Study On Characteristic And Mechanism Of Rats' Craniocerebral Injury By Explosion In Closed Space

Background and objective:Incidence of explosion injury is high now in the war and peace time. As the brain tissue is not the target organ of blast wave, our remedy focused on the injury of body surface, lung, gastrointestinal tract, auditory organ and so on previously. It is reported that explosion induced high rate of craniocerebral injury, but blast craniocerebral injury is often ignored. It's difficult to diagnose and treat craniocerebral injury by explosion in closed space precisely for the reasons of researches on this area is limited at present. The topic intends to establish a model to study characteristic and mechanism of the state of injury by explosion in closed space in it's early stage and the blast pressure to provide rationale for pre- protection,fast diagnose and treatment of this kind of injury.Methods:1. The rats model establishment:56 SD male adult rats were divided into two groups randomly which were inner 400mg TNT detonator explosion group and pre-injury normal control group. Exposion groups were vulnerated in a simulation of armed vehicle.In the experiment we tested physico-parameter of blast wave,observed general state of health of rats,death rate,brain moisture, pathology of brain and lung after explosion.2. The characteristic of craniocerebral injury by explosion in closed space: 218 SD male adult rats were divided into six groups randomly which were inner 200mg group,inner 400mg group,inner 600mg group and outer 400mg group,outer 600mg group exploded by coresponding TNT detonator and pre-injury normal control group. Inner groups were vulnerated by the same way of model while outer groups at open space in the same distance. In the experiment we observed general state of health of rats, death rate, brain moisture, recorded HR, MAP, LVSP at 6h after injury, took the blood samples at 1h, 3h, 6h, 12h, 24h, 72h after injury and studied S100B, NSE, BNP in the plasma by ELISA, detected nerve cell apoptosis at 24h after injury by immunostaining. Brain tissue were analyzed by wet - dry weight measurements and the microscope.Results:1. The model of blast injury in closed space: rats'breath became slower and deeper right after injury and then turned fast gradually. No rats died. All rats got back consciousness, free-running, taking food and water in three hours after injury. Reactions of rats after explosion were torporer than control rats. There was subarachnoid hemorrhage on the surface of brain and pneumonorrhagia was manifest. Brain moisture of explosion kept increasing with the prolongation of injured time and reached the maximum level at 6h after injury. Then it decreased gradually but still higher than the control group at 72h.2. The characteristic of explosion injury in closed space: There appeared vascular engorgement in brain mantle and subarachnoid hemorrhage and brain edema in explosion group. Pulmonary parenchyma injury and pneumonorrhagia were obvious and positive correlation with valent weight of explosion.There existed cardiac muscle fibers breakage. S100B, NSE and BNP in the plasma increased obviously after injury, and their high-peak directly correlate with valent weight of explosion. Under coordination valent weight the indicatrix of closed space explosion were much higher than open space. Nerve cell apoptosis was manifest. HR,MAP and LVSP of rats changed at different degree after injury。Conclusions:1. The steady model of craniocerebral injury by explosion in closed space is established.2. The wave shape and parameter of blast wave is different between open and closed space.3. The explosion shock induces obvious craniocerebral injury both in open and closed space.4. The traumatic condition after explosion in closed space is much more serious than open space and is directly correlate with valent weight of explosion.5. The characteristic of craniocerebral injury by explosion in closed space:①brain edema appeared in early stage and its duration is correlation closely with detonation quivalen;②SAH is widespread on the surface of cerebral hemisphere,basalis haematocele exists on heavy injured rats;③nerve cell apoptosis is obvious;④bio-chemical markers of brain injury increases predominantly。6. The explosion usually induce multiple injury especially in lung and cardiac function changes at different degree。7. It's important to strengthen the protection and early remedy of blast craniocerebral injury.