Asthma

Question 0

What changes to the airway wall is seen in asthma?

Answer 0

Thickening of smooth muscle and basement membrane

Damaged epithelium

Question 1

What is asthma?

Answer 1

A chronic condition characterised by

• airway wall inflammation
• airway wall remodelling
• reversible airflow obstruction
• increase in airway responsiveness to various stimuli

Question 2

What happens to airflow when triggers cause airway smooth muscle to contract and why?

Answer 2

Reduced airway radius
Increased resistance
Reduced airflow

Question 3

Risk factors for asthma?

Answer 3

Genetic risk
Hygiene hypothesis
Sensitisation to airborne allergens such as
-pollution
-house dust mites
-pollen
-tobacco smoke

Question 4

Triggers of airway smooth muscle contraction?

Answer 4

Histamine
Muscarinic agonists
Cold air
Arachidonic acid metabolites such as prostaglandins and leukotrienes

Question 5

Symptoms of asthma?

Answer 5

Wheeze
Dry cough - worse at night and can cause lack of sleep, poor performance at school
Breathlessness with exercise
Chest tightness

Question 6

What is a wheeze?

Answer 6

A high pitched, EXPIRATORY sound
Originates in airways narrowed by compression or obstruction
Can be of variable intensity and tone

Question 7

Examinations for asthma?

Answer 7

Inspection - look for hyperexpansion (Barrel chest), general health - eczema, hay-fever, lethargy, can they speak?

Percussion- will be hyper-resonant

Auscultation - polyphonic wheeze

Question 8

How does spirometry help in diagnosis asthma?

Answer 8

Produce a flow volume loop
Have a low peak expiratory flow rate (can’t breathe out quickly)
Low FEV1/FVC a ratio

Question 9

What happens to the FEV1/FVC ratio after administration of salbutamol?

Answer 9

See a greater than 12% increase

Question 10

What allergy testing can be done in aiding diagnosis of asthma?

Answer 10

Skin-prick to aero-allergens of eg
Cat, dog, house dust mites,

Look at blood IgE level,s for specific aero-allergens

Question 11

Why are chest X-Rays used in the diagnosis of asthma?

Answer 11

Can exclude other diseases, inhalation of foreign body, pneumothorax

Question 12

In the pathophysiology of asthma, what does exposure to the antigen cause?

Answer 12

CD4 T cells differentiate into T helper cells

Secrete IL-4 and IL-5

Question 13

What do IL-4 and IL-5 do?

Answer 13

IL-4: causes B cells to differentiate into plasma cells and secrete IgE

IL-5: makes eosinophils and mast cells reactive to new antigen

Question 14

What does IgE do?

Answer 14

Binds to mast cells in the mucosa
Waits to come into contact with the antigen again
On re-exposure, mast cells are activated and de-granulate to release inflammatory mediators

Question 15

What inflammatory mediators are released by mast cells?

Answer 15

Histamine
Prostaglandins
Leukotrienes

Question 16

What does histamine do in an asthma attack?

Answer 16

Smooth muscle contraction

Increased vascular permeability

Question 17

Why do asthmatics have an increased response to antigens?

Answer 17

Increased number of mast cells in their airway secretions and epithelial linings of lungs

Question 18

What is the late phase reaction?

Answer 18

Due to collection of eosinophils and neutrophils

More sustained inflammation, less bronchoconstriction

Question 19

How does remodelling of the airways occur?

Answer 19

Epithelium is stressed and damaged with the loss of ciliated columnar cells
Deposition of collagen causes basement membrane to thicken
Smooth muscle undergoes hyperplasia - thickening

Question 20

Precipitating factors for asthma attacks?

Answer 20

Can occur spontaneously
Lack of treatment adherence
Respiratory virus infections associated with common cold
Exposure to allergen
Exposure to a triggering drug eg NSAID

Question 21

How can education be used in the treatment of asthma?

Answer 21

So patients can recognise symptoms
Use medication timely
Use services appropriately
Develop a personal asthma action plan

Question 22

How can asthma be prevented?

Answer 22

Stop smoking
Fresh air
Reduce exposure to allergens and triggers
Weight loss

Question 23

Pharmacological management of asthma?

Answer 23

β2 adrenoagonists
Muscarinic antagonists to provide short term relief eg salbutamol
Anti-inflammatory agents eg corticosteroids
Preventer therapies