急性主动脉夹层（AAD）是一种病情凶险、进展快、死亡率高的大血管疾病。目前最有效的救治措施为中-深度低温停循环下的外科手术。本课题前期研究发现AAD手术中，低温停循环严重影响患者的凝血功能，且随低温停循环的温度降低，凝血功能的损害越严重。目前国内外关于不同梯度低温停循环手术中血液保护的研究十分有限。据此，本课题组提出“在保护重要脏器的前提下，适当提高AAD手术中低温停循环的温度范围，以减少深低温停循环对血液系统的损害”假设。本研究旨在通过建立不同梯度低温停循环动物模型，采用RT-PCR等多种组织细胞实验方法，比较重要脏器的病理切片、氧化应激及炎症细胞浸润和炎症介质的表达水平，以及细胞凋亡水平的差别，以期在不同梯度低温对保护重要脏器无差别的前提下，应用ELISA等多种检测方法明确不同梯度低温停循环对凝血系统的影响及变化规律，为AAD患者术中低温范围选择和血液保护策略提供临床指导。

Acute aortic dissection (AAD) is a serious macrovascular disease with rapid progression and high mortality. Nowadays, surgical operation under moderate to deep hypothermic circulatory arrest is the most effective treatment for this disease. Our previous studies have shown that hemostatic function were severely influenced by hypothermic circulatory arrest in surgical operation for AAD, and there was more damage for hemostatic function if the lower hypothermia. However, the current research on blood system protection during surgical operation under hypothermic circulation arrest is very limited. Based on these findings, we hypothesized that if vital organ protection is no difference using different gradient hypothermia, aortic dissection surgery can be safely performed under the higher hypothermic circulatory arrest temperature range to reduce the damage to the hemostatic system in deep hypothermic circulatory arrest. Through the establishment of animal model in different gradient hypothermic circulatory arrest, the present study aimed to evaluate the distinction for vital organ protection influenced by different gradient hypothermia through the tissue and cell experiments in vitro using real-time PCR in order to comparing pathological section, oxidative stress, inflammatory cell infiltration, inflammatory mediators and cell apoptosis levels. On the basis of the similar vital organ protection, this study also clarified the effects and regulation of different gradient hypothermic circulatory arrest for the hemostatic system with ELISA methods for providing clinical direction for AAD patients in the hypothermia range selection and blood system protection.