Li Lian Yun, Xu Xing
Department of Anesthesiology, Peking University First Hospital, Beijing, China.
Beijing Da Xue Xue Bao Yi Xue Ban. 2008 Jun 18;40(3):292-300.
To observe acute progressive normovolemic hemodilution with lactated Ringer's, gelatins, and hydroxyethyl starch in vivo and in vitro on blood coagulation and survival rate and time in rabbits.
Thirty male Chinese white rabbits were randomly assigned to three groups that underwent acute progressive normovolemic hemodilution with one of three solutions: (1) lactated Ringer's solution (LR group, n=10). (2) 4% succinylated gelatin (GEL group, n=11), (3) 6% hydroxyethyl starch (HES group, n=9). After anesthesia, a 22-gauge catheter was placed in the central ear artery and blood samples were obtained before hemodilution. In vitro, 50% and 75% hemodilutions were completed by doubling the volume of blood sample with a 10 mL syringe in two times. In vivo, 50% and 75% (50%,75% of estimated blood volume removed) hemodilutions were performed by removing an equal volume of blood from a femoral arterial catheter, simultaneously administering the marginal ear vein as previous solutions (water warmed to 39 degrees C). Mean arterial pressure (MAP), heart rate (HR), and body temperature were measured and arterial blood samples were obtained after 30 min of equilibration to determine blood gas, electrolytes, hematocrit, and thrombelastography variables at 37 degrees C, after 75% hemodilution rabbits survival rates within 1 h and survival times were observed.
MAP with progressive hemodilutions (50%, 75%) significantly decreased (P<0.01); However, HR and body temperature remained virtually unchanged. the p(O(2)) increased, the p(CO(2)) decreased,blood sodium and calcium markedly decreased with progressive hemodilutions (50%, 75%), Blood potassium decreased in 50% but increased in 75% hemodilution. In vitro pH values were found to be constant in three groups, p(CO(2)) and the blood sodium greatly increased within HES and GEL groups, and blood potassium and calcium throughout progressive hemodilution significantly decreased. In vitro hemodilution with the three solutions, initiation of coagulation was not affected or prolonged but the toughness of clot decreased. In vivo hemodilution, initiation of coagulation was accelerated or unchanged but also with decreased clot toughness. In comparing the three solutions, in vitro hemodilution with LR had no effect on initiation of coagulation but GEL and HES prolonged the procedure. In vivo hemodilution with the three replacement solutions accelerated the initiation of coagulation, making it more weakly in GEL and HES than in LR. Either in vivo or in vitro the three solutions could decrease the toughness of clot. The survival rates within 1 hour after 75% hemodilution were not significantly different among LR(6/10), GEL(5/11) and HES(8/9) groups(chi(2)=4.093,P>0.05), survival times of the LR, GEL and HES groups were (50.50+/-62.38) min,(324.55+/-777.32) min,(748.89+/-881.67) min, respectively. The difference between LR and GEL survival times was nonsignificant (t=0.243,P>0.05), the average survival time of HES solutions was longer than that after LR or GEL infusion (t=3.012,P<0.01 and t=2.781,P<0.01, respectively).
With in vitro hemodilution, the initiation of coagulation is unaffected or decreased. However with in vivo hemodilution, initiation of coagulation is accelerated or unchanged. The discrepancy between in vivo and in vitro hemodilution, indicates an unknown internal mechanism to promote initiation of coagulation. Hemodilution makes the toughness of clot soften. and the longest survival time in profound hemodilution associated with hydroxyethyl starch.
观察乳酸林格液、明胶和羟乙基淀粉进行急性渐进性等容血液稀释对兔体内外凝血及生存率和生存时间的影响。
30只雄性中国白兔随机分为三组，分别用三种溶液之一进行急性渐进性等容血液稀释：（1）乳酸林格液组（LR组，n = 10）。（2）4%琥珀酰明胶组（GEL组，n = 11），（3）6%羟乙基淀粉组（HES组，n = 9）。麻醉后，将22号导管置于中耳动脉，在血液稀释前采集血样。体外，通过用10 mL注射器分两次将血样体积加倍完成50%和75%的血液稀释。体内，通过从股动脉导管抽出等量血液，同时经耳缘静脉给予先前溶液（加热至39℃的水）进行50%和75%（去除估计血容量的50%、75%）的血液稀释。测量平均动脉压（MAP）、心率（HR）和体温，并在平衡30分钟后采集动脉血样，以测定37℃时的血气、电解质、血细胞比容和血栓弹力图变量，在75%血液稀释后观察兔1小时内的生存率和生存时间。
随着渐进性血液稀释（50%、75%），MAP显著降低（P<0.01）；然而，HR和体温基本保持不变。随着渐进性血液稀释（50%、75%），p(O₂)升高，p(CO₂)降低，血钠和血钙显著降低，50%血液稀释时血钾降低，75%血液稀释时血钾升高。发现三组体外pH值恒定，HES组和GEL组p(CO₂)和血钠大幅升高，整个渐进性血液稀释过程中血钾和血钙显著降低。用三种溶液进行体外血液稀释，凝血启动未受影响或延长，但血凝块韧性降低。体内血液稀释时，凝血启动加速或不变，但血凝块韧性也降低。比较三种溶液，用LR进行体外血液稀释对凝血启动无影响，但GEL和HES延长了该过程。用三种替代溶液进行体内血液稀释加速了凝血启动，GEL和HES组比LR组更弱。无论体内还是体外，三种溶液均可降低血凝块韧性。75%血液稀释后1小时内LR组（6/10）、GEL组（5/11）和HES组（8/9）的生存率无显著差异（χ² = 4.093，P>0.05），LR组、GEL组和HES组的生存时间分别为（50.50±62.38）分钟、（324.55±777.32）分钟、（748.89±881.67）分钟。LR组和GEL组生存时间差异无统计学意义（t = 0.243，P>0.05），HES溶液的平均生存时间长于LR或GEL输注后的生存时间（分别为t = 3.012，P<0.01和t = 2.781，P<0.01）。
体外血液稀释时，凝血启动未受影响或降低。然而，体内血液稀释时，凝血启动加速或不变。体内和体外血液稀释之间存在差异，表明存在促进凝血启动的未知内在机制。血液稀释使血凝块韧性变软，与羟乙基淀粉相关的深度血液稀释中生存时间最长。
