Biochemistry

Question 1

What are the causes of COPD?

Answer 1

• Host e.g. genetic susceptibility (anti-trypsin deficiency, matrix metalloproteinases)
• Environment e.g. smoking, cannabis, other smokes, mineral dusts e.g. coal

Question 2

What is the histology of COPD?

Answer 2

• Goblet cell hyperplasia

- Airway narrowing - inflammation, fibrosis and scarring of bronchial wall due to mucous production by goblet cells

Question 3

What causes the symptoms of COPD?

Answer 3

• Goblet cell hyperplasia - cough and sputum (chronic bronchitis)
• Airway narrowing - breathlessness and wheeze
• Alveolar destruction - breathlessness

Question 4

Describe the progression of cor pulmonale

Answer 4

1. Hypoxia
2. Pulmonary artery vasoconstriction
3. Increased pulmonary artery pressure
4. Right ventricular hypertrophy
5. Right ventricular failure

Question 5

Why is there CO2 retention in COPD?

Answer 5

Elastic recoil of lungs is lost so there is gas trapping and reduced excretion of CO2. In the blood CO2 combines with H2O to form carbonic acid (acute setting would cause ill patient) but CO2 retention is progressive. Body can compensate by kidneys reabsorbing more bicarbonate which neutralises the carbonic acid and thus restoring pH to the normal range.

Question 6

What is cor pulmonale?

Answer 6

Right heart failure caused by chronic pulmonary artery hypertension.

Question 7

What are the lung causes of cor pulmonale?

Answer 7

• COPD
• Bronchiectasis
• Pulmonary fibrosis
• Severe chronic asthma
• Lung resection

Question 8

What are the most common causes of infective exacerbation of COPD?

Answer 8

1. Haemophilius influenze
2. Moraxella Catarrhalis
3. Streptococcus pneumoniae

Question 9

When should long-term oxygen therapy be offered to COPD patients?

Answer 9

Offer LTOT to patients with a pO2 of < 7.3 kPa or to those with a pO2 of 7.3 - 8 kPa and one of the following:

• secondary polycythaemia
• peripheral oedema
• pulmonary hypertension

Question 10

What are the causes of obstructive lung disease?

Answer 10

• COPD
• Asthma
• Emphysema
• Bronchiectasis
• CF

Question 11

What are the causes of restrictive lung disease?

Answer 11

• Pulmonary fibrosis
• Parenchymal lung tumour
• Skeletal e.g. kyphoscoliosis
• Neuromuscular e.g. MND, myasthenia gravis, Guillan-Barre syndrome
• Obesity or pregnancy