Date of Award

Summer 1983

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)


Biomedical Engineering

First Advisor

Jeutter, Dean C.


Impedance cardiographic data measurements made by a standard hand-digitizing method were compared with those made by a new ensemble averaging technique. Five healthy, young males were monitored in the supine and seated positions during rest and two stages of bicycle exercise. We found ensemble averaging to be a valid technique for measuring Hr, Zo, dZ/dtmin, LVET, SV, SVI and HI at rest and during exercise. PET measurements did not show a strong correlation, which implied some discrepancy between the ensemble-average and the digitization measurements of this timing interval. Ensemble averaged impedance measurements of left ventricular volumes and various contractility indices were compared with left ventricular volumes and ejection fraction measured by gated pool radionuclide ventriculography. Concurrent measurements by both techniques were performed on nine coronary artery disease outpatients during supine rest and bicycling exercise. Stroke volume measurements were found to correlate well at rest (r=0.682) and when combined with exercise (r=0.600). EF was found to have a poor negative correlation (r=-0.429) between the two techniques. From these results, it can be concluded that ensemble averaging is a useful signal processing tool when employed with impedance cardiographic data.



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