Lecture 7: Asthma Flashcards
What is the WHO definition of asthma?
Is a disease characterized by recurrent attacks of breathlessness and wheezing, which vary in severity and frequency from person to person. In an individual, they may occur from hour to hour and day to day
When does asthma most commonly present?
In childhood or in middle age
What % of children with mild asthma will be symptom free by 21yo?
50%
What % of people with more persistent asthma will continue to have symptoms into adulthood?
70%
What causes airflow obstruction in asthma?
Bronchoconstriction - contraction of the smooth muscle in the bronchial wall
Bronchial secretions and plugs of mucus - due to inflammation of the bronchial wall
Oedema of the bronchial wall - due to inflammation the lining mucosa of the bronchial wall
What is atopy?
Asthma in young people usually linked to atopy
Tendency to form IgE antibodies to allergens (such as pollen, house dust mites or animals)
Often associated hay fever or eczema in the personal or family history
Which interleukins are associated with B cell and plasma cell activation?
IL-4 and IL-13
What receptor is expressed by bast cells and basophils that are activated in asthma?
FCeRI
What interleukin is associated with activation of eosinophils?
IL-5
What is released in response to mast cell, basophil and eosinophil activation in asthma?
Histamine
Leukotrienes
Prostaglandins
Cytokines
What are the symptoms of asthma?
Cough
Wheeze
Breathlessness
Chest tightness
Occurs in episodes with periods of no (or minimal symptoms)
Diurnal variability-so worse at night or early morning
What mechanisms can act as triggers in asthma?
Aspirin
Ibuprofen
Beta blockers
What must be taken into account when diagnosing asthma?
History is crucial-need more than one symptom
Symptom free periods
Past medical history (previous wheezing illness, hay fever, eczema), family history (of any atopic disease), and social history (occupation, pets) can provide clues
Alternative diagnosis unlikely-what could these be?
Physical examination may be normal except during an attack
What investigations can be carried out to assess asthma?
GP:
- peak flow monitoring-twice day for 2 weeks
- spirometry may show airflow obstruction, but may be normal between attacks
GP/Hospital:
- chest X-ray often normal, but may show hyperinflation
- increased eosinophil count in the blood
- fraction exhaled nitric oxide (FeNO)
Hospital:
- skin prick or blood tests may confirm allergies
How do you know if theres airflow obstruction?
FEV1/FVC ratio <70