Experimental Study On Blast Brain Injury In Beagle Dogs Caused By Explosion In Warship Multiple Cabins

ObjectiveTo establish an animal model of craniocerebral blast injury of Beagle dogs by simulating the condition of multiple cabins explosion in warship.Then to check in the beagle dogs of the neurological function score,serology,brain imaging and immunohistochemistry and other aspects after the blast injuries.To investigate the characteristics of craniocerebral blast injuries in the Beagle dogs by explosion shock wave and quasi-static pressure in the multiple cabins.And provide experimental and theoretical basis for further study of the human brain blast injury.MethodsA total of 24 Beagle dogs were randomly divided into 2 groups,with 12 dogs in each group,and the Beagle dogs of 2 groups were tested in the multiple cabins with the same size of the real warship.A 0.65 kg TNT equivalent bare explosive which equals the 76 mm caliber artillery shell was blasted in the cabins,which was defined as the target cabin(Ⅰgroup),and the neighbouring one was defined as the adjacent cabin(Ⅱ group).The animals were fixed on the cabinet models in the cabins,and to simulate the crews in the operation of equipments were suffering blast injuries.Physical parameters of shock waves were measured using pressure transducers.The micro-pressure transducers were used to measure the intracranial shock wave pressures in the Beagle dogs.The survival status of dogs,basic vital signs,neurological function scores,serology,brain imaging,the changes of the general morphology of the brains and the immunohistochemistry of the brains were observed at the different time points before and after the explosion.ResultsAfter the explosion,the shock waves were reflected by the bulkheads and cabinets and other objects.There were twice reflected shock waves after the explosion in the cabins,and the peak pressures of the second reflected shock waves were about 0.46 times of the peak pressures of the first reflected shock waves.The peak pressures of the shock waves in the adjacent cabin were about 0.39 times of the target cabin pressures.After the explosion,the intracranial pressure of the shock waves of the dogs in the cabin and the adjacent compartment increased significantly,the pressure increased to 2.1~57 KPa.The peak pressures were attenuated more than 90% after the shock wave through the skulls of Beagle dogs.There were seven Beagle dogs died instantly after the explosion,and four died within 24 hours.The mortality rate of the dogs was 45.83 %(11/24),with that in the target cabin being 66.67%(8/12)and that in the adjacent cabin being 25.0%(3/12).The basic vital signs of the survival Beagle dogs had obvious changes on the first moments after the explosion.And the basic vital signs were still poor at the 3h after the explosion,and the neurological function scores were also poor;but which basically recovered after 24 hours.The levels of serum IL-8,Tau and NSE in the surviving Beagle dogs were significantly higher than those of normal at the 3h and 24 h after the explosion.The levels of Tau and NSE decreased at 24 h after the explosion,indicating that the dogs had brain injuries after the explosion,the cascade of inflammations occurred gradually and sustained.But with prolonged the observation time,in the animal’s stress response and self-regulation,the injuries were stable.There was no abnormality in the brain CT of the surviving Beagle dogs.The Beagle dogs immediately died after the explosion had fractures of the skulls and obvious brain tissue contusions,and cerebral hemorrhage and cerebral edema were found in the dogs died within 24 hours after explosion.The damage of the brain morphology and neuronal structural of the dogs immediately died after explosion was not obvious,with that of the dogs died within 24 h after the explosion being obvious,and gradually increased.The degree of damage of the brain morphology and neuronal structural of the surviving dogs was light.The expression of IL-6 was up-regulated after the craniocerebral blast injury in Beagle dogs.ConclusionIn multiple cabins explosion,the peak pressure of the shock waves in the target cabin is significantly higher than that in the adjacent cabin.There are twice reflected shock waves in the cabins,which increases the damage to the dogs.The peak pressure of the shock waves is significantly reduced through the skulls of the Beagle dogs.The mortality rate of the Beagle dogs in the target cabin is higher than that in adjacent cabin.The acute injuries of the Beagle dogs immediately after the explosion are the most serious ones,and the basic vital signs and neurological function scores are worst,but there is a certain degree of recovery after 24 h.The inflammatory indexes and the emergence of cell damages of the survival Beagle dogs are most obviously at the 3h after the explosion,and increase gradually,and tend to stable in 24 h.