Ohmi M, Sato S, Ito T, Haneda K, Mohri H
Department of Thoracic and Cardiovascular Surgery, Tohoku University School of Medicine, Japan.
Cryobiology. 1990 Feb;27(1):31-41. doi: 10.1016/0011-2240(90)90050-e.
To evaluate the effects of 5% carbon dioxide (CO2) administration for hypothermic circulatory arrest, neurological evaluation and pathological studies were carried out on the canine brain. Twenty-two dogs were assigned to five groups: Group 1: Three dogs without hypothermia were sacrificed as the control group. Group 2: Nine dogs were subjected to surface hypothermia (20 degrees C) under deep ether anesthesia with 100% oxygen (O2) and hyperventilation. Circulatory arrest time was 30 min in Group 2A and 60 min in Group 2B. Group 3: Ten dogs were surface cooled (20 degrees C) under deep ether anesthesia with a 95% O2 and 5% CO2 mixture. Thirty minutes of circulatory arrest was instituted in Group 3A and 60 min in Group 3B. Dogs in Groups 2 and 3 were surface rewarmed and kept alive until they were sacrificed electively 6 or more months later. Results were as follows: (i) Postoperative neurological disturbance was detected in only two dogs in Group 2B. (ii) The percentage of damaged nerve cells among the total nerve cells counted in the cerebral cortex of the frontal lobe was significantly greater in Groups 2A (22.4%), 2B (30.1%), 3A (19.6%), and 3B (22.2%) compared with Group 1 (7.1%). (iii) The number of glia cells per nerve cell in the cerebellar dentate nucleus was significantly higher in Group 2B (27.2) than in Groups 1 (11.8), 2A (16.7), 3A (17.9), and 3B (18.6). (iv) The number of Purkinje cells in a 10-mm length of the cerebellum was markedly reduced to 89 in Group 2B compared with 122, 134, and 117 in Groups 1, 2A, and 3A, respectively. In conclusion, the results of quantitative pathological brain analysis reflected the incidence of postoperative neurological disturbance and suggested that the administration of 5% CO2 could prolong the time limit for circulatory arrest.
为评估5%二氧化碳（CO₂）用于低温循环骤停的效果，对犬脑进行了神经学评估和病理学研究。22只犬被分为五组：第1组：3只未进行低温处理的犬作为对照组被处死。第2组：9只犬在深度乙醚麻醉、100%氧气（O₂）和过度通气条件下进行体表低温（20℃）处理。第2A组的循环骤停时间为30分钟，第2B组为60分钟。第3组：10只犬在深度乙醚麻醉、95% O₂和5% CO₂混合气体条件下进行体表降温（20℃）。第3A组进行30分钟的循环骤停，第3B组为60分钟。第2组和第3组的犬进行体表复温并存活，直到6个月或更久后被选择性处死。结果如下：（i）第2B组仅2只犬术后出现神经功能障碍。（ii）与第1组（7.1%）相比，第2A组（22.4%）、第2B组（30.1%）、第3A组（19.6%）和第3B组（22.2%）额叶大脑皮质中受损神经细胞占所计数神经细胞总数的百分比显著更高。（iii）第2B组小脑齿状核中每个神经细胞的神经胶质细胞数量（27.2）显著高于第1组（11.8）、第2A组（16.7）、第3A组（17.9）和第3B组（18.6）。（iv）与第1组、第2A组和第3A组分别为122、134和117相比，第2B组小脑10毫米长度内的浦肯野细胞数量显著减少至89个。总之，脑定量病理学分析结果反映了术后神经功能障碍的发生率，并表明给予5% CO₂可延长循环骤停的时间限制。
