Evaluation of ischemic damage of immature brain by acoustic densitometry

脑瘫的预防是新生儿医学中最重要的问题之一。众所周知，脑室周围白质软化是早产儿脑瘫的最重要原因。但是脑室周围白质软化的预防还没有建立，因为不可能真实的及时检测脑缺血。本研究的目的是应用超声声学密度定量技术评价未成熟脑的缺血性损伤。对36小时龄内的新生猪进行了检查。新生猪用乙醚吸入麻醉，进行机械通气。制作每只动物颅骨的回波窗。通过下述方法加载对动物未成熟脑的缺血性损伤。(1)结扎双侧颈总动脉;（2）抽取血液;（3）结扎双侧颈总动脉并过度换气。这些程序是使用血压、脉搏和近红外光谱监测器进行的。在缺血负荷前后，静脉注射5%白蛋白后，用声学密度计记录强度。记录部位为双侧丘脑和室周白色物质。结果与讨论未成熟动物脑内强度变化不一致。在这项研究中，声学密度测定法不能检测缺血性变化。需要改进方法。

Puroose and BackgroundPrevention of cerebral palsy is one of the most important problem in neonatal medicine. It is well known that periventricular leukomalacia is the most important cause of cerebral palsy in premature infants. But prevention of periventricular leukomalacia has not been established because the detection of cerebral ischemia is impossible on real time. The purpose of this study is to evaluate ischemic damage of immature brain by acoustic densitometry using ultrasonography.Materials and Methods1. Newborn pigs within 36 hours of age were examined. Newborn pigs were anesthetized by diethyl ether inhalation and mechanical ventilation was carried out. Echo-windows of the skull bone in each animal were made. Ischemic damage to immature brain of the animals were loaded by the methods described below. (1) ligation of bilateral carotid arteries, (2) extraction of blood, (3) ligation of bilateral carotid arteries and hyperventilation. These procedures were performed using monitors of blood pressure, pulse and near infrared spectroscopy.2. Before and after ischemic load, intensities were recorded by acoustic densitometry after intravenous injection of 5 % albumin sonicated. The recorded sites were bilateral thalainus and periventricular white matters.Results and DiscussionThe changes of intensity of the brains of immature animals were inconsistent. Acoustic densitometry cannot detect ischemic change in this study. The improvement of methods will be needed.