Electric impedance tomography discriminates asthmatics during methacholine challenge test

Background: Bronchial asthma is not always easily diagnosed in children because of poor compliance performing spirometric manoeuvres. Little is known about the distribution of pulmonary regional ventilation in these patients. Electric Impedance Tomography (EIT) is a technique where the electrical conductivity and impedance of ventilation is inferred from surface electrodes to form a tomographic image. Objectives: This study aims to determine the role of EIT to investigate the distribution of ventilation during methacholine challenge test (MCT) in order to discriminate healthy from asthmatic patients. Methods: Patients from 5 to 16 years old were enrolled. Positive MCT was defined as a reduction of FEV1 ≥20%. For each patient, spirometry and EIT were assessed at baseline (B), at PD20 (or Step 6 of the MCT) and 10 minutes after administration of the bronchodilator. Results: 36 positive and 7 negative patients were found. Positive group at PD20 showed a significant air trapping (550 ±180 ml, p Conclusions: EIT is a good tool to evaluate regional pulmonary ventilation without requiring collaboration. It could be useful to identify an early air trapping in patients with methacholine challenge test and, possibly, discriminate severe asthmatic in order to administer specific therapy.