Zohar E, Fredman B, Ellis M H, Ifrach N, Stern A, Jedeikin R
Department of Anesthesiology and Critical Care, Division of Transfusion Medicine, Meir Hospital, Kfar Saba, Israel.
Transfusion. 2001 Oct;41(10):1285-9. doi: 10.1046/j.1537-2995.2001.41101285.x.
Tissue hypoxia and reperfusion induce abnormal hemostatic function. Therefore, bleeding after total knee replacement (TKR) may be a result of a tourniquet-induced imbalance of the procoagulant and fibrinolytic systems. Because laboratory confirmation of tourniquet-induced abnormal hemostasis is difficult to obtain, indirect evidence must be sought.
A prospective, single-blind study of 40 patients undergoing TKR was performed. In the tranexamic acid (TA) group, in the 30 minutes before the limb tourniquet was deflated, an IV bolus dose of TA (15 mg/kg) was administered. Thereafter, a constant IV infusion of 10 mg per kg per hour was administered until 12 hours after tourniquet deflation. In the desmopressin group, desmopressin (0.3 mg/kg) and saline were administered by a similar protocol. No blood was administered intraoperatively. A postoperative Hct <27 percent constituted the postoperative transfusion trigger. Patients were examined daily for signs of lower-limb deep vein thrombosis, and they underwent lower-limb Doppler ultrasound on postoperative Day 5. Three months after surgery, the incidence of delayed thromboembolic events was assessed.
During the first 12 postoperative hours, blood accumulation in the surgical drain was significantly (p<0.05) lower in the TA group (162 mL +/- 129) than in the desmopressin group (342 mL +/- 169). From the sixth postoperative hour until 3 days postoperatively, Hct levels were significantly lower in the desmopressin group than in the TA group. Significantly more allogeneic blood was transfused in the desmopressin group (11 patients received 16 units) than in the TA group (3 patients each received 1 unit) (p<0.02). There were no clinical signs of deep vein thrombosis or abnormal Doppler ultrasound studies. Three months postoperatively, there were no thromboembolic events among the 37 patients interviewed.
TA induces better blood sparing than desmopressin. Therefore, a tourniquet-induced increase in fibrinolysis is the likely cause of delayed bleeding after TKR surgery. However, before routine administration, the effect of TA on the incidence of thromboembolic events requires further investigation.
组织缺氧和再灌注会导致止血功能异常。因此，全膝关节置换术（TKR）后出血可能是止血带导致的凝血和纤溶系统失衡的结果。由于很难通过实验室证实止血带引起的异常止血，所以必须寻找间接证据。
对40例行TKR的患者进行了一项前瞻性单盲研究。在氨甲环酸（TA）组中，在肢体止血带放气前30分钟，静脉推注TA（15mg/kg）。此后，以每小时10mg/kg的速度持续静脉输注，直至止血带放气后12小时。在去氨加压素组中，按照类似方案给予去氨加压素（0.3mg/kg）和生理盐水。术中未输血。术后血细胞比容（Hct）<27%构成术后输血触发指标。每天检查患者下肢深静脉血栓形成的体征，并在术后第5天行下肢多普勒超声检查。术后3个月，评估延迟性血栓栓塞事件的发生率。
术后前12小时，TA组手术引流管中的积血量（162mL±129）显著低于去氨加压素组（342mL±169）（p<0.05）。从术后第6小时直至术后3天，去氨加压素组的Hct水平显著低于TA组。去氨加压素组输注的异体血明显多于TA组（11例患者输注16单位）（3例患者各输注1单位）（p<0.02）。没有深静脉血栓形成的临床体征或多普勒超声检查异常。术后3个月，接受访谈的37例患者中未发生血栓栓塞事件。
TA比去氨加压素能更好地节约用血。因此，止血带引起的纤溶增加可能是TKR手术后延迟出血的原因。然而，在常规给药之前，TA对血栓栓塞事件发生率的影响需要进一步研究。
