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Detection of Muscle Tremors and Baseline Sway in an ECG

IP.com Disclosure Number: IPCOM000046640D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bonner, RE: AUTHOR

Abstract

A method is described for processing an electrocardiogram (ECG) waveform to detect the presence of "noise" caused by muscle tremors or baseline sway. Muscle tremors are manifested in an ECG as a waveform with a large number of maxima and minima compared to the ECG waveform. Baseline sway is a relatively low frequency signal of an unpredictable nature, primarily caused by a change in contact resistance between the ECG electrodes and the patient's body. Unfortunately, the frequency content of some muscle tremors and baseline sway substantially overlaps the frequency range of the ECG signal, making standard filtering techniques inadequate. In certain applications it is only necessary to be able to detect the presence of excessive muscle tremors and baseline sway and to signal the technician of their presence.

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Detection of Muscle Tremors and Baseline Sway in an ECG

A method is described for processing an electrocardiogram (ECG) waveform to detect the presence of "noise" caused by muscle tremors or baseline sway. Muscle tremors are manifested in an ECG as a waveform with a large number of maxima and minima compared to the ECG waveform. Baseline sway is a relatively low frequency signal of an unpredictable nature, primarily caused by a change in contact resistance between the ECG electrodes and the patient's body. Unfortunately, the frequency content of some muscle tremors and baseline sway substantially overlaps the frequency range of the ECG signal, making standard filtering techniques inadequate. In certain applications it is only necessary to be able to detect the presence of excessive muscle tremors and baseline sway and to signal the technician of their presence. If A, B, and C are three consecutive sample points in the ECG waveform (with noise), the average of A and C can be used to predict B successfully if the wave is linear over these three points. Therefore, the absolute value of [B - (A+C) / 2 is a measure of nonlinearity.

Since the maximum or minimum is a point of high non-linearity, this function can be used to obtain a rough estimate of the number of the occurrences of a non-linearity. It has been empirically determined that for an ECG sampled at 250 samples per second, muscle tremor is present if the count of the number of times that the value of the expr...