Cerebral Autoregulation

The purpose of this study is to determine the feasibility of using the NeuraSignal transcranial doppler robot in a neuro ICU setting to measure cerebral blood flow correlated with arterial blood pressure to generate individualized cerebral autoregulatory curves

This multicenter, prospective, observational diagnostic accuracy study enrolls patients undergoing thrombectomy with intraoperative cerebral autoregulation monitoring and follows them up at predefined time points up to 90 days post-enrollment. The study aims to determine whether impaired cerebral autoregulation during thrombectomy can serve as an ultra-early biomarker for predicting futile recanalization in patients with acute ischemic stroke.

This study aims to better understand how short periods of exposure to high oxygen levels affect blood flow in the brain of patients who are intubated and mechanically ventilated in the Intensive Care Unit (ICU). Many ICU patients receive more oxygen than strictly necessary, and high blood oxygen levels (hyperoxemia) are very common. However, the immediate effects of short hyperoxic exposures on cerebral circulation and autoregulation remain poorly understood. In this study, patients who already require mechanical ventilation for medical reasons will undergo a brief and controlled increase in the oxygen delivered through the ventilator (FiO₂). During this time, we will continuously monitor blood flow in one of the main brain arteries using a non-invasive ultrasound technique called transcranial Doppler (TCD). The goal is to evaluate how cerebral blood flow, pulsatility, and autoregulatory capacity change during and after a short hyperoxic stimulus. No additional invasive procedures are required beyond standard ICU monitoring, except for the temporary adjustment of the ventilator's oxygen settings and arterial blood gas sampling, which are part of usual care in critically ill patients. Participation does not provide direct clinical benefit but may help improve future oxygen management in ICU patients. The study involves minimal risk, as short hyperoxic exposures are already common in routine care and will be interrupted immediately in case of any adverse event.

Remote Ischaemic Conditioning (RIC) is the process of inducing short periods of ischaemia in a limb with the aim of improving vascular health systemically. Recent findings have demonsatrated efficacy in a variety of clinical settings. However, the ideal protocol of RIC \[dose\] is unknown. Dynamic Cerebral Autoregulation (dCA) has been shown to increase in response to RIC. The goal of this trial is to study whether an increase in RIC protocol intensity results in a larger effect on biomarkers of vascular health such as dCA. Participants shall: Receive RIC daily, RIC thrice weekly or sham RIC thrice weekly for 6 weeks Visit the School of Medicine at baseline and at 6 weeks for measurement of biomarkers of vascular health including blood pressure, indices od dCA and blood plasma samples

Carotid endarterectomy (CEA) is used to treat symptomatic extracranial internal carotid artery stenosis. The occult stroke of CEA patients evaluated by magnetic resonance imaging 3 days after operation was as high as 17%. Cerebral blood flow autoregulation (CA) is the ability of the brain to maintain the relative stability of cerebral blood flow, and cerebral oxygen index (COx) can be used to reflect CA. A negative value of cerebral oxygen index or a value near zero indicates that CA is complete, and cerebral oxygen index close to 1 indicates that CA has lost its ability. In theory, real-time monitoring of CA function by cerebral oxygen index and individualized management strategy with this goal can potentially reduce perioperative ischemic brain injury. The purpose of this study is to explore the influence of the management strategy of monitoring CA function based on regional cerebral oxygen saturation on the postoperative neurological complications of CEA patients.

The aim of the study is to evaluate autonomic function and cerebrovascular control in 60 healthy subjects by means of noninvasive analysis of time series variability. To this extent, heart period, systolic and mean arterial blood pressure, cerebral blood velocity, peripheral resistances, respiration will be recorded from subjects during an orthostatic challenge. The interactions between autonomic cardiovascular function, cerebrovascular and peripheral control will be evaluated exploiting the most advanced signal processing techniques.

Introduction. Initiation of acute kidney replacement therapy (KRT) is common in critically ill adults admitted to the intensive care unit (ICU), and is associated with increased morbidity and mortality. KRT has been linked to poor neurocognitive outcomes, leading to a reduced quality of life, as well as increased utilization of healthcare resources. Adults initiated on dialysis in the ICU may be particularly at risk of neurocognitive impairment, as survivors of critical illness are already predisposed to developing cerebrovascular disease and cognitive dysfunction over the long-term relative to healthy controls. Regional cerebral oxygen saturation (rSO2) may provide a critical early marker of long-term neurocognitive impairment in patients in this population. The INCOGNITO-AKI study aims to understand cerebral oxygenation in patients undergoing KRT, either continuous or intermittent, in the ICU. These findings will be correlated with long-term cognitive and functional outcomes, as well as structural brain pathology. Methods and analysis. 108 patients scheduled to undergo treatment for acute kidney injury with KRT in the Kingston Health Sciences Centre ICU will be recruited into this prospective observational study. Enrolled patients will be assessed with intradialytic cerebral oximetry using near infrared spectroscopy (NIRS). Delirium will be assessed daily with the Confusion Assessment Method-Intensive Care Unit (CAM-ICU) and delirium severity quantified as cumulative CAM-ICU-7 scores. Neurocognitive impairment will be assessed at 3- and 12-months after hospital discharge using the Kinarm and Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Structural brain pathology on MRI will also be measured at the same timepoints. Driving safety, adverse events, and medication adherence will be assessed at 12-months to evaluate the impact of neurocognitive impairment on functional outcomes. Ethics and dissemination. This study has been approved by the Queen's University Health Sciences and Affiliated Teaching Hospitals Research Ethics Board (Approval number: DMED-2424-20). Results will be presented at critical care scientific conferences and a lay summary will be provided to patients and families in their preferred format.