Asthma - Acute Paediatric - 1
Important: Accurate assessment of severity is crucial for appropriate management - ask for help if you are unsure
Pathophysiology of asthma
Three core components :
1) Bronchospasm
2) Mucosal oedema
3) Hypersecretion
All lead to obstruction of air flow into (but more importantly) out of the lungs giving wheeze, chest tightness, inadequate oxygenation and ventilation/ perfusion mismatch.
Chronic changes
This inflammatory process can cause permanent changes in the airways.
Long term changes include increased smooth muscle, increase in bronchial blood vessels, thickening of collagen layers and loss of normal distensibility of the airway.
Education
If people with asthma understand that asthma is caused by more than bronchospasm, they will appreciate the need for separate types of medication for asthma management:
- Bronchodilator (also referred to as reliever) medication
- Anti-inflammatory (also referred to as preventer) medication
- Long-acting beta2 agonist (also known as symptom controller) medication
Detection and diagnosis
The diagnosis of asthma is based on:
- history
- physical examination
- supportive diagnostic testing
How do you tell if it is asthma ?
Characteristic symptoms include:
- wheeze
- chest tightness
- shortness of breath and
- cough
Symptoms suggesting asthma
These tend to be:
- recurrent
- worse at night or in the early morning, or
- obviously triggered by exercise, irritants, allergens
or viral infections
In children a chronic or recurring cough, in the absence of any wheeze or associated atopic features, is unlikely to be asthma.
Diagnosis
Children below one year with wheezing are generally diagnosed as 'bronchiolitis' to avoid a normal airway inflammatory response to viral infection being labelled as 'asthma'.
The diagnosis of asthma for the majority of children is entirely clinical, and is based on a history of recurrent or persistent wheeze in the absence of any other apparent cause.
A clinical response to an inhaled bronchodilator is the most usual comfirmation in young children. Only those over 7 years are likely to be able to perform a lung function test consistently and reliably.
A history of atopy - associated eczema, urticaria or a history of asthma in a first degree relative makes the diagnosis more likely.
Wheeze in children - does it mean asthma ?
Wheeze due to asthma is generally accompanied by shortness of breath and/or cough. Cough is a very common symptom in children, particularly those of pre-school age.
In the mid-1980s, 'cough variant asthma' was a popular label for the symptom of recurrent cough. This resulted in the overdiagnosis of asthma and inappropriate therapy.
While cough can be the predominant symptom of asthma, it is extremely rare for it to be the only symptom.
Other causes of wheezing in infants :
- cystic fibrosis
- inhaled foreign body
- cardiac abnormality
- milk aspiration - especially in children with developmental delay
- transient infant wheezing
- structural abnormality
