Management of Childhood Asthma

Asthma is the commonest respiratory disorder of children. Chronic inflammation of the bronchial mucosa and hyperreactive airways result in bronchoconstriction and reversible airway narrowing. Wheezing in infants is usually associated with acute viral infection such as bronchiolitis.

Prevalence

Research done between the 1960s and 90s showed a rise in the prevalence in childhood asthma from 4 to 10% with a six fold increase in hospital admissions in England and Wales.² The cause of this rise is still uncertain - one important factor may be the increased readiness to diagnose asthma with increased treatment options. More recently, the burden of self-reported asthma amongst 10-14 year olds has actually fallen across the British Isles, in line with hospital admissions and GP consultations for acute asthma.³ This may be due to the impact of effective treatment reducing severity of symptoms but there was also a reduction in reported mild wheeze symptoms which could reflect a change in underlying prevalence.

Risk factors⁴

• Family history of atopy - both parental (most strongly maternal) and sibling
• Co-existing atopic disease - markers of allergic disease at presentation are related to current asthma severity and risk of persistence through childhood
• Male sex increases risk of asthma in prepubertal children but female sex increases risk of persistence of asthma in transition to adulthood.
• Bronchiolitis in infancy - association weakens with age
• Parental smoking (especially maternal) is linked to higher rates of wheezing illness in early childhood
• Prematurity

Symptoms

• Wheeze
• Dry cough
• Breathlessness
• Noisy breathing

Symptoms are often worse at night or on exercise.

Signs

Prolonged expiration and generalised expiratory wheeze

Parents approach health professionals asking for advice regarding "asthma-type" symptoms in their child.

• Diagnosing asthma can be difficult in young children where objective measurement of variable airways obstruction is impossible so diagnosis should be based on the presence of key features, assessing response to empirical trials of treatment and ongoing assessment.
• In school children, peak flow variability, bronchodilator responsiveness or bronchial hyper-reactivity tests (eg. cold air challenge) can be used to confirm diagnosis as for adults.
• Allergy tests may be helpful in confirming causal factors. Extrinsic asthma is the norm in school-age children so the absence of allergy may point to alternative diagnoses.
• Useful additional history to support a tentative diagnosis may include: personal or family history of asthma or atopy, history of worsening with NSAID use, recognised triggers and patterns and severity of symptoms and exacerbations.
• Triggers and perpetuating factors such as infection, house dust mites, pet allergens, tobacco smoke exposure and anxiety are worth looking for and avoiding where possible.
• Reassess the child repeatedly, questioning the diagnosis if management is not proving effective.
• Always consider differential diagnoses.

Refer when⁴

(Differential diagnoses in parentheses)

• Diagnosis is unclear
• Symptoms from birth or perinatal lung problem (cystic fibrosis, chronic lung disease, ciliary dyskinesia, developmental anomaly)
• Excessive vomiting or posseting (Reflux with possible aspiration)
• Severe URTIs (immune deficiency)
• Persistent wet cough (CF, recurrent aspiration, immune deficiency)
• FH of unusual chest disease (CF, developmental anomaly, neuromuscular disorder)
• Failure to thrive (CF, immune deficiency, GORD)
• Unexpected clinical findings eg. focal chest signs (Developmental disease, post viral syndrome, Bronchiectasis , TB), abnormal cry/voice (laryngeal disorder), dysphagia (swallowing problems with possible aspiration), stridor (central airway or laryngeal disorder)
• Failure to respond to conventional treatment
• Frequent use of oral steroids
• Parental anxiety

Non-drug⁴

• Allergen avoidance⁵ - commonly recommended in patients with asthma but lack of good evidence showing its efficacy.
• Dietary manipulation⁵ - studies looking at supplementation with Vitamin C, E, magnesium and fish oil have not shown significantly beneficial effects.
• Buteyko technique - encourages patients to control their rate of breathing based on the idea that symptoms are due to hyperventilation and hypocapnia. A Cochrane Review failed to find any improvement in lung function when incorporated into the routine care of asthmatic patients.⁶
• Smoking cessation advice to care givers and teenage asthmatics.
• Patient/Carer education with aim to create partnership with family and child and confident self-care.⁷
• Written asthma action plans for self-management lead to consistently improved outcomes.⁸
• Consider care links eg to school and transition to adult services.⁷
• Links to local and national patient groups for support and information.⁷

Drug

Chronic asthma

As for adult management of chronic asthma, current national guidelines advocate stepwise approach.⁴ Start at the step most appropriate to the initial severity of symptoms. Aim to achieve early control and then decrease treatment by stepping down once stable again.

β2-agonists⁹

• Short-acting β₂-agonists work quickly and provide symptomatic relief. No benefits shown from regular dosing. Using >1 canister/month or >10-12 puffs/day are markers of poor control. If using more than 3 times per week, should add in regular preventer therapy.
• Long-acting β₂ -agonists are useful in symptomatic control, particularly in the treatment of nocturnal asthma but should not be used as relief for an acute attack. Any child using a LABA should also be using regular inhaled corticosteroid as failure to do this, increases the risk of life-threatening attacks. Note, these are not licensed for use with under fives.
• Oral preparations of β₂-agonists have been used extensively in the past with children but are less effective than inhaled preparations and have more side-effects.
• Parents often worry about the side-effects of β₂-agonists, particularly sleep and behaviour disturbance, but evidence for links to hyperactivity is weak.¹⁰

Inhaled Corticosteroids⁹

• Regular inhaled corticosteroids are recommended where β₂-agonists are being used more than 3 times per week, symptoms disturb sleep more than once a week or if the child has had an exacerbation in the last 2 years requiring systemic corticosteroid or nebulised bronchodilator.⁴
• They should be taken regularly and concordance may be an issue. Improvement in symptoms usually takes 3-7days.
• Increasing inhaled steroids over an exacerbation has not been shown to be an effective strategy - oral steroids are indicated in this situation.
• Concerns surrounding systemic absorption abound. Those on high doses should receive a "steroid card". Inhaled corticosteroids have only occasionally been associated with adrenal crisis. Paediatric licensed doses should not be exceeded in primary care. Similarly concerns regarding long-term reduction in bone-mineral density suggest that children should receive the minimum dose sufficient to control their asthma. Growth does not appear to be retarded with recommended doses of inhaled steroids - initial growth velocity (in the first year of treatment) may be reduced but there does not appear to be an effect on ultimate adult height.¹¹ The CSM nonetheless suggests that the height of children on prolonged treatment should be monitored and where slowed growth is detected, these children should be referred to a paediatrician.
• Candidiasis of the throat and mouth may occur, particularly with higher doses of inhaled corticosteroids. Strategies to reduce the risk include use of a spacer and rinsing the mouth with water or cleaning the teeth following inhalation.

Cromoglycate and related drugs^1,9

These drugs are not as effective as inhaled steroids for prevention and should not be used in acute asthma but may have some value as prophylaxis in mild asthma with an allergic basis in children aged 5-12 (evidence less clear in those under 5) where there is reluctance to use inhaled steroids.

Leukotriene receptor antagonists⁹

• These are an option to add in to poorly controlled asthma.
• They must be used with inhaled corticosteroids and appear to have an additive effect but should not be considered "steroid-sparing".
• They appear of benefit in the control of exercise-induced asthma.

Immunisation

Influenza vaccine¹² - asthmatic children who require continuous or repeated use of inhaled/systemic steroids or with previous exacerbations requiring hospital admission should be immunised. If children receive repeated systemic steroids sufficient to cause immunosuppression they also require pneumococcal vaccination.

Drug delivery devices

NICE guidelines for inhaler use in children:^13,14

• MDI plus spacer device is the first-line choice for the delivery of inhaled corticosteroid therapy in those aged 5-15years. Where poor compliance with MDI and spacer is likely to jeopardise good asthma control, alternative devices should be considered whilst still looking to minimise systemic absorption. For other inhaled drugs, a wider range of devices can be considered taking into account the need to transport and use spontaneously.
• For those aged less than 5, corticosteroid and bronchodilator therapy should be delivered via MDI/Spacer and facemask combination. Nebulisers or, in those aged over 3 years, dry powder inhalers may be considered where MDIs and spacers are not effective or if the child's clinical condition is poor.
• The device with the lowest overall cost should be chosen but only after consideration of the child's needs ability to maintain good technique and likelihood of good compliance.
• Children and their carers need to be trained in the use of their chosen device and suitability reviewed at least annually looking at compliance and technique.

Acute asthma⁴

Acute asthma is a relatively common paediatric emergency. 38 deaths due to asthma in the 5-14 age range were recorded in 2003 for England and Wales¹⁵ which underlines the necessity to treat acute asthma as severe until proven otherwise and to refer immediately to hospital where a child does not respond adequately to treatment in the community.

Child under 2 years

Intermittent wheezing attacks are usually in response to viral infection and response to bronchodilators and oral steroids is inconsistent. Nebulised β₂-agonists have been associated with paradoxical bronchospasm.
For mild/moderate wheeze, deliver a trial of short-acting β₂-agonist (MDI via spacer and mask, 1 puff every 15-30 second up to a maximum of 10 puffs). If response is poor or asthma is moderate to severe, send child immediately to hospital for further assessment and treatment.

Child over 2 years

Mild to moderate exacerbation -

• Short-acting β₂-agonist via spacer - use 1 puff every 15-30seconds for up to 10 puffs. Repeat every 20-30minutes, reducing frequency to every 1-4 hours as improvement.
• Consider soluble prednisolone (2-5 year olds 20mg, >5year olds 30-40mg) for up to 3 days
• If poor response or relapse within 3-4 hours, arrange admission to hospital.
• If good response, ensure carer aware of what to do if situation deteriorates and arrange f/u clinic appointment.

• Arrange immediate blue-light admission
• Oxygen via face mask aiming for 02 sats >92%.
• 10 puffs short-acting β₂-agonist via spacer /-mask or nebulised salbutamol (2.5mg in under 5s, 2.5-5mg in over5s) or terbutaline (5mg in under 5s, 5-10mg in over 5s) repeating every 20-30minutes. Ensure nebuliser is oxygen-driven
• If condition not improving, add nebulized ipratropium (0.25mg).
• Soluble prednisolone (doses as above) or IV hydrocortisone (10mg)
• Send written assessment, pre-admission and referral details.
• Stay with patient until ambulance arrives.

• Reduced quality of life
• Reduced growth, usually as a result of poor control rather than treatment
• Psychological morbidity - although differences appear to be the result of poor health rather than asthma itself.¹⁶
• Absence from school and educational disadvantage
• Death

• The earlier the onset of wheeze, the better the prognosis. Children presenting before 2 years are likely to become asymptomatic by 6-11years versus children presenting after 2 years are more likely to develop persistent asthma symptoms.
• Male pre-pubescent "wheezers" are more likely to "grow out" of their symptoms by adulthood compared to female sufferer.