| BackgroundHigh-speed projectiles can cause damage to organs of distant parts outside trajectory, this indirect damages include transient and secondary damage in time, mainly caused by as far as effects of gunshot wounds and the body stress response. Although there has a lot of studies about mechanisms and imaging of indirect injury, However, whether consistent on distant organ damage degree caused by different degrees gunshot wound; there is rarely study about the time features of progress changes in distant organ indirect injury, and the factors analysis of the early injury and cardiac function and the image of morphological changes after gunshot wounds. Studies have shown that CT can accurately display pathological features of lung indirect injury induced by the limbs gunshot wounds, and the evaluation advantages of heart function and morphology scan with 64-slice CT. In this study, we produce different injury models of gunshot wounds in the pig hind limbs, and observe morphology of cardiopulmonary indirect injury for multiple time points in the early by 64-slice CT, also analysis inflammatory response indicators (body temperature, WBC count, IL-6) and vasoactive substances (AngⅠ, AngⅡ, ET) , this may provide experimental evidence to clarify the laws of occurrence and evolution of distant organ injury caused by the gunshot wounds.ObjectivesTo study VCT performance laws at different time points and characteristics of coronary artery injury before and after lung indirect injury caused by pig lower limbs different gunshot wounds. We detect inflammatory indicators (body temperature, WBC, IL-6) and vasoactive substances (AngⅠ, AngⅡ, ET). And investigate mechanisms of cardiopulmonary indirect injury caused by lower limbs gunshot wounds, provide references for the early comprehensive treatment of woundeds with limbs gunshot wounds in peacetime and wartime.Methods14 Plain pigs were offered by Experimental Animal Center of Fourth Military Medical University, Female pigs, 5-7 months, 35-45kg. Under effectively fixed, with 81-1 semi-automatic rifle made in China, 7.62mm bullets. Pigs were divided into minor injury group (M) and seriously injured group(S) in according to injury degree. Minor injury group (M): bullets trajectory passed through the hind limb soft tissue, not directly damaged the femoral vein trunk; Seriously injured group(S): bullets trajectory passed through the hind femur, causing fractures. Two groups were enhanced scan chest lungs were scanned, at the same time, scanned coronary artery VCT at M group, 0.625mm thickness, 0.625mm layers, 120kV voltage, 450-550mA current. Axial images were reconstructed according to bone algorithm and the standard algorithm, 5mm thickness, 0mm spacing, window level 40HU with measurement, bandwidth 350HU; and coronary arteries were reconstructioned at 5mm thickness, 0mm spacing. Respectively taken pig ear edge vein blood before shooting and transient, 10min, 40min, 6h after shooting, and detectted the total number of WBC in peripheral blood leukocytes, IL-6, plasma ET, AngⅠ,AngⅡand VCT scan. The animals were killed, and instantly taken heart and lung tissue for pathological examination.Results1. The results showed that the frequency of abnormal CT signs of S group were more than M group at instantaneous trauma. At instantaneous trauma, pigs lung indirect injury mainly showed effusion, consolidation and hemorrhage of lung parenchyma, and pulmonary interstitial exudation, 10 min after injury, appeared pleural effusion, bronchiolitis, and in addition to the above consolidation in the lung parenchyma, the other injuries were more serious than at instantaneous trauma. The occurrence of pulmonary interstitial exudation, bronchiolitis were significantly higher than the instantaneous (P<0.05), but there was no significant difference between S and M groups; The incidence of pleural effusion at S group, compared with M group, was significantly increased (P<0.05). 40 min after injury, a variety of lung injuries developed and increased, in which the incidence of bronchiolitis, S group was significantly higher than M group (P<0.05). 6h after injury, damages of lung parenchymal and pulmonary interstitial were further increased, the incidence of exudation, consolidation, pleural effusion and pulmonary interstitial exudation at S group was higher than M group (P<0.05).2. Pigs rectal temperature did not change significantly within 40min after injury, However, 6h after injury, the body temperature rised 1℃than before shot, rectal temperature trends of M group and S group were consistent, but there was no difference between groups. The total number of peripheral WBC decreased after shot, but the total number of peripheral WBC at each time point after shot was no significant difference at M group, 6h after shot, the total number of peripheral WBC of S group significantly decreased than before shot (P <0.05). The total number of peripheral WBC at each time point after shot of S group and M group was no significant difference. IL-6 increased after shot, 10min after shot, IL-6 of S group and M group significantly increased than before shot (P <0.05). In addition, the IL-6 levels of S group at 40min and 6h after shot significantly increased than M group (P <0.05).3. There was a common trend phenomenon at IL-6 levels and the development of lung indirect injury in M group and S group. 10 min after injury, with the levels of IL-6 increased, the of degree lung indirect injury of two groups animals in different injury degree significantly increased. 40min and 6h after injury, development of exudation, consolidation and bronchiolitis remain the same upward trend with IL-6 levels, the development area of bleeding and pulmonary interstitial leakage did not change significantly.4. Bilateral coronary artery diameter reduced after shot, diameter was the minimum at 10min (P>0.05). Although changes of trunk diameter of coronary artery were no statistically significant, the trends of change and changes in biochemical indicators was consistent.5. AngⅠlevels before shot compared with the other four time points significantly changed (P<0.05), there was significant change at 5min after injury and 40min after injury (P<0.05), with linear graph, AngⅠhas gradually approached the levels before shot at 40min after injury; AngⅡin shot after shot before a statistically significant difference in 10min(P<0.05); ET levels significantly changed before shot and the shooting transient, 5min and 10min after injury, between the shooting transient and 40min after injury, between 5min and 10min after injury, there was a significant change (P<0.05), with linear graph, ET has basically restored the levels before shot at 40min after injury.Conclusion1. Instantaneous lung injury after gunshot wounds and degree of gunshot wounds was consistent.2. Lung injury gradually increased after wounds, development trends and change trends of stress inflammation indicators was consistent.3. Moment of gunshot wounds in the pig hind limbs, under stress response and the influence of blood flow disturbances, caused damage of vascular endothelial, and induced coronary artery spasm.4. The smallest diameter of coronary artery and the highest concentration values of AngⅡand ET was basically consistent in time. This suggested that AngⅡand ET played an important role in remote effect on coronary artery.5. There were strict requirements to heart rate and respiratory rate when scanning coronary artery with 64-slice CT, early diagnosis of cardiac remote effect damage has some limitations. With the use of 256-slice CT, 320-slice CT and cardiac dual-source CT, we expect to obtain more satisfactory results in continuously supplement and improvement of the latter experiment. |
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