Cerebral Autoregulation Monitoring Research Articles

Monitoring of Cerebral Blood Flow Autoregulation after Cardiac Arrest.

Background: Cardiac arrest remains one of the leading causes of death. After successful resuscitation of patients in cardiac arrest, post-cardiac arrest syndrome develops, part of it being an impaired cerebral blood flow autoregulation. Monitoring cerebral blood flow autoregulation after cardiac arrest is important for optimizing patient care and prognosticating patients' survival, yet remains a challenge. There are still gaps in clinical implications and everyday use. In this article, we present a systematic review of studies with different methods of monitoring cerebral blood flow autoregulation after non-traumatic cardiac arrest. Methods: A comprehensive literature search was performed from 1 June 2024 to 27 June 2024 by using multiple databases: PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials. Inclusion criteria were studies with an included description of the measurement of cerebral blood flow autoregulation in adult patients after non-traumatic cardiac arrest. Results: A total of 16 studies met inclusion criteria. Our data show that the most used methods in the reviewed studies were near-infrared spectroscopy and transcranial Doppler. The most used mathematical methods for calculating cerebral autoregulation were cerebral oximetry index, tissue oxygenation reactivity index, and mean flow index. Conclusions: The use of various monitoring and mathematical methods for calculating cerebral blood flow autoregulation poses a challenge for standardization, validation, and daily use in clinical practice. In the future studies, focus should be considered on clinical validation and transitioning autoregulation monitoring techniques to everyday clinical practice, which could improve the survival outcomes of patients after cardiac arrest.

The Association of Cerebral Autoregulation Dysfunction and Postoperative Memory Impairment in Cardiac Surgery Patients.

Background and Objectives: Cardiac surgery is associated with various durations of cerebral autoregulation (CA) impairment and can significantly impact cognitive function. Cognitive functions such as memory, psychomotor speed, and attention are significantly impacted after cardiac surgery, necessitating prioritization of these areas in cognitive function tests. There is a lack of research connecting cerebral autoregulation impairment to specific cognitive function domains after cardiac surgery. This study aimed to determine if impaired cerebral autoregulation is associated with postoperative memory impairment and to test the hypothesis that the duration of this impairment affects the development of postoperative memory issues. Materials and Methods: A prospective study was conducted in 2021-2023. After approval of the Ethics Committee and with patient's written consent, 83 adult patients undergoing elective on-pump coronary artery bypass graft (CABG) surgery were enrolled. All patients were assessed for cognitive function 1 day before surgery using the Mini-Mental state examination (MMSE-2) test as a screening tool and the Hopkins Verbal Learning Test-Revised (HVLT-R) to assess memory specifically. To diagnose possible memory impairment (IM), all patients underwent a repeat assessment of cognitive function on the 7th-10th postoperative day. Cerebral autoregulation monitoring using transcranial Doppler was performed. Cerebral autoregulation status index (Mx) was recorded using Intensive Care Brain Monitoring System software, 9.1.5.23 (Cambridge, UK). Results: According to our research, the incidence of postoperative memory impairment is 30.1%. Temporary cerebral autoregulation impairment occurs in all patients undergoing elective in-pump CABG surgery. The duration of the single longest CA impairment event in seconds (LCAI) and the LCAI dose were higher in patients with postoperative memory impairment, p = 0.006 and p < 0.007, respectively. Conclusions: Cerebral autoregulation impairment is important in developing memory loss after cardiac surgery. The duration and dose of the LCAI event are predictive of postoperative memory impairment.

A novel noninvasive method for dynamic cerebral autoregulation monitoring based on near-field coupling

Dynamical cerebral autoregulation (dCA) is crucial for optimizing blood pressure (BP) management and enhancing the prognosis of stroke patients. This study aims to obtain detailed cerebral blood flow (CBF) based on near-field coupling (NFC) and establish a novel method for evaluating dCA comprehensively. We developed a synchronized monitoring system of photoplethysmography-based mean arterial pressure (MAP) and NFC-based CBF. Fifteen healthy volunteers underwent dCA measurements before and after a body tilt. The multiple CBF parameters derived from NFC, along with synchronized MAP data, were used to compute the new dCA indices. Through a comparative analysis with TCD and NIRS, we studied the ability of NFC to assess dCA accurately and comprehensively. The results show that the trend in CBF changes measured by NFC before and after body tilt corresponded to the fluctuations observed in MAP. Compared to CBFV from TCD and rSO2 from NIRS, the NFC-derived parameters provide both intracranial hemodynamics and microcirculation. The dCA indices from NFC show high consistency with those from TCD, and the RFx-PVD, RFx-VEI, and RFx-HFC are the ideal indices for assessing dCA. The CAT of RFx-HFC has the largest effect size in distinguishing different dCA levels. These results demonstrate the feasibility and reliability of integrating NFC with synchronized MAP data collection to comprehensively and accurately assess dCA. It is expected to overcome the mutual constraints of existing methods in terms of time resolution, detection range and depth, and provide a new solution for continuous bedside assessment of dCA in patients with stroke.

Continuous Monitoring of Cerebral Autoregulation in Adults Supported by Extracorporeal Membrane Oxygenation.

Impaired cerebral autoregulation (CA) is one of several proposed mechanisms of acute brain injury in patients supported by extracorporeal membrane oxygenation (ECMO). The primary aim of this study was to determine the feasibility of continuous CA monitoring in adult ECMO patients. Our secondary aims were to describe changes in cerebral oximetry index (COx) and other metrics of CA over time and in relation to functional neurologic outcomes. This is a single-center prospective observational study. We measured COx, a surrogate measurement of cerebral blood flow measured by near-infrared spectroscopy, which is an index of CA derived from the moving correlation between mean arterial pressure (MAP) and slow waves of regional cerebral oxygen saturation. A COx value that approaches 1 indicates impaired CA. Using COx, we determined the optimal MAP (MAPOPT) and lower and upper limits of autoregulation for individual patients. These measurements were examined in relation to modified Rankin Scale (mRS) scores. Fifteen patients (median age 57years [interquartile range 47-69]) with 150 autoregulation measurements were included for analysis. Eleven were on veno-arterial ECMO (VA-ECMO), and four were on veno-venous ECMO (VV-ECMO). Mean COx was higher on postcannulation day 1 than on day 2 (0.2 vs. 0.09, p < 0.01), indicating improved CA over time. COx was higher in VA-ECMO patients than in VV-ECMO patients (0.12 vs. 0.06, p = 0.04). Median MAPOPT for the entire cohort was highly variable, ranging from 55 to 110mm Hg. Patients with mRS scores 0-3 (good outcome) at 3 and 6months spent less time outside MAPOPT compared with patients with mRS scores 4-6 (poor outcome) (74% vs. 82%, p = 0.01). The percentage of time when observed MAP was outside the limits of autoregulation was higher on postcannulation day 1 than on day 2 (18.2% vs. 3.3%, p < 0.01). In ECMO patients, it is feasible to monitor CA continuously at the bedside. CA improved over time, most significantly between postcannulation days 1 and 2. CA was more impaired in VA-ECMO patients than in VV-ECMO patients. Spending less time outside MAPOPT may be associated with achieving a good neurologic outcome.

Poor olfaction prior to cardiac surgery: Association with cognition, plasma neurofilament light, and post-operative delirium.

Post-operative delirium (POD) affects up to 50% of cardiac surgery patients, with higher incidence in older adults. There is increasing need for screening tools that identify individuals most vulnerable to POD. Here, we examined the relationship between pre-operative olfaction and both incident POD and POD severity in patients undergoing cardiac surgery. We also examined cross-sectional relationships between baseline olfaction, cognition, and plasma neurofilament light (NfL). Individuals undergoing cardiac surgery (n=189; mean age=70years; 75% men) were enrolled in a clinical trial of cerebral autoregulation monitoring. At baseline, odor identification performance (Brief Smell Identification Test), cognitive performance, and plasma concentrations of NfL levels (Simoa™ NF-Light Assay) were measured. Delirium was assessed with the Confusion Assessment Method (CAM) or CAM-ICU, and delirium severity was assessed using the Delirium Rating Scale-Revised-98. The association of baseline olfaction, delirium incidence, and delirium severity was examined in regression models adjusting for age, duration of cardiopulmonary bypass, logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE), and baseline cognition. Olfactory dysfunction was present in 30% of patients, and POD incidence was 44%. Pre-operative olfactory dysfunction was associated with both incident POD (OR=3.17, p=0.001) and greater severity of POD after cardiac surgery (OR=3.94 p<0.001) in models adjusted for age, duration of bypass, and a surgical risk score. The addition of baseline cognition attenuated the strength of the association, but it remained significant for incident POD (OR=2.25, p=0.04) and POD severity (OR 2.10, p=0.04). Poor baseline olfaction was associated with greater baseline cognitive dysfunction (p<0.001) and increased baseline plasma NfL concentrations (p=0.04). Neither age, cognition, nor baseline NFL concentration modified the association of impaired olfaction and delirium outcomes. Olfactory assessment may be a useful pre-surgical screening tool for the identification of patients undergoing cardiac surgery at increased risk of POD. Identifying those at highest risk for severe delirium and poor cognitive outcomes following surgery would allow for earlier intervention and pre-operative rehabilitation strategies, which could ultimately impact the functional disability and morbidity associated with POD.

B - 92 Poor Olfaction Prior to Cardiac Surgery: Associations with Cognition, Plasma Neurofilament Light and Postoperative Delirium in a Prospective Nested Cohort Study.

This study examined the association between pre-operative olfactory performance and delirium after cardiac surgery. As a secondary aim, we examined the relationship between baseline olfaction, cognitive functioning, and plasma neurofilament light (NfL). Individuals undergoing cardiac surgery were recruited as part of a clinical trial in which blood pressure during bypass was targeted using cerebral autoregulation monitoring. There were 189 participants (mean age = 70years; 75% men). At baseline, olfaction, cognition, and plasma concentrations of NfL were assessed using the 12-item Brief Smell Identification Test (BSIT), a battery of neuropsychological tests, and the Simoa™ NF-Light Assay, respectively. Impaired olfaction was defined as a score of ≤8 for men and ≤ 9 for women. Delirium was assessed using the Confusion Assessment Method (CAM) and CAM-ICU, and delirium severity was assessed using the Delirium Rating Scale-Revised-1998 (DRS-R-98). The association of baseline olfaction and delirium and delirium severity was examined in regression models adjusting for age, duration of bypass, a surgery risk score, and baseline cognitive performance. In adjusted models, impaired olfaction at baseline was associated with both incident delirium (OR = 2.25, p = 0.04) and greater delirium severity (OR = 2.10, p = 0.04) after cardiac surgery. Furthermore, worse baseline olfaction was associated with impaired cognition (p < 0.001) and increased perioperative concentrations of plasma NfL (p = 0.04). Pre-operative olfactory testing may provide insight into brain vulnerability, cognitive dysfunction, and delirium risk in individuals undergoing cardiac surgery. Psychophysical olfactory assessment may inform strategies for patient risk stratification and early identification of individuals at risk for post-operative delirium, allowing for delirium-prevention strategies.

Comparison of Near-Infrared Spectroscopy-Based Cerebral Autoregulatory Indices in Extremely Low Birth Weight Infants.

Premature infants are born with immature cerebral autoregulation function and are vulnerable to pressure passive cerebral circulation and subsequent brain injury. Measurements derived from near-infrared spectroscopy (NIRS) have enabled continuous assessment of cerebral vasoreactivity. Although NIRS has enabled a growing field of research, the lack of clear standardization in the field remains problematic. A major limitation of current literature is the absence of a comparative analysis of the different methodologies. To determine the relationship between NIRS-derived continuous indices of cerebral autoregulation in a cohort of extremely low birth weight (ELBW) infants. Premature infants of birth weight 401-1000 g were studied during the first 72 h of life. The cerebral oximetry index (COx), hemoglobin volume index (HVx), and tissue oxygenation heart rate reactivity index (TOHRx) were simultaneously calculated. The relationship between each of the indices was assessed with Pearson correlation. Fifty-eight infants with a median gestational age of 25.8 weeks and a median birth weight of 738 g were included. Intraventricular hemorrhage (IVH) was detected in 33% of individuals. COx and HVx demonstrated the highest degree of correlation, although the relationship was moderate at best (r = 0.543, p < 0.001). No correlation was found either between COx and TOHRx (r = 0.318, p < 0.015) or between HVx and TOHRx (r = 0.287, p < 0.029). No significant differences in these relationships were found with respect to IVH and no IVH in subgroup analysis. COx, HVx, and TOHRx are not numerically equivalent. Caution must be applied when interpreting or comparing results based on different methodologies for measuring cerebral autoregulation. Uniformity regarding data acquisition and analytical methodology are needed to firmly establish a gold standard for neonatal cerebral autoregulation monitoring.

Cerebral oximetry and autoregulation monitoring in shock patients

Background: Data on regional cerebral oxygen saturation (rSO2) and cerebral autoregulation monitoring in shock patients are limited. This study aimed to find the optimal range of rSO2 and cerebral oximetry index (COx), an autoregulation index correlated with adequate tissue perfusion determined by standard clinical and laboratory assessment. Method: We plan to monitor cerebral oximetry using near-infrared spectroscopy in shock patients admitted to the medical intensive care unit (MICU) at Siriraj Hospital. The rSO2 are continuously recorded for 72 hours [48] after admission or 24 hours after cessation of vasopressor infusion. The COx is calculated from the correlation coefficient between rSO2 and MAP. Data on patient demographics, treatments, physiologic parameters, and outcomes are recorded. The primary objective is to identify the optimal rSO2 and COx correlated with adequate tissue perfusion assessed by the current standard method. Adequate tissue perfusion as is defined as MAP ≥65 mmHg and two of the following criteria: urine ≥0.5 ml/kg/hour, capillary refill time ≤3 seconds, improvement in consciousness, lactate reduction ≥10% in 1 hour, serum lactate &lt;2 mmol/L, or central venous oxygen saturation (ScVO2) ≥70%. Since the optimal values of rSO2 and COx in shock patients are unknown, we are unable to perform the sample size calculation. Thus, for this study, we plan to collect data on rSO2 and COx in 30 patients. Hypothesis: We hypothesize that the values of rSO2 and COx are different between patients with adequate and inadequate tissue perfusion. Ethics statement: The study was reviewed and approved by the Human Research Protection Unit of Siriraj Hospital, Mahidol University (certificate of approval no. si 410/2022).

Multimodal Neuromonitoring in Pediatric Neurocritical Care: Current Perspectives.

Children with neurological illness in the critical care unit are always at higher risk of developing secondary brain injury (SBI). Brain insult can lead to changes in cerebral autoregulation, intracranial pressure (ICP), cerebral oxygenation, and metabolism. This can cause a raised ICP, cerebral ischemia, hypoxia, excitotoxicity, cellular energy failure, and nonconvulsive status epilepticus. Simultaneous and continuous assessment of these parameters will help to improve patient care and neurological outcomes. Even thoughclinical examination and neuroimaging can help in the initial diagnosis of the neurological illness, they may not be helpful in continuous monitoring of cerebralpathophysiological changes. The ideal single neuromonitoring device to detect these real-time changes is currently unavailable. However, a range of invasive and noninvasive monitors are available to monitor these cerebral functional parameters. Invasive monitoring techniques include invasive ICP monitoring, cerebral autoregulation monitoring, brain tissue partial oxygen pressure, and cerebral microdialysis. Noninvasive-monitoring techniques include pupillometry, brain and ocular ultrasonography, near-infraredspectroscopy, and electrophysiological monitoring. Multimodal (MM) neuromonitoring involves incorporating these techniques and tools for the early identification and treatment of primary and secondary brain insults. The utility and feasibility of most of these techniques are well described in adult neurocritical care. Even though the evidence on their usage in children is primarily available in pediatric traumatic brain injury, the emerging data help to further expand their utility in pediatric nontraumatic coma. MM neuromonitoring aims to provide clinical and pathophysiological information to the intensivists to improve their understanding of the child's neurological status and to formulate patient-specific treatment approaches.

IMPAIRED CEREBRAL AUTOREGULATION IN PATIENTS WITH ADVANCED LIVER FAILURE: AN UNDER-RECOGNIZED PHENOMENON

IMPAIRED CEREBRAL AUTOREGULATION IN PATIENTS WITH ADVANCED LIVER FAILURE: AN UNDER-RECOGNIZED PHENOMENON

Pro-Con Debate: The Clinical (Ir)relevance of the Lower Limit of Cerebral Autoregulation for Anesthesiologists.

In this Pro-Con commentary article, we discuss whether the lower limit of cerebral autoregulation is clinically relevant for anesthesiologists. The central question regarding this issue is whether mean arterial blood pressure below the lower limit of autoregulation is detrimental for the brain. The Pro side argues that continuous monitoring of cerebral autoregulation has revealed an association between going below the lower limit and mortality in the critically ill patient. Conversely, the Con side argues that cerebral autoregulation is only one of various defense mechanisms of the brain that protect against cerebral hypoperfusion, and that cerebral autoregulation may be more important to protect against intracranial hypertension.

Cerebral Autoregulation Monitoring in Traumatic Brain Injury: An Overview of Recent Advances in Personalized Medicine.

Impaired cerebral autoregulation (CA) in moderate/severe traumatic brain injury (TBI) has been identified as a strong associate with poor long-term outcomes, with recent data highlighting its dominance over cerebral physiological dysfunction seen in the acute phase post-injury. With advances in bedside continuous cerebral physiological signal processing, continuously derived metrics of CA capacity have been described over the past two decades, leading to improvements in cerebral physiological insult detection and development of novel personalized approaches to TBI care in the intensive care unit (ICU). This narrative review focuses on highlighting the concept of continuous CA monitoring and consequences of impairment in moderate/severe TBI. Further, we provide a comprehensive description and overview of the main personalized cerebral physiological targets, based on CA monitoring, that are emerging as strong associates with patient outcomes. The CA-based personalized targets, such as optimal cerebral perfusion pressure (CPPopt), lower/upper limit of regulation (LLR/ULR), and individualized intracranial pressure (iICP) are positioned to change the way we care for patients with TBI in the ICU, moving away from the "one treatment fits all" paradigm of current guideline-based therapeutic approaches toward a true personalized medicine approach tailored to the individual patient. Future perspectives regarding research needs in this field are also discussed.

Perioperative Neurofilament Light Plasma Concentrations and Cognition before and after Cardiac Surgery: A Prospective Nested Cohort Study.

Neurofilament light is a marker of neuronal injury and can be measured in blood. Postoperative increases in neurofilament light have been associated with delirium after noncardiac surgery. However, few studies have examined the association of neurofilament light changes with postdischarge cognition in cardiac surgery patients, who are at highest risk for neuronal injury and cognitive decline. The authors hypothesized that increased neurofilament light (both baseline and change) would be associated with worse neuropsychological status up to 1 yr after cardiac surgery. This observational study was nested in a trial of cardiac surgery patients, in which blood pressure during bypass was targeted using cerebral autoregulation monitoring. Plasma concentrations of neurofilament light were measured at baseline and postoperative day 1. Neuropsychological testing was performed at baseline, 1 month after surgery, and 1 yr after surgery. Primary outcomes were baseline and change from baseline in a composite z-score of all cognitive tests. Among 167 patients, cognitive outcomes were available in 80% (134 of 167) and 61% (102 of 167) at 1 month and 1 yr after surgery, respectively. The median baseline concentration of neurofilament light was 18.2 pg/ml (interquartile range, 13.4 to 28.1), and on postoperative day 1 was 28.5 pg/ml (interquartile range, 19.3 to 45.0). Higher baseline log neurofilament light was associated with worse baseline cognitive z-score (adjusted slope, -0.60; 95% CI, -0.90 to -0.30; P < 0.001), no change in z-score from baseline to 1 month (0.11; 95% CI, -0.19 to 0.41; P = 0.475), and improvement in z-score from baseline to 1 yr (0.56; 95% CI, 0.31 to 0.81; P < 0.001). Whereas some patients had an improvement in cognition at 1 yr and others a decline, an increase in neurofilament light from baseline to postoperative day 1 was associated with a greater decline in cognition at 1 yr. Higher baseline neurofilament light concentration was associated with worse baseline cognition but improvement in cognition at 1 yr. A postoperative increase in neurofilament light was associated with a greater cognitive decline at 1 yr.

Postoperative but not preoperative depression is associated with cognitive impairment after cardiac surgery: exploratory analysis of data from a randomized trial

BackgroundIn this study we hypothesize that depression is associated with perioperative neurocognitive dysfunction and altered quality of life one month after surgery.MethodsData were obtained as part of a study evaluating cerebral autoregulation monitoring for targeting arterial pressure during cardiopulmonary bypass. Neuropsychological testing was performed before surgery and one month postoperatively. Testing included the Beck Depression Inventory, a depression symptoms questionnaire (0–63 scale), as well as anxiety and quality of life assessments. Depression was defined as a Beck Depression Inventory score > 13.ResultsBeck Depression data were available from 320 patients of whom cognitive domain endpoints were available from 88–98% at baseline and 69–79% after surgery. This range in end-points data was due to variability in the availability of each neuropsychological test results between patients. Depression was present in 50 (15.6%) patients before surgery and in 43 (13.4%) after surgery. Baseline depression was not associated with postoperative domain-specific neurocognitive function compared with non-depressed patients. Those with depression one month after surgery, though, had poorer performance on tests of attention (p = 0.017), memory (p = 0.049), verbal fluency (p = 0.010), processing speed (p = 0.017), and fine motor speed (p = 0.014). Postoperative neurocognitive dysfunction as a composite outcome occurred in 33.3% versus 14.5% of patients with and without postoperative depression (p = 0.040). Baseline depression was associated with higher anxiety and lower self-ratings on several quality of life domains, these measures were generally more adversely affected by depression one month after surgery.ConclusionsThe results of this exploratory analysis suggests that preoperative depression is not associated with perioperative neurocognitive dysfunction, but depression after cardiac surgery may be associated with impairment in in several cognitive domains, a higher frequency of the composite neurocognitive outcome, and altered quality of life.Trial Registrationwww.clinicaltrials.gov, NCT00981474 (parent study).

Perspective on Cerebral Autoregulation Monitoring in Neonatal Cardiac Surgery Requiring Cardiopulmonary Bypass.

The autoregulation of cerebral blood flow protects against brain injury from transient fluctuations in arterial blood pressure. Impaired autoregulation may contribute to hypoperfusion injury in neonates and infants. Monitoring cerebral autoregulation in neonatal cardiac surgery as a guide for arterial blood pressure management may reduce neurodevelopmental morbidity. Cerebral autoregulation monitoring has been validated in animal models and in an adult trial autoregulation monitoring during bypass improved postoperative delirium scores. The nuances of pediatric cardiac disease and congenital heart surgery make simply applying adult trial findings to this unique population inappropriate. Therefore, dedicated pediatric clinical trials of cerebral autoregulation monitoring are indicated.

The perioperative application of continuous cerebral autoregulation monitoring for cerebral protection in elderly patients.

The majority of surgical patients aged 65 years and over are accompanied with underlying conditions, making them susceptible to perioperative cerebral complications. Here, we investigated the clinical value of continuous cerebral autoregulation (CA) monitoring in protecting against cerebral dysfunction in elderly patients undergoing surgery. This study enrolled 40 elderly patients (aged ≥65 years) and 40 middle-aged patients (aged 45 to 64 years) selected to undergo robotic-assisted laparoscopic radical prostatectomy. Cerebral oxygenation was assessed by regional cerebral oxygen saturation (rScO2) using near-infrared spectroscopy (NIRS). CA function was estimated using the cerebral oximetry index (COX), which is the rolling correlation between rScO2 and the mean arterial pressure (MAP). With the patient in the Trendelenburg position, the rScO2, MAP, calculated COX, HR, end-tidal CO2, and sevoflurane concentrations were continuously recorded. Standardized anesthesia was administered to all patients (sevoflurane, propofol, remifentanil, and rocuronium). Postoperative delirium (POD) was screened for daily using the Confusion Assessment Method (CAM). The primary outcome was the difference in periods of CA dysfunction between the elderly and middle-aged groups. Secondary outcomes included the incidence of POD and the optimal MAP range in the 2 groups. Taking positive COX values (cutoff ≥0.3) to reflect periods of CA dysfunction, we found that the cumulative duration of CA dysfunction in the Trendelenburg position was longer in elderly patients than in middle-aged patients [ratio of cumulative time of CA dysfunction: middle-aged group, 32.8% (26.3%, 43.1%) vs. elderly group, 42.2% (33.1%, 51.2%)] (P<0.01), which showed that CA function was less efficient in elderly patients. Three patients (7.5%) in the elderly group and 1 patient (2.5%) in the middle-aged group screened positive for POD on at least 1 day during their hospital stay. Additionally, using the COX-based method, we estimated the optimal MAP targets in the middle-aged and elderly groups to be (67.8±8.9, 116.4±10.5) and (71.2±12.5, 111.3±8.9) mmHg, respectively. The brains of patients ≥65 years are more vulnerable to systemic insult compared with those of middle-aged patients. POD may be associated with CA dysfunction. NIRS-derived COX can be used to identify the optimal MAP range.

Is a Mean Arterial Pressure Less Than 65 mm Hg an Appropriate Indicator of the Quality of Anesthesia Care?

Is a Mean Arterial Pressure Less Than 65 mm Hg an Appropriate Indicator of the Quality of Anesthesia Care?

Serum biomarkers and cerebral autoregulation as early warnings of delayed cerebral ischemia risk in patients after aneurysmal subarachnoid haemorrhage

BackgroundIdentifying patients at risk of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid haemorrhage (aSAH) remains challenging. This study aimed to evaluate the concentration of serum biomarkers along with cerebral autoregulation impairment on DCI. Methods55 patients suffering from aSAH were enrolled in the study. Serum S100protein B (S100B) was tested both on the day of admission and over three consecutive days following the occurrence of aSAH. Cerebral autoregulation was assessed using a tissue oxygenation index (TOxa) based on near-infrared spectroscopy. ResultsChanges in serum S100B levels interacted with DCI status (presence vs. absence): F = 3.84, p = 0.016. Patients with DCI had higher S100B concentration level on day 3 than those without DCI (3.54 ± 0.50 ng/ml vs. 0.58 ± 0.43 ng/ml, p = 0.001). S100B concentration on day 3 following aSAH predicted DCI (AUC = 0.77, p = 0.006). Raised level of serum S100B on day 3 was related with higher TOxa, thus with impaired cerebral autoregulation (rS = 0.52,p = 0.031). Multivariate logistic regression analysis showed thatimpaired cerebral autoregulation andelevatedS100B concentration on day 3 increasethe likelihood of DCI. ConclusionsTracking changes in the serum biomarkers concentration along with monitoring of cerebral autoregulation, may play a role in early detection of patients at risk of DCI after aSAH. These results need to be validated in larger prospective cohorts.

Use of Direct Intracranial Pressure and Brain Tissue Oxygen Monitoring in Perioperative Management of Patients with Moyamoya Disease.

Intracranial pressure monitoring and brain tissue oxygen monitoring are commonly used in head injury for goal-directed therapies, but there may be more indications for its use. Moyamoya disease involves progressive stenosis of the arterial circulation and formation of collateral vessels that are at risk of hemorrhage. The risk of ischemic events during revascularization surgery and postoperatively is high. Impaired cerebral autoregulation may be one of the factors that are implicated. We present our experience with monitoring of cerebral oxygenation and autoregulation in the pathological hemisphere during the perioperative period in four patients with moyamoya disease.

Personalized Blood Pressure Management During Cardiac Surgery With Cerebral Autoregulation Monitoring: A Randomized Trial

The purpose of this study was to determine if setting mean arterial pressure (MAP) targets during cardiopulmonary bypass (CPB) based on individualized cerebral autoregulation data reduces the frequency of neurological complications compared with usual care. Patients (n = 460) ≥ 55 years old at risk for neurological complications were randomized to have MAP targets during CPB to be above the lower limit of transcranial Doppler determined cerebral autoregulation versus usual institutional practices. The primary outcome was the frequency of the composite endpoint of clinical stroke, or new brain magnetic resonance imaging-detected ischemic injury, or cognitive decline 4-6 weeks after surgery from baseline. Secondary outcomes were components of the primary composite outcome and clinically detected delirium. Complete outcome data were available from 194 patients (stroke assessments, n = 460; magnetic resonance imaging data, n = 164; cognitive data n = 336). There was no difference between groups in the frequency of the composite neurological end-point or its components (P = 0.752). Compared with the usual care there was a 45% reduction in the frequency of clinically detected delirium in the autoregulation group (8.2% vs 14.9%, risk ratio = 0.55, 95% confidence interval = 0.32, 0.93, P = 0.035) and improved performance on test of memory 4-6 weeks after surgery from baseline (P = 0.019). Basing MAP during CPB on cerebral autoregulation monitoring did not reduce the frequency of the primary neurological outcome in high-risk patients compared with usual care but it was associated with a reduction in the frequency of delirium and better performance on tests of memory 4-6 weeks after surgery.