Bailes J E, Leavitt M L, Teeple E, Maroon J C, Shih S R, Marquardt M, Rifai A E, Manack L
Department of Neurosurgery, Allegheny General Hospital, Pittsburgh, Pennsylvania.
J Neurosurg. 1991 May;74(5):781-8. doi: 10.3171/jns.1991.74.5.0781.
The potential for hypothermia to prevent or ameliorate ischemic injury to the central nervous system is well known. To determine if a more prolonged period of metabolic suppression with blood substitution is possible, a method was developed to lower body temperature to near the freezing point. Eight adult mongrel dogs underwent closed-chest extracorporeal circulation with both external and internal body cooling. As they were cooled, progressive hemodilution was employed until complete exsanguination and blood substitution with an aqueous solution was accomplished. Continuous circulation and a core temperature at a mean of 1.7 degrees C were maintained from 2 1/2 to 3 hours. After rewarming to 20 degrees C, the animals were autotransfused and allowed to recover. Of the eight animals, two died due to technical factors related to cardiac defibrillation. Of the six surviving animals, five survived over a long period and one died on the 10th postoperative day with hepatorenal failure resulting from a presumed blood transfusion incompatability reaction. All six showed normal neurological function and kennel behavior, except one dog with mild weakness of a hindlimb. When the dogs were sacrificed 1 to 2 months postoperatively, all organs were histologically normal. Specifically, there was no gross or microscopic evidence of ischemic or hypoxic injury to any central nervous system structures. This pilot study demonstrates that it is possible to successfully achieve complete exsanguination, blood substitution, and ultraprofound body temperature, while continuous circulation of the blood substitute is maintained. With the capability of controlling and repeatedly performing washout of the extracellular environment and by reaching lower temperatures, it may be possible to attain greater cellular metabolic suppression. This perhaps will extend the allowable times for circulatory arrest procedures. In addition, "bloodless ischemia" may be beneficial in removing both blood substances and formed elements which may mediate organ ischemia. With replacement of blood at warm temperatures, coagulopathy is avoided. This preliminary evidence demonstrates potential in the combination of ultraprofound hypothermia and complete blood component substitution. However, further study is required to confirm the potential of achieving circulatory arrest of longer duration.
低温预防或改善中枢神经系统缺血性损伤的可能性是众所周知的。为了确定通过血液置换实现更长时间代谢抑制是否可行，人们开发了一种将体温降至接近冰点的方法。八只成年杂种狗接受了体外循环，同时进行体外和体内降温。随着它们被冷却，采用逐步血液稀释，直到完全放血并用一种水溶液进行血液置换。持续循环并将核心温度维持在平均1.7摄氏度达2.5至3小时。复温至20摄氏度后，动物进行自体输血并使其恢复。八只动物中，两只因与心脏除颤相关的技术因素死亡。在六只存活的动物中，五只长期存活，一只在术后第10天死于肝肾衰竭，推测是由输血不相容反应导致的。除一只后肢轻度无力的狗外，所有六只动物的神经功能和犬舍行为均正常。术后1至2个月处死这些狗时，所有器官在组织学上均正常。具体而言，没有任何中枢神经系统结构出现缺血或缺氧损伤的大体或微观证据。这项初步研究表明，在维持血液替代品持续循环的同时，成功实现完全放血、血液置换和超低温体温是可能的。通过控制和反复进行细胞外环境冲洗的能力以及达到更低温度，可能实现更大程度的细胞代谢抑制。这或许将延长循环停止程序的允许时间。此外，“无血缺血”可能有利于清除可能介导器官缺血的血液物质和有形成分。在体温较高时进行血液置换，可避免凝血障碍。这一初步证据证明了超低温和全血成分置换相结合的潜力。然而，需要进一步研究来证实实现更长持续时间循环停止的潜力。
