103 - COPD Flashcards
What happens to the lungs in emphysema?
The alveolar membranes break down
What happens to the lungs in chronic bronchitis?
The airways (bronchioles) narrow due to inflammation and excess mucus
Define forced vital capacity
Deepest breath in followed by deepest breath out
Define FEV1
How much air can be expired in 1 second
Impact of COPD on FEV1 - why?
FEV1 is reduced in COPD due to gas trapping, OBSTRUCTIVE lung disease.
What is the dead space of a lung?
Area of lung which does not participate in gas exchange
How to test physiological dead space?
Bohr equation
How to test anatomical dead space
Nitrogen washout/Fowler’s method
How to test functional residual capacity
Helium dilution
What should be encouraged at all stages of COPD? Why?
Stop smoking - doesn’t stop degeneration but slows rate
What improves quality of life and reduces mortality in COPD?
Pulmonary rehabilitation
How to treat COPD
Short acting bronchodilators THEN Long acting bronchodilators THEN Inhaled corticosteroids
What does SABA stand for? Name an example.
Short acting B2 adrenoreceptor agonist.
Salbutamol.
What does SAMA stand for? Name an example?
Short acting muscarinic antagonist.
Ipratropium
What does LABA stand for?
Name an example
Long acting B2 adrenoreceptor agonist.
Salmertarol
What does LAMA stand for?
Name an example.
Long acting muscarinic antagonist.
Tiotripium
What inhaled corticosteriod should be prescribed in COPD? When/Why
Beclomethasone
Anti-inflammatory immunosupressant. Used in exacerbations.
What is COPD?
Umbrella term covering chronic bronchitis, emphysema and small airways disease.
What is chronic bronchitis?
Symptom. Cough productive of purulent sputum for at least 3 months of the year for at least 2 successive years.
What is emphysema?
Structural abnormality - destruction of lung tissue distal to terminal bronchioles. Degenerative loss of radial traction to bronchiole walls
What is small airways disease?
Thickening of airway walls as part of repaid process and fibrosis.
COPD incidence
One of biggest killers in UK. Increases with age, severity and poverty. Mostly in smokers or those exposed to coal dust
Genetic predisposers to COPD
Alpha-1-antitrypsin-deficency. Patients develop empysema.
What causes chronic bronchitis?
Tobacco smoke/irritants cause inflammatory response in bronchus.
Stimuate goblet cells - increased mucus secretion in airway.
Destruction of cilia and flattening of epithelial cells.
Reduced mucosal clearance.
What causes emphysema?
Inflammatory response - cells release proteases which overwhelm natural anti-proteases to cause destruction of alveolar walls.
Loss of small airway support by elastic tissues cause floppy airways - narrow/collapse on expiration causing a wheeze.
Signs/symptoms of emphysema
Airflow obstruction Gas trapping Hyperinflation of chest Loss of capillary bed Reduced blood flow through lungs Pulmonary hypertension/cor pulmonale
Signs/symptoms of bronchitis
Production of purulent sputum.
Treatment of COPD
Stop smoking
Pulmonary rehabilitation
Surgery - lung transplant, lung volume reduction surgery
B2 agonists and muscarinic antagonists (short/long acting)
Why are bronchodilators used?
Reduce acute breathlessness (Short acting) and reduce freq of exacerbations (long acting)
B agonists - what do they do?
Agonists at B2-adrenergic receptors.
Side effects - tachycardia
Muscarinic antagonists - what do they do?
Inhibit parasympathetic receptors in smooth muscle.
Side effects - dry mouth
What is Symbicort and why is it used?
Combination bronchodilator & corticosteroid. Used to reduce freq of exacerbations.
Combination of formoterol and budesonide
What do Xanthines do?
Bronchiodilators by inhibition of phosphodiesterase.
Need to monitor blood levels as have narrow therapeutic window as eliminate P450 liver enzymes.
Only use in severe disease
Toxicity symptoms of Xanthines
Nausea and vomiting Tachycardia Tremor Agitation Diuresis Seizures