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

深低温停循环常用于胸主动脉瘤和先天性心脏病。但允许循环停搏的时间往往是一个有争议的问题。我们研究了深低温间歇停循环(DHICA)延长全循环停搏允许时间的可能性。25只比格犬以100ml/kg/min的速度进行体外循环，冷却至18ﾟC(深低温)。将动物随机分为5组，每组10只，每组10只。第1组：DHT术中不间断体外循环；第2组：DHT术中停循环40min；第3组：DHT术中停循环60min；第4组：DHT术中CA80min；第5组：CA20min，再循环10min，重复6次。用近红外分光光度计测CA过程中脑组织氧合血红蛋白的变化。在第2/3/4组中，氧合血红蛋白随着CA的开始逐渐降低，并在平均24.9(sy.+-)时进入平台期。[)1.2，这意味着氧合血红蛋白不能再为脑组织提供氧气。5组在氧合血红蛋白进入平台期前开始再循环，在再循环10分钟内氧合血红蛋白恢复到停搏前水平。实验结束后，动物复温至35ﾟC，取脑组织测定线粒体呼吸指数和含水率。第4组RCI显著低于其他组(p&lt；0.05)。5组保持良好的RCI，但总停循环时间比4组长40分钟。此外，5组的脑水肿(反映脑水肿的指标)明显轻于其他组。这些结果表明，DHICA可以延长全循环停搏允许时间，而DHICA在预计LOGN停循环时可能是一种有用的选择。

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.