Dexter F, Hindman B J, Cutkomp J, Smith T
Department of Anesthesia, University of Iowa, Iowa City 52242.
Perfusion. 1994;9(6):393-7. doi: 10.1177/026765919400900604.
Hypothermia protects the brain from injury during cardiopulmonary bypass and hypothermic circulatory arrest. However, when the arterial cannula is at sites other than the ascending aorta, brain cooling before circulatory arrest may be incomplete, contributing to poor neurological outcome. The authors performed an experiment using a rabbit model of cardiopulmonary bypass with femoral arterial perfusion. Arterial perfusate and carotid artery temperatures were simultaneously measured in six rabbits undergoing cardiopulmonary bypass, three with femoral artery cannulation, and three with subclavian artery cannulation. The subclavian artery site was chosen as a surrogate for ascending aortic cannulation. Carotid blood temperature was 3.7 degrees C to 0.3 degree C warmer than arterial perfusate temperature during femoral arterial perfusion. The temperature difference decreased over time (p = 0.0007). The temperature gradient was significantly less (p = 0.002) when subclavian arterial perfusion was used. Carotid blood temperature was 1.1 degrees C to 0.0 degree C warmer than arterial perfusate temperature during subclavian cannulation. The authors conclude that when femoral perfusion cooling is used, blood is warmed as it flows in a retrograde direction in the descending aorta to the carotid artery.
低温可在体外循环和低温循环停搏期间保护大脑免受损伤。然而，当动脉插管位于升主动脉以外的部位时，循环停搏前的脑降温可能不完全，导致神经功能预后不良。作者使用兔体外循环股动脉灌注模型进行了一项实验。在六只接受体外循环的兔子中，同时测量动脉灌注液温度和颈动脉温度，其中三只进行股动脉插管，三只进行锁骨下动脉插管。选择锁骨下动脉部位作为升主动脉插管的替代部位。在股动脉灌注期间，颈动脉血温比动脉灌注液温度高3.7℃至0.3℃。温差随时间降低（p = 0.0007）。使用锁骨下动脉灌注时，温度梯度明显更小（p = 0.002）。在锁骨下动脉插管期间，颈动脉血温比动脉灌注液温度高1.1℃至0.0℃。作者得出结论，当使用股动脉灌注降温时，血液在降主动脉中逆行流向颈动脉的过程中会升温。
