O'Rourke M M, Nork K M, Kurth C D
Department of Anesthesiology and Critical Care Medicine, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, 19104-4399, USA.
Crit Care Med. 2000 Jan;28(1):157-62. doi: 10.1097/00003246-200001000-00026.
Despite technical advances, neurologic sequelae continue to occur in neonates after heart surgery using deep hypothermic cardiopulmonary bypass (dhCPB) and circulatory arrest (DHCA). This study sought to determine the cerebral microcirculatory responses to hypoxia, hypotension, hypocapnia, and hypercapnia after dhCPB and DHCA.
Prospective laboratory animal trial.
Research laboratory.
Twenty-eight newborn pigs.
Piglets were divided into control, dhCPB, and DHCA groups. The control group received surgery. The dhCPB group received surgery and deep hypothermic CPB for 40 mins. The DHCA group received surgery, deep hypothermic CPB for 40 mins, and circulatory arrest for 60 mins. Two hours after the intervention, cerebral microcirculatory responses were examined.
Cerebral microcirculatory responses consisted of changes in cerebral oxygen saturation (Sco2) and pial arteriolar diameter measured by near- infrared spectroscopy and intravital microscopy, respectively. All groups experienced similar decreases in Sco2 and increases in pial arteriolar diameter in response to moderate and severe hypoxia (Pao2, 35 and 25 torr, respectively) and moderate and severe hypotension (mean pressure, 30 and 20 mm Hg, respectively). Sco2 and pial arteriolar diameter decreased to hypocapnia (Paco2, 25 torr) similarly in all groups. To hypercapnia (Paco2, 70 torr), Sco2 increased in the control group, did not change in the dhCPB group, and decreased in the DHCA group. Pial arteriolar diameter to hypercapnia increased in the control and the dhCPB groups but did not change in the DHCA group.
Cerebral vascular and oxygenation responses to hypoxia, hypocapnia, and hypotension were preserved after dhCPB and 1 hr of DHCA. By comparison, cerebral vascular and oxygenation responses to hypercapnia were not; both vascular and oxygenation responses were altered after DHCA, but only the oxygenation response was altered after dhCPB. These data suggest a selective disturbance in the microcirculation and/or parenchymal oxygen metabolism after DHCA and dhCPB.
尽管技术不断进步，但在使用深低温体外循环（dhCPB）和循环停止（DHCA）进行心脏手术的新生儿中，神经系统后遗症仍持续出现。本研究旨在确定dhCPB和DHCA后大脑微循环对缺氧、低血压、低碳酸血症和高碳酸血症的反应。
前瞻性实验室动物试验。
研究实验室。
28头新生猪。
仔猪分为对照组、dhCPB组和DHCA组。对照组接受手术。dhCPB组接受手术并进行40分钟的深低温体外循环。DHCA组接受手术、40分钟的深低温体外循环以及60分钟的循环停止。干预后两小时，检查大脑微循环反应。
大脑微循环反应分别通过近红外光谱法和活体显微镜测量脑氧饱和度（Sco2）和软脑膜小动脉直径的变化来体现。在中度和重度缺氧（动脉血氧分压分别为35和25托）以及中度和重度低血压（平均压分别为30和20毫米汞柱）时，所有组的Sco2均出现相似程度的下降，软脑膜小动脉直径均出现增加。在低碳酸血症（动脉血二氧化碳分压为25托）时，所有组的Sco2和软脑膜小动脉直径均出现相似程度的下降。在高碳酸血症（动脉血二氧化碳分压为70托）时，对照组的Sco2升高，dhCPB组的Sco2不变，DHCA组的Sco2下降。对照组和dhCPB组的软脑膜小动脉直径在高碳酸血症时增加，而DHCA组未发生变化。
在dhCPB和1小时的DHCA后，脑血管和氧合对缺氧、低碳酸血症和低血压的反应得以保留。相比之下，脑血管和氧合对高碳酸血症的反应则未保留；DHCA后血管和氧合反应均发生改变，但dhCPB后仅氧合反应发生改变。这些数据表明DHCA和dhCPB后微循环和/或实质氧代谢存在选择性紊乱。
