1: Resp - Asthma Flashcards
What is asthma
Chronic disease with airway inflammation, bronchial hyper-reactivity and reversible airway obstruction
What age will the majority of cases of childhood asthma present before
10y
Give 5 triggers for asthma
- Exercise
- Dust mite
- Smoking
- Viruses
- Pollen
- Fur/Feathers
What are 5 risk factors for asthma
- FH
- Low birth weight
- Parents smoking
- Bottle fed
- ADAMS33 gene
- History eczema or allergic rhinitis
How will asthma present in a child
- Dyspnoea
- Nocturnal cough
- Chest tightness
- Expiratory wheeze
In which age-group is breathlessness more common
Pre-School
What type of asthma do children typically have
Exercise-Induced
What are three signs of long-standing asthma
- Barelled chest
- Polyphonic expiratory wheeze
- Harrison Sulci
What is a Harrison sulci
If asthma is present during infancy, there will be a horizontal line along lower border of the thorax due to costal insertion of diaphragm
What is first-line investigation for asthma
Spirometry and Bronchodilator Reversibility Testing
When is spirometry with reversibility suitable
Children >5Y
What is a positive test with spirometry and bronchodilator reversibility
Improvement in FEV1 >12% with bronchodilator
What does a negative test in spirometry and bronchodilator reversibility mean
Does not exclude a diagnosis of asthma
When is spirometry and bronchodilator reversibility not suitable
If a child is under 5
What is second-line investigation in children with asthma
Peak Expiratory Flow
What is a positive result on peak expiratory flow
Diurnal variability of more than 20%
What does a ‘negative’ peak expiratory flow result mean
Does not exclude a diagnosis of asthma
What is third-line investigation for asthma
Direct Challenge Test
What is the direct challenge test
Histamine or Methacholine are administered at increasing doses. The dose at which a 20% reduction in FEV1 is noted
What is a positive test
Concentration <8 required to reduce FEV1 by 20%
What does a negative methacholine challenge test mean
In schoolchildren, a negative methacholine test makes a diagnosis of asthma unlikely
What is the exercise challenge
Fall in FEV1 of 15% on exercising
What does a positive exercise challenge indicate
Highly indicates asthma in school-aged children
When can FeNO only be performed
Children >3-4Y
What FeNO is a positive test in children
> 35ppb
What FeNO is positive in adults
> 40ppb
Why may a skin prick test be performed
to look for atopy
How does a positive skin prick test affect the probability of the condition being asthma
increases probability it is asthma in school children
Following clinical assessment what is first-line investigation in children >5Y
Spirometry and bronchodilator reversibility testing