Doctoral Dissertations

Date of Award

5-1996

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Electrical Engineering

Major Professor

Paul Benjamin Crilly

Committee Members

Don Bouldin, Danieal Koch, Bill Holls

Abstract

Currently, the invasive scalp electrode and Doppler ultrasound (DUS) have proved to be reliable techniques for monitoring fetal status via heart rate (HR). However, these methods have various limitations. The invasive scalp electrode has risk factors and a monitoring window that only occurs around delivery time because of the requirement of ruptured fetal membranes. Both techniques, particularly the DUS, cannot be used to acquire fetal electrophysiological information. A non-invasive fetal electrocardiogram (FECG) has potential to convey fetal HR and electrophysiological information for many gestational ages. From the above information, certain conditions of the fetus such as stress, acidosis, and uterine activity from the abdominal electromyographic signal can be determined along with other clinical information.

Research in the area of non-invasive FECG monitoring was first reported by Cremer in 1906. In the last 90 years, many advances have been made. However, only one commercial monitor (Hewlett Packard 8040) currently exists. The lack of commercial monitors is directly related to the inability to acquire an abdominal electrocardiogram (AECG) for a variety of patients that has a clinically useful FECG. Clinical information cannot be determined because the AECG's FECG has a poor signal-to-noise ratio (SNR). Therefore, much signal processing has to be done before a clinically applicable FECG can be obtained. Signal processing embodies abdominal maternal electrocardiogram (MECG) cancellation and FECG SNR enhancement. This study focuses on developing the CH2 (Crilly - advisor, Holls - second inventor, and Horner - first inventor) algorithm for suppressing the abdominal MECG and ascertaining its effectiveness. Effectiveness determination will be done with synthesized and clinical data along with comparing the CH2 method to eight previous publications. Synthesized and clinical data from 14 patients produced promising results. Furthermore, the CH2 technique for abdominal MECG cancellation had more favorable quantitative effectiveness marks than the eight previous publications studied. The results from synthesized and clinical data and the eight comparisons indicate that the CH2 technique is a stable and flexible method for abdominal MECG cancellation. Thus, the CH2 algorithm would be a good method to combine with an FECG SNR enhancement technique to obtain a non-invasive FECG.

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