L4 - Airway Diseases Flashcards
List 4 main airway diseases.
The main airway diseases include:
1 - Asthma.
2 - COPD.
3 - Bronchiectasis.
4 - Cystic fibrosis
*3 and 4 are covered in the respiratory infections lecture.
What feature on a lung function test indicates airflow obstruction?
What feature on a lung function test indicates airflow restriction?
- Airflow obstruction is indicated by an FEV1/FVC ratio of <0.7.
- Airflow restriction is indicated by a normal or elevated FEV1/FVC ratio.
What features on a flow volume loop indicates airflow obstruction?
What features on a flow volume loop indicates airflow obstruction?
- Airflow obstruction is indicated by a reduced flow but normal volume.
- Airflow restriction is indicated by normal flow but reduced volume.
What is asthma?
- Asthma is an obstructive airway disorder caused by chronic inflammation and airway hyperresponsiveness.
- By definition, asthma must improve post-bronchodilator by 12% FEV1 and 200ml FVC.
Describe the pathogenesis of asthma.
- Th2 cells are activated by either of / a mix of 2 mechanisms:
1 - An allergen activates a dendritic cell, which then activates the Th2 cell.
2 - A pathogen activates a dendritic cell, which then activates a Th1 cell, which then activates the Th2 cell.
- The activates Th2 cell activates B cells, mast cells and eosinophils.
- Activated B cells secrete IgE.
- Activated mast cells and eosinophils secrete inflammatory mediators such as leukotrienes.
- Airway inflammation results in:
1 - Airway smooth muscle contraction.
2 - Airway wall scarring.
3 - Mucus hypersecretion.
Why is asthma often worse at particular times of day?
Asthma is often worse at particular times of day due to changing levels or cortisol, which suppresses the inflammation.
What is meant by good asthma control?
Good asthma control means:
1 - No daytime symptoms.
2 - No night time awakenings due to asthma.
3 - No need for reliever medication.
4 - No exacerbations.
5 - No limitation of physical activity.
6 - >80% predicted peak expiratory flow or FEV1.
Describe the pathogenesis of COPD.
- Exogenous oxidants, e.g. from cigarette smoke, activate inflammatory cells to release proteases.
- The oxidants and the proteases cause:
1 - Airway inflammation.
2 - Direct damage to the lung parenchyma, resulting in structural changes.
3 - Mucus hypersecretion.
4 - Bronchospasm.
5 - Other systemic effects such as cardiovascular disease (due to systemic inflammation), weight loss and muscle dysfunction.
How is COPD assessed?
1 - Breathlessness score is assessed using the MRC dyspnoea scale (assesses breathlessness during different activities).
2 - A BODE index is taken, which integrates BMI, FEV1, dyspnoea and 6-min walk distance.
3 - Severity is assessed by spirometry.
List the diseases that comprise COPD.
What is the difference between them?
COPD comprises:
1 - Chronic bronchitis.
- This is persistent inflammation with fibrosis causing a chronic cough and sputum production for at least 3 months within 2 years.
2 - Emphysema.
- This is destruction and enlargement of the walls of the airspace that precede the terminal bronchioles in the absence of fibrosis.
- The two diseases are not mutually exclusive.
List 6 differences between asthma and COPD.
1 - COPD patients are commonly smokers / ex-smokers, whereas this is not necessarily true for asthma patients.
2 - COPD patients rarely experience symptoms under the age of 35, whereas this is common for asthma patients.
3 - COPD patients commonly present with a chronic productive cough, whereas this is uncommon for asthma patients.
4 - COPD patients rarely experience night time waking with breathlessness / wheezing, whereas this is common for asthma patients.
5 - COPD patients rarely experience diurnal variability of symptoms, whereas this is common for asthma patients.
List 4 drug treatments for COPD and asthma.
1 - Short-acting beta 2 agonists, e.g. salbutamol.
2 - Long-acting beta 2 agonists, e.g. salmeterol
3 - Steroids (for selected patients), e.g. fluticasone.
4 - Long-acting muscarinic antagonist, e.g. tiotropium.
What is omalizumab?
Omalizumab is an anti-IgE antibody used as a new asthma drug.
Why is total lung capacity increased in some obstructive airway disorders?
Total lung capacity is increased in some obstructive airway disorders due to air trapping, which occurs due to narrowing of the airways.
List 2 common causes of death in COPD.
1 - Lung cancer (not from COPD directly but from smoking).
2 - Cardiovascular disease (due to systemic inflammation).
