Asthma

Question 1

Define asthma

Answer 1

Chronic inflammatory disorder of the airways secondary to a type 1 hypersensitivity reaction

Question 2

When does asthma typically develop?

Answer 2

Childhood

Common to grow out of asthma

Question 3

What is the nature of the symptoms of asthma?

Answer 3

Variable, recurring

Manifest as reversible bronchospasm –> airway obstruction

Question 4

What are risk factors for asthma?

Answer 4

Personal/FH of atopy
Antenatal factors - maternal smoking, viral infection during pregnancy (esp RSV)
Low birth weight
Maternal smoking around child
Exposure to high concentrations of allergens, e.g. HDM
Air pollution

Question 5

What is the hygiene hypothesis?

Answer 5

Increased risk of asthma + other allergic conditions in developed countries due to reduced exposure to infections preventing normal development of the immune system

Question 6

What other atopic conditions are you more likely to suffer from if you have asthma?

Answer 6

Atopic dermatitis (eczema)
Allergic rhinitis (hayfever)

Question 7

What ENT condition is asthma associated with?

Answer 7

Nasal polyps

Question 8

What medication are a lot of asthma patients sensitive to?

Answer 8

Aspirin

Question 9

What are common examples of occupational allergens?

Answer 9

Isocyanates and flour

Question 10

What is atopy?

Answer 10

Inherited tendency to IgE response to allergens (food allergy, hayfever, asthma, eczema)

Question 11

What are symptoms of asthma?

Answer 11

Cough - often worse at night
SoB
Wheeze, chest tightness

Question 12

What are signs of asthma?

Answer 12

Expiratory wheeze on auscultation

Reduced PEFR

Question 13

What does spirometry measure?

Answer 13

Volume and flow of air during inhalation and exhalation

Question 14

What is spirometry useful for?

Answer 14

Distinguishing restrictive from obstructive lung disorders

Question 15

What are restrictive disorders?

Answer 15

Due to restriction to the lungs, e.g. lung fibrosis

Question 16

What are obstructive disorders due to?

Answer 16

Obstruction to airflow

Question 17

What is FEV1?

Answer 17

Forced expiratory volume - volume that has been exhaled at the end of the first second of forced expiration

Question 18

What is FVC?

Answer 18

Forced vital capacity - volume that has been exhaled after a maximal expiration following a full inspiration

Question 19

What FVC, FEV1 and FEV1% (FEV1/FVC) are typical of asthma?

Answer 19

FEV1 slightly reduced
FVC normal
FEV1% <70%

Question 20

What are common asthma triggers?

Answer 20

Exercise
Cold air
Smoke
Perfume 
URTIs
Pets
Tree/grass pollen
Food
Aspirin

Question 21

What investigations should be done in an adult who is suspected of having asthma?

Answer 21

FEV1/FVC ratio
Peak expiratory flow rate
CXR - exclude other pathologies

if spirometry shows FEV1% <70% –> consider full pulmonary function tests, reversibility with beta-agonist and steroids?

If spirometry normal –> PEFR, then consider bronchial provoaction/nitric oxide

Question 22

Why can fractional exhaled nitric oxide be useful to measure in asthma?

Answer 22

NO is produced by 3 types of nitric oxide synthases (NOS)
One of these is inducible and levels of it rise in inflammatory cells, esp. eosinophils

SO - levels of NO correlate with levels of inflammation

Question 23

What does the reversibility to bronchodilator test involve?

Answer 23

Baseline, 15 min post 400ug inhaled salbutamol/post-neb 2.5-5mg salbutamol
Significant reversibility if change in FEV >200ml or FEV >15% baseline

Question 24

How is reversibility to steroids assessed?

Answer 24

Oral corticosteroids

0.6mg/kg prednisolone for 14 days with baseline and 14 day spirometry

Question 25

What is the most common cause of occupational asthma?

Answer 25

Isocyanates (common in spray paints/foam moulding)

Question 26

What is the best way to investigate occupational asthma?

Answer 26

Serial measurements of PEFR at work and away from work

Question 27

All patients >= 5 years old should have what type of test to confirm a diagnosis of asthma?

Answer 27

Objective tests

Question 28

What is involved in the diagnostic testing of asthma of someone who is >=17 years?

Answer 28

Are symptoms better when away from work? --> if so refer to specialist on basis it may be occupational asthma All patients should have spirometry with bronchodilator reversibility test + FeNO test

Question 29

What is involved in the diagnostic testing of asthma of someone who is 5-16 years?

Answer 29

All patients should have a spirometry with bronchodilator reversibility test FeNO test should be req if normal spirometry or obstructive spirometry with negative BDR test

Question 30

What is involved in the diagnostic testing of asthma of someone who is <5 years?

Answer 30

Clinical judgement

Question 31

What FeNO level is considered positive in adults?

Answer 31

>=40 ppb

Question 32

What FeNO level is considered positive in kids?

Answer 32

>= 35 ppb

Question 33

What FEV1/FVC ratio is considered obstructive?

Answer 33

<70%

Question 34

What is a positive reversibility test in an adult?

Answer 34

FEV1 improvement of 12% or more and increase in vol of 200ml+

Question 35

What is a positive reversibility test in a child?

Answer 35

Improvement in FEV1 of 12% or more

Question 36

What is the criteria for moderate acute asthma?

Answer 36

PEFR 50-75% best/predicted Speech normal RR <25/min Pulse <100bpm

Question 37

What is the criteria for severe acute asthma?

Answer 37

PEFR 33-50% best/predicted Can't complete sentences RR >25/min Pulse >110bpm

Question 38

What is the criteria for life-threatening acute asthma?

Answer 38

``` PEFR <33% best/predicted O2 sats <92% Silent chest, cyanosis or feeble resp effort Bradycardia, dysrhythmia or hypotension Exhaustion, confusion or coma Normal pCO2 indicates exhausation ```

Question 39

What is the criteria for severe acute asthma in a child?

Answer 39

``` SpO2 < 92% PEF 33-50% best or predicted Too breathless to talk or feed Heart rate >125 (>5 years) >140 (1-5 years) Respiratory rate >30 breaths/min (>5 years) >40 (1-5 years) Use of accessory neck muscles ```

Question 40

What is the criteria for life threatening acute asthma in a child?

Answer 40

``` SpO2 <92% PEF <33% best or predicted Silent chest Poor respiratory effort Agitation Altered consciousness Cyanosis ```