A dynamic study of the thermal components in electrical injury mechanism for better understanding and management of electric trauma: an animal model

Microtrap electrode devices for single cell trapping and impedance measurement

This paper reports the design and fabrication of electrode microtraps for single cell trapping and impedance measurement. In this work, the microtrap electrodes of parallel and elliptical geometry have been fabricated by electroplating of gold electrodes of optimum thickness. This has enabled the formation of electrode traps without requiring any precision alignment between separate insulating traps like PDMS and the bottom gold electrodes. Further the improved uniformity of the electric field between the trapping electrodes as observed from COVENTORWARE simulation significantly reduces the effect of cell position inside the microwell on the electrical measurement unlike previous reports. This makes it possible to directly extract the equivalent cell parameters from the electrical measurement without introducing any correction factor corresponding to cell position. We have performed impedance spectroscopy with both the microwell electrode structures with single HeLa cell at two different positions of trapping. It has been observed that there is almost no change in the extracted values of cell resistance and capacitance for different positions within parallel electrodes and there is only 0.7 % and 0.85 % change in cell resistance and capacitance for the two positions within elliptical electrodes. Thus these microwell electrode structures can be used as an improved and a more convenient platform for single cell electrical characterization.

QUANTIFICATION AND THE UNDERLYING MECHANISM OF SKIN THERMAL DAMAGE: A REVIEW

Skin thermal damage is the most common thermal trauma in civilian and military communities. Besides, advances in laser, microwave, and similar technologies have led to recent developments of thermal treatments for diseases involving skin tissue aiming at inducing damage precisely within targeted tissue structures without affecting the surrounding healthy tissue. Pain sensation accompanying thermal damage is also a serious problem for burn patients. Therefore, it is of great importance to quantify the thermal damage in skin tissue. In this review, we detail the progress of the state-of-the-art mathematical models and experimental methods for the quantification of thermal damage (both heat damage and cold damage) and the general development of thermal treatments in tissue engineering. This could enable better understanding of the underlying mechanisms of skin thermal damage and the optimization of clinical thermal therapies.

Examination of local and systemic in vivo responses to electrical injury using an electrical burn delivery system

Electrical injuries are devastating and are difficult to manage due to the complexity of the tissue damage and physiological impacts. A paucity of literature exists which describes models for electrical injury. To date, those models have been used primarily to demonstrate thermal and morphological effects at the points of contact. Creating a more representative model for human injury and further elucidating the physics and pathophysiology of this unique form of tissue injury could be helpful in designing stage-appropriate therapy and improving limb salvage. An electrical burn delivery system was developed to accurately and reliably deliver electrical current at varying exposure times. A series of Sprague-Dawley rats were anesthetized and subjected to injury with 1000 V of direct current at incremental exposure times (2-20 seconds). Whole blood and plasma were obtained immediately before shock, immediately postinjury, and then hourly for 3 hours. Laser Doppler images of tissue adjacent to the entrance and exit wounds were obtained at the outlined time points to provide information on tissue perfusion. The electrical exposure was nonlethal in all animals. The size and the depth of contact injury increased in proportion to the exposure times and were reproducible. Skin adjacent to injury (both entrance and exit sites) exhibited marked edema within 30 minutes. In adjacent skin of upper extremity wounds, mean perfusion units increased immediately postinjury and then gradually decreased in proportion to the severity of the injuries. In the lower extremity, this phenomenon was only observed for short contact times, while longer contact times had marked malperfusion throughout. In the plasma, interleukin-10 and vascular endothelial growth factor levels were found to be augmented by injury. Systemic transcriptome analysis revealed promising information about signal networks involved in dermatological, connective tissue, and neurological pathophysiological processes. A reliable and reproducible in vivo model has been developed for characterizing the pathophysiology of high-tension electrical injury. Changes in perfusion were observed near and between entrance and exit wounds that appear consistent with injury severity. Further studies are underway to correlate differential mRNA expression with injury severity.

Computerized image analysis in differentiation of skin lesions caused by electrocution, flame burns, and abrasion

In the practice of forensic science, sometimes, it is not easy to understand whether skin lesion is due to electrocution and to differentiate the thermal burns and abrasion-type lesions, especially when electricity source cannot be revealed by death science investigation. Based on the causes of the lesions, cases were classified into three groups. Group 1 included 30 deaths from electrocution. Group 2 included 30 deaths with flame burns. Group 3 included 30 deaths from traffic accident cases, which had abrasions. In this study, epidermal nuclear area, perimeter, nuclear form factor, nuclear minimum axes, nuclear maximum axes, and minimum axes/maximum axes ratio were measured. As a result, we think that computerized image analysis beside light microscopic examination can be useful in the differentiation of the electrocution, flame burn, and abrasion type lesions.

Establishment of soft-tissue-injury model of high-voltage electrical burn and observation of its pathological changes

A realistic model is very useful in laying the foundation for clinical treatment and further study of high-voltage electrical burns. We therefore established a soft-tissue-injury model of high-voltage electrical burn in rabbits using the highest voltage alternating current reported. Twenty-five healthy big-ear white rabbits were randomly divided into five groups (five in each group): control group (C group) before injury and 0.5-h, 24-h, 48-h and 72-h groups after injury. Except for the control group, the rabbits in the other four groups were anaesthetised with ketamine and the electrodes were placed in their left limbs. Electric shock was administered from a distance of 7 cm at 3000 V output voltage for 0.1s to observe the skin temperature, electric resistance, wound morphology, histological change and to measure the level of muscle viability and serum myocardial enzymes, among others. Instant current application reached 3-5A (mean: 4.1+/-0.8A), and electric shock voltage was fixed at 3000 V. The resistance between the two electrodes in the left limb decreased from between 1500 and 3600 Omega (mean: 2590.3+/-812.9 Omega) to 921.5+/-528.7 Omega after the electric shock. The skin temperature of the control group was 30.1+/-2.5 degrees C, which elevated to 50.3+/-4.5 degrees C after the electric shock. Muscle necrosis occurred progressively 24-72 h after the injury with obvious acute inflammation. Electron microscopic examination revealed a bilaminar sarolemma membrane structure, multiple mitochondria between muscle bundles and disappearance of shortened mitochondrial crista 48 h after injury. Additionally, the muscle viability index decreased gradually to 0.376+/-0.071 72 h after the injury, while in the control group it was 1.354+/-0.117. The skin, arterial walls, and peripheral nerves showed obvious degeneration and necrosis. Moreover, pathological changes were found in vital organs distal to the electric shock sites, such as the heart, liver, lung and kidney, indicating systemic injuries. The level of serum myocardial enzymes was significantly elevated, especially 24h after injury. Thus, electric shock at 3000 V output electric voltage for 0.1s can cause severe, focal, soft-tissue injury and pathological changes in the vital organs such as heart, liver, kidney and lung with the characteristics similar to those of high-voltage-electrical-burn patients.

Hippocampal neuron loss due to electric injury in rats: a stereological study

Electric injury may cause different changes from minimal damage (e.g. small burns) to severe complications up to death. Several morphological changes of the skin and the internal organs are used for the diagnosis of electrical injury. However, macroscopic findings and histological changes of the internal organs and the skin may be absent in many cases. Furthermore, neuropsychological changes including deficits of cognitive functions may be seen in survivor victims. The aim of the present study is to examine whether electric injury causes decreasing in the number of pyramidal neurons in the rat hippocampus and whether this decreasing can be demonstrated by stereological method. The rats were separated into three groups: first group, native control group; second group, the points of electrical contact were on the back skin in this group; third group, the points of electrical contact were on the temporal region in this group. The current was the usual city current (110V, 50Hz, 100A AC). On the third day, the rats were decapitated; the brains were removed, and sectioned horizontally through the hippocampus and samples chosen according to the systematic random sampling strategy. Afterwards the samples were stained by H&E and optical fractionator method, one of the unbiased stereological methods, was used to estimate the total pyramidal neuron number. The results showed that the total number of pyramidal neurons in three subdivision of the hippocampus (CA3-2 and CA1) was 242,141+/-31,167, 193,388+/-24,795 and 187,448+/-28,300 in the first, second and third groups, respectively. The differences between first and second-third groups were statistically significant (p<0.05). There was not any significant difference between the second and the third groups. In conclusion, electrocution causes loss of the pyramidal neuronal in CA3-2 and CA1 subdivisions of the rat hippocampus in this study.

Repeated Thoracic Discharges From a Stun Device

BACKGROUND

Little objective laboratory data are available describing the physiologic effects of stun guns or electromuscular incapacitation (EMI) devices, but increasing morbidity and even deaths are associated with their use. We hypothesized that exposure to EMI discharges in a model animal system would induce clinically significant acidosis and cardiac arrhythmia.

METHODS

Ten Yucatan mini-pigs, six experimental and four sham controls, were anesthetized with ketamine, xylazine, and glycopyrrolate. Experimental pigs were exposed to two 40-second discharges from an EMI device over the left thorax. Electrocardiograms, troponin I, blood gases, and lactate levels were obtained pre-exposure, at 5, 15, 30, 60 minutes, and at 24, 48, and 72 hours postdischarge.

RESULTS

No acute or delayed cardiac arrhythmias were seen. Heart rate was not affected significantly (p>0.05). A subclinical increase in troponin I was seen at 24 hours postdischarge (0.040+/-0.030 ng/mL, p>0.05). Central venous blood pH (7.432+/-0.014) and pCO2 (36.1+/-0.9 mm Hg) were not changed significantly (p>0.05) during the 60-minute postdischarge period. A moderate significant increase in lactate occurred in the 5-minute postdischarge group (4.9+/-0.3 mmol/L, p=0.0179). All blood chemistry and vital signs were normal at 24, 48, and 72 hours postdischarge.

CONCLUSIONS

Although significant changes in some parameters were seen, these changes were small and of little clinical significance. Lengthy EMI exposures did not cause extreme acidosis or cardiac arrhythmias. These findings may differ from those seen with other EMI devices because of the unique MK63 waveform characteristics or to specific characteristics of the model systems.