Instrumentation design for high-voltage electrical injury studies.
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Animals↗
Biomedical subjects
M Chilbert
Publications and source records attributed to M Chilbert.
A new technique for subchoroidal implantation of experimental malignant melanoma.
A new technique for implanting Greene hamster amelanotic melanoma cells into the rabbit eye is described. The technique involves the deposition of a tumor fragment into the subchoroidal space via a transvitreal approach. Thirty rabbit eyes were implanted with 26 successful tumor growths producing solitary choroidal nodules. This technique offers the advantages of rapid implantation, the ability to precisely choose the site of implantation including posterior sites, and eliminates the need for a large scleral incision.
Animals↗
Measure of tissue resistivity in experimental electrical burns.
Studies were conducted in 14 mongrel dogs to compare resistivities in normal muscle with those from muscle subjected to electrical burns. One-ampere, 60-Hz currents were passed between the hind limbs of the dogs producing injury in three measurement regions of the gracilis muscle. Histology, heart rate, body temperature, arterial and pulmonary artery pressure, cardiac output, hematocrit, leukocyte counts, fibrinogen levels, and platelet levels were determined. Muscle resistivity associated with severe tissue necrosis was 70% lower than control values. Resistivity in tissue showing edema and minimal necrosis decreased 20 to 40% from control values. Muscle showing only edema had a 10 to 30% decrease in resistivity.
Animals↗
Current pathways in high-voltage injuries.
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Animals↗
Compression injuries of the cervical spine: a biomechanical analysis.
Three intact cadavers and 10 isolated cervical spinal columns underwent compression, with forces directed vertically, forward, or rearward. Failure modes were often different than force directions. The loads required to produce bony injury or ligamentous disruption ranged from 645 to 7439 N. Flexion and extension injuries were produced at approximately 50% of the loads required for axial compression failures. The direction of force delivery correlated only partially with the resulting pathological condition. Clinical decisions based on retrospective analysis of roentgenograms may not account for the variability of forces and the prominence of ligament injuries seen in spinal trauma. Some of the difficulties encountered in biomechanical analyses of spinal trauma are discussed.
Accidents, Traffic↗
Experimental electrical injury studies.
Voltages from 10 to 14,000 volts demonstrated currents up to 70 amperes with resistances of approximately 200 ohms in studies in hogs. Below 1,000 volts, a current reduction is observed following arcing and skin necrosis. At the higher voltages, this phenomenon was not observed. The energy required for tissue damage was dependent upon the voltage and time of application. The tissue electrode resistance with stainless steel disc was proportional to the diameter. Skin buring commenced at the periphery of the electrodes and moved inwards. For application of currents between the hindlimbs of the hog, the current per tissue cross-section was greatest in artery and nerve, followed by muscle, fat, bone marrow, and bone cortex.
Animals↗
Determination of tissue viability in experimental electrical injuries.
Electrical burns or ischemia (induced by vascular ligation) were produced in the legs of 15 anesthetized dogs to study evolution of tissue changes compared with impedance alterations. After the application of 1-ampere currents at 60 Hz, animals were monitored from 1 to 4 days. Muscle impendance was measured with frequency sweeping to determine tissue destruction. Nuclear magnetic resonance spectroscopy (phosphorus 31) was used to assess metabolic activity, and results were compared to impedance measurements. In burned limbs, 70% reduction in muscle impedance was seen, which corresponds to decreased metabolic activity (absent organic phosphates) and suggests necrosis. Visually viable tissue had impedance decreases of 25% and levels of organic phosphates slightly lower than normal. Relaxation frequencies in dogs with severe burns exceeded 80 kHz; in viable tissue, 30 to 40 kHz (normal: 30 kHz). In ischemic muscle, organic phosphates decreased rapidly (1 to 2 hours); impedance changes evolved more slowly (1 day), but they ultimately reached the same degree of severity. Measurement of impedance may be a valuable adjunct in the evaluation of electrical burns, since significant changes strongly suggest nonviability.
Animals↗