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Year 3 - CR > Asthma > Flashcards

Flashcards in Asthma Deck (82)
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1

What is the definition of asthma

- a combination of cough, wheeze or breathlessness with variable airflow obstruction

2

what type of disease is asthma

Heterogenous disease usually characterised by chronic airway inflammation

3

what are the 4 symptoms of asthma

- wheeze
- shortness of breath
- chest tightness
- cough

- with evidence of variable airflow limitation - its reversible

4

How many people does asthma affect

◦5.4 million people in the UK receive treatment for asthma: 1 in 11 children and 1 in 12 adults
◦Affecting 1 – 18% of the population of different countries

5

what is a phenotype

A phenotype is defined as the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

6

Name the 5 differnet phenotypes of asthma

◦Allergic asthma
◦Non-allergic asthma
◦Adult-onset (late-onset) asthma
◦Asthma with persistent airflow limitation
◦Asthma with obesity

7

Describe allergic asthma

- asthma due to allergies
- has lots of eosinophils

8

describe non allergic asthma

- more neutrophil based
- do not have an allergen that triggers asthma
- not responsive to steroids

9

Describe adult-onset asthma

- can be due to occupational asthma - working in a bakery or a factor

10

describe asthma with persistent airflow limitation

- due to chronic inflammation that has become irreversible

11

what receptors cause bronchodilation

- sympathetic = b2 receptors - these cause bronchodilator and mucocillary clearance

12

what receptors cause bronchoconstriction

- Parasympathetic = muscarinic receptors and causes bronchoconstriction

13

What holds the large airways open

- Cartilage holds the large airways open

14

How do you work out flow

pressure change/resistance

15

what causes an increase in flow

- increased pressure change
- or decreased resistance (pouseille's law: resistance 1/r4)

16

Describe the pathology of asthma

Inflammatory process:
- obstruction
- airway hyper-responsiveness

17

Describe what happens in the acute and late phase pathology of asthma

Acute phase:
Mast cells cause
- bronchospasm
- oedema
- mucous

Late phase
TH2 helper cells cause B cells to be produced and this causes IgE and eosinophil production this leads to:
- constriction
- muco-secretion

18

What are the extrinsic, intrinsic and occupational causes of asthma

Extrinsic
- air pollution
- allergen exposure
- maternal smoking
- hygiene hypothesis
- genetics

Intrinsic
- non allergic
- less responsive
- colds/infections

Occupational
- allergens at work

19

how can you diagnose asthma

- no single diagnostic test
- clinical assessment supported by objective evidence of variable airflow obstruction or airway inflammation

20

What are the features that make asthma more likely

More than one episode of
- wheeze
- breathlessness
- chest tightness
- cough

Variability
- worse at night and in the O-ring (diurnal variability)

- trigged by allergen, exercise, cold air, aspirin or beta blocker
- atomic features
- family history of asthma/atopy
- objectively auscultated wheeze on clinical examination
- low PEFR or FEV

21

why do you produce NO in asthma

- due to high eosinophils which help activate NO producing
- eosinophils use inducible nitric oxide synthetase (iNOS) to produce NO

22

What are the differential diagnosis of asthma

- COPD
- Obstruction due to a foreign body
- anaphylaxis
- pulmonary oedema

23

What are the differences between Asthma and COPD

Asthma
- reversible
- daily FEV1 variation
- can be related to eosinophils and allergies

COPD
- older
- smoking history
- sputum production
- not reversible

24

what is the treatment difference between asthma and COPD

Asthma is chronic inflammation so you use a higher dose of steroids whereas COPD you use lower doses of steroids

25

Name the ways in which you can measure asthma

- spirometry
- fraction exhaled nitric oxide (FENO)
- Direct challenge testing (e.g. methacholine)
- peak flow variability

26

What does spirometry measure

- FEV1/FVC

27

what is the diagnostic result of asthma in spirometry

- FEV1/FVC less than 70%

28

How can bronchodilators reversibility prove asthma

- FEV1 is measured pre and post beta agonist (salbutamol) inhalation with a spirometry
- if there is an improvement of 12% or 200ml in FEV1 then it shows that there is asthma

29

How can FENO show asthma

- Breath test - marker of eosinophilic inflammation
- greater than 40ppb

- multiple confounders
- 1 in 5 have a false positive/negative

30

How does a direct challenge testing show asthma

- Drop in FEV1 when exposed to provoking substance such as histamine or methacholine
- concentration required to cause 20% fall in FEV1 (PC20) of 8mg/ml or less

- low false negative rate
- 2/3rds with positive test have asthma