头部低温治疗新生猪缺氧缺血性脑损伤脑电功率谱的变化

Changes of EEG frequency power spectrum in newborn piglets with hypoxic-ischemic brain damage during selective moderate head cooling therapy

目的 探讨选择性头部亚低温对缺氧缺血性脑损伤（Hypoxic-lschemic Brain DamageHIBD）新生猪脑电生理的影响。方法 25头5～7d的新生猪随机分为3组：正常常温组（7头）、缺氧缺血常温组（9头）、缺氧缺血低温组（9头）。采用双侧颈总动脉阻断和机械通气吸入6％的氧气制备HIBD模型。缺氧缺血（Hypoxic-Is-chemic HI）后2h低温组采用选择性头部亚低温治疗24h。分别在缺氧缺血前和缺氧缺血后36、48、72h、6d进行EEG记录及脑电功率谱分析。结果 缺氧缺血常温组在缺氧缺血后36和48h各脑区慢波（8波）相对功率较正常组显著升高（P〈0．01），72h有下降趋势，HI后6d继续下降，但与正常组此时间点仍有显著性差异。各脑区快波（α波）相对功率在缺氧缺血后36和48h较正常组显著降低（P〈0．01），72h有升高趋势，HI后6d继续升高，但尚未完全恢复正常。缺氧缺血后亚低温治疗δ功率除在缺氧缺血36和48h仍明显升高外，72h已开始降低，并和缺氧缺血常温组有显著性的差异（P〈0．05），到6d这种差异更显著（P〈0．01），亚低温治疗后6d时α波相对功率较缺氧缺血常温组显著升高（P〈0．05）。结论 缺氧缺血后新生猪大脑皮层功能严重受损，表现在脑电功率谱上为相对功率中δ波频率明显升高，α波频率明显降低。选择性头部亚低温可以增加α波频率，降低δ波频率，从而发挥其脑保护作用。

Purpose To explore the effect of selective moderate head cooling therapy on EEG frequency power Spectrum in neonatal piglets with hypoxic-ischemic brain damage. Methods Twentyfive newborn piglets were randomly divided into three groups： normothermic control group （n = 7）, normothermic hypoxic-ischemic group （n = 9） and mild hypothermia-treated group（n = 9）. HI was induced through temporary occlusion of both carotid arteries, followed by mechanical ventilation with low concentration of oxygen （FiO2 = 0.06）. Selective moderate head cooling therapy was induced by equipment via circulating water. EEG frequency power spectrum（α,β,δ,θ）was recorded and analyzed before HI and 36,48 and 72 h ours, 6 d after HI respectivaly. Results Compared with the normothermic control group,the relative power of δ band of all cortex regions in HI group increased significantly at 36 h and 48 h after HI （P〈0. 01）, and had tendency to decrease at 72 h and decreased significantly within 6d after HI. But the relative power showed significant differences compared with the time of normothermic control group. The relative power of a band of all cortex regions in HI group decreased significantly at 36 h and 48 h after HI （P〈0.01）, and had a tendency to increase at 72 h and continued increasing within 6d after HI. But it did not completely return to normal. Apart from that of 36 h and 48 h still significant increasing, the relative power of δ band in the mild hypothermia-treated group tended to decrease at 72 h and showed significant differences compared with the HI group （P〈0.05） and differed more significantly at 6 d （P〈0. 01）. Compared with the HI group, the relative power of a band in the mild hypothermia-treated group increased significantly at 6 d （P〈0.05）. Conclusions The results suggested that the cortex function of newborn piglet was severely disturbed after hypoxiaischemia, which showed the relative power of slow wave frequency significantly increased and that of fast wave frequency significantly decreased. Selective moderate head cooling therapy decreased the relative power of slow wave frequency and increased that of fast wave frequency. The present experiment suggests that selective moderate head cooling therapy has neuroprotective effect on HIBD.