. 2023 Jun 25;2(1):e000367. doi: 10.1136/bmjmed-2022-000367

Table 1.

Detailed examination of the airway in children with suspected asthma to identify coexisting and alternative airway pathologies and provide targeted treatment

Airway component	Investigative method	Underlying cause	Treatment recommendations	Treatment outcomes
Fixed airflow obstruction	FEV₁ <1.96 SD scores despite prednisolone and acute administration of SABA	Congenital/environmental (eg, cigarette smoke exposure); acquired remodelling	Not treatable, aim to prevent further deterioration, but do not overtreat	Deterioration in airway growth halted
Variable airflow obstruction	Variation in spirometry or peak flow by an arbitrary threshold (usually 15%) over time or with treatment	Bronchoconstriction; airway malacia¹¹⁸; intraluminal mucus/inflammatory debris	SABA and LABA; airway clearance, mucoactive agents	Bronchodilatation; reduction in airflow obstruction
Airway inflammation	Induced sputum; FeNO; peripheral blood eosinophil counts	Eosinophilic; neutrophilic; pauci-inflammatory	ICS; neutrophilic asthma is rare in children, no evidence base for treatment in children,⁶³ determine underlying cause of neutrophilia	Better asthma control, fewer attacks; improved outcomes, especially symptom control; reduction in courses of systemic steroids; avoidance of inappropriate treatments
Airway infection	Cough swab; induced sputum; bronchoscopy	Bacterial, viral, or fungal cause related to systemic or mucosal immune paresis	Targeted antibiotics for bacterial infection; consideration of antifungal treatment for severe asthma with fungal sensitisation¹¹⁹	Improved outcomes, especially symptom control
Heightened cough reflex	Cough challenge (rarely performed in children)	Mechanisms not understood in children	No licensed treatment in children	Nothing to change outcomes

FeNO=fractional exhaled nitric oxide; FEV₁=forced expiratory volume in 1 second; ICS=inhaled corticosteroids; LABA=longacting β2 agonist; SABA=shortacting β2 agonist; SD=standard deviation.