Experimental Study Of Spinal Cord Injury Form Gunshot In Hot And Humid Environment

The number of the spinal cord injury (SCI) from gunshot in the modern times wars accounted for 0.3-4.6%.In USA, the number of the SCI from gunshot constitutes 13-17% total number of spinal cord injury. SCI from gunshot is characterized by emergency, high disability rate and mortality. When people live in the hot and humid environment, especially in military fight and long-time high intensity work, the body has great heat production, eccrine sweat glands evaporation difficulty and accepts large apposition heat, which results in body heat disequilibrium, water-electrolyte metabolism disturbance and blood circulation collapse, and finally causes body temperature raise, metabolic rate increase, body fluid loss and internal environment chaos. When combined with spinal cord firearm wound。Spinal cord tissue pathological lesion becomes more severe and aggravates internal environment turbulence and importance organs'loading and damage including bleeding, cell hurt, brain edema and nerve endocrine system change, which fastens the development of the illness. The study of SCI from gunshot under hot and humid environment have important significance to the patient treatment in the South war zone in the future, in the Taiwan Strait crisis, South China Sea territory guard, as well as the working and living crowd in the district.Objective1. To establish the porcine satisfy models of spinal cord injury to thoracolumbar from gunshot.2. To study vital sign and pathology of lung in the hot and humid environment of SCI from gunshot.3. To investigate the pathological and histological change in the damaged spinal cord.Methods1. To establish the porcine satisfy models of spinal cord injury to thoracolumbar from gunshot in Drugged and waking state.2. To study vital sign and pathology of lung in the hot and humid environment of SCI from gunshot.3. To investigate the pathological and histological change in the damaged spinal cord (GFAF,NSE,S-100 protein and CD34).Results1. Drugs groups and waking group (1)Mean artery blood pressure (MAP):Both MAP level of two groups decreased progressively, but the level of drugs'get more in the 6th hour.(2) Mean heart rate (HR):Both HR level of two groups increased progressively, but the level of hot and drugs'get more in the 6th hour.(3) Rectal temperature:Mean rectal temperature level of drugs'increased.at the level of 2℃in the 2th hour.(4) PaO2 and PaC02:Both PaO2 level of two group decreased progressively, but level of two decreased in two hour because of hyperventilation, and increased after 2th hour。2,vital sign and respire function in the hot and humid environment(1)Mean artery blood pressure (MAP):Both MAP level of two groups' decreased progressively(P<0.05) after gunshot.The difference between pre-injuries'and post-injuries' in control group at 4th hour after gunshot and groups H occurred just after gunshot at every observational time.(2) Mean heart rate (HR):Both HR level of two groups increased progressively after gunshot at every observational time (P＜0.05), and the level of H group's get more at every observational time (P＜0.05)(3) Rectal temperature:Mean rectal temperature level of control changed little after gunshot, otherwise the level of H group's increased.at the level of 2.4℃at the 6th hour.(4) PaO2 and PaC02:Both of two groups'PaO2 level decreased progressively after gunshot, and the H group's got more obviously (P<0.05).The PaC02 of H group's decreased progressively after gunshot, but level of control group's decreased in two hour because of hyperventilation, and increased after 2th hour。(5) There were obvious spotty and patchy bleeding areas in lungs in two group's, especially in H group. Disappearance of alveolar structure, dissolution and degeneration of alveolar epithelial, infiltration of inflammatory cell, patchy bleeding, degeneration and shedding of Bronchial epithelial, substances from hemorrhage and secretions in lumen were all pronounced under Microscope in H group compared with extensive alveolar interstitial vascular congestion with alveolar cavity in different sizes accompanied by less bleeding and inflammatory cell infiltration and mild Bronchial expansion in control group。3 Controlled studies of pathological changes in spinal cord with injury in hot and humid group and control group(1) Optical microscopy:notable expansion of the spinal dural vascular obvious subdural hematoma, partial tear of the arachnoid, exposion of white matter, loosening and swelling of tissue structure, expansion of small blood vessels accompanied by scattered mononuclear cell infiltration were all observed in both groups. Fibrosis were main pathological finding in white matter axis without severe lesion., Degeneration of neurons and disappearance of some Nissl bodies were observed in gray matter. Neuron dissolution with irregular shape appeared in severe conditions. Extensive bleeding appeared in some specimens. Disappearance of normal structure was relatively obvious in tissues near the central canal of the spinal cord in high temperature and humidity group.(2) Electron microscope examination:Enlargement of nuclei in varying degrees and cavity formation in some part of the chromatin margination, mild to severe edema in mitochondrial, increased lysosomes, were all seen in both groups. Mitochondria apparently disappeared with thicken, twisted, loose, ruptured and irregularly layered myelin lamellar structure. Gap formed between axon and myelin sheath due to edema. Axon swelled with some axoplasm overflowed. Edema, intramedullary hemorrhage, necrosis and inflammatory cell infiltration were obvious. These findings were significantly obvious in high temperature and humidity group than in room temperature group.(3) The Nissl bodies:There were reduction in the number of Nissl body with pale staining in both groups which was significant in control group than H group(4) NSE:Expression was reduced significantly in H group than in control group。(5) GFAP:expression was reduced significantly in H group than in control group.(6) S-100:expression was reduced significantly in H group than in control group.(7) CD34:Positive markers were seen scattered in both groups. The number of vessels was significantly small in a single field of vision in H group than in control group.Conclusion1. It was good for pig to survive longer and get less influence in wake. 2.Spinal cord injury from gunshot in the hot and humid environment, the body has great heat production, eccrine sweat glands evaporation difficulty and accepts large apposition heat, which results in body heat disequilibrium, water-electrolyte metabolism disturbance and blood circulation collapse, and finally causes body temperature raise, metabolic rate increase, body fluid loss and internal environment chaos. It woud do more imparement to the pulmonary function and spinal cord injury.