| Objective: To investigate the effect of hemodilution on hemodynamic, hemerheology,oxygen supply and oxygen consumption in minipigs after severe burns.The results will provid foundation for clinical hemodilution on severe burn.Methods: Select 20 experimental Chinese minipigs (about the same weigh).Animals were given 5% thiothal sodium intrapertioneal injection (25-30mg/Kg) one hour before scalded . Then had the hair on their on their necks and backs cut .Separate the left external jugular vein , put the Swan-Ganz catheter (5F) into it . Next, separate the left arteria carotis externa and put another catheter (about 5cm) into the arteria through the Arrow puncture needle . Suture each layer of the skin. According the formular S=17.5· W0.4$ L0.6 calcular the area of 35%TBSA , then delimitthis area to be scalded on its back. With the other area protected properly the animal's back was put into hot water (85℃) for one minute and which made III degree scald (confirned by the pathology slice ). After scalded ,common fluid infusio was given. The volum for the first 24 hours =body weight X area X 1.7+basic volum (2ml/Kg/h),in which electrolyte:colloid=1:1 .The volume for the second 24hours is half of the first one plus the basic volume .After 48PBH(post burn hour), animals were given basic volume fluid infusion and took food freely. All the 20 animals randomly divided into two groups: control group (C, n=10);experimental group (E, n=10). All animals in E group were given isovolumic hemodilution under the hemodanamic monitor at 6PBH. The volume ofbloodletting= V. (Hct(,-Hct1) . (3- Hct0+ Hct1/2 ).(V means the blood volume of minipigs, Hct0 means the hematocrit of before bloodletting, Hcti is the needed hematocrit after bloodletting). In the same time ,same volume of 706 blood substitute was given infusion .The blood was preserved in the blood taking bags which contain anticogulant. The bags were put into refrigerator (0 ℃-4℃ ). E group were given escharectomy at 8PBH. During the operation , blood refusion was given. The level of cardiac output (CO), cardiac index (CI)N right atrial pressure (RAP), plumonary artery wedge pressure (PAWP), viscosity of whole blood, hematocrit (Hct), the RBC aggulation index , oxygen supply (DO2), oxygen consumption (VO2)were measured at normal , 6PBH(before escharectomy), 16PBH(after escharectomy) , 24PBH, 48PBH in E group. The time and indexes for determine in C group were same to E group too . All the indexes presented normal distribution. There was not significant difference after the analysis of t-test for two samples means.Results: 1. The hemodynamic indexes such as CO, CI, RAP, PAWP of two groups were obviously decreased after severe burn. However, indexes of E group were obviously increased after hemodilution when compared with those in C group. 2. The hemerheologic indexes such blood viscosity, hematocrit, the RBC aggulation index were significantly increased , the RBC deformation index decreased obviously . The indexes including blood viscosity,hematocrit,the RBC aggulation index in E group were decreased significantly and obviously when compared with C group. 3. The indexes as DO2 and VO2 in two groups were significantly decreased while the two indexes in E group increased significantly after hemodilution compared with C group.Conclusion: The results indicate: during burn shock stage the hemodynamic indexes of minipigs decreased rapidly , the hemerheologic indexes such as blood viscosity, hematocrit were obviously increased,the RBC deformation index decreased and the RBC aggulation index increased. Both DO2 and VO2 are decreased. After hemodilution ,the hemodynamic indexes were obviously improved which indicated that hemodilution can improve the hemoconcentration, RBC aggulation and blood viscosity , and also do good to RBC deformation during burn shock stage and perioperative stage. Meanwhile, the increase of CO and CI will increase blood volume in circulation, increase oxygen supply and oxygen consumption which are... |
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