Asthma Flashcards
What is the defintion of asthma?
a chronic respiratory condition characterised by hyper-responsive airways which become narrow due to inflammation and tightening of the smooth muscles
What is the prevalence of asthma?
In which group is there a higher incidence?
- 8 million people in the UK with a diagnosis
- 5.4 million are receiving treatment
- there is a higher incidence in children
What is the most common industrial lung disease?
occupational asthma
accounts for 15% of adult-onset asthma
What is the basic aetiology of asthma?
- an allergen enters the airway and triggers an allergic response
- this involves inflammation mediated by mast cells, IgE and eosinophils
- the inflammatory cascade damages the epithelium of the airway, allowing more allergens to enter
- this results in airway hyperresponsiveness, smooth muscle hypertrophy and mucus plugging
What type of airway obstruction is present in asthma?
reversible airway obstruction
the obstruction only happens in response to a trigger
What are the known associations for triggering onset of asthma?
- personal or FH of atopic disease
- social deprivation
- tobacco smoke exposure
- obesity
- pollution
- premature birth / low birth weight
- respiratory infections in infancy
- workplace exposures
What is meant by the atopic triad?
asthma, allergic rhinitis & eczema
there is a tendancy for these 3 conditions to occur together
How does someone with asthma typically present to the GP?
with a history of shortness of breath, dry cough and chest tightness
When taking an asthma history, what questions are important to ask relating to their symptoms?
- “are symptoms always present?” - there must be variability in symptoms
- “do you wake up at night breathless?” - there must be diurnal variation
- “are there noises present when you breathe?”
- “are there any triggers?” - could be dust, pets, smoking or exercise
What other areas are important to cover when taking an asthma history?
Establishing RFs
* FHx of asthma
* FHx or personal Hx of atopy / food allergies
* GORD can make asthma worse
Previous asthma care
* has patient ever been hospitalised, had IV steroids or intubation?
What are the 4 main clinical features of asthma?
What is the pattern of symptoms like?
- cough
- polyphonic wheeze
- chest tightness
- shortness of breath
symptoms are EPISODIC with a DIURNAL VARIATION and occur in response to TRIGGERS
What clinical signs might be present in an asthma patient?
- expiratory polyphonic wheeze
- nasal polyps
- work of breathing
How is asthma diagnosed?
there is no single diagnostic test for asthma
diagnosis involves clinical judgement and supportive tests
What 4 tests may be performed as part of the diagnosis of asthma?
- FeNO
- spirometry
- peak flow
- bronchodilator reversibility testing
What is involved in the FeNO test?
- FeNO = fractional exhaled nitric oxide
- it measures the levels of nitric oxide when breathing out
- NO is produced when the airways are inflamed
What FeNO readings would be expected in asthma?
FeNO is increased in asthma
- > /= 40ppb in adults > 17
- > / = 35 ppb in children aged 5-16
What 4 things are measured in spirometry?
- forced vital capacity (FVC)
- forced expiratory volume (FEV1)
- FEV1 : FVC
- bronchodilator reversibility
What is forced vital capacity (FVC)?
the total amount of air that can be forcibly blown out in one breath
What is forced expiratory volume (FEV1)?
How is this changed in asthma?
the volume of air that can be forcibly blown out in one second
this is REDUCED in asthma
What is the FEV1 / FVC?
How is this changed in asthma?
this is the percentage of air blown out in the first second
this should be < 0.7 in asthma
this is because FEV1 decreases with little change in FVC
What is bronchodilator reversibility?
What reading would be expected in asthma?
this determines whether lung function improves with medication
there should be a >12% and 200ml increase in FEV1 post SABA
Typically, what would a normal spirometry graph look like?
- in healthy lungs, most of the breath is blown out within the first second
What would an obstructive pattern look like on spirometry?
- this is typical of an obstructive lung condition, such as COPD and asthma
- the air flows out of the lungs more slowly than it should (low FEV1)
- less than 70% of the total amount is blown out in the first second
What would a restrictive pattern look like on spirometry?
- the total amount of air that you can breathe in is reduced
- the speed that you can breathe out is preserved
- both the FEV1 and FVC will be lower than predicted, but the ratio between the 2 will not be reduced
How is bronchodilator reversibility testing performed?
- 400 micrograms of salbutamol is administered and spirometry is repeated after 15 mins
What do the results of bronchodilator reversibility show?
- reversibility is present if spirometry improves
- the presence of reversibility suggests a diagnosis of asthma
- the absence of reversibility suggests a fixed respiratory pathology (e.g. COPD)
- partial reversibility suggests a mixed picture
How is peak flow measured?
it measures how fast a patient can breathe out after a full breath in
the score is always lower if the airways are inflamed
When is peak flow used in clinical practice?
- can be used to diagnose asthma, monitor the response to treatment or monitor recovery after an attack
- in diagnosis, a patient is asked to keep a peak flow diary
- this should show > 20% variability over 2-4 weeks
What are the main aims of asthma management?
Before pharmacological treatment, what are the fundamentals of managing asthma?
- ensure correct diagnosis
- avoid triggers
- smoking cessation
- adherence to all medications and ensuring correct technique is used
What are the 2 different groups of medication someone with newly diagnosed asthma is given?
Preventer medication:
* these are inhaled corticosteroids that reduce airway inflammation
Reliever medication:
* these cause smooth muscle relaxation to open the airways to relieve the symptoms
What is the main preventer medication used?
low dose inhaled corticosteroids
(e.g. beclomethasone)
these are taken daily to prevent asthma symptoms and attacks
thiis is the most effective treatment when taken correctly
What is the main reliever medication used?
How long does this last for?
short-acting beta-2 agonists
(e.g. salbutamol)
this has a rapid onset of action and lasts for 4 hours
this is only for symptom relief and is not effective in exacerbations
increased use can predict exacerbations
What additional medications may be added on to asthma treatment?
other more intense reliever medications to reduce symptoms and open the airways
- leukotriene receptor antagonists (LRTA)
- long-acting beta-2 agonists (LABA)
- long acting muscarinic antagonist (LAMA)
What is an example of a LABA?
How do these work and when should they be used?
salmeterol
- they act on beta-2 receptors to cause smooth muscle relaxation
- they have a 12 hour duration of action
- should only be used alongside regular ICS
How is it decided at what level to initiate medical treatment?
How is control maintained and response to treatment measured?
- treatment initiated at a level appropriate to the severity of the patient’s asthma
- control maintained by increasing treatment as necessary
- the response to treatment should be reviewed 4 to 8 weeks after any medication change
What is meant by MART?
maintenance and reliever therapy
combination inhaler with a steroid and fast-acting LABA
What is involved in the stepwise management of asthma in adults?
How often should treatment be reviewed?
What should be done if the treatment is not working?
every 4 to 8 weeks
- if treatment does not work, assess adherence and whether it is being taken correctly
- if satisfied, then stop this treatment
How often should patients with asthma be reviewed?
Which groups may be reviewed more regularly?
- patients with asthma should be reviewed at least annually
- some groups are reviewed more often:
poor lung function
severe asthma
history of asthma attack in last year
increased risk of poor outcomes
What are the important areas to cover in an asthma review?
What are the expected outcomes from an asthma review?
- adjustment of treatment
- review asthma management plan
- education and support
What is particularly important to assess during an asthma review?
inhaler technique
- patient may also have spacers to improve lung deposition of the drug
ask patient to demonstrate how they use their inhaler
What is meant by an acute exacerbation of asthma?
How can it be categorised?
the onset of severe asthma symptoms
- severity can be characterised as moderate, severe or life-threatening
What is meant by a moderate asthma attack?
PEFR will be 50-75% of best/predicted
What is meant by a severe asthma attack?
How might someone present?
- PEFR is 33-50% of best/predicted
- RR >/= 25 per min
- pulse rate >/= 110 bbpm
- often unable to complete sentences and use of accessory muscles
What is meant by a life-threatening asthma attack?
How might someone present?
- PEFR is < 33% of best/predicted
- O2 sats < 92%
- patient is exhausted and may be confused
- there is poor respiratory effort with cyanosis or silent chest
- there may be cardiac arrhythmia or haemodynamic instability
When is hospital admission required for an acute exacerbation?
- hospital admission is needed for severe or life-threatening asthma that does not adequately respond to initial treatment
What is the management for acute exacerbations of asthma?
- increased doses of ICS
- SABA
- short course of oral prednisolone
When should a patient be followed up following an acute exacerbation of asthma?
- if admitted to hospital, they should be followed up within 2 days of discharge
- if not admitted, they should be followed up within 48 hours of presentation
