5 main causes of airflow obstruction
- Bronchospasm (Asthma)
- Airway inflammation (Asthma, bronchitis)
- Mucous hyper-secretion (Bronchitis)
- External airway compression (Goitre)
- Dynamic airway collapse (loss of radial traction/increased lung compliance)
What is Carbon Monoxide transfer factor a measure of
Measure of integrity of alveolar-capillary membrane
Also called TLCO, DLCO, diffusing capacity
When is TLCO reduced
- Emphysema (due to loss of alveolar surface area)
- Interstitial lung disease (due to thickening of alveolar-capillary membrane) e.g. sarcoidosis, silicosis, asbestosis
- Pulmonary vascular disease (loss of vascular bed)
- Anaemia (reduction in available haemoglobin)
- Extra-pulmonary restriction (loss of lung volume)
What does a Plethysmography measure
- FRC - functional residual capacity (air in lungs after passive expiration)
- TLC - total lung capacity
- RV - residual volumes- RV + expiatory residual volume = FRC
What component of the spirometry results should you use to detect obstruction
FEV1/FVC ratio compared to LLN
FEV1/FVC < LLN = obstruction
FER (forced expiratory ratio, just FEV1/FVC as a percentage) is low
What component of the spirometry result should you use to detect restriction
FVC compared to LLN
FVC or VC < LLN = restriction
FER (forced expiratory ratio, just FEV1/FVC as a percentage) is normal or high
Positive bronchodilator response
improvement of
- > 200 ml or
- > 12%
of baseline in FEV1 or FVC
Interpretating DLCO
Mild = >60% and
Interpretation of elevated PaCo2
Alveolar hypoventilation
Interpretation of elevated PaCO2
alveolar hyperventilation
Definition of COPD
irreversible airway obstruction FEV1/FVC <0.7
Subtypes of COPD
Most common
- emphysema
- chronic boncitis
less common
- asthma
- bronchiectasis (mucus hypersecretion following airway widening)
- cystic fibrosis
Role of alpha 1 - antitrypsin deficiency in COPD
Increases susceptibility to smoking resulting in COPD
Pathophysiology of Chronic Bronchitis
Lung inflammation –> injury to bronchial tress -
- Increased inflammatory cell e.g. neutrophil
- Goblet cell proliferation, –> Increase mucus production
- death of airway epitherlium, ciliated cells both
1 –> airway narrowing and fibrosis
2 and 3 –> muscus trapping
Pathophysiology of Emphysema
Lung inflammation –> proteolytic destruction of lung parenchyma -
- Decreases airway elasticity –> trapping of air in lung -
- Decreases structural supports for airway patency –> airway narrowing and collapse -
- Permanent enlargement of alveoli –> hyperinflated lungs and bullae (ruptured airsacs)
Signs of COPD
- Hoover’s sign (paradoxial shrinking of lower chest during inspiration)
- dyspnoea
- Pursed lip breathing
- Barrel chest
CXR findings in COPD
Hyper inflated lungs
- increase anteroposterior ratio,
- flattened diaphragm,
- increased intercostal space and
- hyperlucent lungs
What is the PaO2 in Hypoxemia
PaO2 <70 mmHg
Whats is the PaCo2 in hypercapnia
PaCO2 >45 mmHg
Lung function in mild, moderate and severe COPD
- Mild 60-80 FEV1
- Moderate 40-59 FEV1
- Severe <40
What are the four elements of pulmonary rehabilitation
- Exercise training
- Education
- behaviour modification
- outcome assessment
Only mangement option known to improve SGRQ scores (respiration)
Pulmonary rehabilitation
Non-pharmacological treatment of COPD
- Smoking cesssation
- Influenza vaccine annually, pneumococcal vaccine
- Physical activity
- Pulmonary rehabilitation
- Nutrition review
- Monitor co-morbidities - osteoporosis, coronary disease, lung cancer, anxiety, depression
Phamacological therapy for COPD
- Short acting bronchodilator therapy - reduce bronchoconstriction and air trapping - Salbutamol or tertutaline
- Long acting bronchodilator therapy LABA or LAMA - Salmeterol or tiotropium
- LABA + LAMA combo
- ICS - reduces exacerbations
