Overview Asthma is a chronic airway inflammation disorder due to complex interactions between inflammatory cells, mediators and airway cells. In young children in whom lung function testing is not feasible, including most preschool children, asthma is defined by the presence of variable respiratory symptoms. Asthma is one of the most common causes of presentation to the Emergency department It implies reversible airway constriction (peak flows vary by >20%) +/- wheeze, dyspnoea or cough

Airway obstruction occurs due to a combination of:

• Inflammatory cell infiltration
• Mucus hypersecretion with mucus plug formation
• Smooth muscle contraction

This page will mainly focus on paediatric asthma

Epidemiology

• Paediatric asthma is the most common chronic respiratory disease in the developed world, with the highest prevalence found in English-speaking countries such as the US, the UK, and Australia.
• Good control of asthma and prevention of exacerbations is important.
• There is a variable gender effect, with a higher prevalence in prepubertal males and postpubertal females
• Between 30-80% of children become asymptomatic around the time of puberty.

Infrequent intermittent asthma (70-75% of cases)

• Episodes of asthma lasting days to a week
• Episodes are generally 6 or more weeks apart
• Asthma triggered my URTI
• No need for preventer

Frequent intermittent asthma (20-25% of cases)

• Episodes occur at intervals less than 6 weeks
• Minimal symptoms between episodes
• Children may benefit from regular preventative therapy usually with ICS or Leukotriene antagonist

Persistent asthma (5-10% of cases)

• Symptoms on most days including:
  • Disruption of sleep due to wheeze and cough
  • Early morning dyspnoea
  • Exercise dyspnoea or activity intolerance
• Require preventive therapy
• Referral to a paediatrician

• Allergic sensitisation
• Atopy
• Family History
• Passive or Active tobacoo smoker
• Viral infections
• Higher serum eosinophils

Parental anxiety should not be discounted: it is often of significance even if the child appears relatively well.

Certain thing can trigger a wheezing episode in asthma

• Pollen
• Dust
• Featheres
• Fur
• Excercise,
• Viruses
• Chemical
• Smoke
• Traffic

• Foreign Body
• Pertussis
• Croup
• Pneumonia/TB (Do X-Ray!)
• Aspiration
• Cystic Fibrosis
• Transient infant wheezing
• Sinusitis
• Cardiac failure due to congenital heart disease
• Structural airway abnormality - laryngomalacia, vascular ring

• FBC
• Chest X-ray
• Arterial/Venous blood gas (for severe asthma)
• Spirometry

Diagnosis

• Clinical History
• Clinical features cough, dyspnoea and wheeze
• Clinical Response to bronchodilator

Aetiology

• Genetic predisposition
• Triggers
  • Infections à viral (up to 80% of hospital admissions for asthma are following a viral illness)
  • Exercise (especially in dry, cold air)
  • Allergens (dust mites, pollen, food, animal dander)
  • Environment smoking
  • Chemicals (salicylates)

Pathophysiology

Asthma action plan

The essential elements of asthma self-management education are:

• Written information about asthma and individualised patient details
• Self-monitoring of symptoms and/or lung function (spirometry, peak flow)
• A written asthma action plan
• Regular review by doctor, asthma educator, or nurse on medications and current asthma control, reinforcement of trigger avoidance behaviours and lifestyle changes if warranted, feedback to the patient about how well they are controlling their asthma, and how control can be improved

Assessment of and management of Asthma in Emergency

• Acute Mild/moderate asthma
• Acute asthma
• Life-threathening asthma

Australian Asthma handbook 2015