6.3 Acute asthma
Introduction
The National Asthma Campaign for Australia updated the 2002 guidelines in 20061 and this forms the basis of the chapter. However, there are other best practice guidelines2,3 and national guidelines4–7 and these are important resources for cross-reference and comparison to highlight the controversies.
Acute asthma is one of the commonest reasons for presentation to an emergency department and admission to a hospital. A recent review of admissions to nine paediatric emergency departments in Australia and New Zealand, examining over 300 000 presentations, demonstrated that acute asthma was the fourth most common presentation, accounting for 3.5% of the total number of presentations.8 It is well recognised that in many cases admission to hospital may be preventable9 if managed effectively by the family and medical team involved with a child’s care. There are still great gaps between best practice guidelines and what actually happens in practice.10–12 Practice is highly variable, particularly for severe to critical acute asthma.13
History
Consider acute asthma when a child presents with signs of increase work of breathing, widespread wheezing and shortness of breath. There are other causes to consider such as mycoplasma pneumonia, aspiration, inhaled foreign body, and cardiac failure (Table 6.3.1). In the setting of a child with a previous history of asthma or where asthma seems the most likely diagnosis, one can perform a primary assessment of severity and institute the initial treatment at the onset of history taking.
| Acute | Chronic |
|---|---|
| Bronchiolitis, mycoplasma | Cystic fibrosis |
| Allergy | Cilial dyskinesia |
| Aspiration | Immune deficiency |
| Heart failure | Bronchiectasis |
| Foreign body | Airway abnormalities |
It is important to understand the patterns of asthma in children – infrequent episodic, frequent episodic, and persistent.1 The pattern of asthma determines the need for preventive therapy. When a child is discharged from the emergency department (ED) or ward, consideration of the child’s preventative treatment is essential.
Infrequent episodic asthma
Infrequent episodic asthma (IEA) is the most common pattern, accounting for 70 to 75% of children with asthma. In this pattern, children have isolated episodes of asthma lasting from 1 to 2 days up to 1 to 2 weeks, usually triggered by an upper respiratory tract infection (URTI) or an environmental allergen. The episodes are usually more than 6 to 8 weeks apart and these children are asymptomatic in the interval periods. They require management of the individual episode only and regular preventive therapy is unnecessary. Within this group there is a wide range of severity. Most are mild, but this group accounts for up to 60% of paediatric hospital admissions for asthma.1
Frequent episodic asthma
Frequent episodic asthma (FEA) accounts for approximately 20% of childhood asthma. This pattern is similar to IEA but the interval between episodes is shorter, less than 6 to 8 weeks, and the children have only minimal symptoms, such as exercise-induced wheeze, in the interval period. These children may benefit from regular preventive therapy such as low dose (not greater than 400 mcg per day) inhaled corticosteroids or leukotriene antagonist. Commonly, these children are troubled through the winter months only and may require preventive treatment for that part of the year.1
Persistent asthma
Persistent asthma (PA) accounts for 5–10% of childhood asthma. These children can have acute episodes like the categories above, but they also have symptoms on most days in the interval periods. These symptoms commonly include: sleep disturbance due to wheeze or cough, early morning chest tightness, exercise intolerance and spontaneous wheeze. Again, there is a wide range of severity in this group, ranging from those with mild symptoms 4 to 5 days per week readily controlled with low-dose corticosteroid preventive therapy, to those with frequent severe symptoms and abnormal lung function requiring intensive therapy.1
Acute episode
Examination
The most important parameters in the assessment of the severity of acute childhood asthma are general appearance/mental state and work of breathing (accessory muscle use, recession), as indicated in Table 6.3.2. Initial SaO2 in air, heart rate and ability to talk are helpful but less reliable additional features. Wheeze intensity, pulsus paradoxus, and peak expiratory flow rate are not reliable.2 Clinical signs of acute asthma correlate poorly with the severity of the asthma attack and none of the signs in isolation are predictive of severity.4 Classification of an acute attack, using the NAC Australia guidelines1 is as follows:
Differential diagnosis
During an acute episode of wheezing, asymmetry on auscultation is often found due to mucous plugging, but warrants consideration of foreign body. Consider other causes of wheeze (e.g. bronchiolitis, mycoplasma, aspiration, heart failure, or foreign body). Chronically wheezy children may have a diagnosis other than asthma, such as cystic fibrosis, cilial dyskinesia, immune dysfunction, developmental/congenital abnormality, upper airway problems or bronchiectasis. There may be clues in the family or perinatal history or symptoms and signs that may suggest an alternative diagnosis to asthma.4
Treatment
Treatment – mild
Treatment – moderate
Treatment – severe
Treatment – life threatening
Disposition
Each child should have a written action plan on discharge from the ED. Observe the child’s inhaler technique before discharge. Advise parents to seek further medical review should their child’s condition deteriorate or if there is no significant improvement within 48 hours. At discharge all patients should have an outpatient appointment or appropriate follow up arranged with a paediatrician or local doctor as appropriate. Parents should be informed of other sources of information about asthma such as the Asthma Foundation. The concept of an asthma discharge pack is useful to ensure all aspects of discharge are considered. Adult data suggest that self-monitoring, regular review and written action plans can improve outcomes.17 Two paediatric studies suggest that an intensive nurse-led discharge concentrating on education, written action plans and inhaler technique, appropriate follow up with discharge prescription for steroids can reduce readmissions and following morbidity.18,19 A child should be ready for discharge when it is considered that they can be stable on 3–4-hour inhaled bronchodilators.20 This is often a subjective decision.
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