Analysis of brain activation during cardiopulmonary bypass by positron emission tomography and brain tissue organelle.

深低温循环停搏常用于胸主动脉瘤和先天性心脏病。但是，允许血液循环停止的时间往往是一个有争议的问题。我们研究了深度低温间歇循环停搏（DHICA）延长总循环停搏许可时间的可能性。25只小猎犬以100mL/kg/min的速度体外循环（CPB）。冷却至18ºC （DHT：深度低温）。动物被DHT饲养3小时，分为5组。第一组：DHT期间不间断CPB。第二组：DHT期间循环停止（CA） 40分钟。第三组：DHT期间CA 60分钟。第4组：DHT期间进行80分钟的CA。第五组：CA 20分钟，再循环10分钟，重复6次。用近红外分光光度计测定CA过程中脑组织氧血红蛋白的变化。2/3/4组血氧血红蛋白随CA发病而依次下降，平均24.9(]SY.+- .[)1.2达到平台期，说明血氧血红蛋白不能再向脑组织供氧。另一方面，第5组在氧血红蛋白达到平台之前，开始再循环，在再循环10分钟后氧血红蛋白恢复到停搏前值。实验结束后将大鼠重新加热至35℃，取脑组织测定线粒体呼吸指数（RCI）和含水量比。第4组RCI显著低于其他组（p<0.05）。另一方面，5组RCI保持良好，但总循环停搏时间比4组长40分钟。第5组脑水肿（即脑水肿指数）明显轻于其他各组。这些结果表明，DHICA可以延长总循环骤停许可时间，DHICA可以是一个有用的选择，当长期循环骤停预期。

Deep hypothermic circulatory arrest is commonly used for thoracic aortic aneurysm and congenital heart disease. But circulatory arrest permission time is often a matter of some controversy. We examined possibility of extension of total circulatory arrest permission time by deep hypothermic intermittent circulatory arrest (DHICA). Twentyfive beagles were placed on cardiopulmonary bypass (CPB) at 100mL/kg/min.and cooled to 18ﾟC (DHT : deep hypothermia). The animals are kept DHT for 3 hours and divided into five groups. Group 1 : Uninterrupted CPB during DHT.Group 2 : 40 minutes of circulatory arrest (CA) during DHT.Group 3 : 60 minutes of CA during DHT.Group 4 : 80 minutes of CA during DHT.Group 5 : 20 minutes of CA following 10 minutes of recirculation repeating 6 times. Change of oxy-hemoglobin in brain tissue during CA was measured by near infrared spectrophotometer. In Group 2/3/4 oxy-hemoglobin was decreased sequentially with the onset of CA and became plateau at the mean time of 24.9(]SY.+-。[)1.2, that means oxy-hemoglobin could no longer supply oxygen to brain tissue. On the other hand, in Group 5, before oxy-hemoglobin became plateau, recirculation was begun, and oxy-hemoglobin recovered to prearrest value during ten minutes of recirculation. After the experiment period the animals are rewarmed to 35ﾟC and take brain tissue to measure mitochondrial respiratory index (RCI) and water content ratio. RCI of Group 4 was significantly lower than other Group (p<0.05). On the other hand, Group 5 keep good RCI while total circulatory arrest time was forty minutes longer than Group 4. Moreover, brain edema (that indicates index of brain edema) was significantly slighter in Group 5 than other Groups. These results suggest that DHICA can prolong total circulatory arrest permission time and DHICA can be a useful option when logn circulatory arrest is anticipated.