Objective To evaluate the effect of regional hypothermia on limb ischemia-reperfusion (I/R) injury in a rabbit model of hemorrhagic shock.Methods Eighteen healthy adult New Zealand white rabbits of both sexes,weighing 2.0-2.5 kg,were divided into 3 groups (n=6 each) using a random number table:sham operation group (S group),limb I/R group (I/R group) and regional hypothermia group (RH group).Rabbits were shot with 0.25 g steel ball with a 7.62 mm smoothbore at the middle and lower 1/3 of the left hindlimb in I/R and RH groups.When the blood pressure was stable for 30 min after injury,blood was drawn via the right femoral artery at a rate of 2 ml/min until mean arterial pressure decreased to 45-50 mmHg.Then a rubber tourniquet was used to ligate left hindlimbs 10 min later.The injured limb was cooled down for 4 h after applying tourniquet to maintain the subcutaneous temperature at 9-11 ℃ in group RH.After tourniquet was applied for 4 h,perfusion was restored and lasted 6 h.After catheterization (T0) and at 2,4 and 6 h of reperfusion (T1-3),blood samples were collected from the right femoral artery for blood gas analysis and for determination of tumor necrosis factor-α (TNF-α),interleukin-2 (IL-2) and IL-6 concentrations in serum (by enzyme-linked immunosorbent assay).The animals were sacrificed at T3,and tissues around the margin of the inferior lobe of right lung were obtained for examination of the pathological changes which were scored and for determination of wet to dry weight ratio (W/D ratio).Results Compared with group S,the respiratory rate was significantly increased and PaCO2 was decreased at T2,3,the pathological score and W/D ratio were increased,and the concentrations of TNF-α,IL-2 and IL-6 in serum were increased at T1-3 in I/R and RH groups (P＜0.05).Compared with group I/R,the respiratory rate was significantly decreased and PaCO2 was increased at T2,3,the pathological score and W/D ratio were decreased,and the concentrations of TNF-α,IL-2 and IL-6 in serum were decreased at T1-3 (P＜0.05),and the pathological score was significantly attenuated in group RH.Conclusion Regional hypothermia can reduce limb I/R injury in a rabbit model of hemorrhagic shock,and the mechanism may be related to inhibiting systemic inflammatory responses.

Objective To establish a model of combined injury of thermal radiation and blast wave of gas explosion in closed pipeline,and investigate the characteristics of important organ injury induced by burn-blast combined injury in rats.Methods A total of 72 male SD rats(aged 8～10 weeks,weighing 200～10 g)were randomly divided into control group and mild and severe injured groups.After the model rats were inflicted with blast wave and thermal radiation,their physical parameters were detected and measured.The respiratory function of the survival rats was tested.In 24 h later,arterial blood gas analysis,blood biochemical tests,and detection for serum inflammatory factors and lung injury related protein levels were performed,and the pathological changes in the lung tissue and trachea were observed.Results The peak range of explosive blast wave overpressure was 209～493 kPa,and the temperature was 152～258 ℃.The mortality rate was 8.3％in the mild group and 53.1％in the severe group.Compared with the control group,longer inspiratory time(Ti)and relaxation time(Tr)and larger tidal volume(TV)(P＜0.05),while lower respiratory frequency(f)were observed in the 2 injured groups within 6 h after injury(P＜0.05).At 24 h after injury,the values of partial pressure of carbon dioxide(PaCO2),residual base value(BE)and bicarbonate(HCO3-)were increased significantly(P＜0.05),while partial pressure of oxygen(PaO2)was decreased(P＜0.05).The serum levels of alanine transaminase(ALT),aspartate aminotransferase(AST),alkaline phosphatase(ALP),total bilirubin(TBI)and total bile acid(TBA)were notably elevated(P＜0.05).So were the levels of IL-1 β,TNF-α and IL-6(P＜0.01).Various severities of hyperemia foci and inflammation in the tracheal mucosa were observed in the injured rats.The incidence of lung injury was high,and the pathological manifestations were dot-shaped hemorrhage to diffuse hemorrhage of the whole lobe,rupture of alveolar septum,thickening of septum,and infiltration of red blood cells and inflammatory cells.The levels of serum lung injury-related proteins were significantly increased(P＜0.05).Conclusion A rat model which can highly simulate mild to severe burn-blast combined injury is constructed,which can meet the needs for rat model in study of explosive burn-blast compound injury.The main characteristics of the injury are lung injury,respiratory dysfunction,liver damage and secondary infection.