Asthma Flashcards
Define asthma
A disease characterised by airway inflammation with increased airway responsiveness resulting in airway obstruction
What are the main symptoms associated with asthma
Cough, wheeze, shortness of breath
Describe the nature of asthma
Dynamic and heterogeneous clinical syndrome that has a number of different patterns and which may progress through different stages
How much of the adult population had asthma in the UK
7%
Patients with asthma are also likely to have a high prevalence of what 3 conditions
Rhinitis
Urticaria
Eczema
What environmental change has occurred resulting in a higher prevalence of asthma
A more modern, urban, economically developed society
What 3 allergens are associated with asthma
House dust mites
Pet -derived allergens
Cigarette smoke
What 3 allergens are associated with asthma
House dust mites
Pet -derived allergens
Cigarette smoke
What type of Ig antibody is found in high levels
IgE
What are the effects of the mediators in response to an allergen
Contraction of the airway smooth muscle and increased vascular permeability and stimulation of airway mucus secretion
What do Th2 cells produce
Pro-inflammatory interleukins
What do Th1 cells produce
Cytokines
What is the function of Th2 cells in asthma
Enhancing IgE synthesis and eosinophil and mast cell function
What is the function of Th1 cells in asthma
to down-regulate the atopic response
Describe what happens to the wall of the airway in asthma
It is thickened by oedema, cellular infiltration, increased smooth muscle mass and glands
What occurs which leads to fibrosis of the airway wall
Airway remodelling
What is a prominent feature of acute severe asthma
Mucus plugging o the lumen of the airway
Define atopic asthma
asthma occurring in relation to inhalation of environmental antigens in a susceptible person
Define non-atopic asthma
asthma occurring without any definable relationship to an environmental antigen
What is the difference in airway inflammation of atopic and non-atopic asthma
They are identical pathologically- the inflammatory cascade of asthma can be initiated by a variety of different factors in different patients
What is meant by morning dipping
Peak expirratory flow (PEF) measurements are worse early in the morning
What is meant by nocturnal asthma
Symptoms such as cough and wheeze often distrubing sleep
What does eosinophilic bronchitis usually present with
A chronic cough
Describe the characteristic features on examination of patients with asthma
Diffuse bilateral wheeze
Prolonged expiratory phase
lower costal margin paradox
What are signs of a severe episode of asthma
Tachycardia tachypnoea cyanosis use of accessory muscles features of anxiety and general distress
What might chronic severe childhood asthma cause
chest deformity with the lower rib cage being pulled inwards
What might chronic severe childhood asthma cause
chest deformity with the lower rib cage being pulled inwards
What might be the reasonable next step if a careful history and clinical assessment strongly suggest the diagnosis of asthma
Trial of asthma treatment
What should be done if there is not a clear response to treatment
Reconsider the diagnosis
Confirmation of the diagnosis hinges on what?
demonstration of airflow obstruction that changes over short periods of time, either spontaneously (variability) or in response to treatment (reversibility)
What does spirometry allow that PEAK flow doesnt
a clearer confirmation of airflow obstruction than the PEF
What confirms airway obstruction
A reduced FEV/VC ratio (usually less than 0.7)
What is the standard starting does of salbutamol and when is spirometry repeated
200ug
15-20 minutes after
What is an alternative approach to test reversibility
A 6 weeks trial of inhaled corticosteroid (200ug of beclametasone) or a 2 week trial of an oral steroid (30mg/day prednisolone)
An improvement in FEV1 of what volume strongly suggests asthma
> 400ml
What happens to the total lung capacity in asthma
usually increased as a manifestation of hyperinflation and residual volume is elevated indicating air trapping
What is airway responsiveness
A measure of the general “irritability” of the airways, the degree to which bronchoconstriction develops in response to physical or chemical stimuli
In exercise testing, what is highly suggestive of asthma
Post exercise fall in FEV1 or spirometry before and after 5-10 minutes of exercise
How can the degree of airway responsiveness be measured precisely in the lab
Methacholine provocation tests
What is involved in the methacholine provocation test?
the patient will inhale increasing doses of nebulised methacholine or histamine, starting at a very low dose and serial spirometry is performed
What is involved in the methacholine provocation test?
the patient will inhale increasing doses of nebulised methacholine or histamine, starting at a very low dose and serial spirometry is performed
What is the most common test for hypersensitivity
Skin prick test to identify atopy and to detect particular sensitivity to a specific antigen with a view to exclusion of exposure where possible
What is a positive result to a skin test
A weal with a surrounding erythematous flare at about 15 minutes
What is a means of measuring the level of circulating IgE specifically directed towards a particular antigen
Radioallergosorbent testing (RAST)
What are 3 really good questions to ask during an asthma review consultation
In the last month/ week have you had difficulty sleeping due to your asthma?
Have you had your usual asthma symptoms during the day?
Has your asthma interfered with your usual daily activities
What are 3 really good questions to ask during an asthma review consultation
In the last month/ week have you had difficulty sleeping due to your asthma?
Have you had your usual asthma symptoms during the day?
Has your asthma interfered with your usual daily activities
What two drugs should be avoided in asthamtics
B Blockers and aspirin
What is used to relieve symptoms of bronchoconstriction
SABAs
What is used to treat the underlying chronic inflammatory process in asthma
Inhaled corticosteroids
What is sometimes used with a corticosteroid
LABA
How do SABAs work?
They stimulate B adrenoceptors in the smooth muscle of the airway producing smooth muscle relaxation and bronchidilation
How long does it take SABAs to work and how long do they work for
15 minutes
4-6 hours
What are the side effects of SABAs
Tremor
Palpitations
If a patient needs their reliever more than 3 times in a week what should the clinician do?
Increase the patients maintenance therapy
When do LABAs work
After 12 hours
When is LABA use recommended
with the use of inhaled corticosteroids
As a result, what is often used now in asthma management
Combination inhalers
What can be used as both a reliever and a maintenance therapy
Symbicort
How do anti-muscarinic bronchodilators work
They produce bronchodilation by blocking the bronchoconstrictor effect of the vagal nerve stimulation on bronchial smooth muscle
How do Theophyllines work
They inhibit the metabolism of cAMP by the enzyme phosphodiesterase
What are some side effects of theophyllines
Nausea vomiting headache tachycardia malaise
What are some side effects of theophyllines
Nausea vomiting headache tachycardia malaise
How does magnesium work in asthma
Acts as a smooth muscle relaxant
What is considered a low dose of inhaled steroids
below the equivalent of 800ug/day
What are some side effects of inhaled steroids
Oropharyngeal candidiasis or hoarseness of the voice
What can reduce the hoarseness
Using a spacer device and taking a drink of water after use
What is sodium cromoglycate
A preventative inhaled treatment that has a number of anti-inflammatory actions including stabilisation of mast cells
Is sodium cromoglycate more or less effective than inhaled steroids
Less
Is sodium cromoglycate more or less effective than inhaled steroids
Less
WHen would oral steroid treatment be needed
To control exacerbations of asthma
How long is a typical oral steroid treatment
about 7 days
How do leukotriene receptor antagonists work
They block the effects of cysteinyl leukotrienes - which are metabolites of arachidonic acid with bronchoconstrictor and pro-inflammatory actions
What is Anti-IgE treatment
a monoclonal antibody that binds to IgE
What is control of asthma defined as
No daytime symptoms No night -time wakening due to asthma no need for reliever medication no exacerbations no limitations on activity including exercise normal lung function >80% predicted minimal or no side effects of treatment
Why is the inhaled route for bronchodilator and corticosteroid drugs preferred
The drugs can be delivered directly to the airways reducing the risk of systemic adverse effects
Why is the inhaled route for bronchodilator and corticosteroid drugs preferred
The drugs can be delivered directly to the airways reducing the risk of systemic adverse effects
How are metered dose inhalers drugs metabolised
by first pass metabolism in the liver
What can be used to overcome metered dose inhalers
Large volume spacer devices
What does a large volume spacer result in
Reduced need for coordination of inspiration and actuation of the inhaler
Improves delivery of the drug to the lower airways
How often should spacer devices be replaced
Yearly
What are the 4 signs of an acute severe asthmatic attack
PEF 33-50% of best or predicted
RR 25 or more
HR is 110 or more
Inability to complete sentences in one breath
What are some clinical signs of life threatening asthma
Altered conscious level exhaustion arrhythmia hypotension cyanosis silent chest poor respiratory effort
What are some investigations that should be done for a severe asthmatic attack
ABGs
U&E
ECG
CXR
