Study of platelet injury during profound hypothermic extracorponeal circulation

深低温体外循环过程中血小板损伤的研究

• 批准号: 11671333
• 负责人: MIYAMOTO Shinji
• 金额: $ 1.22万
• 依托单位: OITA MEDICAL UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11671333/
• 关键词: platelet spontaneous aggregation; platelet microaggregation; profound hypothermia; 血小板微少凝集; 超低体温体外循環; ヘパリン

Objective of this research is to study mechanism of bleeding tendency during profound hypothermia (PH) on thoracic aneurysm operation highlighting platelet injury. In vitro experiments, 60 minutes incubation at 4℃ caused no spontaneous aggregation in PRP (platelet rich plasma) without heparin, whereas spontaneous aggregation was observed when it was supplemented with heparin (4u/ml). PRP supplemented with heparin showed small amount of spontaneous aggregation at 10℃ not at 20℃ nor 30℃. In both moderate and PH cardiopulmonary bypass (CPB) cases, 3×10^<-6>mol/L of ADP (adenosine diphosphate) caused platelet micro aggregation (PMA) before heparin administration and 3.9×10^<-7> mol/L of ADP could cause PMA after systemic heparinazation. PH CPB reduced platelet activity (3×10^<-6> mol/L of ADP was not enough to cause micro aggregation) as time went more than moderate hypothermic CPB did. Although particles like spontaneous aggregation were observed 60 minutes after PH was established, it was hard to distinguish them from debris in plasma. In extracorporeal circuit model experiment with blood not containing any cells other than platelets, platelet aggregability was attenuated as time passed. After cooling platelets rapidly lost its activity. However, spontaneous aggregation was not observed even under PH condition. Therefore, bleeding tendency in operations is probably due to reduction of platelet aggregability not due to platelet consumption caused by PH.

本研究的目的是探讨深低温对血小板损伤突出的胸动脉瘤手术出血倾向的影响机制。体外实验显示，不加肝素60分钟后，富血小板血浆（PRP）未发生自发聚集，而添加肝素（4u/ml）时，PRP有自发聚集现象。添加肝素的PRP在10℃时出现少量自发聚集，而在20℃和30℃时则没有。在中度和PH的体外循环（CPB）病例中，肝素给药前3×10^<-6>mol/L的ADP（二磷酸腺苷）引起血小板微聚集（PMA），系统性肝素化后3.9×10^<-7> mol/L的ADP引起PMA。随着时间的推移，PH CPB比中等低温CPB更能降低血小板活性（3×10^<-6> mol/L ADP不足以引起微聚集）。虽然在PH值建立60分钟后观察到自发聚集的颗粒，但很难将其与等离子体中的碎片区分开来。在体外循环模型实验中，血液中除血小板外不含任何细胞，血小板的聚集性随着时间的推移而减弱。冷却后血小板迅速失去活性。然而，即使在PH条件下也未观察到自发聚集。因此，手术中的出血倾向可能是由于血小板聚集性的降低，而不是由于PH引起的血小板消耗。