Lobes of the lung
Left has 2 (superior, inferior)
Right has 3 (superior, middle, inferior)
These are separated by the horizontal and oblique fissures
Define COPD
COPD describes progressive and irreversible obstructive airway disease. Consists of Chronic Bronchitis and Emphysema together.
Risk factors for COPD
O2 saturation targets for a normal person and for someone with an acute COPD exacerbation. And at what O2 sats is someone considered hypoxic
Normal: 95-100%
COPD exacerbation: 88-92% (normal COPD maintained above 92%)
Normal <94%
COPD exacerbation <88%
What 2 organisms usually cause infective exacerbations of COPD
H. influenza
S. pneumoniae
If a young patient presents with COPD symptoms without a smoking history, what should be suspected?
Alpha 1 Antitrypsin deficiency
Define chronic bronchitis
Inflammation of the bronchial tubes. Considered chronic when it causes a productive cough for at least 3 months a year for 2 years.
Pathophysiology of Chronic Bronchitis
Overall
- Hypersecretion
- Ciliary dysfunction
- Narrowed lumen
Explanations:
Why does Chronic Bronchitis increase infection risk
Even a small amount of mucus can block lumen, stopping clearance.
Cilia are also shortened and immobile.
Explain the lung spirometry tests (4)
1) FVC (Forced vital capacity) - Max air volume in 1 breath (<80%)
2) FEV1 (Forced Expiratory Volume in 1 second) - Max air 1 second (<80%)
3) FEV1:FVC Ratio (<0.7 obstructive)
4) TLC (total lung capacity) (increased in COPD due to air trapping)
Signs/symptoms of Chronic Bronchitis
Blue Bloater
- Chronic productive cough
- Cyanosis
- Dyspnoea on exertion
- Usually overweight
- Purulent sputum
- Crackles, wheezes when breathing
Hypoxia/aemia (insufficient oxygen in tissues/blood) and hypercapnia (high CO2)
What are some symptoms of CO2 retention? (as would be seen in COPD)
Complications of chronic bronchitis
Define emphysema
Damage to/destruction of the alveolar air sacs. This causes the alveoli to permanently enlarge and lose elasticity. This means the lungs are unable to recoil, so patients have trouble exhaling
Pathophysiology of emphysema
Irritants trigger inflammation in lungs, releasing proteases (collagenases, elastases), which break down elastin. Normally, elastin prevents low pressure environment from collapsing. In emphysema, elastin is lost and airways collapse.
This causes:
- Air trapping distal to point of collapse
- Airways stretch during inhalation but cant breath out fully.
- Elastin loss also causes breakdown of thin alveolar walls (Septa), causing neighbouring alveoli to coalesce. This reduces the area for gas exchange.
Types of Emphysema
Centriacinar - most common. Damages central/proximal alveoli in each acinus, in the upper lobes of lungs. Seen in smokers.
Pan-acinar - Whole acinus affected. Seen in A1AT, affecting lower lobes.
Para-septal - Distal alveoli, can cause a pneumothorax when alveoli rupture
Irregular - Irregular acinar involvement. Scarring/fibrosis
Signs/symptoms of emphysema
Pink puffer
- Pursed lip breathing
- Barrel shaped chest
- Hyperresonance on percussion
- Downward displacement of liver
- Dyspnoea, cough, weight loss
Imaging signs of emphysema (3)
Signs of COPD (6)
What scale is used to assess breathlessness
MRC dyspnoea scale.
Breathlessness:
1 - on exercise
2 - on hurrying/slight hill
3 - walks slower than others/ has to stop to catch breath
4 - Stops to catch breath after 100m
5 - breathless on minimal activity (getting changed)
Investigations in COPD
Clinical diagnosis - Over 35, smoking history, signs/symptoms of COPD.
Spirometry
- FEV1<80% expected
- FEV1/FVC <0.7, with no bronchodilator reversibility
Chest X ray -
- Flattened diaphragm
- Hyperinflation
- Bullae
CHECK FBC - COPD causes chronic hypoxia -> polycythaemia vera.
Give the difference between type 1 and 2 resp failure. What investigation helps check this?
ABG
1 - low oxygen and normal/low CO2
2 - low oxygen and high CO2
How is COPD classified
GOLD classification
Goes down based on FEV1
e.g. FEV1>80% = 1 (mild),
FEV1 50-79 = 2 (moderate) etc
FEV1 49-30 = 3 (Severe)
FEV1 <30 = 4 (very severe)
Name all 5 drugs used in COPD treatment
Bronchodilators:
- Short acting Beta 2 agonist (salbutamol)
- Long acting Beta 2 agonist (salmeterol)
-
- Short acting muscarinic antagonists (Ipratropium bromide)
- Long acting muscarinic antagonists (Tiotropium)
Inhaled corticosteroid (Beclometasone)