1 Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital , Boston, Massachusetts.
2 Division of Neurosurgery, University of Cambridge , Cambridge, United Kingdom .
J Neurotrauma. 2017 Oct 1;34(19):2743-2752. doi: 10.1089/neu.2016.4787. Epub 2017 May 17.
The brain and heart are two vital systems in health and disease, increasingly recognized as a complex, interdependent network with constant information flow in both directions. After severe traumatic brain injury (TBI), the causal, directed interactions between the brain, heart, and autonomic nervous system have not been well established. Novel methods are needed to probe unmeasured, potentially prognostic information in complex biological networks that are not revealed by traditional means. In this study, we examined potential bidirectional causality between intracranial pressure (ICP), mean arterial pressure (MAP), and heart rate (HR) and its relationship to mortality in a 24-h period early post-TBI. We applied Granger causality (GC) analysis to cardio-cerebral monitoring data from 171 severe TBI patients admitted to a single neurocritical care center over a 10-year period. There was significant bidirectional causality between ICP and MAP, MAP and HR, and ICP and HR in the majority of patients (p < 0.01). MAP influenced both ICP and HR to a greater extent (higher GC, p < 0. 00001), but there was no dominant unidirectional causality between ICP and HR (p = 0.85). Those who died had significantly lower GC for ICP causing MAP and HR causing ICP (p = 0.006 and p = 0.004, respectively) and were predictors of mortality independent of age, sex, and traditional intracranial variables (ICP, cerebral perfusion pressure, GCS, and pressure reactivity index). Examining the brain and heart with GC-based features for the first time in severe TBI patients has confirmed strong interdependence and reveals a significant relationship between select causality pairs and mortality. These results support the notion that impaired causal information flow between the cerebrovascular, autonomic, and cardiovascular systems are of central importance in severe TBI.
大脑和心脏是健康和疾病中的两个重要系统，它们被越来越多地认为是一个复杂的、相互依存的网络，在两个方向上都有持续的信息流。在严重创伤性脑损伤（TBI）后，大脑、心脏和自主神经系统之间的因果、定向相互作用尚未得到很好的确定。需要新的方法来探测复杂生物网络中未被传统方法揭示的未测量的、潜在预后信息。在这项研究中，我们研究了颅内压（ICP）、平均动脉压（MAP）和心率（HR）之间的潜在双向因果关系及其与 TBI 后 24 小时内死亡率的关系。我们应用 Granger 因果关系（GC）分析对来自 171 名严重 TBI 患者的心脑监测数据进行了分析，这些患者在 10 年内被收治于一个神经重症监护中心。在大多数患者中，ICP 和 MAP、MAP 和 HR、ICP 和 HR 之间存在显著的双向因果关系（p<0.01）。MAP 对 ICP 和 HR 的影响更大（GC 更高，p<0.00001），但 ICP 和 HR 之间没有主导的单向因果关系（p=0.85）。死亡患者的 ICP 引起 MAP 和 HR 引起 ICP 的 GC 显著降低（p=0.006 和 p=0.004），并且是独立于年龄、性别和传统颅内变量（ICP、脑灌注压、GCS 和压力反应指数）的死亡率预测因子。首次在严重 TBI 患者中使用基于 GC 的特征来检查大脑和心脏，证实了它们之间的强相互依赖性，并揭示了选择因果关系对与死亡率之间的显著关系。这些结果支持了这样一种观点，即脑血管、自主和心血管系统之间受损的因果信息流在严重 TBI 中具有重要意义。
