Department of Cardiothoracic Surgery, Mount Sinai School of Medicine, One Gustave L. Levy Place, PO Box 1028, New York, NY 10029, USA.
Eur J Cardiothorac Surg. 2009 Dec;36(6):946-55. doi: 10.1016/j.ejcts.2009.05.046. Epub 2009 Jul 28.
To shorten cooling/rewarming associated with hypothermic neuroprotection strategies during complex aortic arch surgery, selective cerebral perfusion (SCP) at 28 degrees C has recently been advocated, although its safe limits - especially with regard to the ischaemic tolerance of the spinal cord - have not been systematically examined.
Twenty juvenile Yorkshire pigs (30.3+/-2.8kg) were randomly allocated to undergo circulatory arrest and SCP at 28 degrees C for 90 min (group A; N=12) or 120 min (group B; N=8) at 50 mmHg using alpha-stat pH management. Spinal cord blood flow (SCBF) was assessed using fluorescent microspheres at baseline (prior to SCP); at 5 and 80 min during SCP, and at 1, 5 and 48 h after cardiopulmonary bypass (CPB). A modified Tarlov score was used to evaluate neurobehavioural recovery in all survivors blindly from videotapes for 5 days postoperatively. Histological ischaemic spinal cord injury was scored after sacrifice.
All pigs could be weaned from CPB and ventilation, but seven pigs (58%) in group A and five (63%) in group B developed multi-organ failure and died within 24h. SCBF diminished immediately after initiation of SCP and was absent throughout SCP in all segments below T8/9, recovering to baseline 1h after SCP at all cord levels. All survivors suffered moderate-to-severe histological lumbar spinal cord damage, more severe in group B (p< or =0.049). Three of five group A pigs recovered normal function, but two suffered paraparesis. Group B survivors had a worse neurologic outcome (p<0.0001): all suffered paraplegia (one immediate, and two on day 2, after initial recovery).
SCP provides insufficient SCBF below T8/9 to sustain cord viability. At 28 degrees C, the ischaemic tolerance of the cord may be exceeded enough by 90 min to impair function; by 120 min, SCP at 28 degrees C invariably results in paraplegia.
在复杂主动脉弓手术中，为缩短低温神经保护策略相关的冷却/复温过程，最近提倡采用 28°C 选择性脑灌注（SCP），但尚未系统地检查其安全限制（特别是脊髓的缺血耐受）。
20 头幼龄约克夏猪（30.3+/-2.8kg）随机分为两组，每组 12 头（组 A）或 8 头（组 B），在循环停止期间行 SCP 于 28°C 50mmHg 下，采用 pH 值阿尔法-stat 管理。在 SCP 前（开始 SCP 前）、SCP 期间的 5min 和 80min、CPB 后 1h、5h 和 48h 评估脊髓血流（SCBF）。所有存活者术后 5 天通过盲法从录像带评估神经行为恢复情况，采用改良的 Tarlov 评分进行评估。所有存活者在牺牲后对脊髓缺血性损伤进行组织学评分。
所有猪都可以从 CPB 和通气中恢复，但组 A 的 7 头（58%）和组 B 的 5 头（63%）猪出现多器官衰竭并在 24 小时内死亡。SCP 开始后 SCBF 立即减少，所有 T8/9 以下节段的 SCP 期间 SCBF 完全消失，所有脊髓水平的 SCP 后 1h 恢复到基线。所有存活者的腰椎脊髓均有中度至重度组织学损伤，组 B 更严重（p<0.049）。组 A 的 5 头中有 3 头恢复正常功能，但有 2 头出现轻截瘫。组 B 存活者的神经功能预后更差（p<0.0001）：所有存活者均出现截瘫（1 例立即发生，2 例在最初恢复后第 2 天发生）。
28°C 下，SCP 在 T8/9 以下提供的 SCBF 不足以维持脊髓存活。90min 可能会导致脊髓的缺血耐受达到足够程度而受损；120min 时，28°C 下的 SCP 总是导致截瘫。
