Asthma

Question 1

Name 4 things chronic asthma is characterised by

Answer 1

1. reversible airflow obstruction
2. Increase in airway hypperactivity causing bronchoconstriction
3. Airway wall inflammation
4. Long term structural changes may occur due to chronic inflammation

Question 2

Name 2 histology features you would see in an asthmatic lung

Answer 2

1. More mucus glands: damaged epithelium

2. Thickened/Hypertrophic basement membrane and airway smooth muscle

Question 3

Which type of asthma (extrinsic or intrinsic) is more common? What are 3 features?

Answer 3

Extrinsic:

1. Early onset triggered by environmental allergens
2. Often a family history
3. Raised IgE and immediate type 1 hypersensitivity reaction to the allergen on skin

Question 4

What happens in the early, late and prolonged hyperactivity phase of extrinsic asthma?

Answer 4

Early: 15 minutes
Allergen crosslinks 2 IgEs on a MAST cell which then degranulates releasing histamine

Late: Hours
Inflammatory mediators from MAST cells activate macrophages and chemotaxis of PMNs and eosinophils into the mucosa lining the bronchia: release histamine, prostaglandin and PAF

Hyperactivity: Days
Exaggerated response in airways, inflammatory cells in bronchial walls continue damaging epithelial cells

Question 5

Which age group is likely to have intrinsic asthma? Name 3 things that can induce it

Answer 5

More common in adults, can be induced by excercise, cold or chronic bronchitis

Question 6

Can perfume cause inflammation?

Answer 6

Perfume is an irritant and can re-trigger symptoms but will not cause them

Question 7

Name 4 things that can elicit an intial trigger for bronchospasms

Answer 7

1. Histamine
2. Muscarinic
3. Cold air: can cause a bronchospasm through 2 different mechanisms
4. Arachadonic acid metabolites

Question 8

When is asthma most evident in the breathing cycle?

Answer 8

Expiration when the small airways are compressed, often hear a wheeze

Question 9

When and why would you give an asthmatic patient methacholine?

Answer 9

When measuring responsiveness of the airways; give continous doses of methacholine and measure how much bronchoconstriction occurs with spirometry. Stop when you’ve reached the dose of methacholine that’s made their FEV1 drop by 20%

Can also measure hyper-responsiveness by performing spirometry before exercise with methacholine, making the patient excercise at time intervals and then re-doing spirometry. Then repeat post-bronchodilator

Question 10

How have researchers justified an increasing prevalence in asthma? Where is it most common?

Answer 10

Although there is a hereditary component, rapid increase indicates environmental triggers such as air pollution, tobacco and fungal spores
More common in developed world

Question 11

What is the hygiene hypothesis?

Answer 11

Hypothesis that if you’re exposed to more infections as an infant your Th1 becomes active, and theres less chance of your Th2 pathway becoming active and developing asthma, unproved

Question 12

What are the causal differences between allergic and non allergic asthma?

Answer 12

Allergic asthma: airway inflammation is caused by eosinophils, MAST cells and IgE

Non allergic asthma: (less research done), may be viral induced, ‘aspirin sensitive’ or occupational (welders, farmers, bakers)

Question 13

When can you diagnose asthma?

Answer 13

If a patient has more than one of the following recurrent symptoms:

1. wheeze
2. breathlessness
3. chest tightness
4. cough
5. variable airflow obstruction

Question 14

Describe the tone of an asthmatic wheeze

Answer 14

Polyphonic: Originates in narrowed small airways so has variable intensity and tone
High pitched in expiration and can be on inspiration when severe

Question 15

What worsens breathlessness in an asthmatic patient, what might occur as a result?

Answer 15

Exercise, worse with acute exacerbation

Tachypnea may occur: Increased resp rate to compensate for decreased tidal volume `

Question 16

Describe the cough of an asthmatic

Answer 16

Dry, worst a night and exercise induced

Question 17

What is barrel chest and why does it occur?

Answer 17

Patient’s chest looks like a barrel due to long term obstruction which has caused excessive air to get trapped in the lungs causing hyperinflation

Question 18

What’s harrison’s sulcus?

Answer 18

A chest wall deformity that morphs the chest wall inward (horizontal lower border of thorax) when patient is trying to use all their respiratory muscles to breathe

Question 19

Describe the percussion on an asthmatic patient

Answer 19

Hyper-resonant: hollow, high and drum like

Question 20

Why is peakflow used for monitoring and not diagnosing?

Answer 20

Peak flow is an insensitive indicator of small airway obstruction as there are a wide range of ‘normal values’ in different patients, there’s no ethnicity correction and it’s less reproducible than FEV1

Question 21

What is often seen in an asthmatic patient’s peak flow over time?

Answer 21

Diurnal variation

Question 22

What can indicate allergic asthma on a blood test? What else can you analyse?

Answer 22

Eosinophils.

Can also analyse sputum

Question 23

What asthmatic characteristics are evident on a spirometry graph

Answer 23

Since it’s an obstructive disease you would see a reduced FEV1/FVC ratio and ‘scalloping’ as the expiratory flow rapidly declines and then tapers off

Question 24

When can spirometry indicate an obstruction?

Answer 24

When the patient is well or unwell (or both)

Question 25

What are doctors hoping to see when they perscribe salbutamol?

Answer 25

Beta 2 agonist: Bronchodilation, a 15-20% improvement in the FEV1

Question 26

What marks on the skin indicate a positive allergy test?

Answer 26

A 3mm sized elevated wheel

Question 27

What might you see in severe cases of asthma on a chest x ray?

Answer 27

Air trapping

Question 28

What are the 2 types of asthma drugs? What’s the difference?

Answer 28

1. Airway relaxants: relievers open the airways and patients will notice a difference; B2 agonists or Muscarininc antagonists
2. Anti-inflammatory agents: Preventers
   Corticosteroids will dampen the asthma pathway but patients will not feel a difference

Question 29

What is the BTS Guidelines general approach to dealing with asthma patients?

Answer 29

Start treatment at step most appropriate to initial severity and maintain control by stepping down or up as necessary

Question 30

What are 5 signs of mild asthma? Woud you admit?

Answer 30

Don’t need to admit:

1. saturation >92%
2. Pulse <110 (slightly tachycardic)
3. Resp rate <25
4. Speech normal + minimal wheezing
5. PEFR should still be >75% predicted

Question 31

What are 2 differences moderate asthma has that mild doesn’t? Woud you admit?

Answer 31

Admit:
Same saturation, pulse and resp rate as mild +normal speech
1. Extra wheezing
2. PEFR is 75-50% of predicted

Question 32

What are 5 signs of severe asthma?

Answer 32

1. Pulse >110
2. Resp rate >25
3. Cannot complete sentences in one breath
4. NO wheeze: dangerous
5. PEFR 33-50% of predicted

Question 33

What are some signs of life threatening asthma, what immediate treatment would you give?

Answer 33

Get help if deteriorating, high dose salbutamol and oxygen if hypoxaemic

1. Saturation <92%
2. Silent Chest
3. Altered consciousness
4. absence of hypocapnia - worsening acidosis
5. PEFR is <33%
6. arrhythmia
7. cyanosis

Question 34

What steps would you do to measure airway hyperresponsiveness with exercise and no methacholine?

Answer 34

1. perform pre-exercise spirometry
2. exercise 6-8 minutes
3. perform spirometry 1,5,10,15 minutes after
4. preform post bronchodilator

Question 35

Name a few factors you could adjust as part of the primary prevention of asthma?

Answer 35

1. reduce exposure to allergens
2. smoking
3. weight loss
4. breastfeeding