Fibrillation induced at powerline current levels

Electrical fibrillation of the human heart results in many unfortunate deaths. Because little information is available on short duration high current fibrillation, current levels below 1 and 50 A were used to induce ventricular fibrillation in hogs. Application times ranged between 16 ms and 3 s. Fibrillation was only produced when currents were applied during the T-wave period of the cardiac cycle. However, only 50 percent of the current application during the T-wave caused fibrillation. The total body resistance of the hogs was also measured at the high voltages and currents. The average resistance for 90 current applications was 284 omega. Trends in the data show that the total resistance decreases for increasing voltage, for increasing electrode size, and for current applications following the first current application.     

Current Pathways in High-Voltage Injuries

Studies were done in the hog with limb-to-limb contacts at potentials up to 2000 V. The current density in nerve, vessels, muscle, bone, fat, lungs, heart, kidney, liver, intestines, and spinal cord were determined. The current densities in the leg are largest in nerve and artery, followed by muscle, fat, and bone. The temperature was greatest in fat and nerve. With forelimb-to-hindlimb current application, the current densities were largest in the back region. The spinal cord current density was approximately twice the average cross-sectional value.     

Instrumentation design for high-voltage electrical injury studies

The experimental study of high-power electrical injuries requires special devices to protect personnel and data recording instruments. A power distribution system is described which was designed to apply 500-20000 V and currents up to 100 A to an experimental preparation and a measurement system for recording 0.02-200.0 V at local sites in the preparation. Data collection and storage are automated with analog and digital devices that minimize personnel contact. For personnel safety, all recording instruments are isolated from the power distribution system by battery-driven standby power supplies and from the experimental high voltages by fiber optic data links. Current-triggering and- interruption mechanisms allow variable-duration voltage applications as short as 25 ms. These applications are also synchronized to the electrocardiogram and can be made to occur during any part of the cardiac cycle