Effects Of Seawater Immersion On Wound Microcirculation In Scalded Rat And Its Treatment

ObjectiveWith the development of modern society,as the interactions and movements related marine have became increasingly frequent,people who operate or battle on the sea are easy to be wounded by all kinds of injuries.Technically,the wound is often contaminated by seawater or even directly immersed in sea water,which would probably do more harm to the whole body and affect wound healing process. Moreover,due to the environmental constraints,it has been difficult for patients to obtain timely and correct treatment.Meanwhile,even up to now,it remains little known the effects of seawater immersion on wound microcirculation and its mechanism.The study based on a model of 10%TBSA deep second degree scalded rats to investigate the effect of seawater immersion on wound microcirculation and its mechanism.From the certain aspects of pathological change in wound,the injury of endothelial cells in wound subcutaneous capillary,wound edema,the serum thromboxane B and oxygen free radicals changes,to provide theoretical reference for clinical treatment of the burn with seawater immersion,also explore the feasibility of topical treatment.Methods1,Animal model:168 SPF level Wistar rats weighted 180-220g were randomly divided into normal control group(groupA),scald control group(groupB), scalded with seawater immersion 1h(groupC) and 3h(groupD),the groupC and groupD were further divided into Simple observation after seawater immersion group (group C1 and D1),rinse on wound 20min with freshwater after seawater immersion group(group C2 and D2),freshwater Hydropathic 1h after seawater immersion group (group C3 and D3).One day before scalded,hair on rats'back was depilated by 80g/ L sodium sulfide.25g/L sodium amytal was injected into the abdominal cavity for anesthesia with the dosage of(35mg/kg) before scalded,then 10%TBSA deep second degree scald was made by immersing rats in 95℃hot water for 12s.Except groupA,hands and feet of the rats were tied up and body below upper limbs in seawater after scalded 1,3h separately.After seawater immersion,randomly selected 21 animals from groupC or groupD with simple observation,rinse with freshwater for 20 minutes,hydropathic with freshwater for 1h.All wound were protected by sterile medical film.2,Test index and Methods:wound swelling and secretions were observed by eyes at 1,3,5d after scalded.Histopathological changes were observed by light microscopy at 1,3,5d after scalded,the injury of endothelial cells in wound subcutaneous capillary were observed by electron microscopy at 1,3,5d after scalded.Thromboxane B(TXB2) and Oxygen free radicals(OFR) contents were determined by enzyme-linked immunosorbent assay(ELISA) at 1,3,5d after scalded.Use wet and dry weight method to determin water content in wound tissue.3,All the data were showed in the form mean±SD,and analyzed by statistical software of SPSS 13.0.Thromboxane B,Oxygen free radicals contents and water content in wound tissue were analyzed by factorial analysis of variance,One-way ANOVA,method of multiple comparisons between Group using SNK,P＜0.05 as significance level.Results 1,General changes of the wounds:1d after scalded,apart from group A,the wound swelling in all other group,exudation can be seen in group B,whereas the wound in group C and group D was dry,and the most evident in group D1.2-3d after scalded, the wound swelling has subsided in group B,but is not completely dry,and a small yellow necrosis can be seen in group B.The area of wound necrotic in group C2 and group C3 and group D2 and group D3 were slightly larger than the group B.In group C1 and group D1,the wound necrosis was more obviously.4-5d after scalded,the larger area of wound necrosis can be seen in group C1 and group D1,and some animals have a small amount of purulent secretions around the wound.The wound in group B and group C2,C3,D2,D3 were almostly dry and turning into scab.2,Pathological and morphologic changes:1d after scalded,apart from group A,the epidermis of wound in all other group came off and turning necrosis,and the dermal attachment necrosis,microvascular congestive expansion,inflammatory cell infiltration happened in this group,the infiltration of inflammatory cell were the most sverest in group D1.3d after scalded,the wound tissue edema,microvascular congestive expansion,is still evident in group B and group C and group D,that an increase in dermal attachment necrosis,there is varying degrees of inflammatory cell infiltration and collagen edema in group C1 and group D1,the most severest in group D1.5d after scalded,the tissue edema,microvascular congestive expansion reduced in group B and group C2 and group C3 and group D2 and group D3,the necrosis of attachment dermis,inflammatory cell infiltration and collagen edema is still significantly than before in group C1 and group D1,and it can be seen some vascular wall is damaged,the erythrocyte exudation and large areas of collagen significantly necrosis with edema in group group D1.3,The morphological changes of capillary network endothelial cells under the Electron microscope:In normal capillaries,the integrity basement membrane can be seen,and the edge of endothelial cells is clear,the connection between endothelial cells and the pinocytotic vesicles in cells can be seen clearly;In group B,the basement membrane of capillary is integrity,the endothelial cell was swelling,the gap between the endothelial cells Widened,there were thrombosis in cavity of capillary,loose cytoplasm;In group C1,the gap between the endothelial cells obviously Widened than group B,and a large number of red blood cells accumulation in the capillary,parts membrane of endothelial cells was lost;In group D1,the basement membrane of capillary disappeared,and some endothelial cell lose their structural integrity,some cell shrinkage,and some cells have been came off;The treatment group shows that basement membrane of capillary was remaining, endothelial cell is still swelling,the cell apparatus had not obviously damaged.4,Change of serum thromboxane TXB₂ and wound tissue homogenate OFR content: Apart from group A,the content of serum TXB2 and wound tissue homogenate OFR in each group increased obviously with the time of seawater immersion extended,and in 1-5d after scalded,was carried out in the trend of rising;The content of serum TXB2 and wound tissue homogenate OFR in treatment group was less than seawater immersion with none treatment.There was significantly changes Between each group and time point(P＜0.05).5,Change of wound tissue water content:apart from group A,the water content in rest groups were increased in 1d after scalded,and reached the highest in 3d after scalded, decline slightly in seawater immersion group 5d after scalded but still significantly higher than group A.There were significantly changes between one group to another (P＜0.05).Conclusion1,The wound microcirculation can increasingly obstacles and the burn wound has been gradually deepened by seawater immersion.Meantime,The mechanism may be:the hypertonic and alkaline.the sea water results in dehydration and necrosis in wound tissue,especially increase endothelial cell injury in the subcutaneous capillary network.In addition,the local OFR and serum TXB2 growing contributes to more severe microcirculation obstacles and wound damage.2,The degree of microcirculation obstacles as well as wound damage increased with the time of seawater immersion extended.Hence,it is suggested that there is a negative impact on wound repair with the seawater immersion.3,After being burned,the wound with seawater immersion,rinsed and hydropathic by fresh water can varying degrees that reduce the negative impact of seawater immersion,which is self-evident that the timely and effective measures to prevent burn wound immediate from the particular circumstances of seawater immersion could be a key measures of injury mitigation.