Horrow J C, Van Riper D F, Strong M D, Grunewald K E, Parmet J L
Department of Anesthesiology, Medical College of Pennsylvania, Philadelphia.
Anesthesiology. 1995 Feb;82(2):383-92. doi: 10.1097/00000542-199502000-00009.
Prophylactic administration of the antifibrinolytic drug tranexamic acid decreases bleeding and transfusions after cardiac operations. However, the best dose of tranexamic acid for this purpose remains unknown. This study explored the dose-response relationship of tranexamic acid for hemostatic efficacy after cardiac operation.
In prospective, randomized, double-blinded fashion, 148 patients undergoing cardiac operation with extracorporeal circulation were divided into six groups: a placebo group and five groups receiving tranexamic acid in loading doses before incision (range 2.5 to 40 mg.kg-1) and one-tenth the loading dose hourly for 12 h. The mass of blood collected by chest tubes over 12 h represented blood loss. Allogeneic transfusions within 12 h and within 5 d of surgery were tallied.
The six groups presented similar demographics. Patients receiving placebo had increased postoperative D-dimer concentration compared to groups receiving tranexamic acid. Patients receiving at least 10 mg.kg-1 tranexamic acid followed by 1 mg.kg-1.h-1 bled significantly less (365, 344, and 369 g.12 h-1, respectively, for those three groups) compared with patients who received placebo (552 g, P < 0.05). Tranexamic dose did not affect transfusions. Only initial hematocrit affected whether a patient received an allogeneic transfusion within 5 days of operation (odds ratio 2.08 for each 3% absolute decrease in hematocrit).
Prophylactic tranexamic acid, 10 mg.kg-1 followed by 1 mg.kg-1.h-1, decreases bleeding after extracorporeal circulation. Larger doses do not provide additional hemostatic benefit.
预防性使用抗纤维蛋白溶解药物氨甲环酸可减少心脏手术后的出血和输血。然而，为此目的使用氨甲环酸的最佳剂量仍不清楚。本研究探讨了氨甲环酸在心脏手术后止血效果的剂量反应关系。
采用前瞻性、随机、双盲方式，将148例接受体外循环心脏手术的患者分为六组：一组安慰剂组和五组在切口前接受负荷剂量氨甲环酸（范围为2.5至40mg·kg-1）并在12小时内每小时接受十分之一负荷剂量的组。12小时内胸腔引流管收集的血液量代表失血量。记录手术12小时内和5天内的异体输血情况。
六组患者的人口统计学特征相似。与接受氨甲环酸的组相比，接受安慰剂的患者术后D-二聚体浓度升高。接受至少10mg·kg-1氨甲环酸继以1mg·kg-1·h-1的患者出血明显少于接受安慰剂的患者（这三组患者分别为365、344和369g·12h-1，而接受安慰剂的患者为552g，P<0.05）。氨甲环酸剂量不影响输血。仅初始血细胞比容影响患者在术后5天内是否接受异体输血（血细胞比容每绝对降低3%，优势比为2.08）。
预防性使用氨甲环酸，先给予10mg·kg-1继以1mg·kg-1·h-1，可减少体外循环后的出血。更大剂量不会提供额外的止血益处。
