
Increased resistance of small airways may be assessed noninvasively by spirometry, nitrogen wash out, body plethysmography, impulse oscillometry (IOS), and using imaging (high resolution computed tomography or conventional chest X-ray).
The use of metered-dose inhaler (MDI) products with extrafine particles of inhaled corticosteroids has been suggested for targeted therapy of small airways. However, studies in pediatrics have generally been inconclusive.
References:
Small Airway Targeted Therapy in Pediatric Asthma: Are We There Yet? Hengameh H. Raissy, PharmD and Kathryn Blake. Pediatr Allergy Immunol Pulmonol. 2013 December 1; 26(4): 204–206.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3869414
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