Chronic obstructive pulmonary disease

Question 1

Define chronic obstructive pulmonary disease (COPD)

Answer 1

COPD = progressive airway disorder characterised by airway obstruction with little or no reversibility

Two types/underlying pathologies – most patients develop varying combinations on a spectrum

Chronic bronchitis
o Inflammation of the lining of bronchiole tubes
o Defined clinically as coughing and sputum production on most days for 3 months of 2 successive years

Emphysema
o Damage to the inner walls of the alveoli causes them to rupture
o Defined histologically as enlarged air spaces distal to the terminal bronchioles, with destruction of alveolar walls

Question 2

How is the severity of COPD classified?

Answer 2

Using FEV1/FVC, given FEV1% compared to expected for age, size etc.

• Mild = >80% of predicted
• Moderate = 50-80% of predicted
• Severe = 30-50% of predicted
• Very severe = <30% of predicted

Question 3

Explain the aetiology of COPD.

Answer 3

Tobacco smoke is the main cause
80% of COPD patients have significant smoking history
20% of smokers develop COPD

Tobacco smoke damages the lungs

• Activates inflammatory cells
• Oxidative stress
• Impairs mucociliary clearance

Emphysema
In COPD, there is a protease-antiprotease imbalance, with excess neutrophil elastases destroying alveolar attachments
o Airways collapse as the alveolar septa are destroyed
o Compliance is increased (reducing elastic recoil and trapping air) causing a ventilation-perfusion mismatch
o Bullae (dilated air spaces >10mm) form – and may cause pneumothoraces

Mucus hypersecretion
o Obstruction occurs - Intraluminal mucus plugs, mucosal oedema, SM hypertrophy, fibrosis
o Bacteria can colonise the mucus

Question 4

Explain the risk factors for COPD.

Answer 4

Smoking

Age (>40)

Environmental - Occupational dusts, Pollutants (outdoor and indoor biomass fuel usage)

Genetic
Alpha-antitrypsin-1 deficiency (2% - rare)
AAt = serum acute phase protein produced in liver which acts as a antiprotease in lung
AD inheritance
Suspected in COPD patients under 40 years old
Also have GI symptoms: Cirrhosis, cholestatic jaundice

Question 5

Summarise the epidemiology of chronic obstructive pulmonary disease

Answer 5

Prevalence of 5-15% in industrialised countries

Major cause of morbidity and mortality
o 2.5 million deaths worldwide annually
o 4th leading cause of death in Europe and US
o Predicted to become the 5th biggest cause of morbidity in 2020

More common in men and over 50s

Increasing prevalence in women

Question 6

Recognise the presenting symptoms of chronic obstructive pulmonary disease

Answer 6

• SOB
• Chronic productive cough
• Chest tightness
• Wheezing
• Frequent respiratory infections
• Unintended weight loss - Associated with risk of lung cancer
• Reduced exercise tolerance

During an exacerbation
• Increased SOB
• Increased cough + sputum purulence + volume
• Increased wheeze
• Increased fatigue + reduced exercise tolerance
• Fluid retention
• Acute confusion

Question 7

Recognise the signs of chronic obstructive pulmonary disease (COPD) on physical examination

Answer 7

Hyperinflation
o Barrel chest
o Decreased cricosternal distance (<3cm)
o Decreased chest expansion

Hyper-resonant percussion

Auscultation
o Quiet breath sounds – due to hyperinflated lung -> reduced air movement
o Polyphonic wheeze
o Coarse crackles

Hypoxia
o Use of accessory respiratory muscles
o Tachypnoea
o Cyanosis

Tar staining

RV HF
o Cor pulmonale
o Oedema
o Basal crepitations

Hypercapnia
o Vasodilation (long cap refill)
o Bounding pulse
o CO2 retention tremor

Pursing lips on expiration
o Due to increased PEEP

Question 8

Identify appropriate investigations for chronic obstructive pulmonary disease

Answer 8

Spirometry = GOLD STANDARD
o TLC increased
o RV increased

Pulse oximetry

ABG - Decreased PaO2 , +/- hypercapnia

Bloods
o FBC - Raised PCV (polycythaemia)
o AAt (if <40 years old)

Sputum culture

CXR
o	Hyperinflation - >6 anterior ribs seen above diaphragm in MCL
o	Flat hemidiaphragms
o	Large central pulmonary arteries
o	Decreased peripheral vascular markings
o	Bullae
o	Elongated cardiac silhouette

ECG
o RAD
o RV hypertrophy
o Cor pulmonale

CT
o Bullae –> pneumothorax risk

Question 9

Generate a management plan for chronic obstructive pulmonary disease

Answer 9

STOP SMOKING

Bronchodilators
Short acting beta 2 agonists (e.g. salbutamol)
Anticholinergics (e.g. ipratropium bromide)
Longacting beta 2 agonis ts (if > 2 exacerbations per year)
Steroids - Inhaled beclamethasone considered in all patients with FEV1 < 50% of predicted OR > 2 exacerbations per year

Regular oral steroids should be avoided if possible

Pulmonary rehabilitation

Oxygen therapy Only for those who stop smoking
Indicated if:
PaO2 < 7.3 kPa on air during a period of clinical stability
PaO2: 7.3-8 kPa and signs of secondary polycythaemia, nocturnal hypoxaemia, peripheral oedema or pulmonary hypertension

Prevention of infective exacerbations: pneumococcal and influenza vaccination

Question 10

How do you manage acute COPD exacerbation?

Answer 10

24% O2 via Venturi mask
Increase slowly if no hypercapnia and still hypoxic (do an ABG)
Corticosteroids
Start empirical antibiotic therapy if evidence of infection
Respiratory physiotherapy to clear sputum
Non-invasive ventilation may be necessary in severe cases

Question 11

What are the potential complications of COPD?

Answer 11

Acute respiratory failure
Infections
Pulmonary hypertension
Right heart failure
Pneumothorax (secondary to bullae rupture)
Secondary polycythaemia

Question 12

Summarise the prognosis for patients with COPD

Answer 12

High level of morbidity

BODE index - 4 year survival prediction
o Factors - BMI, Obstruction (FEV1 after bronchodilator), Dyspnoea, Exercise (distance walked in 6 minute)
o 0-2 points = 80%, 7-10 points = 18%

Most patients die from comorbidities – e.g. MI

Exacerbations have poor prognosis
o Readmission is common (70% in 1 year)
o 25% do not regain original peak flow 1 month later

Hypoxaemia (PaO2 < 8kPa) has a 5YS of less than 50%
o Supplemental O2 reduces mortality