OPTIMAL PERFUSION CONDITION FOR RETROGRADE BRAIN PERFUSION

实验1.犬经矢状窦和上腔静脉逆行灌注，激光流量计测定脑血流量分别为5.5，9.0，10.1ml/100 g/min，驱动压分别为15，25，35 mmHg，中性红活体染色光度法测定脑组织pHi分别为6.38- 6.8，6.73 -7.08，逆行灌注90分钟后，15、25和35 mmHg的驱动压力下，6.79-7.16。微球测得大脑前部/皮质组织血流量分别为2.2/4.0、7.0/12.1和8.1/13.6ml/100 g/min。功能驱动压为25 mmHg或更高的逆行脑灌注可保护大脑。虽然在该动物模型中证实了脑组织中的实质性血流，但存在血流和局部pHi的高前沿性。实验2.在20 ℃条件下进行顺行极低流量灌注（120 min），观察灌注压、脑组织血流量和脑组织pHi之间的关系。10和20 ml/kg/min脑灌注可维持脑组织高pH值120分钟，驱动压力大于10 mmHg时，脑皮质血流量大于10.2 <plus-minus>± 1.9ml/100 g/min。当皮质血流量大于9 ml/100 g/min时，大脑皮质pHi大于7.1，当皮质血流量小于9 ml/100 g/min时，大脑耗氧量和皮质pHi降低，而葡萄糖摄取量不同时降低。这种血流低于10 ml/100 g/min的灌注条件会导致脑酸中毒，并可能导致脑损伤。这种不完全的脑灌注是否保护了大脑，或者相反地损害了大脑，还需要进一步研究。

Experiment 1.Dogs were perfused retrogradely via the sagittal sinus and SVC.Cerebral surface blood flow by laser flowmetry was 5.5,9.0,10.1ml/100g/min with driving pressure of 15,25,35mmHg.Cerebral tissue pHi measured photometrically with Neutral Red vital staining was 6.38-6.8,6.73-7.08,6.79-7.16 after 90 minutes of retrograde perfusion with driving pressure of 15,25 and 35mmHg. Tissue blood flow measured with microspheres in the anterior cerebrum/cortex was 2.2/4.0,7.0/12.1 and 8.1/13.6ml/100g/min, respectively. Retrograde brain perfusion with functional driving pressure of 25mmHg or more protects the brain. Although substancial blood flow in the brain tissue was proved in this animal model, there was a hyperfrontality in blood flow and regional pHi. Homogenous brain perfusion should be experimentally established to examine brain edema after retrograde perfusion.Experiment 2.Antegrade very low-flow perfusion (120 minutes) was tested at 20ﾟC to examine the relationship between perfusion pressure, brain tissue blood flow and brain tissue pHi. Brain tissue pHi was maintained high for 120 minutes by the perfusion with flow-rate of 10 and 20ml/kg/min. Cerebral cortex blood flow was larger than 10.2<plus-minus>1.9ml/100g/min when the driving pressure was above 10mmHg. Cerebral cortex pHi was greater than 7.1 when cortex blood flow was greater than 9ml/100g/min. When the cortex blood flow was smaller than this, brain oxygen consumption and cortex pHi decreased while glucose uptake did not simultaneously decrease. This perfusion condition with blood flow less than 10ml/100g/min causes brain acidosis and may cause brain damage. It should be further investigated whether this incomplete brain perfusion protects the brain or not, or paradoxically insults the brai