This is an observational study in neurocritical care units at University of California San Francisco Medical Center (UCSFMC), Zuckerberg San Francisco General Hospital (ZSFGH), and Duke University Medical Center. In this study, the investigators will primarily use the monitor mode of the Transcranial Doppler (TCD, non-invasive FDA approved device) to record cerebral blood flow velocity (CBFV) signals from the Middle Cerebral Artery and Internal Carotid Artery. TCD data and intracranial pressure (ICP) data will be collected in the following four scenarios. Each recording is up to 60 minutes in length.
Multimodality high-resolution physiological signals will be collected from brain injured patients: traumatic brain injury, subarachnoid and intracerebral hemorrhage, liver failure, and ischemic stroke. This is not a hypothesis-driven study but rather a signal database development project with a goal to collect multimodality brain monitoring data to support development and validation of algorithms that will be useful for future brain monitoring devices. In particular, the collected data will be used to support:
Development and validation of noninvasive intracranial pressure (nICP) algorithms.
Development and validation of continuous monitoring of neurovascular coupling state for brain injury patients
Development and validation of noninvasive approaches of detecting elevated ICP state.
Development and validation of approaches to determine most likely causes of ICP elevation.
Development and validation of approaches to detect acute cerebral hemodynamic response to various neurovascular procedures.