title: The intra- and interobserver variability of impedance cardiography in patients at rest and during exercise.
abstract: We studied the intra- and interobserver variability in the calculation of stroke volume by the impedance technique, using the recently proposed refinements in the electrode configuration and signal processing. Three groups of patients were included in this study: ten stable cardiac patients who underwent a diagnostic heart catheterization, ten patients 24-26 h after coronary artery bypass surgery and ten patients with severe chronic obstructive pulmonary disease (COPD). The first two groups were studied at rest and the COPD group during submaximal exercise. The intra-observer variability was 4.2%, 3.9-4.0% and 6.0-6.9% for the catheterized, surgical and COPD groups, respectively. The interobserver variability was 4.3%, 2.6% and 2.4%, respectively. It is concluded that highly reproducible data can be obtained with the newly proposed impedance technique in patients at rest and exercise which may be comparable or superior to other techniques used in clinical settings.
authors.affiliation: Department of Pulmonary Medicine, Academic Hospital VU, Amsterdam, The Netherlands.
authors.forename: H H
authors.initials: HH
authors.lastname: Woltjer
authors.forename: H J
authors.initials: HJ
authors.lastname: Bogaard
authors.forename: P M
authors.initials: PM
authors.lastname: de Vries
mesh_terms: D006328:Cardiac Catheterization; D002307:Cardiography, Impedance; D003331:Coronary Vessels / Q000601:surgery; D015444:Exercise / Q000502:physiology*; D005541:Forced Expiratory Volume; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000503:physiopathology; D008875:Middle Aged; D015588:Observer Variation; D012146:Rest / Q000502:physiology*; D013318:Stroke Volume / Q000502:physiology