The Characteristics And Interventions Study Of The Blast Injury At High Altitude And Under Water

Explosion wave spreads through the mediator(namely air , water , soil, rock, steel et al). According to the different mediator, blast injury can be divided into air blast injury, underwater blast injury and solid blast injury. In different density of the mediator ,there is visible effect on spread velocity of blast wave and traumatic condition of blast injury. Usually, the higher density, faster and father the spread velocity of the blast wave propagates and more severity of the blast injury will be.The blast injury at special environment mainly includes the blast injury at high attitude , underwater and in an enclosed space(namely tank , armored vehicle, cabin, et al). Blast injury at high attitude occurs at the region of 3000 meters height above sea level. There are scarce air, low barometric pressure and low partial pressure of oxygen. Comparing with the area of sea level, there are only 65% atmosphere density and 61% barometric pressure and partial oxygen pressure in the region of height above sea level 4000 meters. What influence on the characteristics of the blast injury in high attitude environment is still unknown by now . The density of water is 800 times as that of air. Because water is less compressible, an underwater blast wave propagates at high speeds and loses energy less quickly over longer distances. It is estimated that an explosion underwater is approximately three times greater in strength than that which is detonated in the air. The propagating velocity of underwater blast wave is 3～4 times as that of air blast wave. The pressure force is 200 times greater underwater at the same distance from the explosion when TNT of the same quantity exploses under water and in the air. So study emphasis on exploring the characteristics and interventions of the blast injury in special environment (the blast injury at high attitude and underwater blast injury ) with regard to region conflict hot spot area.The present study systemically observed the characteristics and interventions of the blast injury at high attitude and underwater from general, cellular and molecular level based on duplicating the rat blast injury at different attitude and the dog and rabbit underwater blast injury. The main results of the present report are as following:1. The lung was still the main injured target orgen in blast injury at high attitude. The blast injury at high attitude had the characteristics of more severity, fast developing and high mortality . Furthermore, the severity of injuries was increased with rising of the attitude . the most common injury to the lung was hemorrhage and edema, which are 1～3 degree more in severity .than that of the blast injury at plain. When the blast injury occurred at 390meters , 3500meters level ,4000 meters level and 5000 meters level, incidence of severe and very severe hemorrhage of the lung was 16.7%, 43.3%, 60.0%, and 73.3% , respectively, incidence of severe and very severe edema of the lung was 6.6%,13.3%,33.3% and 40.0% ,respectively ; the mortality was 0%, 0%, 20% and 40% respectively; And the mortality occured in 3 hours after injury.2. After blast injury at high attitude(4000 meters) , IL-6,IL-10,TNF-a of the lung tissue were all remarkably increased. The expression of HO-1 mRNA was increased, too. The total protein of the bronchoalveolar lavage fluid was remarkably increased . Arterial oxygen tension (PaO₂)was remarkably decreased .These indicate that the cytokines mentioned above and HO-1 may play an important role in the occurance and development of the blast injury at high attitude .3. The hemin, inductor of HO-1and dexamethason were used to treat the high attitude blast injuried rats. The result showed that they could increase the level of IL-10 of the lung , HO-1 expression and arterial oxygen tension (PaO₂). decrease the level of IL-6 and TNF-a and the total protein of the bronchoalveolar lavage fluid ; All these indicate that the treatment mentioned above could relieve the inflammatory reaction of the lung, which could be protective for the organism to some degree though they had limited effect on very severe blast injury .4. The characteristics of underwater blast injury were explored systemically. The lung was still the main target orgen. Underwater blast injury had the characteristics of high incidence of lung and intestinal tract injuries , low incidence to fluid-filled organs injuries(namely the bladder, the cholecystis, et al), little effect on solid organs(namely the liver ,the spleen ,et al), more typical appearance of light injury outside and severe injury inside, more severity and high mortality(31.58%)et al.5. The warning markers were recommended. It should indicate the severity of the injury when distress of respiratory, brady cardia , no rising or no obvious rising after temperature drop after underwater blast injury appeard. This may be importance to classify and treat the underwater blast injuried patients .6. rewarming, dexamethasone and anisodamine were used to treat the underwater blast injury , respectively. The results showed that all of these could improve pulmonment function , vital sign and prognostic。Among these , combining of these factors had better intervention effects.