Asthma Flashcards
What is asthma defined as?
- Increased responsiveness (irritability) of the trachea and bronchus to stimuli
What does the increased irritability of the trachea and bronchi lead to?
- Narrowing of the airway
What two ways can the extent of the narrowed airway be different?
- Randomly
- From treatment
What is the resolution of spontaneous airway narrowing?
- They usually dilate by themselves
What is the reaction the airway has when a sensitive stimulus is breathed in?
- Always narrows
What is the prevalence of asthma in children?
- 10 - 15%
What is the gender distribution in children?
- More boys than girls
What is the prevalence of asthma in adults?
- 5-10%
What is the gender distribution in adults?
- More women than men
How many deaths are a result from asthma in the UK per annum?
About 1000
What 2 ways is asthma detrimental to the NHS?
- Lots of admissions, GP time
- Costs the NHS £2.35 billion a year
What are the 3 proven risk factors for the development of asthma?
- Genetic
- Occupation
- Smoking
What is atopy?
- Inherited tendency to produce IgE in response to an allergen (hyperallergenic)
Which parent is more influential in the inheritance of familial atopy?
- Maternal atopy 3 times more influential
What two ways can atopy be genetics related?
- Immune genes IL-4 and IL-5
- ADAM-33 gene (airways)
How can occupation lead to asthma?
Exposure to certain antigens for an increased time
Give 3 examples of occupational antigens
- Grains
- Isocyanates
- Enzymes
- Drugs
- Animals
- Crustaceans
How does smoking lead to the development of asthma?
- If the mother smokes during pregnancy it has been shown to modify oocytes
What is the grandmother effect?
- Essentially how if your mothers mum smoked and so did she during pregnancy then it like amplifies your chances
What are speculative risk factors?
- There is a CORRELATION between the two but asthma isn’t actually CAUSED by it
What are examples of speculative risk factors?
- BMI
- Diet
- Exposure to microbes
- Aerosols and cleaning products
- Dust mites
- Cats
- Grass pollen
What is the correlation between BMI and asthma?
- High BMI usually indicated obesity
- Obesity is pro inflammatory
With reference to exposure to microbes and antigens, SPECULATIVELY how can you reduce your chance of becoming sensitive to them?
- Exposure from an early age
- e.g. living on a farm
How do dust mites increase chance of asthma development?
- Produce a lot of shit
- Shit contains an allergenic enzyme
What is the correlation between reduced dust mites and asthma?
- Reducing dust mite levels actually increases asthma prevalence
What is localised airflow obstruction?
- A tumour
- A foreign body like a pea in the airway
What causes generalised airflow obstruction?
- Asthma (reversible)
- COPD (irreversible)
- Bronchiectasis (airways become unusually wide and fill up with mucus)
- Bronchiolitis (bronchiole inflammation)
- CF
What symptom is NEEDED for an asthma diagnosis?
- A wheeze
Why is a wheeze needed for an asthma diagnosis?
- The other common symptoms of asthma fit many other generalised airflow obstructive diseases
What other NON VARIABLE symptoms are common with asthma?
- SOB
- Chest tightness
- Dry cough (wet cough would signify bronchitis
What are the variable trigger of asthma?
- Exercise
- Pets
- Smoke
- Perfume
- Cold air
- Pollen
What is daily variation of asthma?
Is it worst at different times of the day
What is weekly variation of asthma?
Is it worse at work etc
What past medical history is important when diagnosing asthma?
- Childhood asthma
- Eczema
- Hayfever
What past drug history is important when diagnosing asthma?
- Inhalers
- Aspirin
- B blockers
- NSAIDs
What family history is important when diagnosing asthma?
- Atopic disease
What past social history is important when diagnosing asthma?
- Smoking
- Pets
- Occupations
- Psychosocial
Why is phsychosocial history important?
Some asthma symptoms worsen in response to stress
What is the technique used to check for obstructive airways disease?
- Spirometry
What two things does spirometry read?
- FEV1
- FVC
If the airflows are obstructed what happens to FEV1 and FVC
- FEV1 lower
- FVC the same
Why is using spirometry not a good diagnostic tool for asthma?
- Asthma is variable
- The airways could be normal at time of test and a false negative will be given
What is the process of carbon monoxide gas transfer?
- Get patient to breathe in a little CO
- If the alveoli are working properly then most of the CO should diffuse into the blood
- If not then high levels of CO will be detected on exhalation
What type of drugs would you use to differentiate asthma from COPD by administering a test run?
- Bronchodilators and corticosteroids
- These drugs will always get the airways to open if it is asthma
- Will have no effect on COPD (irreversible)
By what volume would FEV1 have to change to say that the bronchodilator or the corticosteroid was effective in opening the airways
- 200ml
How would you diagnose occupational asthma?
- Get the patient to do spirometry in and out of work
What is a specialist way of diagnosing asthma? (last resort almost)
- Checking airway responsiveness to histamine OR the suspected trigger antigen
How can nitric oxide be used to diagnose asthma?
- Get the suspected asthma sufferer to breathe in some nitric oxide
- Test nitric oxide concentration on exhalation and typically you’d detect a much higher conc of nitric oxide in a asthma sufferer
