Asthma - Clinical Features (Adults) Flashcards
What is the definition of asthma?
A disease characterised by an increased responsiveness of the trachea and bronchi to various stimuli and manifested by a widespread narrowing of airways that changes in severity either spontaneously or as a result of therapy.
Summarise the pathophysiology of asthma.
Airway inflammation mediated by the immune system (IgE)
—>
increased airway reactivity/widespread narrowing of the airways
—>
spontaneously/stimuli
Is asthma more prevalent in children or adults?
children
Who is most affected by asthma: males or females?
Male children
Female adults
How many people are receiving treatment for asthma?
5.4m
Who is most likely to die from asthma?
> 60 years
Smoker
How many children in the UK are receiving treatment for asthma?
1.1m
How many adults in the UK are receiving treatment for asthma?
4.3m
What kinds of everyday things are totally or very limited by asthma?
Running Sport Stairs Pets DIY Gardening Pub Walking Sleeping
What is airway reactivity in asthma?
Tendency for airways to narrow/shut either to stimuli or spontaneously.
How much does asthma cost the NHS annually?
£889m
How much does asthma cost the UK annually?
£2,349m
How many working days a year are lost due to asthma?
12.7m
How has asthma prevalence changes over the last 60 years?
Increased massively until about 2010 when it began to drop
What are the main causes of airway obstruction?
- Debris in the alveoli and airways such as mucous and cells.
- Constriction of smooth muscles around airways.
- Inflammation/thickening of the airway walls.
Outline the proven aetiological factors of asthma.
3 points
- Genetics
- Occupation
- Smoking
Define atopy.
Atopy refers to the genetic tendency to develop allergic diseases such as allergic rhinitis, asthma and atopic dermatitis (eczema).
Describe atopic asthma in terms of its triggers and origin.
Atopic asthma is triggered by a variety of environmental agents such as dust, pollens, foods, and pets.
There is often a family history of asthma, hay fever or atopic eczema.
What are the strongest risk factors in terms of atopic asthma (genetic)?
Familial atopic tendency
Maternal atopy is 3x more influential than paternal.
Bronchoconstriction is mediated by a type ____ hypersensitivity reaction.
I
Outline the pathogenesis of allergic asthma.
Inhalation of allergen (antigen) causes degranulation of mast cells bearing specific IgE (antibody) molecules. Release of vasoactive substances from the mast cells causes bronchial constriction, oedema and mucus hypersecretion.
Bronchoconstriction leads to the clinical effects of _________, __________ and ___________.
weezing, dyspnoea, tachypnoea
Which vasoactive substances are released from mast cells exposed to antigens.
Histamine
SRS-A
ECF-A
PAF
Which immune response genes are involved in atopic asthma?
IL-4
IL-5
IgE
Which airway genes are involved in atopic asthma?
ADAM33
How much of adult onset asthma is due to occupation?
Underestimated at 10-15%
What kinds of things are people exposed to at work that leads to asthma?
Isocyanates (twin pack paints) Colophony (welding) Laboratory animals Grains (flour) Enzymes (e.g. amylase, subtilisin) Drugs (salbutamol, antibiotics) Crustaceans (shell fish)
Give some examples of occupations that will increase your risk of developing asthma.
Baker
Welder
Builder
Cleaners
Explain what is meant by the ‘grandmother effect’.
Children are more at risk of asthma if:
Mother smoker - 1.5 (50%)
Maternal grandmother smoker - 2.1 (100%)
Both of the above - 2.6 (150%)
What effect does maternal smoking during pregnancy have on the babies breathing?
- Decreases FEV1
- Increases wheezy illness
- Increases airway responsiveness
- Increases asthma
- Increases severity
Outline the possible (putative) risk factors for asthma?
- Obesity
- Diet
- Reduced exposure to microbes
- Indoors pollution (e.g. chemical household products)
How is obesity considered a possible risk factor for asthma?
BMI is positively associated with: - asthma
- wheezing
- airway hyper-reactivity
- breathlessness (not technically asthma)
What changes in a persons diet is a possible risk factor for asthma?
- Less antioxidants
- Less n-3 polyunsaturated fatty acids
- More n-6 polyunsaturated fatty acids
- More/less vitamin D
What associations have been made between asthma and diet, that could indicate a correlation?
- decreases in FEV1 & decreases in vitamins E/C/D, carotene.
- increased wheeze & decreases in vitamins E/C, fruit, eating margarine.
- decreases in asthma with increased oily fish consumption, and butter
Why do we know reduced exposure to microbes might increase the risk of asthma?
Children born on farms are less likely to develop asthma.
How do we know indoor pollution might increase the risk of asthma?
Cleaners are more at risk of developing asthma.
What are some environmental allergens linked to asthma?
House dust mite
Cats
Grass pollen
What are some things that might cause localised airway obstruction?
Inspiratory stridor
Tumour
Foreign body
What are some things that might cause generalised airway obstruction?
Asthma COPD Bronchiectasis Bronchiolitis Cystic fibrosis
Does allergen exposure cause asthma?
No, it is more to do with the way we live nowadays.
What is most important for making the asthma diagnosis?
History, examination is rarely useful.
What are the symptoms of asthma that you must look out for in the history?
- Wheeze
- Dyspnoea, severity
- Chest tightness (pain)
- Cough, paroxysmal, usually dry
- Sputum (occasional)
Describe the colour and viscosity of sputum produced in asthmatics?
Thick, white to yellowish
What is dyspnoea?
Breathlessness, difficult or laboured breathing.
What is a wheeze?
A high pitched whistling noise from the chest (not throat).
What is paroxysmal?
Sudden intensification of symptoms, exacerbation.
What variations in symptoms must you look out for when taking a history?
- Triggers
- Daily variation (nocturnal or early morning)
- Weekly variation (occupational risk)
- Annual variation (seasonal)
What are some triggers for asthma?
exercise, cold air, smoke, perfume, URTI’s, pets, grass pollen, food, aspirin
What does an asthmatic bringing up green sputum mean?
Not always an infection, neutrophils and polymorphs from inflammation also cause this.
What is important to look out for in patients PMH?
childhood asthma
bronchitis
eczema
hayfever
What is important to look out for in patients DH?
Current inhalers (microg NOT puffs) - check technique/compliance B-blockers Aspirin NSAIDS Effects of previous drugs, inhalers
What is important to look out for in patients FH?
Atopic disease (atopic asthma, eczema, hay fever)
What is important to look out for in patients SH?
Are they a smoker? (or around smokers)
Any pets?
Occupation - past/present
Psychosocial aspects
What are some observations in an examination of an asthmatic?
- Breathless on exertion
- Hyperexpanded chest
- Polyphonic wheezes
What if seen on examination suggests it is not asthma?
- clubbing
- cervical lymphadenopathy
- stridor
- assymetrical expansion
- dull percussion note, (lobar collapse, effusion)
- crepitations (bronchiectasis, CF, alveolitis, LVF)
What is crepitation?
a crackling sound
What is bronchiectasis?
- long-term condition
- airways of the lungs become abnormally widened
- leading to a build-up of excess mucus
- lungs more vulnerable to infection
What are the two main things looked for in investigations?
- Airway obstruction (spirometry)
- variability and/or reversibility of airflow obstruction (drugs/monitoring)
What spirometry results are indicative of an obstructive airway disease?
FEV1 less than 80%
FEV1/FVC ratio less then 70%
May be completely normal though as in asthma airway obstruction is variable.
What investigations should be carried out if there is evidence of an OBSTRUCTED airway from the spirometry?
- Full pulmonary function testing
- Reversibility to bronchodilator (B2-agonist)
- Reversibility to oral corticosteroids (e.g. brown inhaler)
What is the first investigation we do for asthma?
FEV1 testing (spirometry)
What do we do if spirometry testing for FEV1 is NORMAL?
Test variability of airflow obstruction using a peak flow meter and chart twice daily for two weeks.
Variability suggests asthma
If the FEV1 testing is normal, how often and for how long is a peak flow meter used to test variability of airflow obstruction?
Twice daily for 2 weeks
what is full pulmonary function testing?
- Used to exclude COPD or emphysema.
- The two tests carried out are:
1. lung volumes by helium dilution and;
2. carbon monoxide gas transfer (transfer of CO to Hb across alveoli, this tests for tissue destruction).
What does full pulmonary testing exclude?
COPD/emphysema
Increase gas transfer suggests asthma, decreased suggests COPD.
When does full pulmonary testing suggest asthma?
If increase gas transfer
what is the reversibility to bronchodilator test used for?
It tests for bronchoconstriction. For significant reversibility the change in FEV1 must be greater than 200ml and greater than 15% of base line.
When does testing the reversibility to bronchodilator suggest asthma?
Increase in FEV1 after salbutamol suggests asthma, no increase suggests COPD
What is the process of testing reversibility to bronchodilator?
1) Take baseline measurement
2) Give salbutamol
3) Compare the difference
What is the reversibility to oralcorticoseroids test used for?
- It tests for inflammation in airways
- used to separate COPD from asthma when there is an obstructed picture from initial spirometry
What is the prescription for a reversibility to oral corticosteroid test and what is measured?
- 0.6mg/kg of Prednisolone for 14 days.
- peak flow chart and meter
- baseline and 2 week spirometry
When testing reversibility to oral corticosteroids, what suggests asthma?
Improvement suggests reversibility so asthma, no improvement suggests COPD
What is the FEV1/FVC ratio for an airway obstruction?
Less than 70%
What might suggest occupational asthma?
- Suspicion from work related symptoms
- Working with recognised occupational sensitiser
How is occupational asthma confirmed?
Serial peak flow readings, 2 hourly best for 2 days minimum.
Difference in and out of work shows occupational asthma.
What are examples of specialised investigations?
- airway responsiveness to methacholine/histamine/mannitol/exercise
- exhaled nitric oxide
What are some additional useful investigations?
Chest x-ray
Skin prick testing
Total and specific IgE
Full blood count
What could a chest x-ray of someone with asthma show?
looking for hyperinflation, hyperlucent (less dense than normal)
or checking for no effusion, collapse, opacities, interstitial changes
What does skin prick testing; total and specific IgE; and full blood count test?
Atopic status
Blood count: looking for eosinophilia associated with atopy
Why is being objective more important than subjective?
Life threatening asthma may not induce any visible distress
What physiological indicators are checked when dealing with asthma?
Ability to speak Heart rate Respiratory rate PEF Oxygen saturation/arterial blood gases
What is acute asthma?
Flare up of asthma
What are the different kinds of acute asthma?
Mild
Severe
Life threatening
Near fatal
What are the features of an asthmatic in moderate condition?
Essentially increasing symptoms, no features of severe.
Able to speak, complete sentences HR <110 RR <25 PEF 50 - 75% predicted or best SaO2 > 92% (no need for ABG) PaO2 > 8kPa
What are the features of an asthmatic in a severe condition?
Unable to speak, unable to complete sentences HR >110 RR >25 PEF 33 - 50% predicted or best SaO2 > 92% PaO2 > 8kPa
What are the features of an asthmatic in a life threatening condition?
Grunting Impaired consciousness, confusion, exhaustion HR >130, or bradycardic Hypoventilating PEF < 33% predicted or best Cyanosis
SaO2 < 92%
PaO2 < 8kPa
PaCO2 normal (4.6 - 6.0kPa)
When is an asthmatic in a near fatal condition?
PaCO2 is raised
What does near fatal asthma require?
Mechanical ventilation
