A tcd study of zero-crossing dynamics of solid and gaseous microembolic signals (mes)

16th Meeting of the Society of Neurosonology and Cerebral Hemodynamics, 21-24 May, Munich, 2011

R. Hoogenboezem and R.W.M. Keunen

Introduction
Micro-emboli of both solid or gaseous origin can occur during cardiac surgery. It is important to differentiate both, because solid emboli are generally associated with an increased stroke risk, whilst gaseous emboli are not (unless the embolic load is extremely high). Intensity and duration of MES are not reliable indices for discrimination. Therefore, the zero-crossing dynamics of solid and gaseous MES were examined to look whether this parameter could make a reliable distinction between gaseous and solid MES.

Methods
From a recording of a cardiovascular procedure 300 MES which were clearly associated with the entrapment of air into the circulation were selected and labeled by a human expert. Another 300 MES were selected and labeled from a recording of the postoperative phase of carotidendarterectomy. These events were associated with the presence of solid emboli. To make the problem more practical another 300 HITS which were clearly no MES were selected from both files. MES and artefacts were detected by the 2 MHz transcranial Doppler (EMS-9U/DelicaSystem/Shenzen Delicate Electronics Co. Ltd./China). and classified by the Embolus Detection System (see Fig.1) (EDS, SMT Medical, Wuerburg, Germany). The EDS allows to verify of every event the velocity display, the audio file and calculates for every event: intensity, duration and a socalled zerocrossing index (ZCI) For details of ZCI see reference Keunen.

介绍
心脏手术期间可能发生固体或气体来源的微栓塞。 区分两者很重要,因为固体栓子通常会增加中风风险,而气态栓子则不会(除非栓子负荷极高)。 MES的强度和持续时间不是区分的可靠指标。 因此,检查了固态和气态MES的过零动力学特性,看该参数是否可以可靠地区分气态和固态MES。

方法
从心血管程序的记录中,选择了300个与空气进入循环系统明显相关的MES,并由专家进行了标记。 选择了另外300个MES,并从记录了一个全齿状结肠切除术术后阶段的记录中进行了标记。 这些事件与固体栓子的存在有关。 为了使问题更实际,另外两个文件中均未选择MES的300个HITS。 通过2 MHz经颅多普勒仪(EMS-9U / DelicaSystem /深圳市德力凯医疗设备股份有限公司/中国)检测到MES和伪像。 并由栓子检测系统分类(见图1)(EDS,SMT Medical,德国维尔堡)。 EDS可以验证每个事件的速度显示,音频文件并计算每个事件:强度,持续时间和所谓的零交叉指数(ZCI)。有关ZCI的详细信息,请参见参考Keunen。(译文来自GOOGLE)

solidgaseousmes1.pdf