Kheirabadi B S, Pearson R, Rudnicka K, Somwaru L, MacPhee M, Drohan W, Tuthill D
American Red Cross, Holland Laboratory, 15601 Crabbs Branch Way, Rockville, Maryland 20855, USA.
J Surg Res. 2001 Sep;100(1):84-92. doi: 10.1006/jsre.2001.6226.
Sustained hemostatic function of fibrin sealant (FS) is crucial when it is used in cardiovascular surgery. The purpose of this study was to develop a model that can determine the long-term hemostatic efficacy of tissue sealants in a vascular surgery.
To determine the ability of the model to detect differences in FS performance, various concentrations of FS were prepared and tested. Tensile strength of FS clots was determined in vitro using a tensiometer. Laparotomy was performed on 49 anesthetized rabbits, and a segment of the aorta was occluded, transected, and then sutured in an end-to-end fashion with four or eight interrupted 9-O sutures. The four-suture repair was covered with FS or placebo, and blood flow restored. Spilled blood was absorbed with gauze and weighed to estimate blood loss. Four weeks after surgery the animals were euthanized and the vessels recovered for histology.
Average tensile strength of FS clots at 120, 90, and 60 mg/ml topical fibrinogen complex (TFC) concentration was 0.42 +/- 0.07 N, with no significant difference among them. The lowest TFC concentration, 30 mg/ml, produced weaker clots than either 120 or 90 mg/ml (P < 0.05). All rabbits with four-suture anastomoses that were treated with placebo bled to death after the vessel was unclamped (n = 6). Treatment of suture line with standard FS concentration (120 mg/ml TFC, n = 8) sealed the anastomosis and prevented blood loss. Hemostasis was sustained for 4 weeks, allowing vascular healing. All rabbits with the eight-suture anastomosis survived the operation but lost 42 +/- 9.2 ml blood (n = 5). Hemostatic efficacy of FS was unchanged when TFC was diluted to 90 mg/ml (n = 6) but further dilution to 60 mg/ml with water (n = 8) produced significantly less effective clots, with an average blood loss of 5.5 +/- 7.6 ml (P < 0.05) and two fatal clot failures postoperatively. When FS was diluted to 60 mg/ml TFC with a buffer, it maintained its hemostatic strength (n = 6). Further TFC dilution to 30 mg/ml led to consistent bleeding with an average blood loss of 35.3 +/- 10.3 ml (P < 0.001, n = 6).
The four-suture anastomosis of rabbit aorta offers a consistent and reliable method for evaluating the short- and long-term hemostatic efficacy of FS products. This model is not only able to determine the functional differences in various concentrations of FS, but it is also sensitive to detect the subtle changes in FS preparation (e.g., medium composition) that is not detected by in vitro testing.
纤维蛋白密封剂（FS）在心血管手术中的持续止血功能至关重要。本研究的目的是建立一种模型，以确定组织密封剂在血管手术中的长期止血效果。
为了确定该模型检测FS性能差异的能力，制备并测试了不同浓度的FS。使用张力计在体外测定FS凝块的拉伸强度。对49只麻醉的兔子进行剖腹手术，阻断、横断一段主动脉，然后用4或8针间断9-O缝线进行端端缝合。四针缝合修复处覆盖FS或安慰剂，恢复血流。用纱布吸收溢出的血液并称重以估计失血量。术后4周对动物实施安乐死并回收血管进行组织学检查。
局部纤维蛋白原复合物（TFC）浓度为120、90和60mg/ml时，FS凝块的平均拉伸强度为0.42±0.07N，它们之间无显著差异。最低的TFC浓度30mg/ml产生的凝块比120或90mg/ml时更弱（P<0.05）。所有接受安慰剂治疗的四针吻合兔子在血管夹闭后均失血死亡（n = 6）。用标准FS浓度（120mg/ml TFC，n = 8）处理缝合线可封闭吻合口并防止失血。止血持续4周，促进血管愈合。所有接受八针吻合的兔子均存活，但失血42±9.2ml（n = 5）。当TFC稀释至90mg/ml时，FS的止血效果不变（n = 6），但用水进一步稀释至60mg/ml（n = 8）时，凝块效果明显变差，平均失血量为5.5±7.6ml（P<0.05），术后有两例凝块止血失败致死。当用缓冲液将FS稀释至60mg/ml TFC时，其保持止血强度（n = 6）。进一步将TFC稀释至30mg/ml导致持续出血，平均失血量为35.3±10.3ml（P<0.001，n = 6）。
兔主动脉四针吻合为评估FS产品的短期和长期止血效果提供了一种一致且可靠的方法。该模型不仅能够确定不同浓度FS的功能差异，而且对检测FS制剂（如介质成分）中体外测试未检测到的细微变化也很敏感。
