Kise Yuya, Kuniyoshi Yukio, Miyaishi Keita, Ando Mizuki, Higa Shotaro, Maeda Tatuya, Nakaema Moriyasu, Inafuku Hitoshi, Furukawa Kojiro
Department of Thoracic and Cardiovascular Surgery, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan.
Department of Cardiovascular Surgery, Urasoe General Hospital, Urasoe, Okinawa, Japan.
Cardiol Res. 2023 Apr;14(2):115-122. doi: 10.14740/cr1478. Epub 2023 Apr 8.
During thoracoabdominal aortic surgery, the spinal cord is placed under ischemic conditions. Elevation of systemic blood pressure is thus recommended as a method of increasing the blood supply from collateral networks. This study examined the mechanisms by which noradrenaline administration increases spinal cord blood flow (SCBF) by elevating systemic blood pressure.
In beagles ( = 7), the thoracoabdominal aorta and L2-L7 spinal cord segmental arteries (SAs) were exposed and a distal perfusion bypass was created to simulate clinical practice. SCBF was measured by laser flowmetry at the L5 dura mater and spinal cord perfusion pressure (SCPP) was measured inside the clamped aorta. The six pairs of SAs from L2 to L7 were clamped, and mean systemic blood pressure (mSBP), SCBF, and SCPP were measured before and after clamping and after starting continuous infusion of noradrenaline at 0.5 µg/kg/min. Rates of change in systemic vascular resistance (SVR) and spinal cord vascular resistance (SCVR) were calculated from the measured values.
With no SA clamping (control), the rate of increase in SCVR was 0.74 times the rate of increase in SVR (y = 0.2 + 0.74x, r = 0.889, r = 0.789; P < 0.01). When all six pairs of SAs were clamped, a weak correlation was evident between rate of change in SCVR and rate of change in SVR, and the rate of increase in SCVR was lower than the rate of increase in SVR (y = 0.39 + 0.07x, r = 0.209, r = 0.039; P < 0.01). When all six pairs of SAs were clamped in the absence of distal perfusion, a weak correlation was also evident between rate of change in SCVR and rate of change in SVR, and the rate of increase in SCVR was lower than the rate of increase in SVR (y = 0.19 + 0.08x, r = 0.379, r = 0.144; P < 0.01).
The rate of increase in SCVR induced by noradrenaline administration was lower than the rate of increase in SVR in the control group with no spinal cord SA clamping and in both experimental groups with clamped SAs (with and without distal perfusion), creating an environment conducive to spinal cord flow distribution.
在胸腹主动脉手术期间，脊髓处于缺血状态。因此，建议升高全身血压，作为增加侧支循环网络血液供应的一种方法。本研究探讨了通过升高全身血压，去甲肾上腺素给药增加脊髓血流量（SCBF）的机制。
在7只比格犬中，暴露胸腹主动脉和L2-L7脊髓节段动脉（SAs），并建立远端灌注旁路以模拟临床实践。通过激光血流仪测量L5硬脊膜处的SCBF，并在夹闭的主动脉内测量脊髓灌注压（SCPP）。夹闭L2至L7的六对SAs，在夹闭前后以及开始以0.5μg/kg/min持续输注去甲肾上腺素后，测量平均全身血压（mSBP）、SCBF和SCPP。根据测量值计算全身血管阻力（SVR）和脊髓血管阻力（SCVR）的变化率。
在未夹闭SAs（对照组）时，SCVR的增加率是SVR增加率的0.74倍（y = 0.2 + 0.74x，r = 0.889，r = 0.789；P < 0.01）。当夹闭所有六对SAs时，SCVR变化率与SVR变化率之间存在微弱相关性，且SCVR的增加率低于SVR的增加率（y = 0.39 + 0.07x，r = 0.209，r = 0.039；P < 0.01）。当在没有远端灌注的情况下夹闭所有六对SAs时，SCVR变化率与SVR变化率之间也存在微弱相关性，且SCVR的增加率低于SVR的增加率（y = 0.19 + 0.08x，r = 0.379，r = 0.144；P < 0.01）。
在未夹闭脊髓SAs的对照组以及夹闭SAs的两个实验组（有和没有远端灌注）中，去甲肾上腺素给药诱导的SCVR增加率低于SVR增加率，从而创造了有利于脊髓血流分布的环境。
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