Division of Cardiac, Thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Carl-Neuberg-Str 1, 30625 Hannover, Germany.
Eur J Cardiothorac Surg. 2011 Dec;40(6):1492-9; discussion 1499. doi: 10.1016/j.ejcts.2011.03.031. Epub 2011 Apr 30.
Hypothermic circulatory arrest (HCA) at different temperatures is a protection technique for operations involving the aortic arch. In combination with selective cerebral perfusion, higher arrest temperatures for the remaining body may be permitted. However, the ischaemic/reperfusion injury (I/R) in various organ systems, other than the brain, related to the specific HCA temperature has so far not been evaluated.
Fourteen pigs were randomly assigned to 60 min of sole HCA at 20 or 30 °C temperature, weaned from cardiopulmonary bypass (CPB) and followed 4h after HCA. Besides complex haemodynamic monitoring, laser-Doppler spectrophotometry for measuring capillary blood flow, tissue oxygen saturation and post-capillary venous filling pressures of the bowel was installed. At the end of experiment, organs were perfusion fixated and harvested.
During the entire experiment, haemodynamics revealed no differences between the groups. CPB bypass times were 177 ± 12 min in the 20 °C and 158 ± 11 min in the 30 °C group, respectively (p = 0.02). During reperfusion, lactate levels were initially significantly higher in the 30 °C animals (p = 0.001) but subsequently declined. Microcirculatory blood flow and velocity in the bowel were significantly reduced during cooling and reperfusion (p < 0.05), but were independent of final HCA temperature. Histological evaluation revealed significantly more oedema formation in the bowel wall of the 30 °C animals (p = 0.05).
Higher levels of circulating lactate levels during reperfusion indicate less effective organ protection at 30 than at 20 °C after 60 min of HCA. This is further substantiated by histological evidence for a more pronounced oedema inflammatory response within the bowel wall.
不同温度的低温循环停止（HCA）是主动脉弓手术的保护技术。与选择性脑灌注相结合，可能允许对其余身体的更高停止温度。然而，与大脑相关的各种器官系统的缺血/再灌注损伤（I / R）与特定的 HCA 温度有关，迄今为止尚未得到评估。
14 头猪被随机分为 20 或 30°C 温度下 60 分钟的单一 HCA，从心肺旁路（CPB）断奶，并在 HCA 后 4 小时进行随访。除了复杂的血液动力学监测外，还安装了用于测量毛细血管血流、组织氧饱和度和肠后毛细血管静脉充盈压的激光多普勒光谱仪。在实验结束时，对器官进行灌注固定和收获。
在整个实验过程中，两组之间的血液动力学没有差异。20°C 组的 CPB 旁路时间为 177±12 分钟，30°C 组为 158±11 分钟（p=0.02）。再灌注期间，30°C 动物的乳酸水平最初显著升高（p=0.001），但随后下降。冷却和再灌注期间肠的微循环血流和速度明显降低（p<0.05），但与最终 HCA 温度无关。组织学评估显示，30°C 动物的肠壁水肿形成明显更多（p=0.05）。
再灌注期间循环乳酸水平较高表明，在 60 分钟 HCA 后，30°C 时的器官保护效果不如 20°C 时有效。这进一步由肠壁内更明显的水肿炎症反应的组织学证据证实。
