We are interested in analyzing cerebral autoregulation from a dyanmical systems perspective. Therefore, we are constructing a literature review of cerebral autoregulation metrics and physiologic mechanisms from a timescales perspective.
See our preprint below. This review is being significantly reorganized. We appreciate any constructive feedback.
Adequate brain perfusion is required for proper brain function and life. Maintaining optimal brain perfusion to avoid secondary brain injury is one of the main concerns of neurocritical care. Cerebral autoregulation is responsible for maintaining optimal brain perfusion despite pressure derangements. Knowledge of cerebral autoregulatory function should be a key factor in clinical decision-making, yet it is often insufficiently and incorrectly applied. Multiple physiologic mechanisms impact cerebral autoregulation, each of which operate on potentially different and incompletely understood timescales confounding conclusions drawn from observations. Because of such complexities, clinical conceptualization of cerebral autoregulation has been distilled into practical indices defined by multimodal neuromonitoring, which removes mechanistic information and limits decision options. The next step towards cerebral autoregulatory-informed clinical decision-making is to quantify cerebral autoregulation mechanistically, which requires decomposing cerebral autoregulation into its fundamental processes and partitioning those processes into the timescales at which each operates. In this review, we scrutinize biologically, clinically, and computationally focused literature to build a timescales-based framework around cerebral autoregulation. We conclude that the myogenic mechanism acts on timescales faster than one second, the endothelial mechanism acts in one to two minutes, the metabolic mechanism will act on different timescales depending on the circumstance but will not be reflected in dynamic CA testing due to timescale constraints, and the neurologic mechanism acts within two seconds. These timescales have never been synthesized in the literature and lay the foundation for a new framework in which to view and test cerebral autoregulatory function. This new framework will allow us to quantify mechanistic interactions and directly infer which mechanism(s) are functioning based only on current monitoring equipment, paving the way for a new frontier in cerebral autoregulatory-informed clinical decision-making.