Evaluation of ischemic damage of immature brain by acoustic densitometry

目的与背景脑瘫的预防是新生儿医学的重要课题之一。众所周知，脑室周围白质软化是早产儿脑瘫的最重要原因。但脑室周围白质软化的预防尚未建立，因为脑缺血的实时检测是不可能的。本研究的目的是利用超声声学密度测量技术评估未成熟脑的缺血性损伤。材料与方法对36小时以内的新生猪进行检查。新生猪采用乙醚吸入麻醉，机械通气。在每只动物的颅骨上都做了回声窗。采用以下方法对未成熟大鼠脑缺血损伤进行负荷。(1)双侧颈动脉结扎；(2)抽血；(3)双侧颈动脉结扎及过度通气。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%白蛋白超声后，用声密度仪记录强度。记录部位为双侧丘脑和脑室周围白质。结果与讨论未成熟动物脑强度变化不一致。在本研究中，声学密度测定不能检测到缺血性改变。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.