H-磁共振波谱成像评价去甲肾上腺素诱导的高血压灌注对心搏骤停模型猪脑代谢的影响

Evaluation by IH-magnetic resonance spectroscopy of effects of norepinephrine-induced hypertension perfusion therapy on cerebral metabolism in pig model of cardiac arrest

目的用1H-磁共振波谱成像（1H—MRS）技术对去甲肾上腺素（NE）诱导的高血压灌注状态下猪头部进行扫描，观察心搏骤停（cA）动物自主循环恢复（ROSC）后脑代谢的变化。方法12只北京长白猪复制CA心室纤颤（VF）模型4min后，给予标准心肺复苏（CPR），在ROSC后将动物按照随机数字表法分为高血压灌注组[立即给予NE，使平均动脉压（MAP）维持在vF前的130％，维持高血压灌注状态4h]和正常灌注组（给予适量NE，维持MAP在vF前水平）。观察ROSC后不同时间点两组动物血流动力学参数的变化，并于vF前和ROSC后1h、3h用’H—MRS技术进行头部扫描，观察两组动物脑部代谢物的动态变化。结果12只猪中有2只因复苏失败而死亡，存活10只，其中高血压灌注组5只，正常灌注组5只。高血压灌注组心率（HR，次／min）于ROSC后30rain、MAP（mmHg，1mmHg=0．133kPa）和连续心排血量（CO，L／min）于ROSC后1h即较正常灌注组明显升高（ROSC后30minHR：167±8比140±15，ROSC后1hMAP：131±9比108±10，CO：4．9±0．1比3．4±0．5，P〈0．05或P〈0．01）。高血压灌注组ROSC后1hN-乙酰-天门冬氨酸（NAA，mmol／L）、胆碱（Cho，mmool／L）、肌酸（Cr，mmol／L）、Cho／Cr比值即均较正常灌注组明显升高（1hNAA：0．837±0．042比0．594±0．032，Cho：0．827±0．046比0．563±0．030，Cr：0．726±0．076比0．547±0．073，Cho／Cr比值：1．144±0．060比1．038±0．080，P〈0．05或P〈0．01），ROSC后3hNAA／Cr比值明显升高（0．877±0．050比0．770±0．040，P〈0．01）。结论高血压灌注有利于增加脑血流量，降低脑内有害代谢产物，促进神经功能的恢复。’H—MRS技术可对脑代谢物实施动态监测，可对干预措施进行动态评价，为研究各种治疗手段的时间窗提供重要依据。

Objective To observe the changes of cerebral metabolism after the animal＇s recovery of voluntary blood circulation from cardiac arrest （CA）, after norepinephrine-induced hypertension perfusion by 1H-magnetic resonance spectroscopy （1H-MRS） was performed to scan the head region . Methods After the 12 Landrace Beijing white pig models of CA and ventricular fibrillation （VF） were established for 4 minutes, the standard cardiopulmonary resuscitation （CPR） was applied for them. After the recovery of voluntary blood circulation （ROSC）, the animals were randomly divided into two groups ： hypertensive and normal reperfusion groups. In the hypertensive reperfusion group, NE was applied immediately to maintain the mean arterial pressure （MAP）for 4 hours at the level of 130% before VF ; in the normal reperfusion group, appropriate NE was applied to maintain the MAP for 4 hours at the same level before VF. One hour and 3 hours after successful recovery of voluntary blood circulation, the changes of blood flow dynamic parameters were observed in the two animal groups, and before VF and after recovery of circulation at the above time points, IH-MRS technique was used to scan the head region to observe the dynamic changes of cerebral metabolites in the two animal groups. Results Finally, there were 2 pigs died of recovery failure, and 10 pigs survived including 5 in the hypertensive reperfusion group and 5 in the normal reperfusion group. In the hypertensive reperfusion group, the heart rate （HR, bpm） after recovery of circulation for 30 minutes and the MAP （mm Hg, 1 mm Hg=0.133 kPa） and continuous cardiac output （CO, L/rain） after the recovery for 1 hour were significantly higher than those in the normal reperfusion group （30 minutes after ROSC HR ： 167 ＋ 8 vs. 140 ＋ 15,1 hour after ROSC MAP ： 131 _ 9 vs. 108 ＋ 10, CO ： 4.9 ＋ 0.1 vs. 3.4 _ 0.5, P〈 0.05 or P〈 0.01 ）. One hour after ROSC, N-acetyl-L-aspartic acid （NAA, mmol/L）, choline （Cho, mmol/L）, creatine （Cr, mmol/L） and the Cho/Cr ratio in hypertensive reperfusion group were significantly higher than those of the normal reperfusion group （ 1 hour NAA ： 0.837 ＋0.042 vs. 0.594＋0.032, Cho ： 0.827 ＋0.046 vs. 0.563 ＋ 0.030, Cr： 0.726 ＋ 0.076 vs. 0.547 ＋ 0.073, Cho/Cr ratio ： 1.144 ＋ 0.060 vs. 1.038 ＋ 0.080, P〈 0.05 or P〈 0.01 ）, and 3 hours after ROSC, the NAA/Cr ratio was obviously elevated in the hypertensive reperfusion group （0.877 ＋ 0.050 vs. 0.770 ＋ 0.040, P〈 0.01 ） . Conclusions Hypertensive reperfusion is beneficial to the increase of cerebral blood flow, decreases the harmful metabolites in the brain and promotes the recovery of neural functions. ~H-MRS technique can be used to monitor the dynamic changes of cerebral metabolites, evaluate the interventional means for CPR dynamically and provide important basis in the investigation of various therapeutic measures at time points.