| Objective:With the flying development of modern high tech routine weapons, the appear of weapon whose main killing factors blast wave and hypoxia were made it not only a possibility but also a true that a great of blast-hypoxia combined injury would appear in the field. Undergound mine gas explode also begets blast-hypoxia combined injury. The blast-hypoxia combined injury is induced by multi-factors, as makes the injury complex and capricious and the accurate diagnosis and treatment difficult. Nevertheless, seldom study upon such kind of injury has been carried out both at home and abroad. The objective of the study is to set up an animal model, that can accurately expressing the characteristics of the blast-hypoxia combined injury, observe the characteristics and law of the blast-hypoxia combined injury in the early stage of injury, and hence provide a basis for further researches on early protection, diagnosis and treatment.Methods:1. Establishment of rat models: 116 SD rats were divided into four groups randomly, ie, normal control group (Group NG), blast injury group (Group BG), blast-hypoxia combined injury group I (Group BHG-I) and combined blast-hypoxia injury group II (Group BHG-II). The rats in the Group BG were inflicted with blast injury by BST-I bio-shock tube with blast wave overpressure for 482.7kPa and positive press time for 43.6 ms. After blast injury, the rats in the Groups BHG-I and BHG-II were put into the hypoxia-cabin immediately, where mixed gases of 12.5% and 10% oxygen concentrations were given respectively. The rat mortality at the 6th hour, the pulmonary water content and the pathologic change of the lung tissue were observed.2. Characteristics of the blast-hypoxia combined injury: 104 SD rats were randomly divided into four groups, ie, normal control group (NG), blast injury group (BG), hypoxia group (HG) and blast-hypoxia combined injury group I (BHG-I). Respiratory changes, mortality and pulmonary water content were recorded at 1, 3 and 6 hours after injury. In the meantime, TNF- a and IL-8 in blood serum were detected by means of ELISA and the TNF-a in the lung tissues was detected by immunohistochemical methods. The pathological changes of the lung tissues were observed by the light microscope and the electron microscope. Results:1. Rat model of blast-hypoxia combined injury: Posterior to the blast-hypoxia combined injury, the rats became dysphoria and tachypnea with lip empurple, aggravated pulmonary hemorrhage and pneumonedema and increased mortality (P<0.01). The severer hypoxia, pulmonary hemorrhage and pneumonedema would result in the higher mortality. The mortality in 6 hours after injury were 2.78% in the blast injury group, 5.56% in the blast-hypoxia combined injury group I and 41.67% in the blast-hypoxia combined injury. The model of blast injury combined with hypoxia of 12.5% oxygen was stable and fit for the further research on the blast-hypoxia combined injury.2. Characteristics of the blast-hypoxia combined injury: Dysphoria within 1 hour after the blast-hypoxia combined injury was more significant than that after pure blast injury. The mortality was 5.56% in 3 hours after injury and no other rat died after 3 hours in BHG-I. The frequency of respiration was obviously higher in BHG-I than that in the hypoxia group, it reach to the peak, and fall after a rise gradually with time. The pulmonary water content in the Group BHG-I increased immediately after injury, reached the peak at the 3rd hour. The pulmonary water content in the Group BHG-I at the 1st and 3rd hours was significantly higher than that in the hypoxia group (P<0.01). The pulmonary hemorrhage occurred in one or more lung leaves complicated by obvious pneumonedema. The interstitial were permeated with neutrophil leucocyte by light microscope. The alveolar were infiltrated more significantly with more red blood cells and plasmic-fibrous exudation in the Group BHG-I than that in the blast injury group. The electron microscope showed that the neutrophils in the alveolar wall increased in the co...
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