THE EFFICACY OF RETROGRADE CEREBRAL PERFUSION

最近在胸主动脉手术中采用了深低温逆行脑灌注。然而，其中几种方法的疗效仍存在争议。然后，我们在实验上评估了逆行脑灌流(RCP)在循环停止期间的疗效。然后用犬在常温状态下评价RCP的疗效。根据不同个体差异(灌流流量、灌流压力、静脉有无瓣膜等)，采用近红外光谱仪(NIRS)测定脑组织代谢和氧合。用直接刺激脊髓诱发的脑电位来评估脑功能。在常温状态下，将狗分为两组。I组(n=5)：单纯停环15min，再灌注60min，II组(n=S)，RCP停环15min，再灌注60min。结果如下：1)近红外技术在RCP检查中对发现脑内主要通过静脉瓣膜的灌注不良有一定的价值。2)在噪声环境下，直接刺激脊髓诱发的脑电位(体感皮层诱发电位)比刺激周围神经诱发的脑诱发电位更有价值。3)在NIRS控制脑血流灌注的情况下，比较两组诱发电位的潜伏期、潜伏期、消失时间和恢复时间，认为停循环期间逆行脑灌注不足以维持常温状态。那么，只有在深低温停循环期间，RCP才有可能通过周围静脉有效地冷却大脑。

Deep hyporthermic retrograde cerebral perfusion has been employed recently during operation on thoracic aorta. However the efficacy of of the methods are still controversial. Then we estimated the efficacy of retrograde cerebral perfusion (RCP) during circulatory arrest experimentally. Then dogs were used for estimating the efficacy of RCP in normothermic state. Near-infrared spectrophotometory (NIRS) was employed for measurement of cerebral metabolism and oxygenation according to the individual differences (perfusion flow, perfusion pressure, existence of valve in vein, etc.). And evoked cerebral potentials elicited by direct stimulation of the cord was employed for estimating cerebral function. In normothermic state, the dogs were divided into two groups. Group I (n=5) ; simple ciculatory arrest 15 min, reperfusion 60 min, Group II (n=S) ; RCP during ciculatory arrest 15 min, reperfusion 60 min. Results were as follows ; 1) NIRS was useful during RCP for detecting malperfusion of the brain mainly by valve of veins. 2) Evoked cerebral potentials elicited by direct stimulation of the cord was useful in the noisy circumstances compared with them by stimulation of the peripheral nerve (somatosensory cortical evoked potentials). 3) Under controlling cerebral perfusion by NIRS,potentials, latencies, time of their loss and recovering time of evoked potentials were analyzed in groupI and groupII.From this study, we concluded that the efficacy of retrograde cerebral perfusion during circulatory arrest is not enough for maintaining normothermic state. Then RCP might have possibility of cooling brain effectively through veins around it only during deep hypothermic circulatory arrest.