Measurement of airway inflammation in asthmatic children

A group in Italy has been searching for a way to screen children for asthma, and get a reliable indicator of the level of inflammation in the airway. Initially the group looked into measurements of the temperature of exhaled breath to provide a marker of airway remodeling (1). The increase in the exhaled breath temperature (EBT) has been hypothesized to result from increased vascularity of the airway wall (1). Other studies have noted the correlation between inflammation and temperature and given mechanistic hypothesis (4). Previous studies also showed preliminary results that linked metalloprotineinase-9 (MMP-9) to the remodeling process. The preliminary data showed a correlation when children were exposed to allergens between the exhaled temperature and MMP-9, measured through enzyme-linked immunoabsorbant assays on sputum.

The same group abandoned the tempurature measurement to persue measurements of exhaled nitric oxide (eNO) and fractional exhaled nitric oxide (FENO). The measurements of FENO have been shown to correlate with eosinophilic inflammation in asthma patients. The studies indicated that allergen avoidance modifies inflammatory parameters and that the initial extracellular bioelectrical conductivity measurements provided a reliable non-invasive method to assess airway inflammation (2). The method was also tested for correlation against the Childhood Asthma Control Test (C-ACT), when used together produce a reliable diagnostic and predicting tool (3).

(1) Piacentini, G.L. , et. Al. Exhaled breath temperature as a marker of airway remodeling in asthma, a preliminary study, Allergy 2008:63; 484-485
(2) Peroni, D.G., et. Al . Bioimpedance monitoring of airway inflammation in asthmatic allergic children. Allergologia et Immunopathologia 2008
(3) Piacentini, G.L. , et. Al. Childhood Asthma Control Test and airway inflammation evaluation in asthmatic children. Allergy 2009
(4) Piacentini, G.L. , et. Al. Exhaled air temperature in asthma: methods and relationship with markers of disease. Clin Exp Allergy, 2007; Mar;37(3): 415-419