Experimental Researches On The Mechanism Of Compound Injuries Induced By Blast Waves And High Velocity Projetiles In Maxillofacial Regions

Since the world war II, numerous reports have been published on the subject of war injuries from various wars and conflicts throughout the world. Much of those articles were related to the explosive injuries. Today in modern conflicts or wars the explosive ammunitions are widely used, and the incidence of explosive injuries is getting higher. And it is also reported that the explosive injuries more frequently occurred among civilians than before due to the application of explosive devices for the industry, agriculture, and sometimes the terrorism. According to the published papers, the damages or injuries caused by explosion were very serious. The local tissue damages were comprehensive and always combined with multiple organ injuries, mostly with the injury of lung. Blast waves and the high velocity projectiles are accepted as the dominant factors resulting in damage. In addition, the denotation, high temperature and so on are also thought of as the wound factors. Since so many factors are involved in the procedure of explosive injuries, there are still a lot uncertain on the mechanism of wound and the treatment. Among the parts of thebody, maxillofacial region is more susceptible to injuries because of its lack of safeguard or armor. As the anatomical structures and the physiological functions in this region are complex and important, it's necessary to reconstruct the tissue defects and rehabilitate the functions at the early time after injuries for the relief of the suffering.In this study, we intended to establish an animal model of compound injury induced by blast waves and high velocity projectiles in maxillofacial region for further study in this field. And with this kind of model, the mechanism of explosive injury, the injury characteristics were also studied. Four parts were included in this study.Part 1 Establishment of an animal model of compound injury induced by blast waves and high velocity projectiles in maxillofacial region and the study of its characteristicsThe detonators, steel spheres as simulant fragments shot by smooth-bore barrel and synchronizer were used to define the wound model and the maxillofacial regions of dogs were used as targets. The whole system was triggered when shooting. 30 dogs were used in this study and designed to detect the injury effects of the new model at different distances to the explosives. Wounding parameters and the changes of targets after explosion were observed and recorded. In this study, the values of overpressure of blast waves decreased exponentially according to the increasing of distance to the explosive. After wounds, the local traumas of dogs were very serious with extensive tissue damages compounded with injuries of hearts, lungs and brains. The injury was aggravated with the increasing of overpressure and energy absorption. According to the results, conclusions could be drawn that the new wound model can be used for thestudy of explosive injury in maxillofacial region under laboratory conditions, and theexplosive injuries in this regions were characterized by serious tissue damages andmulti-etiology.In addition, the injury severity score (ISS) system were first applied to value theseverity of animals wounds in this study. Results indicated that this system could beused in traumatical experiments of animals to quantify the severity of injurycorresponding to that of the clinical researches.Part 2 Characteristics of compound injuries in maxillofacial regions induced by blast waves and projectiles occurring at different time phasesIn this study, 15 dogs were randomly divided into 3 groups and wounded with the new wound model. In group A, animals were injured first by the projectiles and then by blast waves. In group B, they were wounded by the blast waves and the high velocity projectiles at the same time. And in group C, first blast waves and then projectiles. The time phases were controlled by the synchronizer. Double peak of blast waves in group B were recorded but not found in others. After injury, it was...