title: Linearity of electrical impedance tomography during maximum effort breathing and forced expiration maneuvers.
abstract: Electrical impedance tomography (EIT) provides global and regional information about ventilation by means of relative changes in electrical impedance measured with electrodes placed around the thorax. In combination with lung function tests, e.g. spirometry and body plethysmography, regional information about lung ventilation can be achieved. Impedance changes strictly correlate with lung volume during tidal breathing and mechanical ventilation. Initial studies presumed a correlation also during forced expiration maneuvers. To quantify the validity of this correlation in extreme lung volume changes during forced breathing, a measurement system was set up and applied on seven lung-healthy volunteers. Simultaneous measurements of changes in lung volume using EIT imaging and pneumotachography were obtained with different breathing patterns. Data was divided into a synchronizing phase (spontaneous breathing) and a test phase (maximum effort breathing and forced maneuvers). The EIT impedance changes correlate strictly with spirometric data during slow breathing with increasing and maximum effort ([Formula: see text]) and during forced expiration maneuvers ([Formula: see text]). Strong correlations in spirometric volume parameters [Formula: see text] ([Formula: see text]), [Formula: see text]/FVC ([Formula: see text]), and flow parameters PEF, [Formula: see text], [Formula: see text], [Formula: see text] ([Formula: see text]) were observed. According to the linearity during forced expiration maneuvers, EIT can be used during pulmonary function testing in combination with spirometry for visualisation of regional lung ventilation.
authors.affiliation: Philips Chair of Medical Information Technology, Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: Chuong
authors.initials: C
authors.lastname: Ngo
authors.forename: Steffen
authors.initials: S
authors.lastname: Leonhardt
authors.forename: Tony
authors.initials: T
authors.lastname: Zhang
authors.forename: Markus
authors.initials: M
authors.lastname: Lüken
authors.forename: Berno
authors.initials: B
authors.lastname: Misgeld
authors.forename: Thomas
authors.initials: T
authors.lastname: Vollmer
authors.forename: Klaus
authors.initials: K
authors.lastname: Tenbrock
authors.forename: Sylvia
authors.initials: S
authors.lastname: Lehmann
mesh_terms: D000328:Adult; D017097:Electric Impedance; D045853:Exhalation; D005260:Female; D006801:Humans; D016014:Linear Models; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D013147:Spirometry; D014054:Tomography; D055815:Young Adult