幼猪深低温体外循环最适区域性脑灌注流量的实验研究

目的探索幼猪在深低温体外循环中的最适区域性脑灌注（RCP）流量，为先天性心脏病（先心病）小儿患者术中脑保护策略提供理论基础。方法20只健康幼猪，年龄23．7±2．1d，体重6．4±0．6kg，采用随机数字表法分为4组，每组各5例。对照组为单纯深低温停循环（DHCA组）；实验组按不同RCP流量分为3组：RCP25组，流量为25．9±3．0ml（kg·min）；RCP50组，流量为49．7士1．8ml／（kg·rain）；RCP80组，流量为79．5±0．9ml／（kg·min）；通过检测血浆中建立CPB前（T1）、DHCA或RCP前（T2）、RCP结束后10min（T3）、停机前（T4）、CPB结束后1h（Ts）以及2h（T5）6个时间点检测血浆中的S-100β蛋白、神经元特异性烯醇化酶（NSE）的浓度、脑氧摄取率（CEOz）及大脑皮质半胱天冬氨酸酶3（caspase3）的含量，评估不同RCP流量的脑保护效果。结果各组幼猪血浆中S-100β蛋白和NSE的浓度于T4时明显升高，并于T5时达到高峰（P〈0．05）；RCP50组血浆中S-100β蛋白和NSE的浓度从T4时开始明显低于DHCA组和RCP80组（P〈O．05），与RCP2。组相比，其差异无统计学意义（P〉0．05）。各组CEO2在T1时差异无统计学意义（P〉0．05），在T2时明显降低（P％0．05）。DHCA组、RCPzs组和RCP50组的CEO2在T3时开始升高，RCP20组在T3时稍微下降，但其差异无统计学意义（P〉0．05）；从T4开始，RCP25组和RCPj。组的CEO。与DHcA组和RCP80组更接近于基础值（T1）（P〈0．05）。大脑皮质中caspase3的含量在3种不同流量的RCP组明显低于DHCA组（F=23．54，P〈0．01），其中RCP25组及RCP5。组明显低于RCP80组（F=23．54，P〈0．01），而RCP2s组与RCP50组的caspase3含量差异无统计学意义（P〉0．05）。结论在我们建立的幼猪深低温体外循环模型中，RCP最适灌注流量为25～50ml／（kg·rain），并且趋向于50ml／（kg·rain）。

Optimal Flow Rate for Regional Cerebral Perfusion During Deep Hypothermic Cardiopulmonary Bypass in Piglets

Objective To determine the optimal flow rate for regional cerebral perfusion （RCP） under deep hypothermic cardiopulmonary bypass （CPB） in piglets, and provide a theoretical basis for cerebral protection in infants with congenital heart disease. Methods Twenty healthy piglets with an average weight of 6.4 ± 0. 6 kg and age 23.7±2. 1 days were divided into four groups of five piglets by random digital table. The control group underwent a simple deep hypothermic circulatory arrest （DHCA）, while the experimental groups consisted of three different flow rate RCP groups： an RCPz5 group, with a flow rate of 25.9-4-3.0 ml/（kg min）, an RCP0 group, with a flow rate of 49.7!1.8 ml/（kg-rain）, and an RCPs0 group with a flow rate of 79.50.9 ml/（kg min）. Serum samples were taken at six time points （T1 ： before CPB, Tz ： before DHCA or RCP, T3 ： 10 minutes after RCP, T4 ： before stopping CPB （T4）, T5 ： 1 hour after CPB, T6 ： 2 hours after CPB） to test for S-100t3 protein, neuron-specific enolase （NSE）,and cerebral oxygen extraction （CEO2）. Thecaspase3 level in the cerebral cortex was measured toestimale the extent of cerebral protection. Results The concentrations of S 100β protein and NSE significantly increased at T1 and peaked at Ta （P〈0.05）. These concentrations were significantly lower in the RCP29 group than in the I）HCA group and the RCP80 group （P〈0.05）, but were not significantly different between the RUP50 group and the RCP25 group （P〉0.05）. There were no significant differences among the groups in cerebral oxygen extraction （CEO2） at Tt （P〉 0.05） ; and there were significant differences in CEO2, among all groups at Te （P〈0.05）. The concentration of CEO2 in the DHCA, RCP25 , and RCP,groups increased at T3 , while it declined slightly in the RCP80 group at this time point, but there was no significant difference among the groups （P〉0.05）. The CEO2 levels in the RCO2; and RCP50, groups at T4 were similar to those at baseline （P〈0.05）. All three experimental groups had significantly lower concentrations of caspase 3 in the cerebral cortex than did the DHCA group （F=23. 54, P〈0. 01）. Compared to the RCP25. and RCP50, groups, the caspase 3 level in the RCPs0 group was significantly higher （F=23.54, P%0.01）, but there was no significant difference between the RCP25 group and the RCP50, group （P〉0.05）. Conclusion The optimal RCP flow rate for cerebral protection under deep hypothermic CPB in piglets appears to be between 25 ml/（kg . min） and 50 ml/ （kg . min）, and may be closer to 50 ml/（kg . rain）.