1 International Collaboration on Repair Discoveries, University of British Columbia (UBC) , Vancouver, British Columbia, Canada .
2 Vancouver General Hospital, Division of Critical Care Medicine, Department of Medicine, University of British Columbia (UBC) , Vancouver, British Columbia, Canada .
J Neurotrauma. 2018 Jun 15;35(12):1345-1357. doi: 10.1089/neu.2017.5285. Epub 2018 Mar 28.
Current clinical guidelines recommend elevating the mean arterial blood pressure (MAP) to increase spinal cord perfusion in patients with acute spinal cord injury (SCI). This is typically achieved with vasopressors such as norepinephrine (NE) and phenylephrine (PE). These drugs differ in their pharmacological properties and potentially have different effects on spinal cord blood flow (SCBF), oxygenation (PO), and downstream metabolism after injury. Using a porcine model of thoracic SCI, we evaluated how these vasopressors influenced intraparenchymal SCBF, PO, hydrostatic pressure, and metabolism within the spinal cord adjacent to the injury site. Yorkshire pigs underwent a contusion/compression SCI at T10 and were randomized to receive either NE or PE for MAP elevation of 20 mm Hg, or no MAP augmentation. Prior to injury, a combined SCBF/PO sensor, a pressure sensor, and a microdialysis probe were inserted into the spinal cord adjacent to T10 at two locations: a "proximal" site and a "distal" site, 2 mm and 22 mm from the SCI, respectively. At the proximal site, NE and PE resulted in little improvement in SCBF during cord compression. Following decompression, NE resulted in increased SCBF and PO, whereas decreased levels were observed for PE. However, both NE and PE were associated with a gradual decrease in the lactate to pyruvate (L/P) ratio after decompression. PE was associated with greater hemorrhage through the injury site than that in control animals. Combined, our results suggest that NE promotes better restoration of blood flow and oxygenation than PE in the traumatically injured spinal cord, thus providing a physiological rationale for selecting NE over PE in the hemodynamic management of acute SCI.
目前的临床指南建议提高平均动脉压（MAP）以增加急性脊髓损伤（SCI）患者的脊髓灌注。这通常通过血管加压药如去甲肾上腺素（NE）和苯肾上腺素（PE）来实现。这些药物在药理学特性上有所不同，并且在损伤后对脊髓血流量（SCBF）、氧合（PO）和下游代谢可能具有不同的影响。使用猪的胸段 SCI 模型，我们评估了这些血管加压药如何影响损伤部位相邻脊髓内的脑实质 SCBF、PO、静水压力和代谢。约克夏猪在 T10 处接受挫伤/压缩性 SCI，并随机接受 NE 或 PE 以升高 MAP20mmHg，或不进行 MAP 增强。在损伤之前，将组合的 SCBF/PO 传感器、压力传感器和微透析探针插入到 T10 附近的脊髓中，在两个位置：一个“近端”位置和一个“远端”位置，分别距离 SCI 2mm 和 22mm。在近端部位，NE 和 PE 在脊髓受压期间对 SCBF 的改善很小。减压后，NE 导致 SCBF 和 PO 增加，而 PE 则观察到水平降低。然而，NE 和 PE 均与减压后乳酸/丙酮酸（L/P）比值逐渐降低有关。PE 与损伤部位的出血比对照动物更多。综合来看，我们的结果表明，NE 在创伤性损伤的脊髓中比 PE 更能促进血流和氧合的更好恢复，从而为在急性 SCI 的血流动力学管理中选择 NE 而不是 PE 提供了生理依据。
