Document Type


Date of Award

Fall 10-31-1994

Degree Name

Master of Science in Electrical Engineering - (M.S.)


Electrical and Computer Engineering

First Advisor

Stanley S. Reisman

Second Advisor

Peter Engler

Third Advisor

Thomas W. Findley


Heart rate variability is a result of variation in the activity of the sympathetic and parasympathetic nervous systems. Methods have been developed to determine the level of parasympathetic activity by observing the heart rate variability spectrum. Most of the previously published research uses only level of parasympathetic activity and respiratory rate to draw conclusions about the interactions of the autonomic nervous system with physiological parameters. In order to gain a complete understanding of the autonomic nervous system and the mechanisms responsible for heart rate variability, respiratory volume, cardiac variables and pulmonary variables need to be considered. In addition, amount of sympathetic activity needs to be quantified.

The results of the present study demonstrate that many relationships and interactions exist between the physiological and autonomic parameters. The data indicate that heart rate and overall parasympathetic activity decreases as respiratory volume increases. Statistical analysis has demonstrated that parasympathetic activity, respiratory rate and volume are influenced by and related to respiratory variables such as VO2 I/min. and end tidal CO2. Methods to relate and compare sympathetic influences when subjects change their level of activity are suggested and developed. It is demonstrated that changes in sympathetic influence can be qualitatively determined by comparing changes in HR and parasympathetic activity.

In this research, the experimental protocol was too lengthy to be executed in one day. Therefore, methods to compare data acquired on different days were developed.