Applicability of extracellular electrical impedance tomography in monitoring respiratory tract inflammation.

BACKGROUND: The presence of persistent mild inflammation is widely considered to provide the immunopathogenic basis for bronchial, nasal, or sinusal inflammation between critical phases and in asymptomatic periods. Exhaled nitric oxide (NO) is currently the most reliable marker of rhinobronchial inflammation, but its routine assessment is difficult as the test is available only in highly specialized centers. OBJECTIVE: The aim of this study was to evaluate the agreement between a new diagnostic method (extracellular electrical impedance tomography) and immunological and clinical symptom scores, anterior rhinomanometry, peak expiratory flow rate (PEFR), serum eosinophil cationic protein (ECP) level, and blood eosinophil count in the clinical monitoring of respiratory tract inflammation before and after treatment of asthma or rhinitis. PATIENTS AND METHODS: Eighty-seven patients were studied; 73 had mild persistent asthma (PEFR > or = 20% below predicted) and 14 had rhinitis. At baseline (TO), the patients underwent a medical examination to record symptom scores, PEFR, anterior rhinomanometry, an extracellular electrolytic conductivity test (bioimpedance tomography), serum ECP level and blood eosinophil count. Appropriate treatment was prescribed, following the guidelines of the Global Initiative for Asthma and the Allergic Rhinitis and Its Impact on Asthma. After 21 days of therapy (T1), the patients were re-evaluated for the same parameters. RESULTS AND CONCLUSIONS: This study demonstrates the good agreement (Cohen's kappa = 0.689) between the symptom scores of patients with rhinitis and the findings of extracellular tomography and very good agreement (kappa = 0.846) between symptom scores of asthma patients and extracellular tomography. These findings validate the use of this new technique for the real-time monitoring and adjustment of treatment in these clinical settings.