弥散加权成像观察去甲肾上腺素诱导的高血压灌注对心搏骤停猪脑功能的影响

The evaluation of cerebral function by diffusion weighted imaging after norepinephrine-induced hypertensive perfusion therapy in pig model of cardiac arrest

目的观察高血压灌注心搏骤停猪自主循环恢复（ROSC）后脑功能的变化。方法采用电刺激建立猪心室纤颤（室颤）模型，室颤4min后给予标准心肺复苏（CPR），将ROSC猪按随机数字表法分为两组，每组5只。高血压灌注组立即给予去甲肾上腺素（NE）使平均动脉压（MAP）维持在室颤前血压的130％；正常灌注组给予NE维持MAP为室颤前水平；两组均监测4h观察血流动力学变化；于室颤前及ROSC后1h、3h用弥散加权成像（DWI）技术扫描大脑顶叶皮质，观察脑功能成像的动态变化；于复苏后24h制备脑组织切片，观察顶叶的病理学变化。结果与正常灌注组比较，高血压灌注组于ROSC后不同时间点心率（HR，次／min）、MAP（mmHg，1mmHg=0．133kPa）、心排血量（CO，L／min）、冠状动脉灌注压（CPP，mmHg）均出现升高趋势（ROSC30 min HR：167±8比140±15，ROSC 1h MAP：131±9比108±10，ROSC 1h CO：4．9±0．1比3．4±0．5，ROSC 2h CPP：118±12比88±1，P〈0．05或P〈0．01）。两组复苏前后DWI未见明显异常；复苏后大脑皮质表观弥散系数（ADC）均呈下降趋势，正常灌注组下降趋势较高血压灌注组明显。光镜下观察高血压灌注对脑的保护作用优于正常灌注组。结论高血压灌注可引起心搏骤停猪复苏后血流动力学的改变，增加脑血流量，对脑具有保护作用，有利于促进神经功能的恢复。

Objective To evaluate the changes in cerebral function of pigs with cardiac arrest （CA） after recovery of spontaneous circulation （ROSC） after hypertension perfusion therapy induced by norepinephrine （NE）. Methods Ventricular fibrillation （VF） was induced by electrical stimulation, and standard cardiopulmonary resuscitation （CPR） was performed after VF for 4 minutes. The pigs with successful ROSC were randomly divided into two group, each n =5. The pigs in the hypertensive reperfusion group were given with NE immediately to maintain the mean arterial pressure （MAP） at 130% before VF for 4 hours; MAP of the pigs in normal reperfusion group was maintained for 4 hours as baseline. The changes in hemodynamics were observed for 4 hours in both groups. Cerebral cortex was scanned with diffusion weighted imaging （DWI） before VF and 1 hour and 3 hours after ROSC, and the dynamic changes in brain functional imaging were observed. Twenty-four hours after ROSC, brain biopsy were collected and examined after hematoxylin and eosin staining （HE）. Results Compared with the normal reperfusion group, heart rate （HR, bpm）, MAP （mm Hg, 1 mm Hg=0.133 kPa）, cardiac output （CO, L/min） and coronary perfusion pressure （CPP, mm Hg） in the hypertensive reperfusion group showed a tendency to increase （ROSC 30 minutes HR： 167 ±8 vs. 140± 15, ROSC 1 hour MAP： 131 ±9 vs. 108 ± 10, ROSC 1 hour CO： 4.9 ±0.1 vs. 3.4 ±0.5, ROSC 2 hours CPP： 118 ± 12 vs. 88 ± 1, P〈0.05 or P〈0.01 ）. There was no obvious abnormality as shown by DWI before and after resuscitation, and the apparent diffusion coefficient （ADC） showed a tendency to decrease after resuscitation in both groups. The ADC in the normal reperfusion group was decreased more than that in the hypertensive reperfusion. Pathological study showed that the protective effect of the hypertensive reperfusion on brain tissue was better than that of the normal reperfusion group. Conclusion Hypertensive reperfusion can produce hemodynamic changes, and an increase in cerebral blood flow, thus it produces a protective effect on brain to promote the recovery of neurological function in pigs with CA after resuscitation.