Arterial blood pressure monitoring in stroke cohorts: the impact of reduced sampling rates to optimise remote patient monitoring.

Objective: Remote patient monitoring (RPM) beat-to-beat blood pressure (BP) provides an opportunity to measure poststroke BP variability (BPV), which is associated with clinical stroke outcomes. BP sampling interval (SI) influences ambulatory BPV, but RPM BP SI optimisation research is limited. SI and RPM device capabilities require compromises, meaning SI impact requires investigation.

Impact of different blood pressure targets on cerebral hemodynamics in septic shock: A prospective pilot study protocol-SEPSIS-BRAIN.

Introduction: Septic shock, a life-threatening condition, can result in cerebral dysfunction and heightened mortality rates. In these patients, disturbances in cerebral hemodynamics, as reflected by impairment of myogenic cerebral autoregulation (CA), metabolic regulation, expressed by critical closing pressure (CrCP) and reductions in intracranial compliance (ICC), can adversely impact septic shock outcomes. The general recommendation is to maintain a target mean arterial pressure (MAP) of 65 mmHg but the effect of different MAP targets on cerebral hemodynamics in these patients is not clear and optimal targets might be dependent on the status of CA.

Cognitive activity significantly affects the dynamic cerebral autoregulation, but not the dynamic vasoreactivity, in healthy adults.

Introduction: Neurovascular coupling (NVC) is an important mechanism for the regulation of cerebral perfusion during intensive cognitive activity. Thus, it should be examined in terms of its effects on the regulation dynamics of cerebral perfusion and its possible alterations during cognitive impairment. The dynamic dependence of continuous changes in cerebral blood velocity (CBv), which can be measured noninvasively using transcranial Doppler upon fluctuations in arterial blood pressure (ABP) and CO tension, using end-tidal CO (EtCO) as a proxy, can be quantified via data-based dynamic modeling to yield insights into two key regulatory mechanisms: the dynamic cerebral autoregulation (dCA) and dynamic vasomotor reactivity (DVR), respectively.

The effect of posture on the age dependence of neurovascular coupling.

Previous studies report contradicting age-related neurovascular coupling (NVC). Few studies assess postural effects, but less investigate relationships between age and NVC within different postures. Therefore, this study investigated the effect of age on NVC in different postures with varying cognitive stimuli.

The complexity of cerebral blood flow regulation: the interaction of posture and vasomotor reactivity.

Arterial carbon dioxide ([Formula: see text]) and posture influence the middle (MCAv) and posterior (PCAv) cerebral artery blood velocities, but there is paucity of data about their interaction and need for an integrated model of their effects, including dynamic cerebral autoregulation (dCA). In 22 participants (11 males, age 30.2 ± 14.

Dynamics of Critical Closing Pressure Explain Cerebral Autoregulation Impairment in Acute Cerebrovascular Disease.

Introduction: Cerebral autoregulation (CA) is impaired in acute ischemic stroke (AIS) and is associated with worse patient outcomes, but the underlying physiological cause is unclear. This study tests whether depressed CA in AIS can be linked to the dynamic responses of critical closing pressure (CrCP) and resistance area product (RAP).

Methods: Continuous recordings of middle cerebral blood velocity (MCAv, transcranial Doppler), arterial blood pressure (BP), end-tidal CO2 and electrocardiography allowed dynamic analysis of the instantaneous MCAv-BP relationship to obtain estimates of CrCP and RAP.

The effect of CO on the age dependence of neurovascular coupling.

Prior studies have identified variable effects of aging on neurovascular coupling (NVC). Carbon dioxide (CO) affects both cerebral blood velocity (CBv) and NVC, but the effects of age on NVC under different CO conditions are unknown. Therefore, we investigated the effects of aging on NVC in different CO states during cognitive paradigms.

Blood pressure variability at rest and during pressor challenges in patients with acute ischemic stroke.

Introduction: Patients with acute ischemic stroke (AIS) have elevated blood pressure (BP) variability (BPV) and reduced baroreflex sensitivity (BRS) at rest for several days after initial stroke symptoms. We aimed to assess BPV and BRS in AIS patients during pressor challenge maneuvers in the acute and subacute phases of stroke. Pressor challenge maneuvers simulate day-to-day activities and can predict the quality of life.

Determinants of the dynamic cerebral critical closing pressure response to changes in mean arterial pressure.

. Cerebral critical closing pressure (CrCP) represents the value of arterial blood pressure (BP) where cerebral blood flow (CBF) becomes zero. Its dynamic response to a step change in mean BP (MAP) has been shown to reflect CBF autoregulation, but robust methods for its estimation are lacking.

Statistical Complexity Analysis of Neurovascular Coupling with Cognitive Stimulation in Healthy Participants.

Neurovascular coupling (NVC) is the tight relationship between changes in cerebral blood flow and neural activation. NVC can be evaluated non-invasively using transcranial Doppler ultrasound (TCD)-measured changes in brain activation (cerebral blood velocity [CBv]) using different cognitive tasks and stimuli. This study used a novel approach to analyzing CBv changes occurring in response to 20 tasks from the Addenbrooke's Cognitive Examination III in 40 healthy individuals.

A Comprehensive Perspective on Intracranial Pressure Monitoring and Individualized Management in Neurocritical Care: Results of a Survey with Global Experts.

Background: Numerous trials have addressed intracranial pressure (ICP) management in neurocritical care. However, identifying its harmful thresholds and controlling ICP remain challenging in terms of improving outcomes. Evidence suggests that an individualized approach is necessary for establishing tolerance limits for ICP, incorporating factors such as ICP waveform (ICPW) or pulse morphology along with additional data provided by other invasive (e.

A Multi-Parametric Approach for Characterising Cerebral Haemodynamics in Acute Ischaemic and Haemorrhagic Stroke.

Background And Purpose: Early differentiation between acute ischaemic (AIS) and haemorrhagic stroke (ICH), based on cerebral and peripheral hemodynamic parameters, would be advantageous to allow for pre-hospital interventions. In this preliminary study, we explored the potential of multiple parameters, including dynamic cerebral autoregulation, for phenotyping and differentiating each stroke sub-type.

Methods: Eighty patients were included with clinical stroke syndromes confirmed by computed tomography within 48 h of symptom onset.

Physiological Variability during Prehospital Stroke Care: Which Monitoring and Interventions Are Used?

Prehospital care is a fundamental component of stroke care that predominantly focuses on shortening the time between diagnosis and reaching definitive stroke management. With growing evidence of the physiological parameters affecting long-term patient outcomes, prehospital clinicians need to consider the balance between rapid transfer and increased physiological-parameter monitoring and intervention. This systematic review explores the existing literature on prehospital physiological monitoring and intervention to modify these parameters in stroke patients.

Individual Patient Data Meta-Analysis of Dynamic Cerebral Autoregulation and Functional Outcome After Ischemic Stroke.

Background: The relationship between dynamic cerebral autoregulation (dCA) and functional outcome after acute ischemic stroke (AIS) is unclear. Previous studies are limited by small sample sizes and heterogeneity.

Methods: We performed a 1-stage individual patient data meta-analysis to investigate associations between dCA and functional outcome after AIS.

Depression of dynamic cerebral autoregulation during neural activation: The role of responders and non-responders.

Neurovascular coupling (NVC) interaction with dynamic cerebral autoregulation (dCA) remains unclear. We investigated the effect of task complexity and duration on the interaction with dCA. Sixteen healthy participants (31.

Exploring Physiological Differences in Brain Areas Using Statistical Complexity Analysis of BOLD Signals.

The brain is a fundamental organ for the human body to function properly, for which it needs to receive a continuous flow of blood, which explains the existence of control mechanisms that act to maintain this flow as constant as possible in a process known as cerebral autoregulation. One way to obtain information on how the levels of oxygen supplied to the brain vary is through of BOLD (Magnetic Resonance) images, which have the advantage of greater spatial resolution than other forms of measurement, such as transcranial Doppler. However, they do not provide good temporal resolution nor allow for continuous prolonged examination.

Detection of Blood CO Influences on Cerebral Hemodynamics Using Transfer Entropy.

Cerebral hemodynamics describes an important physiological system affected by components such as blood pressure, CO levels, and endothelial factors. Recently, novel techniques have emerged to analyse cerebral hemodynamics based on the calculation of entropies, which quantifies or describes changes in the complexity of this system when it is affected by a pathological or physiological influence. One recently described measure is transfer entropy, which allows for the determination of causality between the various components of a system in terms of their flow of information, and has shown positive results in the multivariate analysis of physiological signals.

TCD assessment in fulminant hepatic failure: Improvements in cerebral autoregulation after liver transplantation.

Introduction And Objectives: Acute liver failure, also known as fulminant hepatic failure (FHF), includes a spectrum of clinical entities characterized by acute liver injury, severe hepatocellular dysfunction and hepatic encephalopathy. The objective of this study was to assess cerebral autoregulation (CA) in 25 patients (19 female) with FHF and to follow up with seventeen of these patients before and after liver transplantation.

Patients And Methods: The mean age was 33.

Integrative assessment of cerebral blood regulation in COPD patients.

Cerebrovascular responses were compared between COPD and non-COPD participants. The association between COPD severity and cognitive function was also investigated. Cerebral blood velocity in the middle cerebral artery, blood pressure, and end-tidal CO were recorded at rest, followed by a brain activation paradigm, and an inhaled gas mixture (5% CO) to assess cerebral autoregulation (CA), neurovascular coupling (NVC) and cerebrovascular reactivity to carbon dioxide (CVR), respectively.

The effect of hypercapnia on the directional sensitivity of dynamic cerebral autoregulation and the influence of age and sex.

The cerebral circulation responds differently to increases in mean arterial pressure (MAP), compared to reductions in MAP. We tested the hypothesis that this directional sensitivity is reduced by hypercapnia. Retrospective analysis of 104 healthy subjects (46 male (44%), age range 19-74 years), with five minute recordings of middle cerebral blood velocity (MCAv, transcranial Doppler), non-invasive MAP (Finometer) and end-tidal CO (capnography) at rest, during both poikilocapnia and hypercapnia (5% CO breathing in air) produced MCAv step responses allowing estimation of the classical Autoregulation Index (ARI), and corresponding values for both positive (ARI) and negative (ARI) changes in MAP.