Chaotic analysis of autonomic nervous activities during anesthesia

吸入性麻醉药的作用机制尚不清楚，但麻醉药引起的神经元膜改变和混沌抽搐是一个受欢迎的假设。为了评估在清醒状态和麻醉状态下HRV是否同时具有周期性和确定性混沌特性，我们采用功率谱分析和确定性混沌方法对HRV进行了分析。在七氟醚或氟烷全麻状态下，HRV以高分形相关维数的确定性混沌结构为主，而在七氟醚或氟烷全麻状态下，HRV则转变为周期性结构和低相关维数。此外，大胸外科手术，如食管切除术或肺切除术，降低了HRV的分形特征，提示分形分量可以用来估计手术侵袭后的恢复状态。因此，通过分析心率变化，心血管系统的神经控制显示出与确定性混沌相关的特征。这些结果表明，动态心血管系统在一定程度上具有混沌系统的非线性特征。

The mechanism of action of inhalational anesthetics is unknown, but neuronal membrane alteration with chaotic purturbations caused by anesthetics is a favored hypothesis. In order to evaluate whether or not HRV have both periodic and deterministic-chaotic properties in conscious and anesthetized states, we analyzed HRV by power spectral analysis and methods of deterministic chaos.A predominant deterministic-chaotic structure of HRV with high fractal correlation dimension during conscious states altered to a more periodic structure and lower correlation dimension during general anesthesia with sevoflurane or halothane. In addition, major thoracic surgery, such as esophagectomy or pulmonary resection, diminished fractal features of HRV,suggestiong that fractal component could be an estimate of recovery state from surgical invasion.Neural control of cardiovascular system, thus, shows featrues associated with deterministic chaos by analyzing HRV changes. These results indicated the dynamic cardiovascular system that are partly characterized by non-linear natures typical for chaotic systems.