticholinergics = musacrinic receptor antagonists ; ie they block M3 receptor mediated smooth muscle contraction and secretion of mucus. More effective than B2 agonists

Question 10

Vaccination to avoid acute infective exacerbation of COPD

Answer 10

• symptoms are often associated with viral influenza A and B or bacterial ( streptococcus ) infection of the airways
• acute exacerbations are associated with increased morbidity and mortality in COPD

TREATMENT OPTIONS
- vaccination for influenza A and B, injection with inactivated virus or live attenuated virus as nasal drops

• vaccination for streptococcus pneumonia