[3] Asthma Flashcards
How is asthma defined?
As an episodic, reversible, intrathoracic airway obstruction
When does the reversibility occur in asthma?
May occur spontaneously, or because of therapy
What are the symptoms of asthma caused by?
Narrowing of bronchi and bronchioles
What causes the narrowing of bronchi and bronchioles in asthma?
Bronchoconstriction, mucosal swelling, and viscous secretions obstructing the lumen
What initiates the process of airway narrowing in asthma?
Various allergic and non-specific stimuli
How do various allergic and non-specific stimuli initiate the process of airway narrowing in susceptible individuals?
By triggering the release of histamine and other mediators
What stimuli can trigger the process of airway narrowing in asthma?
- Dust mites
- Air pollutants
- Cigarette smoke
- Cold air
- Viral infections
- Stress
- Exercise
What is atopic asthma?
When recurrent wheezing is associated with interval symptoms, and there is evidence of allergy to one or more inhaled allergens, e.g. house dust mites, pollen, or pets
What is atopic asthma strongly associated with?
Other atopic disease, e.g. eczema, rhinoconjuncitivitis, and food allergy
What are the risk factors for asthma?
- Allergies
- Family history of allergies/asthma
- Frequent respiratory infections
- Low birth weight
- Second-hand smoke before and/or after birth
- Growing up in a low income, urban environment
When should you suspect asthma in a child?
When there is wheezing on more than one occasion, particularly if there are interval symptoms.
Describe an asthmatic wheeze?
Polyphonic (multiple pitch) noise coming from the airways
What are the key features are associated with a high probability of asthma?
- Symptoms worse at night and in early morning
- Symptoms that have non-viral triggers
- Interval symptoms
- Personal or family history of atopic disase
- Positive response to asthma therapy
What are interval symptoms?
Symptoms that occur between acute exacerbations
What should be further explored once a diagnosis of asthma is firmly suspected?
The pattern or phenotype
What questions should be asked to determine the pattern or phenotype of asthma?
- How frequent are the symptoms?
- What triggers the symptoms?
- How often is sleep disturbed?
- How severe are the interval symptoms between exacerbations
- How much school has been missed due to asthma?
What is found on examination of the chest between attacks?
It is usually normal
What may be found on examination in long-standing asthma?
- Hyperinflation of the chest
- Generalised polyphonic expiratory wheeze
- Prolonged expiratory phase
What should be done regarding growth in asthma?
Growth should be plotted
What is normally found regarding growth in asthma?
It is usually normal unless asthma is extremely severe
What other conditions should be checked for in asthma?
Other atopic conditions, e.g. eczema, nasal mucosa examination
What might suggest an alternative diagnosis to asthma?
Presence of features such as wet cough or sputum production, finger clubbing, or poor growth
What does the presence of features such as wet cough, sputum production, finger clubbing, or poor growth suggest?
A condition characterised by chronic infection, e.g. cystic fibrosis or bronchiectasis
How is asthma diagnosed in younger children?
Usually from history and examination alone
Why are specific investigations sometimes required in asthma?
- Confirm diagnosis
- Determine severity and phenotype in more detail
What specific investigations may be used in asthma?
- PEFR
- Spirometry
What is often the most useful investigation in asthma?
Peak flow and spirometry before and after bronchodilator
What finding on peak flow/spirometry before and after bronchodilator is characteristic of asthma?
An improvement of 12% or more, confirming bronchodilator reversibility
What often happens to bronchodilator reversibility in asthma after treatment?
It reduces or disappears completely
What is peak flow?
A person’s maximum speed of expiration
What is a peak flow meter?
A small, hand-held device used to monitor a person’s ability to breathe out air
What are the advantages of peak flow?
- Helpful for serial measurements
- Portable
- Can be used to assess how well asthma is controlled
Why can peak flow be used to assess how well asthma is controlled?
Because poorly controlled asthma leads to increased variability in peak flow, with both diurnal variability and day-to-day variability
What diurnal variability is there in poorly controlled asthma?
Peak flow is usually lower in the morning than the evening
What does spirometry involve?
The measurement of forced expiratory volume in 1 second
How is forced expiratory volume measured?
The patient has to breathe out as hard and fast as possible
What are the advantages of spirometry?
- Provides non-invasive measure of flow through larger airways
- Better than peak flow at detecting changes in airway calibre
Why might skin-prick testing for common allergens be done in asthma?
- Aid diagnosis of atopy
- Identify allergens which may be acting as triggers
What are the differential diagnoses of asthma?
- Bronchiolitis
- Viral wheeze
- Cystic fibrosis
- Recurrent anaphylaxis
- Chronic aspiration
- Bronchopulmonary dysplasia
- Bronchiolitis obliterans
- Tracho-bronchomalacia
What it the aim of asthma management?
Complete symptom control
What is complete symptom control in asthma management defined as?
- Absence of daytime or nighttime symptoms
- No limit on activities, including exercise
- No need for reliever use
- Normal lung function
- No exacerbations (need for hospitalisation or oral steroids) in previous 6 months
How is the treatment of asthma determined?
It increases from step 1 to step 5, stepping down when control is good