title: Development of a wearable multi-frequency impedance cardiography device.
abstract: Cardiovascular diseases as well as pulmonary oedema can be early diagnosed using vital signs and thoracic bio-impedance. By recording the electrocardiogram (ECG) and the impedance cardiogram (ICG), vital parameters are captured continuously. The aim of this study is the continuous monitoring of ECG and multi-frequency ICG by a mobile system. A mobile measuring system, based on 'low-power' ECG, ICG and an included radio transmission is described. Due to the high component integration, a board size of only 6.5 cm×5 cm could be realized. The measured data can be transmitted via Bluetooth and visualized on a portable monitor. By using energy-efficient hardware, the system can operate for up to 18 hs with a 3 V battery, continuously sending data via Bluetooth. Longer operating times can be realized by decreased transfer rates. The relative error of the impedance measurement was less than 1%. The ECG and ICG measurements allow an approximate calculation of the heart stroke volume. The ECG and the measured impedance showed a high correlation to commercial devices (r=0.83, p<0.05). In addition to commercial devices, the developed system allows a multi-frequency measurement of the thoracic impedance between 5-150 kHz.
authors.affiliation: Medical Information Technology, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University , Aachen , Germany.
authors.forename: Sören
authors.initials: S
authors.lastname: Weyer
authors.forename: Tobias
authors.initials: T
authors.lastname: Menden
authors.forename: Lennart
authors.initials: L
authors.lastname: Leicht
authors.forename: Steffen
authors.initials: S
authors.lastname: Leonhardt
authors.forename: Tobias
authors.initials: T
authors.lastname: Wartzek
mesh_terms: D002307:Cardiography, Impedance / Q000295:instrumentation* / Q000379:methods; D003020:Clothing; D004562:Electrocardiography / Q000295:instrumentation* / Q000379:methods; D004566:Electrodes; D006801:Humans; D018670:Monitoring, Ambulatory / Q000295:instrumentation*
keywords: Impedance cardiography; multi-frequency; personal healthcare; portable