Cheng W, Hartmann J F, Cameron D E, Griffiths E M, Kirsch J R, Traystman R J
Division of Cardiac Surgery, Johns Hopkins Medical Institutions, Baltimore, Maryland.
Ann Thorac Surg. 1995 Apr;59(4):880-6. doi: 10.1016/0003-4975(95)00048-p.
Because disordered autoregulation of cerebral blood flow may underlie neurologic injury associated with cardiopulmonary bypass (CPB), we studied the effects of normothermic (37 degrees C) and hypothermic (18 degrees C) CPB on cerebral vascular reactivity in 6 to 8-week-old piglets. Hypothermic CPB animals were subdivided into alpha-stat and pH-stat groups (n = 6 animals each group) according to acid-base management protocol. Cerebral blood flow (CBF), cerebral oxygen consumption (CMRO2), cerebral vascular resistance (CVR), and CBF response to hypercapnia were examined before, during, and 1 hour after CPB and used to calculate CVR per millimeter of mercury change in arterial partial pressure of CO2: (CVRnormocapnia - CVRhypercapnia)/(PaCO2 hypercapnia - PaCO2 normocapnia). Before CPB, CBF, CMRO2, and vascular reactivity to elevated CO2 were similar in the three groups; these parameters remained unchanged by normothermic CPB. However, during hypothermic CPB, CBF and CMRO2 decreased in both alpha-stat and pH-stat groups; in the alpha-stat group, CBF decreased from 27 +/- 5 mL.min-1.100 g-1 (normothermic CPB) to 5 +/- 1 mL.min-1.100 g-1 (hypothermic CPB) (p < 0.05) and CMRO2 decreased from 1.8 +/- 0.21 to 0.24 +/- 0.04 mL.min-1.100 g-1 (p < 0.05), whereas in the pH-stat group CBF decreased from 28 +/- 2 to 9 +/- 1 mL.min-1. 100 g-1 (p < 0.05) and CMRO2 decreased from 1.63 +/- 0.07 to 0.31 +/- 0.09 mL.min-1.100 g-1 (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
由于脑血流的自动调节紊乱可能是与体外循环（CPB）相关的神经损伤的基础，我们研究了常温（37摄氏度）和低温（18摄氏度）CPB对6至8周龄仔猪脑血管反应性的影响。根据酸碱管理方案，低温CPB动物被分为α稳态和pH稳态组（每组n = 6只动物）。在CPB前、期间和之后1小时检查脑血流量（CBF）、脑氧耗量（CMRO2）、脑血管阻力（CVR）以及CBF对高碳酸血症的反应，并用于计算每毫米汞柱动脉二氧化碳分压变化时的CVR：（正常碳酸血症时的CVR - 高碳酸血症时的CVR）/（高碳酸血症时的PaCO2 - 正常碳酸血症时的PaCO2）。在CPB前，三组的CBF、CMRO2以及对升高的CO2的血管反应性相似；这些参数在常温CPB期间保持不变。然而，在低温CPB期间，α稳态组和pH稳态组的CBF和CMRO2均降低；在α稳态组中，CBF从27±5 mL·min-1·100 g-1（常温CPB）降至5±1 mL·min-1·100 g-1（低温CPB）（p < 0.05），CMRO2从1.8±0.21降至0.24±0.04 mL·min-1·100 g-1（p < 0.05），而在pH稳态组中，CBF从28±2降至9±1 mL·min-1·100 g-1（p < 0.05），CMRO2从1.63±0.07降至0.31±0.09 mL·min-1·100 g-1（p < 0.05）。（摘要截短于250字）
