Clinical features of asthma Flashcards
What is asthma?
A chronic inflammatory disorder of the airways secondary to type 1 hypersensitivity*
The symptoms are variable and recurring and manifest as reversible bronchospasm resulting in airway obstruction
(*asthma isnt actually due to allergies though its v complicated)
Describe the presentation of asthma
Wheeze
Cough
Dyspnoea
Variable & reversible
Identifiable trigger (usually)
Must respond to asthma treatment
Histologically - what features are seen in very severe asthma?
Mucosal oedema of the bronchi
Infiltration of the bronchial mucosa or submucosa with inflammatory cells, especially eosinophils
Shedding of epithelium and obstruction of peripheral airways with mucus
Nobody reall understands what actually causes asthma
But what relevence does genetics play?
Up to 80% of asthma causation can be explained by heriditary factors (genetics)
~10 genetic variations linked
Most important:
- ADAM33
- ORMDL3
Aside from genetics - what other factors have a role in asthma causation?
Environmental factors - eg infection, exposure to certain dusts etc
‘the genes load the gun - environment pulls the trigger’
Diagnostic tests are pretty useless in asthma but still are done
Give an overview of the tests available for asthma
Describe the pathway (use the image)
1) Spirometry
2) BDR*
3) FeNO*
4) Peak flow
*BDR - bronchodilator reversibility
*FeNO - Fractional exhaled Nitric oxide
Describe the wheeze seen in asthma
No wheeze = no asthma
A must have - but not in isolation
Wheeze is often not the predominant symptom
Describe the cough seen in asthma?
Dry
Usually not productive
Often worst at night - ie nocturnal
Often exertional
Describe the SOB seen in asthma?
Significant respiratory difficulty - ~<30% of lung function
Reduced PEFR
‘Sooking in of ribs’ often seen
Often described as chest tightedness
What atopic features might you see in someone with asthma?
Eczema
Hay-fever
Not that common though
One of the key features in diagnosing asthma is the response of it to treatment
How is this carried out?
Inhaled Corticosteroids for 2 months - do symptoms improve?
Then stop (holiday) - do symptoms come back?
If both true - in keeping with diagnosis of asthma
When would a trial of Inhaled corticosteroids be indicated for investigating asthma?
If Quality of life is being affected by asthma
If not - watch and wait
What are the differentials for asthma (ie kid with wheeze) in an individual under the age of 5?
Bronchitis
VIW (viral induced wheeze)
Congenital cause
CF - cystic fibrosis
PCD - primary ciliary dyskinesia
Foreign body
What are your differentials for asthma in an older child (>5)
Dysfunctional breathing
Vocal cord dysfunction
Habitual cough
Pertussis
How would you differentiate between VIW and asthma?
VIW only happens to <5 year olds - asthma can occur in <5s and older kids (and adults)
Asthma has interval wheeze - ie the wheeze in asthma can occur in between ‘attacks’ ie - on exercise, trampoline etc
VIW would only occur during a cold or other viral illness…
