Research On The Characteristic And Mechanism Of Liver When Crush Injury Combined With Hypoxia And Deprivation Of Food And Water

In recent years, natural disasters (earthquakes, landslides, tsunamis, etc.),engineering accidents (such as coal mine collapse) and terrorist attacks (especially theexplosion terrorist attacks) happened frequently, which makes Crush Injury common.Crush Injury can easily cause Crush Syndrome（CS）if it gets no timely treatment[1-2].Crush Injury attracts much attention due to it attacks suddenly and fast and always bewith a high mortality rate (For example, in the WenChuan earthquake in2008, deathrate caused by Crush Syndrome came just after the death that directly caused bysevere trauma, and the death rate of the Crush Syndrome patients reached15.2%,even as high as50%-70%[4]). Crush Injury has been one of the hot spots in thetrauma research field both at home and abroad for it is common caused by buildingcollapse and its damage is characterized by local injury which seems minor while itssystemic secondary pathological changes hidden, which often lead to severe injury insuch remote organs as kidney, heart, lungs, liver until results in traumatic multipleorgan dysfunction syndrome (MODS) and severe injuries.So far, the studies on the crush injury focused on the pathological physicalcharacteristics, damage mechanism and treatment which are generated after the reliefof the crush. What’s more, the build of many animal models of crush injury adoptedheavy pressure, Pneumatic tourniquet extrusion or glycerin muscle injection method.Our previous animal experiments have confirmed that the injury of these compoundCrush Injuries accompanied by the lack of oxygen, food and water is very serious. Inaddition, there will be new features which are different from the simple crush injury.In addition, this study has successfully established and adopted clamps method tobuild the crush injury model for the first time. that is, when the animals are awake,applied the self-made clamps extrusion machines so as to put the extrusion force onthe bottom of the hind limbs of rats.(pressure is4.5±0.3kg), which is closer to the scene of the accident and the clinical practice. What’s more, it has many advantages,such as simplicity, adjustable pressure, and continuous extrusion which could lead tothe damage of parts of the body (such as necrosis, ulceration, dry, peeling, etc.). itmakes it easier for us to study the damage of the remote organs (the pressure can lastfor1-2weeks. The life tolerance can be studied too).As is known to all, There are two ends for the patients who suffered thecompound crush injury when they are buried(especially when buried deep): one kindis the death caused by continuous extrusion for not being rescued, and another issurviving by the treatment after being rescued by forcible entry and mining. Becausethe clinical pathological process, vital signs, especially faint signs of life, changinglaw and its tolerance of life of the former is unknow so far, system testing reportpointed out that " it has not been studied in domestic and at abroad "[13]. although thelatter has been discussed by large number of research reports, they all involved the“general conditions or the biochemical index change after being rescued from thecrush injury and the treatment nursing content "[13]. Under the support from709projects of national counter-terrorism organization, this team studies vital signs(especially weak vital signs) and the change rule of important organs as well as thelife tolerance under the condition of simulating the Crush Injury combined withhypoxia and deprivation of water and food (combined crush injury). This paperfocuses on the features and the mechanism of the damaged liver which is one of theremote organs damaged by the Crush Injury.In view of the continuous extrusion, this study makes use of144male Wistar rats.They were randomly divided into four groups: control group, crush group, hypoxiacombined with deprivation of water and food group (three lack group), and crushinjury combined with hypoxia and deprivation of water and food group (combinedgroup). Crush injury model was established by clamping the near ends of double hindlimbs (pressure for4.5±0.3kg). The experiment data was recorded at every time afterinjury, to study rats tolerance, liver function, the characteristics of pathologicalchanges and liver cell apoptosis and its mechanism when sustained crush injurycombined with hypoxia and deprivation of food and water under simulant condition ofdeeply buried.As for removing extrusion,144male Wistar rats were randomly divided intofour groups: control group, crush group, hypoxia combined with deprivation of waterand food group (three lack group), and crush injury combined with hypoxia and deprivation of water and food group (combined group). Crush injury model wasestablished by clamping the near ends of double hind limbs (pressure for4.5±0.3kg).To study the function and pathological changes of rat’s liver combined with hypoxiaand deprivation of food and water for3days（i.e. simulate "Golden rescue time72h"）under simulated condition of deeply buried.After systematically and in-depth research, the following progress has beenmade:I. On the Injury of the Liver Caused by Continuous Extrusion1. the performance of the life tolerance is that in the combined group, all ratsdied within4.2-6.8d after injuried. For three lack group, all rats died in6.5~11d afterinjury. No death was seen in control group and crush group2. ALT values of combined group rose rapidly in1d-5d until death, and thisoccurred just5d after injury for three lack group. For crush group, ALT values roserapidly1d, decreased gradually3d-5d, and recovered7d.3. In combined group, hepatocellular degeneration, apoptosis and necrosisoccurred, and glycogen extremely reduced close to disappearing. Kupffer cells, storedfat cells and endothelial cells were all involved. The severity and scope ofpathological changes further aggravated and expanded with time extension. Thepathological changes of three lack group and crush group were alleviated in turn.4. Compared with control group, liver cell apoptosis index of crush group, threelack group and combined group in1d-5d showed a trend of increased gradually. Therewere significant statistical differences (P <0.05, P <0.01), among which the result isobvious in the combined group (P <0.05, P <0.01).5. The expression of apoptosis factors: the expression of the Bax increasedgradually, MOD increased gradually too. crush group, three lack group and combinedgroup in1d-5d were significantly higher than that of control group (P <0.05, P <0.01); The Bcl-2expression is weakening progressively, MOD is decreasing.Compared with control group, crush group and t three lack group in3d and5d hadstatistically difference (P <0.05, P <0.01). combined group had the greatest reduction.in1d-5d, there were statistical difference (P <0.05, P <0.01), and was significantlylower than the former two groups.6. The above results suggest that continuous crush can cause obvious damage tothe rat’s liver function and structure in the compound three lack group. the liver cellapoptosis index increased dramatically, the features of which are high incidence of sexual diversity, fast onset, progressive, and diversity of the involving cell. Bax andBcl–2were involved in liver injury process.II. The progress made in the laws and characteristics of liver functionrecovery when the crush is released in3d is as follow:1.1rat suddenly died when extrusion was removed in compound group, whichdid not happen both in pure extrusion group and three lack group.2. The ALT value increased dramatically in compound and single group when theextrusion was removed. The result is obvious especially in the composite group (P <0.01). It restored to normal level after3d. It showed that the physical function of theliver presents rapid spontaneous recovery process.3. The weight of their body and livers for the three groups significantly reducedafter lifting injuries (P <0.05), which increased in1d and3d. However, to28d itwas always lower than the control group. The weight of the compound groupincreased the most slowly. The three lack group next, and then the single4. The liver atrophy, liver cell degeneration, necrosis and apoptosis, glycogendecreased, mitochondrial cavitation, and involvement of kupffer cells, fat cells,hepatic sinus and vascular endothelial cells happened in compound group when theextrusion was removed. It gradually reduced in3d-7d. however, in14d-28d,there were still few liver cells, kupffer cells which did not completely go back tonormal morphology. We can know that the removing of the extrusion can lead to thespontaneously recovery of the liver structure. The recovery degree was different.Single group, the three lack group reduced in turn.5. The above research results suggest that after the crush is released, the threelack rats which are injured shows instant damage in its liver function and structure.however this damage will be recovered in3-28d gradually. It illustrates that liver hasa strong potential in repairing spontaneously. The features are that early lesionsinvolving the whole liver, restorative, synchronicity for the recovery of the functionand the structure.(that is, the recovery of the structure is slower than its function) aswell as the difference in the degree of recovery (namely compared with singlecrowded group and three short, the degree of the liver damage in compound group isthe most serious. The speed and the degree of its restore are also the worst).This study showed that the liver is one of the important remote organs whichcould worsen MODS, accelerate the death. It can even lead to the death for itsfunctional failure. Because liver is an important organ that have the function of metabolism, detoxification, immune and biological transformation, under thecondition that many patients are buried (especially deep buried) in all kinds of disastercaused by the frequent disasters as well as the scene of the rescue and the subsequenttreatment process, in order to reduce the number of the injury, it is an crucial step forus to strengthen the protection of liver and promote restoration of the injury.