The silent zone of paediatric asthma: integrating small airway dysfunction assessment into clinical practice.

Abstract

Small airway dysfunction (SAD) is increasingly recognised as a clinically relevant component of paediatric asthma because peripheral airway abnormalities may precede spirometric impairment and contribute to poor disease control despite preserved FEV₁. This narrative review summarises current evidence on the assessment and clinical implications of SAD in children, based on studies identified through PubMed/MEDLINE and the Cochrane Library. Spirometry remains the cornerstone of asthma evaluation but has limited sensitivity for early peripheral airway disease. Impulse oscillometry provides the most practical effort-independent assessment of distal airway mechanics, particularly in preschool children, while body plethysmography, multiple-breath nitrogen washout, high-resolution computed tomography, and inflammatory biomarkers including FeNO, alveolar nitric oxide, and volatile organic compounds offer complementary information in selected settings. Current evidence supports a multimodal and clinically integrated approach when symptoms and spirometry are discordant. However, standardised paediatric reference values, cost-effectiveness analyses, and randomised trials demonstrating improved outcomes with SAD-guided management are required before routine implementation in clinical guidelines.