Regional Obstruction in Cystic Fibrosis Patients

Objective: Cystic fibrosis (CF) causes airway obstruction that can be detected in a spirometry test. We hypothesized that with Electrical Impedance Tomography (EIT), not only the information of global but also that of regional obstruction can be captured. Method: In this preliminary study, totally three CF patients and one healthy subject were examined. The subjects were asked to take deepest breath and exhale as hard as possible three times. EIT measurements were performed during spirometry tests. Flow-volume curves obtained from spirometer were compared to that from EIT. Ratio of maximum expiratory flow between 25% and 75% of vital capacity (MEF₂₅/MEF₇₅) were calculated for lung regions in EIT imaging. Results: Relative low MEF₂₅ values in CF patients were detected in global flow-volume curves, both in spirometry and EIT measurements. Further, the EIT measurement revealed a variation of MEF₂₅/MEF₇₅ from 0.05 to 0.4 in different lung regions. Conclusion: Compared to the global parameters provided by spirometer, EIT is able to deliver both global and regional information to assess the airway obstruction in CF patients. The regional information may be useful for long term monitoring of disease progression.