Week 7 - COPD and Lung Cancer

Question 1

Define chronic bronchitis.

Answer 1

Defined as the presence of cough and excessive mucus production on most days for at least 3 consecutive months for 2 successive years

Question 2

Define emphysema.

Answer 2

Defined as the permanent destructive enlargement of air spaces distal to the terminal bronchiole

Question 3

State the pathological features of chronic bronchitis which result in expiratory airflow limitation in COPD.

Answer 3

1. Increased number of goblet cells in epithelium - increased mucus production
2. Reduced cilia (loss of ciliated epithelium) - ciliary dysfunction prevents mucus from being swept up
3. Submucous gland hyperplasia - thickening of the bronchial wall and increased mucus production

Increased bronchial wall thickness and excess mucus - reduced calibre of the lumen and airways obstruction

Question 4

State the pathological features of emphysema which result in expiratory airflow limitation in COPD.

Answer 4

1. Progressive destruction of alveolar walls and reduction in capillary bed
2. Loss of radial traction of lung tissue on bronchioles - airways narrowing
3. Enlarged airways and airspaces (bullae)
4. Reduced elastic recoil
5. Reduced alveolar surface for gas exchange

Question 5

What lung function tests can be used to investigate COPD?

Answer 5

1. Spirometry - tidal volume, vital capacity, measurement of FVC, FEV1, ratio of FEV1/FVC, flow-volume loops
2. Measurement of lung volumes - helium dilution or by plethysmography
3. Measurement of diffusion - CO transfer factor

Question 6

What are the changes in a flow-volume loop for an individual with COPD?

Answer 6

1. Low PEFR
2. Scooped-out flow volume curve
3. Normal inspiratory airflow

Question 7

Why is the diffusion capacity (as measured by TLCO) reduced in patients with COPD?

Answer 7

Destruction of alveolar walls and reduction of capillary bed in emphysema reduce overall surface area available for gas exchange

Question 8

What are the typical radiological findings in COPD?

Answer 8

1. Hyperinflation of the lungs - more than 6 ribs seen anteriorly
2. Flattening of the diaphragm
3. Heart may appear elongated and thin
4. Ribs may appear to be more horizontal

Question 9

Outline the features of chronic type 2 respiratory failure.

Answer 9

1. CO2 retention: bounding pulse, warm hands, flapping tremors
2. Pulmonary hypertension and right heart failure: cor pulmonale
3. Compensatory changes for hypoxia including polycythaemia

Question 10

Outline the type of respiratory failure seen in COPD patients.

Answer 10

Initially Type 1: ventilation-perfusion mismatch due to poor ventilation of parts of the lung
Type 2 later: hypoventilation - late stages, when FEV1 < 1 litre, this occurs gradually and so patients show features of chronic type 2 RF

Question 11

What are the possible consequences of using oxygen in patients with chronic hypercapnia?

Answer 11

1. Risk of CO2 retention - O2 in blood rises but CO2 also rises
2. Can cause acidosis and organ dysfunction, and when severe, coma

Question 12

What are the mechanisms by which administering high dose oxygen to patients with chronic hypercapnia can cause harm?

Answer 12

1. Hypoxic drive reduced: hypoxia acting via peripheral chemoreceptors stimulates breathing, central chemoreceptors adapted to higher carbon dioxide levels
2. Worsening V/Q mismatch: when oxygen is given, hypoxic vasoconstriction is reduced, and poorly ventilated areas of the lung receive more blood causing worsening V/Q mismatch

Question 13

How should oxygen be administered to COPD patients?

Answer 13

Low dose titrated oxygen - constantly monitor arterial blood gas to ensure hypercapnia is not worsening

Question 14

What structure in the CNS coordinates coughing?

Answer 14

Medulla oblongata

Question 15

What is coughing initiated by?

Answer 15

Irritation of cough receptors in upper airway

Question 16

Outline the steps involved in coughing.

Answer 16

1. Glottis closes
2. Strong contraction of the expiratory muscles - abdominal muscles and internal intercostals - builds up intrapulmonary pressure
3. Glottis suddenly opens –> explosive discharge of air

Question 17

What are important aspects to inquire about while taking an asthma history?

Answer 17

1. Allergies
2. Family history
3. Maternal smoking (for children)
4. Social
5. House: pets, carpet

Question 18

What does eczema look like?

Answer 18

1. Red, scaly patches of skin
2. Usually itchy
3. Often confined to flexures of limbs

Question 19

Why is eczema relevant to asthma?

Answer 19

It is part of generalised atopy

Question 20

What drugs are commonly used for long-term prophylaxis of asthma?

Answer 20

Inhaled corticosteroids

Question 21

State 2 topical B2 agonists that can be used in asthma.

Answer 21

1. Salbutamol

2. Terbutaline

Question 22

State how B2 agonists can be administered for children.

Answer 22

1. Usually via an inhaler device - young children have difficulty coordinating inspiration with activation of the device
2. Therefore, a spacer device is used where the child simply breathes in and out through the device or using a face mask

Question 23

How would you confirm suspicion that someone has asthma?

Answer 23

1. Examination
2. Lung function tests with response to bronchodilators
3. Daily peak flow recordings to demonstrate variability, especially during working days
4. Bronchial challenge test

Question 24

Outline what the bronchial challenge test demonstrates.

Answer 24

• This test demonstrates hyper-reactive airways
• Involves giving a cholinergic drug (inhaled methacholine or histamine)
• Stimulation of muscarinic receptors
• Contraction of smooth muscle in the airway
• May induce acute asthma and may have to be reversed with a bronchodilator

Question 25

Which substance in paint can contribute to asthma?

Answer 25

Isocyanate

Question 26

What is the mechanism by which some chemicals cause asthma?

Answer 26

Irritants

Question 27

List 6 occupations in which asthma can occur and the chemicals involved.

Answer 27

``` Bakers - yeast Plastic workers - isocyanate Healthcare workers - latex in gloves Solderers - Collophony Lab animal workers - rat urine Wood workers - pliatic acid (constituent of wood) ```

Question 28

What are the harmful effects of long-term oral steroids in adults?

Answer 28

1. Adrenal suppression 2. Skin thinning, bruising, osteoporosis 3. Oral candidiasis 4. Central obesity, glucose intolerance, increased appetite 5. Hypertension 6. Depression/mania (Long - term oral steroids in COPD are associated with increased mortality independent of the severity of disease)