Asthma is a chronic inflammatory disease affecting the lower airways, which manifests as reversible airway obstruction and mucosal inflammation, resulting in airway narrowing (bronchoconstriction). Children with asthma experience recurrent symptoms of cough, wheeze and breathlessness, and acute exacerbations or attacks. Symptoms can be caused by a variety of triggers principally infection, allergy, airborne chemicals, passive smoking, and exercise.
Acute episodes may be experienced by children with any level of chronic asthma. While symptoms vary in individual cases, acute episodes may have the following characteristics: mild episodes – cough, audible wheeze, normal speech between breaths, and peak expiratory flow rate and forced expiratory volume above 75% of predicted values; severe episodes – severe distress, cyanosis (bluish lips), reduced ability to speak (often limited to only a few words between breaths), and being chair or bed bound.
Childhood asthma is common – studies suggest that the prevalence of diagnosed childhood asthma is between 10% and 23% in England. However, not all cases are diagnosed or treated, and it is estimated that in England and Wales 12% of boys and 10% of girls aged 5 to 15 years are treated for asthma. These treatment rates are higher than in any other age group and in the overall population (for which the treatment rate is 7%).
A steady rise in the diagnosis of childhood asthma is reported in England and Wales, with increases from 7% to 13% in girls and from 10% to 17% in boys aged 5 to 14 years between 1990 and 1998.
Childhood asthma is a rare cause of death. However, the burden of the disease is considerable, in terms of physical and psychological morbidity (that is, anxiety and stigma), reduced quality of life for children and their carers, and impact on schooling and social activities. Childhood asthma also presents an economic burden on health care resources.
The goals of asthma treatment are primarily the prevention of chronic symptoms, maintenance of near normal lung function and normal activity levels, and prevention of recurrent acute episodes (which may lead to hospitalisation), in order to maximise quality of life and satisfaction with the care being provided. It is likely that currently many asthma sufferers are achieving sub-optimal control of symptoms because of inadequate or inappropriate use of preventive therapy.
A number of approaches to managing asthma are available, including non-pharmacological strategies (for example, allergen and air pollutant avoidance), oral pharmacological therapy (for example, corticosteroids, leukotriene receptor antagonists), and inhaled pharmacological therapy.
Inhaled therapy aims to reverse and prevent airway inflammation and constriction, in order to control acute symptoms and maximise respiratory flow. Where available as a therapeutic option, inhaled, rather than oral, administration is generally preferred, in order to reduce the total dose of drug required to produce a treatment effect, reduce the potential for systemic effects, and allow the drug to act in the lung as quickly as possible.
Two therapeutic approaches are used, often in combination.
Bronchodilators (beta-2 agonists, antimuscarinic bronchodilators) relieve symptoms of bronchoconstriction. Short-acting beta-2 agonists deliver rapid relief, with a peak effect within 20 minutes. Long-acting beta-2 agonists, which act for at least 12 hours, are used in conjunction with inhaled corticosteroids to treat children with more severe chronic asthma. Most children with chronic asthma are treated with inhaled bronchodilators.
Anti-inflammatory agents (corticosteroids, cromoglicate and related compounds) act to prevent asthma symptoms. Three corticosteroid compounds are available: budesonide, beclometasone dipropionate, and fluticasone propionate. Sodium cromoglicate and nedocromil sodium are non-steroidal alternatives. Children with moderate or severe chronic asthma usually require inhaled anti-inflammatory treatment as well as bronchodilators.
A guideline on the management of asthma in adults and children were issued by the British Thoracic Society (BTS) in 1997. These guidelines are the most commonly used in the UK, but are not explicitly evidence based. They outline a 5-step approach to managing asthma in adults and schoolchildren, usually starting with inhaled short-acting beta-2 agonists, and introducing anti-inflammatory therapy, long-acting beta-2 agonists and antimuscarinic bronchodilators if symptom control is not achieved. General guiding principles are set out regarding the appropriate selection of devices, though specific device recommendations are not made. The guideline is currently being updated in conjunction with the Scottish Intercollegiate Guidelines Network (SIGN).
The vast majority of chronic asthma care takes place in a primary care setting, often involving practice nurses. The aim is to maximise self-management of the disease. If symptom control is not achieved, drugs, doses, device suitability, inhaler technique and adherence should be reviewed. Doses of inhaled steroids and other drugs should be regularly monitored and slowly stepped down to the minimum dose required to maintain good control of symptoms.