Automatic assessment of electromyogram quality .
C., Sinderby, L. Lindstr[diaeresis]om, A. E. Grassino.
Department of medicine, Notre Dame Hospital, University of Montreal
and Meakins-Christie Laboratories, McGill University, Montreal,
Quebec, Canada, and Spinal injuries unit, Sahlgrenska Hospital,
G[diaeresis]oteborg, Sweden, and Department of medical information
Processing, Sahlgrenska Hospital, G[diaeresis]oteborg, Sweden
APStracts 2:0286A, 1995.
Power spectrum analysis of the diaphragm electromyogram (EMGdi) is
time consuming and no criteria have been developed to objectively
quantify contamination of the signal. The present work describes a
set of computer algorithms which automatically select EMGdi free of
the electrocardiogram (ECG), and numerically quantify the common
artifacts which affect the EMGdi. The algorithms were tested: 1) on
human EMGdi (n=5) obtained with esophageal electrodes positioned at
the level of the gastro-esophageal junction, 2) on EMGdi obtained in
mongrel dogs (n=5) with intra-muscular electrodes in the costal
diaphragm and 3) on computer simulated power spectrums. For both
authentic and simulated power spectrums, indices were obtained by the
algorithms, and were able to quantify signal disturbances induced by
noise, electrode motion, esophageal peristalsis (in humans) and non
-QRS complex related ECG activity. With the index incusion thresholds
set to levels which allowed for a high signal acceptance rate with
relatively small artifact induced fluctuations (10-15 %) of the EMGdi
center frequency, the computer algorithms were found to be either
equally or more reliable than other methods, including careful visual
selection of the time domain signals by experienced analysts. In
conclusion, the frequency domain application of computer algorithms
offers a reliable and reproducible means to objectively quantify the
sources which contaminate the interference pattern EMG.
Received 16 September 1994; accepted in final form 12 June 1995.
APS Manuscript Number A970-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.