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
What is step 1 in asthma management?
Inhaled short acting ß2 agonist as required
What are short acting ß2 agonists often called?
Relievers
Give two examples of short acting ß2 agonists
- Salbutamol
- Terbutaline
After how long is the maximum effect of ß2 agonists?
After 10-15 mins
How long are short acting effective for?
2-4 hours
On what basis are short acting ß2 agonists used in asthma?
‘As required’ for increased symptoms
They can also be used in high doses for acute asthma attacks
What does the device in which inhaled drugs are administered chosen based on?
Child’s age and preference
What devices can be used to administer inhaled drugs?
- Pressured metered dose inhaler (and spacer)
Breath-actuated metered dose inhalers - Dry powder inhalers
- Nebulisers
What age group are pressured metered dose inhalers suitable for?
All age groups
What should children aged 0-2 years be given with a pressured metered dose inhaler?
Space and face mask
When is a spacer used with a metered dose inhaler?
Recommended for all children, but definitely needed in children >3 years
Why are spacers recommended for all children?
- Increases drug depositions for lungs
- Reduced oropharyngeal deposition
What is the advantage of reduced oropharyngeal deposition?
It reduces side effects when using a steroid inhaler
Why are spacers useful in acute asthma attacks?
Because poor inspiratory effort may impair the use of inhalers directly into the mouth
Who can breath-actuated metered dose inhalers be used in?
Children 6+ years
What is the advantage of breath-actuated metered dose inhalers?
Less co-ordination is required then with a pressured metered dose inhaler without a spacer
What is the result of breath-actuated metered dose inhalers not requiring a spacer?
They are good when ‘out and about’ in older children
What age group are dry powder inhalers useful in?
4+ years
When are dry powder inhalers not good?
- Severe asthma
- Acute attack
Why are dry powder inhalers not good in severe asthma or acute attacks?
Because they need a good inspiratory flow
What age group are nebulisers used in?
Any age
When are nebulisers used?
Only in acute asthma, when oxygen is required in addition to inhaled drugs
When can nebulisers be used at home?
Occasionally as part of an acute management plan in those with rapid-onset severe asthma
What is ipratropium bromide?
An anti-cholinergic bronchodilator
What is ipratropium bromide used for?
Sometimes given to young infants when other bronchodilators are found to be ineffective, or in treatment of acute severe asthma
What is step 2 in asthma management?
Regular preventer therapy
What is the most effective inhaled preventer therapy?
Inhaled corticosteroids
What is the action of inhaled corticosteroids?
Decrease airway inflammation, resulting in decreased symptoms, asthma exacerbations, and bronchial hyperactivity q
What are the side effects of low-dose inhaled corticosteroids?
They have no clinically significant side effects when given in low dose, although they cause a mild reduction in height velocity, which is usually followed by a catch-up growth in late childhood
What are the side effects of high-dose inhaled corticosteroids?
Systemic side effects, such as impaired growth, adrenal suppression, and altered bone metabolism
How are the side effects of inhaled corticosteroids minimised?
Treatment should always be at lowest dose possible
What is step 3 in asthma management?
Initial add on therapy
What is the first-choice add on therapy in children under 5?
An oral leukotriene receptor antagonist
Give an example of an oral leukotriene receptor antagonist
Montelukast
What is the first-choice initial add on therapy in children over 5?
LABA (long-acting ß-agonists)
What should be done following giving the first-choice initial add on therapy?
Assess response
What should be done if good response to initial add on therapy in over 5’s?
Remain as is
What should be done if there is a partial response to initial add on therapy in over 5’s?
Increase ICS dose
What should be done if there is poor response to initial add on therapy in over 5’s?
Stop LABA and increase ICS dose. Consider oral leukotriene receptor antagonist, and/or slow release theophylline
Give 2 examples of LABAs
- Salmeterol
- Formoterol
How long are LABAs effective for?
12 hours
When should LABAs not be used?
- Acute asthma
- Without inhaled corticosteroids
When are LABAs particularly useful?
In exercise-induced asthma
What is step 4 in asthma management?
Persistent poor control
What should be done when there is persistent poor control in <5 year olds?
Refer to respiratory paediatrician
What should be done when there is persistent poor control in 5-12 year olds?
Increase ICS dose
What should be done when there is persistent poor control in adolescents and young adults?
Increase ICS and consider leukotriene receptor antagonists, or slow release theophylline
What is step 5 in asthma management?
Continuous or frequent use of oral steroids
What inhaled steroid dose should be used in step 5 in 5-12 year olds?
You should maintain inhaled steroid dose at 800μg/day
What oral steroid dose should be used in step 5 in 5-12 year olds?
Use lowest possible dose to maintain adequate control
What should be done in addition to giving steroids in step 5 management in 5-12 year olds?
Refer to respiratory paediatrician
What inhaled steroid dose should be used in step 5 in adolescents and young adults?
1600μg/day
When is oral prednisolone given in step 5 asthma management?
Alternate days
Why is oral prednisolone given on alternate days in step 5 asthma management?
To minimise the adverse effect on growth
Who should all children on oral steroid therapy for asthma be managed by?
A specialist in childhood asthma
Give an example of an anti-IgE therapy used in asthma
Omalizumab
Who can administer anti-IgE therapy with omalizumab in asthma?
Only a specialist in childhood asthma
What is omalizumab?
An injectable monoclonal antibody that acts against IgE, which is the natural antibody that mediates allergy
What is omalizumab used for?
The treatment of severe atopic asthma
Are antibiotics useful in asthma?
Most antibiotics are of no value in the absence of bacterial infection
Are cough medicines and decongestants useful in asthma?
No
Are anti-histamines useful in asthma?
No, but useful in treatment of allergic rhinitis
What are the complications of asthma?
- Acute asthma exacerbations
- Permanent narrowing of airways
- Missed school days or getting behind in school
- Poor sleep and fatigue
- Symptoms that interfere with sports, play, or other activities
