中度急性等容性血液稀释对凝血功能的影响

Effect of Acute Normovolemic Hemodilution with 6% Hydroxyethyl Starch （HES, 200/0.5） on Coagulation

目的：观察6％羟乙基淀粉（200/0.5，HES）作为稀释液时，中度急性等容性血液稀释（ANH）对凝血功能的影响。方法：择期手术患者20例，ASAⅠ-Ⅱ级，无凝血和肾功能异常。全麻诱导后，手术主要出血步骤开始前，经桡动脉采血，同时等速输入等量的6％HES进行血液稀释，目标Hct为25％-30％。血液稀释前，后15min及回输前，后15min各时点监测循环动力学指标、血常规、动脉血气分析指标，传统实验室凝血指标（PT、aPTT、Fib）和Sonociot凝血指标。结果：①稀释后，Hct为27.7±1.8％，相对稀释度24.8±3.8％。②术中各点HR变化无显著性差（P〉0.05）。稀释后，MAP由89.3±4.6mmHg降至82.9±5.6mmHg（P〈0.01），自体血回输后，显著恢复（P〈0.05）。稀释后，MAP由89.3±4.6mmHG降至82.9±5.6mmHg（P〈0.01），变化范围未超过基础值±3cmH2O。③PaO2、PCO2值均在正常范围：PH值，Na^＋浓度变化无显著性差（P〉0.05）。K^＋、iCa^2＋浓度在稀释后低于稀释前（P〈0.01），回输自体血后升高（P〈0.01）。均在正常范围。④稀释后，PT、aPTT分别从30.50±4.50s，1.66±1.03s延长至34.48±3.62s，14.14±0.86（P〈0.01），但均小于1.5倍正常对照值，血液回输后，有所改善（p〈0.01）；术中各点ACT变化无显著性差异（P〉0.05）。稀释后，Fib显著减少，但远离于临界值，CR由26.1±7.1U/min降至17.5±6.6U/min（P〈0.01），自体血回输后，二者均显著升高。⑤稀释后，Pit显著减少（P〈0.01）。但未达临界值；PF显著降低（P〈0.01），TP显著延长（P〈0.01）。Pit、PF、TP在自体血回输后得到较大程度的恢复（P〈0.01）。结论：①中度ANH过程中，循环稳定、氧供充分，内环境稳定。②用6％HES进行中度ANH后对机体凝血功能有一定的影响，aPTT，PT明显延长，但均小于1.5倍正常对照值，ACT基本无变化，对临床影响甚微。③自体血回输后，Pit、PF、TP有较大程度的恢复，因此，ANH能部分保护血小板功能。

Objective; To evaluate the influence of preoperative acute normovolemic hemodilution with 6% hydroxyethyl starch （HES. 200/0.5） on coagulation. Methods： Twenty ASA Ⅰ - Ⅱ patients scheduled for elective surgery were randomly assigned to receive 6% HES. whose body weight was 65.3 ± 10.9kg. baseline hemoglobin was 124.52 ± 7.26g/L, and baseline hematocrit was 36.88 ± 2.57%, and patients underwent moderate hemodilution to a target hematocrit of 25 - 30%. Patients with coagulation abnormalities or kidney dysfunction were excluded from the study. Anesthesia was induced with midazolam, propofol, fentanyl and vecuronium and maintained with inhalation of isoflurane and intermittent intravenous boluses of fentanyl and vecuronium. The patients were mechanically ventilated and PaO2and PaCO2 were maintained with normal range. After blood was harvested from radial artery and collected in CPDA-1 blood bags contanining anticoagulant before the onset of surgical blood loss, and at the same time replaced with HES （equal volume）. Blood routine, prothrombin time （PT）, activated partial thromoplastin time （aPTT）. flbrinogen level and sonoclot measurements were obtained at similar time points in the procedure. The time points were before and 15rain after hemodilution and retransfusion of autologous blood. Results： （1） Hct was 27.71 ± 1.81%, between 25% and 30%, and relative hemodilution degree was 24.8 ± 3.8% after hemodilution. The average volume of collected blood was 44.2 ± 4.2 ml （11.5 ± 6.7 ml/kg）, and the volume of HES for hernodilution was 744.1 ± 82.3 ml. （2） There was no marked change in heart rate （P 〉 0.05）. Mean arterial pressure （MAP） was decreased from 89.3 ± 4.6 mmHg to 8,2.9 ± 5.6 mmHg （P 〈 0.01）, while its fluctuation did not exceed ± 20% still. The central venous pressure （CVP） was not higher than the value of baseline plus 3cmH2O. （3） Both partial pressure of oxygen （PaO2） and carbon dioxide （PCO2） , were in normal range. The values of pH and sodium ion （Na^＋） concentration remained unchanged （P〉 0.05）. The concentrations of Potassium ion （K^＋） and ionic calcium （iCa^2＋） after hemodilution were less than those of before hemodilution （P 〈 0,01 ）. The concentrations of K^＋ and iCa^2＋ would increase after retransfusion of the autologous blood （P 〈 0.01）, but were in normal range. （4） After hemodilution, aPTT and PT were prolonged respectively from 30.50 ± 4.50s, 12.66 ± 1.03s to 34.48 ± 3.62s, 14.14 ± 0.86s （P 〈 0.01）. But they were both less 1.5 times than the normal values respectively. After retransfusion, both of them could be retrieved （P 〈 0.01）. Activated clotting time （ACT） had no changes all the while （P 〉 0.05）. After hemodilution Fib decreased significantly （P 〈 0.01）, but it still away above the critical value （0.75g/L）, and CR decreased from 26.1 ± 7.1 U/min to 17.5 ± 6.6 M/min（P 〈 0.01）. Both of them increases significantly after retransfusion （P〈 0.01）. （5） Pit after hemodilution is less than that of before hemodilution significantly （P〈 0.01）. But the value did not exceed the critical value （50 × 10^9/L）. PF decreased significantly （P 〈 0.01） and TP was significantly （P 〈 0.01） prolonged after hemodilution, Pit, PF and TP were recovered to a great extent （P 〈 0.01）. Conclusions： （1） It could be maintained that hemodynamics stability, oxygen supply and internal environment stability in the course of moderate ANH. （2） There was influence to some extent of moderate ANH with 6% HES on the function of coagulation, aPTT and PT were significantly prolonged after hernodilution, but they were still less 1.5 times than the normal values respectively. And ACT had no changes all the while. （3） Pit, PF and TP would be revovered to a great extent. So Platelet function could be shielded in ANH.