Autoregulation-Oriented Blood Pressure Management in Acute Brain Injury

Cerebrovascular autoregulation is the brain's intrinsic ability to maintain stable blood flow despite changes in cerebral perfusion pressure. Patients with acute brain injury are vulnerable to disturbed autoregulation from ischemia-induced vasoparesis and/r reperfusion-related vascular injury. As a result, changes in systemic pressure are passively transmitted to the cerebral circulation with consequent risk of ischemia and infarction from insufficient flow or conversely, intracranial hypertension, cerebral edema, and/or hemorrhage due to excessive flow.

Our overall hypothesis is the blood pressure outside of the range of autoregulation leads to secondary brain injury and is, therefore, a modifiable risk factor to improve outcome. However, it remains unclear which patients are ideal candidates for therapeutic blood pressure manipulation. Real-time, physiologic measures to gauge the adequacy of cerebral perfusion are urgently needed.

We have shown that near-infrared spectroscopy can be used to identify limits of autoregulation and the blood pressure range in individual patients at which cerebral autoregulation is most preserved (Figure 1). Furthermore, we found that exceeding this blood pressure range is associated with an increased risk of hemorrhagic transformation and worse functional outcome after stroke and subarachnoid hemorrhage.

However, besides compelling conceptual reasons and robust pilot data, we currently lack rigorous clinical evidence to support autoregulation-guided BP management as a potential neuroprotective strategy after acute brain injury. Our studies will test whether autoregulation-guided blood pressure management may present a better strategy compared to the classical approach of maintaining blood pressure below a fixed, predetermined value. We will utilize cutting-edge neuromonitoring technology combined with real-time data processing to define the limits of autoregulation in individual patients and determine patient-specific, dynamic blood pressure targets. Given the current paucity of prospective data to guide blood pressure management after brain injury, our research will have important implications for clinical practice and the potential to substantially change our approach to blood pressure management after stroke and traumatic brain injury.