COPD

Question 1

What % of heavy smokers develop COPD?

Answer 1

10-20%

Question 2

Pathophysiology of COPD

Answer 2

• Increased mucous secreting goblet cells
• Bronchi inflamed
• Infiltration of inflammatory cells
• Lymphocytic infiltrate is mainly CD8+
• Inflammation followed by scarring and thickening of the walls
• Eventually fibrosis occurs

Question 3

Asthma involves the infiltration of eosinophils, what cell type is seen in COPD?

Answer 3

Neutrophils

Question 4

What diseases come under the COPD umbrella☂️?

Answer 4

Chronic bronchitis - pink puffer

Emphysema - blue bloater

Question 5

How does smoking cause COPD?

Answer 5

Cigarette smoke stimulates epithelial cells, macrophages and neutrophils to release inflammatory mediators and proteases - especially neutrophil elastase

Inflammatory mediators destroy lung tissue

Proteases are normal in humans but smokers have soooo many that they overwhelm the anti-proteases = protease-antiprotease imbalance

Cigarette smoke impairs ciliary movement

Question 6

Discuss a1-antitrypsin deficiency

Answer 6

a1-antitrypsin (acute phase protein produced in the liver) usually acts as an anti-protease in the lung and inhibits neutrophil elastase

Deficiency causes protease-antiprotease imbalance

Deficiency results in early onset emphysema (<40yrs) and death

Autosomal dominant

Question 7

What is emphysema?

Answer 7

PINK PUFFER

• Permanent enlargement of the air spaces distal to terminal bronchiole
• Due to alveolar spetal destruction because of protease-antiprotease imbalance
• The walls are destroyed and airways collapse - hence the OBSTRUCTION
• Two types:
  1. Centriacinar
  2. Panacinar

Question 8

What is chronic bronchitis?

Answer 8

Persistent cough with sputum production for at least 3mo of the year for 2 consecutive years

Question 9

How does smoking cause chronic bronchitis?

Answer 9

Smoking causes hyperplasia and hypertrophy of mucus-secreting glands found in the submucosa of large airways.

Small airways become blocked with mucous plugs, mucosal oedema and smooth muscle hypertrophy

Bacterial colonisation occurs due to accumulation of secretions

All of the above cause obstruction and increased resistance to airflow

Question 10

Upon examination of a patient with emphysema, what would you expect?

Answer 10

PINK PUFFER

• Thin: weight loss due to work of breathing
• Marked chest hyperinflation
• Cor pulmonale absent
• Cyanosis absent
• Low P_aCO₂

Question 11

Upon examination of a patient with chronic bronchitis, what would you expect?

Answer 11

BLUE BLOATER

• Obese
• Cor pulmonale present
• Central cyanosis
• Raised P_aCO₂

Question 12

Complications of COPD

Answer 12

1. Exacerbation: acute worsening usually due to infection
2. Respiratory failure: unable to maintain normal blood gases - normal type 2 failure, leading cause of death in COPD
3. Cor pulmonale: occurs due to pulmonary hypertension which causes RrV hypertrophy and failure

Question 13

Investigations for COPD

Answer 13

• Spirometry is gold standard and shows an obstructive pattern (reduced FEV1/FVC ratio)
• Diagnosis is made if FEV1/FVC ratio is <70%
• Bronchodilator reversibility should be tested to exclude asthma
• Chest x-ray shows hyperinflation/ flat hemidiaphragm
• FBC may show polycythaemia (RBC+++ due to hypoxia triggering EPO production in kidneys)

Question 14

Treatment for COPD

Answer 14

• Smoking cessation slows process and is the key intervention
• Bronchodilators: anticholinergics more effective than b2 agonists but a combination may help
• Inhaled corticosteroids: not all patients will respond
• Antibitoics: to shortern exacerbations, always give during acute episodes
• Vaccine: annual flu vaccine
• O2 therapy if necessary
• Surgery
• a1-antitrypsin therapy for those with genetic defect

Question 15

What are the two types of emphysema?

Answer 15

1. Centriacinar: Septal destruction and dilatation limited to centre of acinus, around terminal bronchiole and mainly upper lobes
2. Panacinar: Whole of acinus is involved distal to terminal bronchiole, lower lobes mainly

*panacinar emphysema is characteristic of a1 antitrypsin deficiency

Question 16

Stages of COPD

Answer 16

Based on FEV1

Mild = >80% predicted

Moderate = <80% but >50%

Severe = <50% but >30%

Very severe = <30%

Question 17

Symptoms of COPD based on severity

Answer 17

Mild: no abnormal signs, smokers cough, little/ no breahtlessness

Moderate: Breathlessness + wheeze on exertion, cough, reduction in breath sounds

Severe: breathlessness on exertion/ at rest, wheeze and cough often prominent, cyanosis, peripheral oedema, polycythaemia

Question 18

Discuss use of anticholinergics in COPD

Answer 18

Competetive antagonists of muscarinic acetlycholine receptors

Block vagal control of bronchial smooth muscle tone in response to irritants

ipratropium bromide and oxitripium bromide

• Reduce bronchoconstriction
• Reduce mucous secretions by antagonising muscarinic receptors on goblet cells

*poorly absorbed orally so given via aerosol

Question 19

Side effects of antimuscarinics

Answer 19

• Xerostomia
• Urinary retention
• Constipation

Question 20

Discuss mucolytics

Answer 20

Carbocistene and methylcysteine

Reduce viscosity of sputum

May be of benefit in acute exacerbations of COPD

Question 21

What is doxapram?

Answer 21

Respiratory stimulant

Given in cases of resp. failure

ANALEPTIC - means it stimulates the CNS

Increases tidal volume and resp. rate

Question 22

What signs of COPD can be seen on chest x-ray?

Answer 22

• Hyperinflation
• Bullae
• Flat hemidiaphragm

Question 23

Signs on hyperinflation on chest x-ray

Answer 23

• Flattened hemidiaphragm
• More than 6 anterior or 10 posterior ribs in the mid-clavicular line at the lung diaphragm level

Question 24

What is theophylline?

Answer 24

Xanthine derivative similar to caffeine

Smooth muscle relaxant, bronchial dilation, cardiac and central nervous system stimulant

Question 25

Which organisms most commonly cause infective exacerbations of COPD?

Answer 25

Haemophilus influenzae (most common) Strep. pneumoniae Moraxella catarrhalis

Question 26

Discuss NICE guidelines re long term oxygen therapy

Answer 26

- Patients on long term oxygen should breath supplementary oxygen for at least 15hrs/day - Offer to patients with a pO2 of \<7.3kPa (normal is 10.5-13.5) - Offer to patients with a pO2 of 7.3-8kPa if they also have polycthaemia, oedema or pulmonary hypertension) \*\*do not offer to people who continue to smoke