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目的:研究家兔脑急性出血时脑阻抗的定性变化及频率特性。方法:采用第四军医大学医学电子工程教研室研制的阻抗监护系统,用自体血注入法建立兔脑实质出血模型后对7只家兔进行脑阻抗监测。结果:出血初期,阻抗实部明显下降,虚部变化不明显,但随时间推移,脑阻抗实部、虚部绝对值均明显升高。对兔脑阻抗出血前后数据进行配对t检验,具有显著性差异(P<0.001),有统计学意义。在150s时阻抗实部、虚部、模变化率绝对值随频率升高而升高;900s时,在20kHz频率点,阻抗模变化率绝对值最大(|-3.12%|)。结论:采用电阻抗技术对脑急性出血进行监测是可行的,采用不同的测量频率会得到不同的脑部电阻抗变化量,阻抗最大变化率频率点随时间推移向低频转移。随着时间推移,脑急性出血后阻抗实部、虚部和模变化率的频谱特性在变化中,这意味着以往单一频率的监测并不能全面反映脑急性出血后的阻抗变化信息。
Objective: To study the qualitative changes and frequency characteristics of brain impedance in rabbits with acute cerebral hemorrhage. Methods: Impedance monitoring system developed by the Department of Medical Electronic Engineering, Fourth Military Medical University was used to monitor the brain impedance of 7 rabbits after establishment of a rabbit model of parenchymal hemorrhage by autologous blood injection. Results: In the early stage of hemorrhage, the real part of impedance decreased significantly and the imaginary part changed insignificantly, but the absolute value of real part and imaginary part of brain impedance increased obviously with the passage of time. There was significant difference (P <0.001) between paired t-test before and after data of cerebral hemorrhage in rabbits with statistical significance. At 150s, the absolute value of the real part, the imaginary part and the modal change rate of the impedance increase with the increase of the frequency. At 900s, the absolute value of the impedance mode change rate is the largest (-3.12% |) at 20kHz. Conclusion: It is feasible to use electrical impedance technique to monitor acute cerebral hemorrhage. Different measured frequency will result in different changes of brain electrical impedance. The frequency of maximum impedance change will shift to low frequency with time. With the passage of time, the spectral characteristics of impedance real part, imaginary part and modal change are changing after acute cerebral hemorrhage, which means that the previous single frequency monitoring does not fully reflect the impedance change information after acute cerebral hemorrhage.