Asthma
Table 1: Physiological Testing Suggesting the Diagnosis of Asthma
Any evidence of obstructive physiology on spirometry Documented bronchodilation after acute administration of short-acting β-2 agonist
Peak flow variability during a short period of home monitoring Positive bronchial challenge (exercise, methacholine)
Table 2: Test to Distinguish Severe Asthma from Alternative Diagnosis that May Mimic Asthma
Suspected Diagnosis Structural abnormalities
(tracheobronchial malacia, vascular
rings, tracheal stenosis/webs, cystic lesions/masses, tumours, lymphadenopathy, cardiomegaly) Intrabronchial obstruction
(e.g. inhaled foreign body) Dysfunctional breathing
Gastro-oesophageal reflux with/
without aspiration Cystic fibrosis
Immune abnormalities Bronchiectasis (cystic fibrosis,
primary ciliary dyskinesia) Bronchopulmonary dysplasia Bronchiolitis obliterans
CT = computed tomography.
medicines, locally appropriate protocols and educational material is not available.6
Patterns of Presentation
From a clinical point of view, different categories of children with severe asthma seem to be of particular importance. Most paediatric definitions are arbitrary and not evidence based unless otherwise stated.7–9
The symptom patterns are not mutually exclusive and include one or more of the following.10
•
Persistent (most days, for at least three months) chronic symptoms (the need because of symptoms for short-acting β-2 agonists at least three times per week) of airways obstruction despite high-dose ICS and additional controllers.
•
Type 1 brittle asthma (dramatic within day swings in peak flow over a prolonged period of time); type 2 brittle asthma (a rapid onset of an acute attack of asthma requiring admission to a high-dependency unit at the very least). The definitions and most data are arbitrary in paediatrics.
•
Recurrent severe asthma exacerbations that despite daily anti-inflammatory therapy have required during the past year: • either one or more admissions to an intensive care unit, • or two or more hospital admissions requiring intravenous treatment, or
• two or more courses of oral steroids. •
Persistent airflow obstruction: post-oral steroid, post-bronchodilator Z score of less than -1 96 (from 70 % to 80 % of the predicted value, according with the age of the subject) for forced expiratory volume
92 Diagnostic Test
Fibreoptic bronchoscopy, thorax CT scan
•
in one second (FEV1), with normative data from appropriate reference populations.11
The necessity of prescription of alternate day or daily oral steroids to achieve control of asthma.
Clinical Characteristics and Features Unlike in adults,12,13 paediatric series.14,15
there is no significant gender difference in the Morbidity for many children is considerable;
Typically, children are highly atopic, and, unlike in adults, there is no neutrophilic inflammation preponderance.14,15,17,18 Spirometry can vary from normal to severe obstruction with variable response to acute bronchodilator inhalation.14,15,16,19
prescription of multiple courses of oral steroids, healthcare use, admissions to hospital and ventilation in the Intensive Care Unit are all common.14–16
Hyperinflation,
manifested by an elevated residual volume to total lung capacity ratio, is frequent in the group, particularly in males.14,20 responsiveness to methacholine21
or exercise22 Rigid bronchoscopy
History, direct observation pH study
Sweat test
Serum immunoglobulins, including subclasses; vaccine antibody responses
High-resolution CT scan History of prematurity
High-resolution CT scan, lung biopsy (not usually needed)
Increased bronchial is a constant feature of
severe asthma. Exhaled nitric oxide (FeNO) may be normal or high.14,15
Assessment of Problematic Severe Asthma Children referred to a specialist for symptoms consistent with problematic severe asthma should be systematically evaluated by a multidisciplinary team. This may be obtained through a step-wise methodological work-up (see Figure 1).
Step One – Is It Asthma at All?
A detailed re-assessment of the diagnosis should be performed in all patients whose asthma does not appear to be responding to treatment. The differential diagnosis of asthma in childhood encompasses virtually the whole of paediatric respiratory medicine. However, within the several alternative diagnoses that should be considered, some are more frequent than others. There is no absolutely diagnostic test for asthma; however, a detailed history, physical examination and simple physiological testing can be used to assess a diagnosis of asthma.23 in this situation.
Some simple key questions may help
• Does the child have a true polyphonic expiratory wheeze or are the described noises less specific?
•
Are there features on history and examination that suggest an alternative diagnosis?
• Is the child atopic? •
Does the child have evidence of variable airflow obstruction over time and with treatment?
As a principle, because of possible misinterpretation of respiratory sounds by parents, a physician should confirm the sounds of bronchial obstruction as they are often confused with other respiratory sounds.25
In many parts of Europe there is no word to describe polyphonic wheeze, and even where there is, there is no guarantee that it will be used correctly.24
Wheeze may be due to many other conditions;
however, its absence should at least raise doubts about an asthma diagnosis. A persistent isolated cough, which was previously considered an asthma variant, is now regarded as a different disorder and usually responds poorly, if at all, to anti-asthma treatment.26
If a
child referred as problematic severe asthma is non-atopic, then the diagnosis should be carefully reviewed. Finally, physiological testing is important to address the diagnosis of asthma (see Table 1). Any physiological test may be negative in asthma, but the more that the paediatrician seeks for and fails to find variable airflow obstruction,
EUROPEAN RESPIRATORY DISEASE
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