Electroretinogram as a Monitor of Depth and Brain Ischemia, and as a model to study mechanisms of anesthesia.

实验一研究了吸入麻醉药甲氧氟醚、氟烷、安氟醚和异氟醚对家兔视网膜电图（ERG）的影响。根据a波和b波中的第一振荡分量（OP-1）分析ERG。当麻醉剂潮气末浓度超过0.8 MAC时，OP-1峰潜伏期显示出显著的剂量相关性延长。α波和O-1波幅呈剂量依赖性降低，但其变化不如OP-1潜伏期明显。用同样的方法，观察缺氧对脑组织a波潜伏期的影响。呼吸暂停3 min后，a波和OP的峰潜伏期均延长，a波振幅降低，而麻醉药仅延长OP的峰潜伏期。PaO_2 <50 ℃时，出现低通气性改变。实验二采用牛蛙眼杯模型研究麻醉对ERG的影响，并初步建立麻醉深度和脑缺氧的ERG监测系统。为此，我们设计了一种特殊的接触式透镜型ERG电极，它配有一根光纤，并与一个频闪光源相连。此外，还编制了信号处理程序，实现了快速诊断。该系统的临床评价正在调查中。

In the first experiment, the effects of volatile anesthetics, i.e. methoxyflurane, halothane, enflurane and isoflurane, on the electroretinogram (ERG) were studied in rabbits. The ERG was analyzed in terms of the a-wave and the first oscillatory component (OP-1) in the b-wave. The OP-1 peak latency showed a significant dose-related prolongation when anesthetic end-tidal concentrations were in excess of 0.8 MAC. The amplitudes of the a-wave and the O-1 decreased in dose-dependent manners, but their changes were less striking than those of the OP-1 latency. The peak latency of the a-wave remained unchanged.Using the same preparation, the effects of hypoxia were studied. After 3 min apnea, both peak latencies of the a-wave and the OP were prolonged and the amplitude of the a-wave decreased, while the anesthetics prolnged only the OPs' latencies. Hypoxic changes were observed under PaO2 less than 50 torr. Therefore, ERG would be a useful intraoperative monitoring to brain hypoxia and anesthetic depth.In the second experiment, anesthetic effects on the ERG were studied using a bull frog eye-cup preparation.Finnaly, we intended to develop the ERG monitoring system for anesthetic depth and brain hypoxia. For this purpose, we designed a special contact lens type ERG electrode equipped with a optical fiber which was connected to Xe strobophotic light sourse. In addition, a signal processing program was induced for rapid diagnosis. The clinical evaluation of the system is under the investigation.