Department of Cardiac Surgery, Asahikawa Medical University, Midorigaoka-Higashi 2-1-1-1, Asahikawa, Hokkaido, 078-8510, Japan.
Department of Cardiovascular Surgery, Heinrich Heine University, Düsseldorf, Germany.
J Artif Organs. 2022 Dec;25(4):314-322. doi: 10.1007/s10047-022-01324-5. Epub 2022 Mar 18.
Hypothermic circulatory arrest (HCA) is an essential procedure during aortic surgery to protect organs; however, hypothermia is believed to cause coagulopathy, which is a major fatal complication. This study aimed to clarify the impact of hypothermia on coagulation by eliminating clinical biases in vitro. In the hypothermic storage study, blood samples from five healthy volunteers were stored at 37 ℃ (group N) for 3 h or at 20 ℃ for 2 h, followed by 1 h of rewarming at 37 ℃ (group H). Thromboelastography was performed before and after 3 h of storage. In the mock circulation loop (MCL) study, blood samples were placed in the MCL and (a) maintained at 37 ℃ for 4 h (group N, n = 5), or (b) cooled to 20 ℃ to simulate HCA with a 0.1 L/min flow rate for 3 h and then rewarmed to 37 ℃ (group H, n = 5). The total MCL duration was 4 h, and the flow rate was maintained at 1 L/min, except during HCA. Blood samples collected 15 min after the beginning and end of MCL were subjected to standard laboratory tests and rotational thromboelastometry analyses. Hypothermia had no impact on coagulation in both the hypothermic storage and MCL studies. MCL significantly decreased the platelet counts and clot elasticity in the INTEM and EXTEM assays; however, there was no effect on fibrinogen contribution measured by FIBTEM. Hypothermia does not cause irreversible coagulopathy in vitro; however, MCL decreases coagulation due to the deterioration of platelets.
低温循环停止（HCA）是主动脉手术中保护器官的必要程序；然而，低温被认为会导致凝血功能障碍，这是一个主要的致命并发症。本研究旨在通过在体外消除临床偏倚来阐明低温对凝血的影响。在低温储存研究中，来自五名健康志愿者的血液样本在 37°C（组 N）下储存 3 小时或在 20°C 下储存 2 小时，然后在 37°C 下再升温 1 小时（组 H）。在储存前和储存 3 小时后进行血栓弹性描记术。在模拟循环回路（MCL）研究中，将血液样本放置在 MCL 中，并（a）在 37°C 下保持 4 小时（组 N，n=5），或（b）冷却至 20°C 以模拟 HCA，以 0.1 L/min 的流速持续 3 小时，然后再升温至 37°C（组 H，n=5）。总 MCL 持续时间为 4 小时，流速保持在 1 L/min，除了在 HCA 期间。在 MCL 开始和结束后 15 分钟采集的血液样本进行标准实验室测试和旋转血栓弹性测定分析。低温在低温储存和 MCL 研究中均对凝血无影响。MCL 显著降低 INTEM 和 EXTEM 测定中血小板计数和凝块弹性；然而，对 FIBTEM 测量的纤维蛋白原贡献没有影响。低温不会在体外引起不可逆的凝血功能障碍；然而，MCL 会因血小板恶化而降低凝血。
