From the Joint Department of Biomedical Engineering of University of North Carolina - Chapel Hill and North Carolina State University, Raleigh, North Carolina.
Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina.
Anesth Analg. 2023 Sep 1;137(3):682-690. doi: 10.1213/ANE.0000000000006357. Epub 2023 Jan 24.
Bleeding is a serious complication of cardiopulmonary bypass (CPB) in neonates. Blood product transfusions are often needed to adequately restore hemostasis, but are associated with significant risks. Thus, neonates would benefit from other effective, and safe, hemostatic therapies. The use of fibrinogen concentrate (FC; RiaSTAP, CSL Behring, Marburg, Germany) is growing in popularity, but has not been adequately studied in neonates. Here, we characterize structural and degradation effects on the neonatal fibrin network when FC is added ex vivo to plasma obtained after CPB.
After approval by the institutional review board and parental consent, blood samples were collected from neonates undergoing cardiac surgery and centrifuged to yield platelet poor plasma. Clots were formed ex vivo from plasma obtained at several time points: (1) baseline, (2) immediately post-CPB, and (3) post-transfusion of cryoprecipitate. In addition, we utilized post-CPB plasma to construct the following conditions: (4) post-CPB +0.5 mg/mL FC, and (5) post-CPB +0.9 mg/mL FC. The resultant fibrin networks were imaged using confocal microscopy to analyze overall structure, fiber density, and alignment. Clots were also analyzed using a microfluidic degradation assay. Fibrinogen content was quantified for all plasma samples.
The addition of 0.5 or 0.9 mg/mL FC to post-CPB samples significantly enhanced the median fiber density when compared to untreated post-CPB samples (post-CPB = 0.44 [interquartile range {IQR}: 0.36-0.52], post-CPB +0.5 mg/mL FC = 0.69 [0.56-0.77], post-CPB +0.9 mg/mL FC = 0.87 [0.59-0.96]; P = .01 and P = .006, respectively). The addition of 0.9 mg/mL FC to post-CPB samples resulted in a greater fiber density than that observed after the in vivo transfusion of cryoprecipitate (post-transfusion = 0.54 [0.45-0.77], post-CPB +0.9 mg/mL FC = 0.87 [0.59-0.96]; P = .002). Median fiber alignment did not differ significantly between post-CPB samples and samples treated with FC. Degradation rates were not statistically significant from baseline values with either 0.5 or 0.9 mg/mL FC. In addition, we found a significant correlation between the difference in the baseline and post-CPB fibrinogen concentration with patient age ( P = .033) after controlling for weight.
Our results show that clots formed ex vivo with clinically relevant doses of FC (0.9 mg/mL) display similar structural and degradation characteristics compared to the in vivo transfusion of cryoprecipitate. These findings suggest that FC is effective in restoring structural fibrin clot properties after CPB. Future studies after the administration of FC in vivo are needed to validate this hypothesis.
出血是新生儿体外循环（CPB）的严重并发症。为了充分止血，经常需要输血，但这会带来显著的风险。因此，新生儿将受益于其他有效且安全的止血治疗。纤维蛋白原浓缩物（FC；CSL Behring，马尔堡，德国的 RiaSTAP）的使用越来越普及，但在新生儿中的研究还不够充分。在这里，我们描述了 FC 被添加到 CPB 后获得的血浆中时对新生儿纤维蛋白网络的结构和降解的影响。
在获得机构审查委员会和家长同意后，从接受心脏手术的新生儿中采集血液样本并离心以获得血小板贫血浆。从以下时间点的血浆中体外形成凝块：（1）基线，（2）CPB 后即刻，和（3）冷沉淀输血后。此外，我们利用 CPB 后的血浆构建以下条件：（4）CPB+0.5mg/mL FC 和（5）CPB+0.9mg/mL FC。使用共聚焦显微镜分析所得纤维蛋白网络以分析整体结构、纤维密度和排列。使用微流控降解测定法分析凝块。对所有血浆样本进行纤维蛋白原含量的定量。
与未处理的 CPB 后样本相比，添加 0.5 或 0.9mg/mL FC 可显著增加 CPB 后样本的纤维密度中位数（CPB=0.44[四分位距{IQR}：0.36-0.52]，CPB+0.5mg/mL FC=0.69[0.56-0.77]，CPB+0.9mg/mL FC=0.87[0.59-0.96]；P=0.01 和 P=0.006）。CPB 后样本中添加 0.9mg/mL FC 可导致纤维密度大于体内输注冷沉淀后观察到的纤维密度（CPB+0.9mg/mL FC=0.54[0.45-0.77]，CPB+0.9mg/mL FC=0.87[0.59-0.96]；P=0.002）。CPB 后样本和用 FC 处理的样本之间的纤维排列中位数无显著差异。两种浓度（0.5 和 0.9mg/mL）的纤维蛋白降解率与基线值相比无统计学意义。此外，在控制体重后，我们发现基线和 CPB 后纤维蛋白原浓度之间的差异与患者年龄呈显著相关（P=0.033）。
我们的结果表明，用临床相关剂量（0.9mg/mL）的 FC 形成的体外凝块与体内输注冷沉淀的结构和降解特征相似。这些发现表明，FC 可有效恢复 CPB 后的结构纤维蛋白凝块特性。需要在体内给予 FC 后进行进一步的研究来验证这一假设。
