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Handbook of Electrogastrography$
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Kenneth L. Koch and Robert M. Stern

Print publication date: 2003

Print ISBN-13: 9780195147889

Published to Oxford Scholarship Online: November 2020

DOI: 10.1093/oso/9780195147889.001.0001

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PRINTED FROM OXFORD SCHOLARSHIP ONLINE (oxford.universitypressscholarship.com). (c) Copyright Oxford University Press, 2021. All Rights Reserved. An individual user may print out a PDF of a single chapter of a monograph in OSO for personal use. date: 17 June 2021

Recording the Electrogastrogram

Recording the Electrogastrogram

(p.69) 4 Recording the Electrogastrogram
Handbook of Electrogastrography

Kenneth L. Koch

Robert M. Stern

Oxford University Press

Electrogastrograms (EGGs) are recorded by placing electrocardiogram (ECG)-type electrodes on the surface of the epigastrium. The EGG is one of several biological signals that can be recorded from the electrodes on the epigastrium. Some of these signals, like the EGG, are much stronger than the EGG. The EGG signal is relatively low amplitude, ranging from approximately 100 to 500 (μV. Thus, the EGG signal must be properly amplified and filtered for quality recordings. To reduce baseline drift and to remove unwanted cardiac and respiratory signals, a 0.016-Hz high-pass filter and a 0.25-Hz low-pass filter are used. These filters create a bandpass, or window, from approximately 1 cycle per minute (cpm) to 15cpm through which the desired gastric myoelectrical signals pass during the EGG recording. In this chapter, the equipment needed to record the EGG, the EGG recording procedure, and how to identify and reduce artifacts in EGG recordings are discussed. For additional information on the acquisition and analysis of EGG data, the reader is referred to several reviews and texts. High-quality, fresh, disposable electrodes such as those used for electrocardiogram (EGG) recording are recommended. To minimize artifacts in the EGG recording caused by electrode movement on the skin, it is best to use electrodes that adhere very well to the skin (e.g., Cleartrace; ConMed Corp., Utica, NY; or BioTac; Graphic Controls, Inc., Buffalo, NY). Reusable silver/silver chloride electrodes are available (e.g., 1081 Biode; UFI, Morro Bay, CA). The size of the electrode surface is not important, but the electrical stability of the electrode is important. The electrodes should show little bias or offset potential because the EGG signal is relatively low amplitude and low frequency. A high-quality recording system is needed to amplify and process the 100 to 500-μV EGG signal that ranges from 1.0 to 15.0 cpm. Some older physiological polygraphs have appropriate amplifiers and filters that can be used to record the EGG. Several medical device companies produce complete EGG recording and analysis systems that include appropriate amplifiers and filters with analog-to-digital boards that digitize the EGG signal for analysis with software (e.g., 3CPM Company, Crystal Bay, NV; Medtronic, Shoreview, MN).

Keywords:   Electrode placement, Electrodes, Harmonics, Recording equipment, Respiratory artifacts

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