Chronic inflammatory airways disease characterised by variable reversible
airway obstruction, airway hyper-responsiveness and bronchial inflammation.
A E T I O L O G Y
Genetic factors: Positive family history of asthma or atopy.
Environmental triggers: Passive or active smoking, URTIs, exercise, cold weather, inhalant
allergies (house dust mite/pollens/moulds/pets) and food allergens.
A S S O C I A T I O N S / R E L A T E D
Eczema, allergic rhinitis, previous CLD of prematurity.
‘Hygiene’ hypothesis: Exposure to microbial products in infancy leads to switching off Th2
predispositionof T cells and increasingregulatory T cellsto prevent an allergic predisposition.
DD in <2 years: Aspiration, pneumonia, tracheomalacia, CF, tracheo-oesophageal fistula
E P I D E M I O L O G Y
Prevalence: 10–15%. Age: 80% of asthmatic children are symptomatic by the age of 5. M:
F, 2:1; equalises in adulthood. Distribution: Viral-associated wheeze/recurrent wheezy
bronchitis " in urban areas and in children of low socio-economic status families.
H I S T O R Y
<1 year: Persistent or recurrent nocturnal cough, wheezing with URTIs.
Assess severity: Frequency of attacks (mild: <1 attack in 2 months; moderate: >1 attack
in 2 months; severe: persistent symptoms, #exercise tolerance), effect on school
attendance, hospital attendances and admissions to PICU.
E X A M I N A T I O N
Respiratory: End-expiratory wheeze, recession, use of accessory muscles, tachypnoea,
hyper-resonant percussion note, diminished air entry, hyperexpansion, Harrison sulcus
(anterolateral depression of thorax at insertion of diaphragm).
Peak flow: Useful in >5 years of age; use as baseline (predicted best) and as determinant for
efficacy of treatment.
BTS guidelines for assessment of acute asthma attack
Too breathless to speak or feed
>120 bpm in 2–5 years
Poor respiratory effort
>130 bpm in <2 years
>30 breaths/min in 2–5 years
>50 breaths/min in <2 years
P A T H O P H Y S I O L O G Y
Acute phase (within minutes): Contact with exacerbating factor (cigarette smoke, inhalant
or food allergen or viral infection) leads to " airway receptor hyper-responsiveness !
narrowing of airways.
Late phase (onset after 2–4 hours, effect may last up to 3–6 months): Persistent
bronchoconstriction 2˚ to vicious cycle of inflammation, oedema and excess
I N V E S T I G A T I O N
CXR: In acute severe cases to exclude pneumothorax or first presentation to exclude
Lung function (spirometry): Can be performed in >5 years. Obstructive airways disease:
FEV1 <80%, FVC normal or reduced, FEV1/FVC <70%. Assess reversibility after 400 mg
M A N A G E M E N T
BTS guidelines 2008 for the management of acute asthma attack
High-flow oxygen via reservoir bag.
Discharge criteria: Patients can be discharged when stable on 3–4-hourly inhaled
bronchodilators. Peak flow 75% of predicted best, and O2 saturations >94%.
Education: On adherence to medication, recognition of acute attacks, emergency protocol,
maintaining normal activities.
BTS stepwise management of chronic asthma
1. Avoid obvious precipitants, e.g. passive smoking, allergen avoidance.
2. Ensure good inhaler technique þ / volumatic spacer.
3. Check compliance.
4. Review treatment every 3–6 months.
5. ‘Rescue’ prednisolone in acute deterioration.
6. If obese advise weight reduction.
When to start preventer inhaler:
1. Symptomatic/use b2-agonist inhalers 3 times/week.
2. Waking one night/week.
3. Frequent exacerbations.
Children <5 years
Step 1, mild intermittent asthma: Short-acting b2-agonist inhalers (e.g. salbutamol)
Step 2, regular preventer control: Add low-dose inhaled steroid (200–400 mg/day
budesonide equivalent) or leukotriene receptor antagonist if steroid cannot be used.
Step 3, add-on therapy: Trial of leukotriene receptor antagonist.
Step 4, persistent poor control: Refer to respiratory paediatrician.
Children 5–12 years
Step 1, mild intermittent asthma: Short-acting b2-agonist inhalers as necessary.
Step 2, regular preventer control: Add low-dose inhaled steroid (200–400 mg/day).
Step 3, add-on therapy: Add LABA, e.g. salmeterol.
1. Good response: continue LABA.
2. Benefit from LABA but control still inadequate: "dose of inhaled steroids to 400 mg/day.
3. No response to LABA: stop LABA, " dose of inhaled steroids to 400 mg/day, and add trial of
oral theophylline (monitor plasma levels) or leukotriene receptor antagonist.
Step 4, persistent poor control: " Dose of inhaled steroids to 800 mg/day.
Step 5, continuous or frequent use of oral steroids: Maintain " dose of inhaled steroids.
Add oral prednisolone at lowest dose to provide adequate control.
Refer to respiratory paediatrician.
C O M P L I C A T I O N S
Decreased linear growth rate due to poorly controlled asthma more
usual than from overprescription of inhaled steroids, chest wall deformity, recurrent infections,
status asthmaticus can be fatal. One-third of deaths occur under the age of 5 years.
P R O G N O S I S
Asthma often remits during puberty and many children are symptom free as
adults, especially those who have mild asthma and are asymptomatic between attacks, or
who develop asthma at >6 years. Rates of admission and mortality in asthma have # since the