Date of Award
Spring 1983
Document Type
Dissertation - Restricted
Degree Name
Doctor of Philosophy (PhD)
Department
Electrical and Computer Engineering
Abstract
The study of current distribution in the experimental animal was performed to relate clinical sequelae to current density in electrical injury. Studies of tissue resistivity were conducted to characterize the electrical properties of the tissue and to determine the cause of change in resistivity. Post-mortem resistivity was shown to increase within the first five hours after death, then to decrease by one day. The increase was due to temperature change and degradation of the tissue. Resistivity changes following electrical burn injury of muscle were noted and compared to histologic alterations. Clincial [sic] parameters were monitored in these studies for determination of burn severity. Electrically-produced thermal injury is dependent on the current density, resistivity and the length of time the current is flowing. Current density was measured in the tissues of the hindlimb, various organs, and the spinal cord. The current density was greatest in the hindlimb due to its small cross-section. In this region, the current density was greatest in the nerves and arteries; however, the greatest amount of current flowed through the muscle. The current distribution in the thorax and abdomen favored the spinal region when the current passed from hindlimb to forelimb. The current flowing through the spinal cord is about one percent of the total applied current, while the cord's cross-section is 0.2% of the total body cross-section. Thermal injury induced in the limb was generated with one ampere of current at 500 volts, applied for 7-20 minutes. The temperature increased to approximately 60°C in the measurement region. With ten amperes at 2000 volts, applied forelimb to hindlimb, spinal cord temperature increased 1.5°C in 30 seconds. Temperatures of 50°C block the evoked response of the peripheral nerve. Current densities of 20 mA/cm2 also block the evoked response, however recovery of the response occurs.