Tanaka H
First Department of Surgery, Chiba University School of Medicine, Japan.
Jpn J Thorac Cardiovasc Surg. 1998 Jun;46(6):532-7. doi: 10.1007/BF03250595.
The validity of transcranial doppler (TCD) as a monitor of cerebral blood flow during hypothermic selective cerebral perfusion (SCP) was investigated in dogs. Cerebral flow was maintained by infusing blood into the aortic arch while the descending aorta was totally crossclamped. The anterior cerebral arterial blood flow velocity (ACAv) was continuously measured with the EME TC2-64 TCD velocimeter by transorbital approach. In five dogs, cerebral flows were varied in steps from 5 to 10, 15, and 20 ml/kg/min in both cooling phase (rectal temp.: 25 degrees C, 20 degrees C) and rewarming phase (25 degrees C, 30 degrees C). ACAv was 46 +/- 7 cm/sec before cardiopulmonary bypass (CPB) started. Correlations between cerebral perfusion flow rate and ACAv were 0.59 in cooling phase and 0.85 in rewarming phase. In eight beagles, after core cooling at a constant systemic perfusion flow rate of 80 ml/kg/min, SCP was performed for 90 min at 25 degrees C; Group I (n = 4): 5 ml/kg/min, Group II (n = 4): 10 ml/kg/min, and rewarmed. Carotid arterial pressure (CAP) and ACAv were monitored continuously. Furthermore changes of jugular venous blood lactate/pyruvate concentration ratio after SCP were compared between groups. Percent changes of CAP during SCP for pre-CPB value were not significant between groups. Percent change of ACAv during SCP was significantly higher in Group II (59 +/- 12%) than in Group I (34 +/- 8%). Ninety minutes after SCP, lactate/pyruvate concentration ratio was increased in Group I (125 +/- 44%) and decreased in Group II (73 +/- 18%) for pre-CPB value. In Group I, it was considered that anaerobic metabolism and glycolysis were progressed. These results suggest that changes in ACAv reliably correlate with changes in cerebral perfusion flow rate and reflect cerebral metabolism. In five clinical cases, ACAv during SCP were about 50% of preoperative values. All the patients awoke well after operations and had no neurological complications. In conclusion, ACAv measured with TCD is available in monitoring cerebral blood flow during hypothermic SCP.
在犬类动物中研究了经颅多普勒（TCD）作为低温选择性脑灌注（SCP）期间脑血流监测手段的有效性。在降主动脉完全阻断的情况下，通过向主动脉弓内输注血液来维持脑血流。采用经眶入路，使用EME TC2 - 64 TCD测速仪连续测量大脑前动脉血流速度（ACAv）。在5只犬中，在降温阶段（直肠温度：25℃、20℃）和复温阶段（25℃、30℃），脑血流以5至10、15和20 ml/kg/min的梯度变化。在体外循环（CPB）开始前，ACAv为46±7 cm/秒。降温阶段脑灌注流速与ACAv的相关性为0.59，复温阶段为0.85。在8只比格犬中，在以80 ml/kg/min的恒定全身灌注流速进行核心降温后，于25℃进行90分钟的SCP；第一组（n = 4）：5 ml/kg/min，第二组（n = 4）：10 ml/kg/min，然后复温。连续监测颈动脉压力（CAP）和ACAv。此外，比较了两组在SCP后颈静脉血乳酸/丙酮酸浓度比值的变化。两组在SCP期间CAP相对于CPB前值的百分比变化无显著差异。SCP期间，第二组（59±12%）的ACAv百分比变化显著高于第一组（34±8%）。SCP 90分钟后，相对于CPB前值，第一组的乳酸/丙酮酸浓度比值升高（125±44%），第二组降低（73±18%）。在第一组中，认为发生了无氧代谢和糖酵解。这些结果表明，ACAv的变化与脑灌注流速的变化可靠相关，并反映脑代谢。在5例临床病例中，SCP期间的ACAv约为术前值的50%。所有患者术后恢复良好，无神经并发症。总之，用TCD测量的ACAv可用于监测低温SCP期间的脑血流。
