6.4 Pathophysiology of Asthma Flashcards
Define asthma
Wheeze, shortness of breath, chest tightness and cough that vary over time and in intensity, together with variable expiratory airflow limitation.
What % of people have clinical asthma in Australia vs the world?
Australia: 10%
The World: 4.5%
(Hygiene hypothesis?)
Correlation between NO2 (nitrogen dioxide) emissions and asthma
Positive (it seems to cause it)
At what age do our lungs stop growing? What are the implications of this on lung growth?
- Stop growing when we are 24
- Exposuire to irritants before this age (e.g. smoking) can lead to smaller lungs and increased chance of infection
Describe four clinical features of asthma. How do we identify what might cause them>
Features:
- Coughing
- Dyspnoea
- Chest tightness
- Wheeze
To identify the cause, you need a detailed history
Describe the different thresholds for asthma control scoring. What else needs to be taken into account?
25: Complete control
20-24: On target
<20: Off target
Need to take into account what therapies have already been put into place to gauge severity
How is asthma diagnosed?
- History
- treatment success (= asthma)
Describe the pathophysiology of acute bronchoconstriction during an asthma exacerbation
- Irritant inhaled
- Cross-linking IgE antibodies on mast cells
- Release of inflammatory mediators
- Constriction of smooth muscle and airway inflammation
- Constriction of airways
Describe the role of airway inflammation in the clinical presentation of asthma
- When irritant is inhaled, inflammatory mediators are released
- Leads to airway inflammation, which causes clinical features such as dyspnoea (air has a harder time moving through airways due to decreased diamter), coughing (in response to asthma), wheeze (narrowing)
List some theories on the aetiology of asthma
- NO2 release
- Smoking during pregnancy/childhood
- Hygiene hypothesis
