停通气大鼠脑电和神经功能的变化

Changes of electroencephalogram and neurofunction in asphyxial rats

目的:观察大鼠给予不同时间停通气后脑电图和神经功能的变化。方法:实验于2005-03在北京神经外科研究所提供实验室完成。4月龄雄性清洁级Wistar大鼠144只,体质量260～290g,随机数字表法分为停通气1,2,3,4,5,6和7min组和对照组,每组18只。气管插管后应用肌松药消除大鼠自主呼吸,停通气相应预定的时间(停通气1,2,3,4,5,6和7min)后立即恢复通气和心肺复苏,记录从开始停通气至平均动脉压<25mmHg的时间(TCA)和从开始复苏至收缩压≥60mmHg的时间(TROSC),复苏成功者继续呼吸机支持60min,全程记录脑电图变化。记录复苏后24,48和72h神经功能评分情况。结果:①对照组、停通气1,2,3min组大鼠全部存活;停通气4,5,6min组分别有12,8和3只大鼠复苏成功,停通气4和5min组各有1只大鼠在复苏后24h内死亡,以上3组死亡率分别为33%、61%和83%;停通气7min组大鼠无1只复苏成功,死亡率100%。②停通气3min以上组所有大鼠均发生循环停止,开始停通气到循环停止的时间组间差异无显著性意义。停通气4,5和6min组开始复苏到自主循环恢复的时间较停通气3min组明显延长(P<0.05),停通气5和6min组较停通气4min组亦明显延长(P<0.05)。③停通气后脑电图频率和波幅降低直至等电位,随停通气时间的延长,恢复通气后持续脑电图出现时间明显延长(P<0.05)。④对照组和停通气1,2,3min组神经功能评分均正常,停通气4,5和6min组神经功能评分显著低于对照组(P<0.01),停通气6min组较停通气4min组亦明显降低(P<0.01),各组神经功能评分组内比较差异无显著性意义。结论:大鼠停通气2min内无循环停止,恢复通气后可直接出现持续脑电图;3min时均循环停止,但都可成功复苏且神经功能评分未受影响,恢复通气后首先出现单个爆发棘波,随后棘波出现频率逐渐增多并最终出现持续脑电图;4min以上时仅部分大鼠可成功复苏,随停通气时间的延长,复苏后神经功能评分明显降低,死亡率明显升高,棘波出现时间和持续脑电图出现时间也明显延长;7min时无一复苏成功。通过实验建立了不同时间停通气损伤后大鼠死亡率、脑电图和神经功能的变化规律的动物模型。

AIM： To observe the changes of electroencephalogram （EEG） and neural function in rats with different-time asphyxia. METHODS： The experiment was conducted in the Laboratory Beijing Neurosurgical Institute at March 2005. 144 healthy male Wistar rats of clean grade with the body mass of 260-290 g were selected and randomly divided into control group and 1, 2, 3, 4, 5, 6, 7 minutes asphyxia group with 18 rats in each group. The muscle relaxant was used to eliminate the spontaneously breathing of rats after tracheal intubation （TI） at asphyxial time corresponding with the given time （the 1^st, 2^nd, 3^rd, 4^th, 5^th, 6^th, 7^th minutes）, and ventilation as well as cardiopulmonary were resuscitated immediately after that. The time from asphyxia to mean arterial pressure （MAP） 〈 25 mm Hg （TCA） as well as the time from cardiopulmonary resuscitation （CPR） to systolic blood pressure （SBP） 360mm Hg （TROSC） were recorded. Subjects with successful resuscitation respired for 60 minutes under the help of breathing machine. The changes in EEG were monitored throughout the experiment. Neurofunctional scores were recorded at the 24^th, 48^th and 72^rd hours after resuscitation. RESULTS： ①Rats in the control group, 1, 2 and 3 minutes asphyxia groups all survived, and there were 12, 8 and 3 rats in 4, 5, 6 asphyxia groups successfully resuscitated respectively, while one rat died within 24 hours after resuscitation respectively in 4 and 5 minutes asphyxia groups, and the death rate of above 3 groups were 33%, 61% and 83% respectively. No rat in 7 minutes asphyxia group resuscitated successfully.②The circulatory arrest was found in rats of 4, 5, 6, 7 minutes asphyxia groups, and there were no Significant differences in TCA and TROSC among each time groups. TROSC was obviously prolonged in 4, 5, 6 minutes asphyxia. groups than that in 3 minutes asphyxia group （P 〈 0.05）, and it was remarkably prolonged in 5 and 6 minutes asphyxia groups than the 4 minutes asphyxia group （P 〈 0.05）.③The frequency and amplitude of EEG directly lowered to isopotentiality after asphyxia, and with the asphyxial time prolonging, the onset of continuous EEG after recuperation was markedly prolonged （P 〈 0.05）.④The neurofunctional scores were normal in 1, 2 and 3 minutes asphyxia groups as well as the control group, while those were significantly lowered in 4, 5, 6 minutes asphyxial groups than the control group （P 〈 0.01）, and it was significantly reduced in the 6 minutes asphyxial group than 4 minutes asphyxial group （P 〈 0.01）. There were no significant differences in neurofunctional score among each groups （P 〈 0.01）. CONCLUSION： No circulatory arrest is found in rats within 2 minutes of asphyxia, and continuous EEG can be seen after ventilation. There was cir culatory arrest in the 3^rd minute, while successful resuscitation can be achieved and there is no influence on neurofunctional score. Single exploded vertex sharp transient wave （V wave） can be found after resuscitation, the frequency of which is gradually increased and continuous EEG represents at last. Most of rats can successfully resuscitated after the 4^th minute. With the prolonging of asphyxial time, the neurofunctional score after resuscitation is greatly decreased, while the death rate is remarkably increased, and the time of V wave as well as the time of continuous EEG are markedly prolonged. No rat is successfully resuscitated at the 7^th minute. Animal models representing death rate after injury at different asphyxial time, EEG and neurofunctional rules are established through experiment.