Characteristics And Mechanisms Of Mine-blasts Wounds In Shoals

BackgroundIn the amphibious landings, enemy will laid large number of mines in shoals. Resultingin many casualties, so we must realize the characteristics of mine-blast wounds in shoals,and taken into account while performing evacuation, diagnostic and medical measures insuch patients.Mines were always set underwater. Due to the density of water is different from the air,the peak value and duration time of blast wave after the mine blast in water were differentfrom that in the air. The injury characteristics and mechanisms caused by mine blasts inshoals might be different compared with that on the land.We studied the characteristics and mechanism base on the experimental model ofmine-blast in shoals. To understand the damage characteristics in the different depth ofwater, and research the mechanics mechanisms, provide guidance for evacuation, therapyand protection.PurposesThe purpose of this subject was to investigate the characteristics and mechanisms ofextremity and organs injury caused by mine blasts in shoals, and provide theoretical basisfor treatment and protection.Materials and methodsThe experiment was implemented in the central of a pool. The forelimbs ofanesthetized animals were fixed to a special metal holder, adjusted the height of the metalholder, make sure the double hindpaws stood on the ground. The fore-and-aft clearance ofthe bilateral hindpaws was11cm, and the space between the left and right hindpaws was9cm. In order to simulate the damage effect caused by anti-personnel mines, rabbits weighing2.19±0.12kg (range of2.00-2.40kg) were used, and the600mg RDX paper electricdetonators were used to simulate mines and they were placed under the rabbit’s right foot and ignited electronically. The water was maintained at20±2°C, and the room temperaturewas maintained at22±2°C. All wounds were sutured and bandaged immediately for allrabbits after the detonation. In the shoal1group, the water height reached the midpoint ofthe thigh in the shoal1group. In the shoal2group, the water came up to the rabbit’s xiphoidprocess. In the land group, the water in the pool was extracted, and the ground was coveredwith sandy soil. Sham group simulated the shoal group without detonation. To investigatethe damage characteristics and mechanisms after blast.Research contents1. Characteristics and mechanisms of extremity injuries due to mine blasts in shoals.2. Characteristics and mechanisms of cardiopulmonary and abdominal injury causedby mine blasts in shoals.3. Characteristics of central nervous due to mine blasts in shoals.Results1. The lower third of the calf almost completely destroyed by the mine blasts on land,but only the foot and the ankle were destroyed on the shoal. The bones, arteries and sciaticnerve were more seriously injured in the shoal than on the land.2. Necropsy revealed scattered petechiation and hemorrhaging on the surfaces of thelung lobes in animals from the land group. Pulmonary hemorrhage showed sheet cloudy inshoal1group. However, animals in the shoal2group were observed to have extensivehemorrhaging at the lung boundaries, including the bilateral apex of the lungs, around theheart and above the diaphragm. CT revealed pneumothorax in4animals and rib fractures in3animals. However, no cases of pneumothorax or rib fracture were observed in the landgroup and shoal1group.3. Abdominal viscera not seen obvious abnormity in the land group. In the shaol1group, the incidence of colon contusion after blast was25%, followed by jejunum (18.75%),appendix (12.5%) and ileum(12.5%). The incidence of colon contusion after blast was25%,followed by appendix (12.5%) and ileum12.5%. In the shoal2group, the most seriousdamage viscera was rectum, the incidence was62.5%, and the incidence of rectal rupturewas18.75%. In addition, we found12.5%animals had retroperitoneal hematoma.4. The characteristics of spinal cord injury showed as subarachnoid hemorrhage, spinalcord contusion and dotted around nerve root bleeding due to mine blasts in shoals, but no obvious spinal cord injury in the land group. The westen blot showed the GFAP expressionlevels significant increased in shoal1and shoal2group compared with land group. TheMBP and NSE levels in shoal2group were markedly increased at3h、6h、12h comparedwith the land group, but the MBP and NSE levels in shoal2group at3h、6h、12h werenot significant compared with the land group.5. High-speed photography revealed that a bubble of gas formed in the water after theexplosion in the shoal2group, but the gas was directly injected into air in the shoal1group.6. The peak overpressure recorded in each part of the extremity and the peakacceleration recorded in the right femurs of the land group were significantly different fromthose of the shoal1and shoal2groups. The peak overpressure recorded in each part of theextremity in the shoal2group was significantly higher than that of the shoal1group. Thedifferential pressurebetween the thorax and abdomen in the shoal2group was significantly different fromthat in the shoal1group and land group. The peak positive acceleration of the thorax in theshoal2group was significantly differed from that in the shoal1group and land group.Conclusions1. The detonation products and soil dissolved in the water after the explosions on theshoal and thus they caused less disruption of soft tissue than on land. In addition, theincidence of closed fractures of the tibia and femoral shaft was significantly higher after theexplosions on the shoal, because the pressure wave was transmitted with greater intensityand had a more intense shattering effect on the bone. Furthermore, the bilateral thigh tissueat the water-air interface exhibited serious contusions in the shoal1group because theliberation of kinetic energy by the pressure wave. Finally, the incidence of contralateraltibial fractures was significantly higher in shoal2group than in the shoal1group because ofthe different processes for generation of the blast wave at the various water depths.2. Our results indicate that severe cardiopulmonary injury and dysfunction after mineblasts in shoals. We suggest that the mechanisms of cardiopulmonary injury result from theshear waves produce strain at the water-air interface in shoal2group. Another mechanism ofinjury in the shoal2group includes the propagate of the shock wave from the pelma to thethorax, which causes the peak overpressure to be much higher in the enterocoelia than in the thorax; as a result, the abdominal organs and diaphragm rush to the thorax, damaging thelungs and heart.3. The characteristics of spinal cord injury showed as subarachnoid hemorrhage, spinalcord contusion and dotted around nerve root bleeding due to mine blasts in shoals, but noobvious spinal cord injury in the land group. Therefore, spinal cord injury was serious inshoals than on the land.