Overview
Asthma is a chronic respiratory condition associated with airway inflammation and hyperresponsiveness leading to bronchoconstriction and wheezing. An acute asthma exacerbation describes the onset of severe asthma symptoms which may be life-threatening.
Epidemiology
- The incidence of asthma is higher in children
- During childhood, the prevalence of asthma is higher in boys than in girls
- During adolescence, the prevalence of asthma is around the same in boys and girls
- In adulthood, the prevalence of asthma is higher in girls than in boys
Risk Factors
- Personal or family history of atopy (e.g. asthma, eczema, allergic rhinitis, allergic conjunctivitis)
- Respiratory infections in infancy
- Pre- and postnatal exposure to tobacco smoke
- Prematurity
- Low birth weight
- Obesity
Presentation
Patients present with wheezing, cough, breathlessness, or chest tightness:
- May be diurnal – worse at night or early morning
- May be triggered – examples are exercise, viral infection, cold air, allergens, emotions and laughter
- Auscultation shows expiratory wheezing
- Focal wheezing suggests an inhaled foreign body or tumour
Diagnosis
Overview
For children aged 5-16 years:
- Spirometry with bronchodilator reversibility (BDR) testing:
- Spirometry – FEV1/FVC ratio <70% suggests an obstructive picture
- BDR – an improvement in FEV1 of 12% or more is positive
- If normal or BDR negative: request fractional exhaled nitric oxide (FeNO) testing:
- FeNO level ≥35 ppb is positive
For children <5 years:
- Diagnose clinically
Differential Diagnoses
Bronchiolitis
- Infants <2 years old present with 1-3 days of fever and coryza followed by:
- Persistent cough
- Either tachypnoea, chest recessions, or both
- Wheeze, crackles, or both
Viral-induced wheeze
- Wheezing is only triggered by viral infections
- There may be no history of atopy
Inhaled foreign body
- Symptoms such as cough present more suddenly
- Auscultation shows focal wheezing
Management
Children aged 5-16 years old
The management of asthma in children aged 5-16 years old is similar to that of adults:
- Step 1: newly-diagnosed asthma: short-acting beta agonist (SABA, e.g. salbutamol)
- Step 2: If symptoms occur ≥3 days a week or night-time waking or symptoms not controlled with SABA alone: SABA + paediatric low-dose inhaled corticosteroid (ICS)
- Step 3: SABA + paediatric low-dose ICS + leukotriene receptor antagonist (LTRA)
- Step 4: SABA + paediatric low-dose ICS + long-acting beta-agonist (LABA) + stop LTRA if it is not working at this point
- Step 5: SABA + change ICS or LABA to maintenance and reliever therapy (MART) that includes paediatric low-dose ICS
- Step 6: SABA + MART that includes paediatric moderate-dose ICS or paediatric moderate-dose ICS + separate LABA
- Step 7: SABA + one of:
- High-dose paediatric ICS either as a fixed-dose regime or as a MART
- Trial adding theophylline
- Seeking help from an asthma specialist
Children <5 years old
- Step 1: newly-diagnosed asthma: SABA
- Step 2: If symptoms occur ≥3 days a week or night-time waking or symptoms not controlled with SABA alone: SABA + 8-week trial of paediatric moderate-dose ICS
- After 8 weeks, stop paediatric moderate-dose ICS and monitor:
- If symptoms did not resolve – alternative diagnosis likely
- If symptoms resolved and recurred within 4 weeks of stopping ICS, restart ICS but use low-dose instead
- If symptoms resolved and recurred beyond 4 weeks after stopping ICS, repeat 8-week trial of paediatric moderate-dose ICS
- After 8 weeks, stop paediatric moderate-dose ICS and monitor:
- Step 3: SABA + paediatric low-dose ICS + LTRA
- Step 4: stop LTRA and refer to paediatric asthma specialist
Monitoring
- Asthma control is monitored at every review. If control is suboptimal:
- Confirm if the patient is adhering to treatment
- Review the patient’s inhaler technique
- Review if treatment needs changing
- Ask about occupational asthma and/or other triggers
Complications
- Death
- Airway remodelling
- Impaired quality of life
Prognosis
- Male children are more likely to outgrow asthma during adolescence
- The earlier the onset of asthma, the better the prognosis. Most children presenting <2 years of age become asymptomatic by 6-11 years