title: Regional lung response to bronchodilator reversibility testing determined by electrical impedance tomography in chronic obstructive pulmonary disease.
abstract: Patients with obstructive lung diseases commonly undergo bronchodilator reversibility testing during examination of their pulmonary function by spirometry. A positive response is defined by an increase in forced expiratory volume in 1 s (FEV1). FEV1 is a rather nonspecific criterion not allowing the regional effects of bronchodilator to be assessed. We employed the imaging technique of electrical impedance tomography (EIT) to visualize the spatial and temporal ventilation distribution in 35 patients with chronic obstructive pulmonary disease at baseline and 5, 10, and 20 min after bronchodilator inhalation. EIT scanning was performed during tidal breathing and forced full expiration maneuver in parallel with spirometry. Ventilation distribution was determined by EIT by calculating the image pixel values of FEV1, forced vital capacity (FVC), tidal volume, peak flow, and mean forced expiratory flow between 25 and 75% of FVC. The global inhomogeneity indexes of each measure and histograms of pixel FEV1/FVC values were then determined to assess the bronchodilator effect on spatial ventilation distribution. Temporal ventilation distribution was analyzed from pixel values of times needed to exhale 75 and 90% of pixel FVC. Based on spirometric FEV1, significant bronchodilator response was found in 17 patients. These patients exhibited higher postbronchodilator values of all regional EIT-derived lung function measures in contrast to nonresponders. Ventilation distribution was inhomogeneous in both groups. Significant improvements were noted for spatial distribution of pixel FEV1 and tidal volume and temporal distribution in responders. By providing regional data, EIT might increase the diagnostic and prognostic information derived from reversibility testing.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany;
authors.forename: Barbara
authors.initials: B
authors.lastname: Vogt
authors.affiliation: Department of Biomedical Engineering, Furtwangen University, Villingen-Schwenningen, Germany; and.
authors.forename: Zhanqi
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Department of Pneumology, Medical Clinic, Research Center Borstel, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Zabel
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany;
authors.forename: Norbert
authors.initials: N
authors.lastname: Weiler
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany; frerichs@anaesthesie.uni-kiel.de.
authors.forename: Inéz
authors.initials: I
authors.lastname: Frerichs
mesh_terms: D000280:Administration, Inhalation; D000368:Aged; D000369:Aged, 80 and over; D000420:Albuterol / Q000008:administration & dosage*; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008168:Lung; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000503:physiopathology; D013147:Spirometry; D014054:Tomography; D016896:Treatment Outcome; D014797:Vital Capacity
chemical_list: D001993:Bronchodilator Agents; D000420:Albuterol
keywords: COPD; EIT; pulmonary function testing; spirometry; ventilation distribution