Assessment in Paediatrics

• Spirometry is recommended to help confirm diagnosis and for monitoring at each clinic visit, including FEV₁, FEV₁/FVC, FEF25-75% and bronchodilator response. For more information see Diagnosis – Lung Function Assessments
• Standard spirometry is limited by the child’s ability to perform a dynamic airway manoeuvre. Generally, children aged over 5 years can perform spirometry.
• The shape of the flow volume loop including inspiratory loops can help discriminate asthma from non-asthmatic upper airway obstruction
• Children with severe asthma may have a normal FEV₁ between exacerbations (van den Wijngaart et al. 2015).
• Children with poorly controlled asthma may adapt to prolonged impaired lung function and report feeling ‘fine’ despite poor lung function, hence spirometry is essential in children from 5 years of age.
• NOTE: In children with poorly controlled asthma, lung function may be poor with little or no bronchodilator responsiveness. Poor bronchodilator responsiveness is also typical during a viral exacerbation.

• Generally, not recommended in children for a number of reasons:
  • Primarily a measure of large airway patency, while peripheral airway disease is more important in severe asthma.
  • There is high inter-subject variation and results are effort-dependent
  • Does not improve asthma control better than regular follow-up
  •  PEF diaries can be unreliable
• PEF can be useful in children with poor perception of airways obstruction or dysfunctional breathing (van den Wijngaart et al. 2015).

Use pulse waves to measure resistance and reactance during tidal breathing. Studies specifically assessing use in children with severe asthma are lacking. Generally only available in tertiary care settings. For more information see Diagnosis –Lung Function Assessments

• Can be useful in confirming bronchodilator response (BDR) in children that cannot perform spirometry. Bronchodilator response is defined using the 5th/95th centiles of the response to bronchodilators in healthy populations. These have been reported to be between −33 and −42 % for Rrs, 61 and 70 % for Xrs and approximately 80 % for AX, irrespective of the dose of the salbutamol (Hall et al. 2015).
• Interpretation of test results requires clinical correlation (Shi et al. 2013, Schulze et al. 2016).

FeNO measures nitric oxide in exhaled breath, a biomarker of allergic / Type-2 inflammation in the airways. Specific evidence in children with severe asthma is lacking.  For more information see Diagnosis – Phenotyping

The main value of FeNO in children is as an assessment of adherence. FeNO levels drop quickly following inhaled corticosteroids (ICS) use, so ongoing high values on FeNO may indicate poor adherence.

A normal value supports an alternative diagnosis or non-eosinophilic inflammation causing asthma. There is very little evidence to support the use of FeNO as a monitoring tool over standard care, in children with severe asthma (Gomersal et al. 2016).

Interpretation of FeNO Results (Dweik et al. 2011, Bjermer et al. 2014)

• Testing includes quantification of serum total IgE or specific IgE to allergens, and aeroallergen skin prick testing. Blood eosinophils may also be measured as a readout of systemic eosinophilic inflammation. For more information see Allergy Assessments & Phenotyping
• Useful for the identification of potential allergen triggers
• Desensitisation may be of benefit if only 1 major allergen is identified (e.g. house dust mite – HDM), but there is very limited literature in children (Compalati et al. 2009)
• In severe asthma, mould allergens are common (Guilbert et al. 2014)
• Allergic Bronchopulmonary Aspergillosis should be considered in adolescents with severe asthma (very rare)
• Documentation of elevated levels is an eligibility criterion for targeted monoclonal antibody treatment (For more information see Medications in Paediatrics)
  • IgE levels for omalizumab
  • Peripheral blood eosinophil counts for mepolizumab

True treatment refractory severe asthma in children is rare, so exclusion of alternative diagnoses should be considered, especially if treatment adherence has been assessed to be good [See Management in Paediatrics].

Bronchoscopy and chest CT scans may be useful and effective investigations to exclude alternative diagnoses, particularly if there is a history of chronic productive cough, poor response to bronchodilators or steroids or previous severe respiratory infections .

During bronchoscopy, bronchoalveolar lavage can be performed for microbiology, cell counts, and to investigate for lipid-laden macrophages to exclude infection and aspiration, respectively. Visualisation of the airways during dynamic breathing may diagnose bronchomalacia, as a cause of recurrent cough or wheeze.

CT is useful for evaluating:

• Airway abnormalities and foreign bodies
• Quantify the extent of small airways disease signified by gas trapping
• Bronchial wall thickening
• Bronchiectasis
• Suspected interstitial lung disease

Low or normal dose CT chest is usually sufficient, but HRCT may be required to exclude interstitial lung disease, if clinically suggested (e.g. persistent hypoxia or diffuse changes on chest X-ray).

An inflammatory profile on lavage may be useful to help differentiate inflammation caused by eosinophils or neutrophils. For more information see Diagnosis – Phenotyping

• This is a low value test in children, as sputum cellular phenotypes are not stable in paediatric patients longitudinally (Fleming et al. 2012). This may be related to high rates of viral infection in children, particularly for rhinovirus (approximately 12 infections per year) which causes neutrophilic lower airways inflammation in children with asthma

• See sub-section on Psychosocial Issues in Paediatrics

• Gastroesophageal reflux is a common co-morbidity in patients with severe asthma, although whether treatment is associated with an improvement in asthma control is contentious (Thakkar et al. 2010)
• Impedance testing, with a 24-hour impedance probe is the most rigorous test for gastroesophageal reflux
•  A treatment trial with proton pump inhibitors (PPIs) may be considered. For more information see Comorbidities – GORD

• Echocardiogram is not recommended routinely but may be performed to exclude cardiogenic forms of wheeze (e.g. pulmonary hypertension or vascular compression of the airways)
• Right ventricular dysfunction is associated with severe refractory asthma, therefore ECHO may be considered in those children with severe, persistent symptoms, particularly if there is evidence of hypoxia

• Should be considered particularly when spirometry is relatively normal and exercise symptoms are substantial
• Cardiopulmonary exercise testing has a role in clarifying other differential diagnoses and contributing comorbidities.

• May be useful to exclude the diagnosis of primary ciliary dyskinesia, if symptoms of chronic or recurrent wet cough are present.

• May be useful to exclude the alternative diagnosis of cystic fibrosis, if symptoms of chronic or recurrent wet cough are present.