Asthma

Question 1

What is the prevalence of asthma?

Answer 1

adults 10-12%

children 15%

Question 2

What is the hygeine hypothesis?

Answer 2

early childhood infections alter the immune response by directing T cell differentiation towards TH1 phenotype and away from TH2 (allergy causing)

Question 3

What are the risk factors for asthma?

Answer 3

allergy
atopy
family history
smoke exposure - smoker or passive

Question 4

What is the main inflammatory response in asthma?

Answer 4

TH2 response - IL4, IL5, IL13

Question 5

What are some triggers for asthma?

Answer 5

allergen exposure (house dust mite, animal dander etc.)
infection - viral URTI
Cold air
inhaled irritants
B-blockers
stress
excercise

Question 6

Clinical features of asthma?

Answer 6

cough - dry or productive
dynsnoea 
wheeze - mostly expiratory
chest tighness
symptoms occur more at night

Question 7

Diagnosis of asthma?

Answer 7

clinical picture
spirometry with reversibility and bronchial challenge (if indicated
- FEV1/FVC less then 0.7
- reversibility greater then 12% and improvement of FEV1 by 200mls

Question 8

What is a bronchial challenge?

Answer 8

administer bronchoconstricting substance (methacholine, histamine etc.)
FEV1 should decrease by 20% or more to have a positive test
often done in those with normal spirometry to confirm diagnosis

Question 9

Features of exercise induced bronchospasm

Answer 9

occurs a few minutes after intense excercise
peaks 5-10 minutes after and resolves within 30 minutes
due to dryness and cooling of airways with increased ventilation
treat with prior b-agonist or leukotriene blocker

Question 10

Features of vocal cord dysfunction?

Answer 10

prominent wheezing on inspiration and heard loudest over throat
can co-exist with asthma
monophonic wheeze (compared with polyphonic in asthma)
abrupt onset and termination
flow volume loop - inspiration part of loop flat (form of variable extrathoracic obstruction)

Question 11

What are some conditions that may lead to poor asthma control?

Answer 11

Non compliance
rhinosinusitis
GORD
mycloplasma/chlamidia pneumonia
aspirin/nsaids/b-blockers
pre-menstral phase
hypo or hyperthyroidism
vocal cord dysfunction

Question 12

What is aspirin sensitive asthma?

Answer 12

1-5% of asthmatics are exacerbated by COX inhibitors

Samter triad of severe asthma, aspirin sensitivity and nasal polyps

Question 13

What is the treatment for aspirin sensitive asthma?

Answer 13

Refer for de-sensitisation (only indication for desensitization testing in asthma)

Question 14

What is the treatment ladder for asthma?

Answer 14

SABA PRN
Low dose ICS
Low dose ICS + LABA
Medium dose ICS + LABA
High does ICS + LABA + consider omiluzumab
High dose ICS + LABA + oral steroids + consider omulizumab

Question 15

What is the caution with LABA in asthma?

Answer 15

Should never be started without ICS as can mask symptoms and increase mortality

Question 16

What is Omalizumab?

Answer 16

antibody against Fc portion of IgE
neutralises circulating IgE and reduces asthma exacerbations
ADR: risk of anaphylaxis

Question 17

What is lebrikizumab?

Answer 17

monoclonal antibody against IL 13

reduced exacerbations

Question 18

What are leukotriene inhibitors?

Answer 18

Montelukast
block leukotriene receptors and reduce bronchoconstricting effect
useful add on therapy - good in excercise induced bronchospasm
Less effective then ICS for reducing inflammation

Question 19

What happens in pregnancy with asthma?

Answer 19

1/3 get better
1/3 get worse
1/3 stay the same

Question 20

What is the classification of asthma?

Answer 20

Intermittent - symptoms less then 2 days a week
Persistent
Mild: symptoms greater then 2 days per week with SABA use more then 2 days per week
Moderate: daily symptoms and SABA use
Severe: daily symptoms, nightly awakenings, SABA use throughout day

Question 21

When is ICS use indicated?

Answer 21

For all other categories except for mild intermittent

- shown to reduce permanent airway re-modelling if started early

Question 22

Treatment of acute asthma exacerbation?

Answer 22

Moderate PEF 40-69%
- bronchodilator via spacer, increase reliever, oral steroids 5-7 days, can be managed as OP if stable
Severe PEF less then 40%
- inh b-agonist (as good as nebs)
- oral steroids (as good as IV)
- magnesium (broncodilator)
- oxygen to keep sats greater than 90
- early intubation

Question 23

How do inhaled corticosteroids work to prevent inflammation in asthma?

Answer 23

switches off trascription of activated genes that encode inflammatory proteins, reduces inflammatory cell recruitment and activation

Question 24

What is theophylline?

Answer 24

Oral bronchodilator

Inhibits phosphodiesterase in smooth muscle which increases cAMP and bronchodilates

Question 25

What are some negatives of theophylline?

Answer 25

ADRs are common at dose required to achieve bronchodilation
N+V, headache, dizziness, arrythmias, seizures
multiple drug interactions as metabolised by CYP