Consensus summary statement of the International Multidisciplinary Consensus Conference on Multimodality Monitoring in Neurocritical Care : a statement for healthcare professionals from the Neurocritical Care Society and the European Society of Intensive Care Medicine

Hemodynamic management of acute brain injury caused by cerebrovascular diseases: a survey of the European Society of Intensive Care Medicine

BACKGROUND

The optimal hemodynamic targets and management of patients with acute brain injury are not completely elucidated, but recent evidence points to important impact on clinical outcomes. We performed an international survey with the aim to investigate the practice in the hemodynamic targets, monitoring, and management of patients with acute ischemic stroke (AIS), intracranial hemorrhage (ICH) and subarachnoid hemorrhage (SAH).

METHODS

This survey was endorsed by the European Society of Intensive Care (ESICM). An electronic questionnaire of 76 questions divided in 4 sections (general information, AIS, ICH, SAH specific questions) was available between January 2022 to March 2022 on the ESICM website.

RESULTS

One hundred fifty-four healthcare professionals from 36 different countries and at least 98 different institutions answered the survey. Routine echocardiography is routinely performed in 37% of responders in AIS, 34% in ICH and 38% in SAH. Cardiac output monitoring is used in less than 20% of cases by most of the responders. Cardiovascular complications are the main reason for using advanced hemodynamic monitoring, and norepinephrine is the most common drug used to increase arterial blood pressure. Most responders target fluid balance to neutral (62% in AIS, 59% in ICH,44% in SAH), and normal saline is the most common fluid used. Large variability was observed regarding the blood pressure targets.

CONCLUSIONS

Hemodynamic management and treatment in patients with acute brain injury from cerebrovascular diseases vary largely in clinical practice. Further research is required to provide clear guidelines to physicians for the hemodynamic optimization of this group of patients.

Vector Angle Analysis of Multimodal Neuromonitoring Data for Continuous Prediction of Delayed Cerebral Ischemia

BACKGROUND

Dysfunctional cerebral autoregulation often precedes delayed cerebral ischemia (DCI). Currently, there are no data-driven techniques that leverage this information to predict DCI in real time. Our hypothesis is that information using continuous updated analyses of multimodal neuromonitoring and cerebral autoregulation can be deployed to predict DCI.

METHODS

Time series values of intracranial pressure, brain tissue oxygenation, cerebral perfusion pressure (CPP), optimal CPP (CPPOpt), ΔCPP (CPP - CPPOpt), mean arterial pressure, and pressure reactivity index were combined and summarized as vectors. A validated temporal signal angle measurement was modified into a classification algorithm that incorporates hourly data. The time-varying temporal signal angle measurement (TTSAM) algorithm classifies DCI at varying time points by vectorizing and computing the angle between the test and reference time signals. The patient is classified as DCI+ if the error between the time-varying test vector and DCI+ reference vector is smaller than that between the time-varying test vector and DCI- reference vector. Finally, prediction at time point t is calculated as the majority voting over all the available signals. The leave-one-patient-out cross-validation technique was used to train and report the performance of the algorithms. The TTSAM and classifier performance was determined by balanced accuracy, F1 score, true positive, true negative, false positive, and false negative over time.

RESULTS

One hundred thirty-one patients with aneurysmal subarachnoid hemorrhage who underwent multimodal neuromonitoring were identified from two centers (Columbia University: 52 [39.7%], Aachen University: 79 [60.3%]) and included in the analysis. Sixty-four (48.5%) patients had DCI, and DCI was diagnosed 7.2 ± 3.3 days after hemorrhage. The TTSAM algorithm achieved a balanced accuracy of 67.3% and an F1 score of 0.68 at 165 h (6.9 days) from bleed day with a true positive of 0.83, false positive of 0.16, true negative of 0.51, and false negative of 0.49.

CONCLUSIONS

A TTSAM algorithm using multimodal neuromonitoring and cerebral autoregulation calculations shows promise to classify DCI in real time.

Relationship Between Brain Tissue Oxygen and Near-Infrared Spectroscopy in Patients with Nontraumatic Subarachnoid Hemorrhage

BACKGROUND

Continuous monitoring of cerebral oxygenation is one of the diagnostic tools used in patients with brain injury. Direct and invasive measurement of cerebral oxygenation with a partial brain oxygen pressure (PbtO₂) probe is promising but invasive. Noninvasive assessment of regional transcranial oxygen saturation using near-infrared spectroscopy (NIRS) may be feasible. The aim of this study was to evaluate the interchangeability between PbtO₂ and NIRS over time in patients with nontraumatic subarachnoid hemorrhage.

METHODS

This retrospective study was performed in a neurocritical care unit. Study participants underwent hourly PbtO₂ and NIRS measurements over 72 h. Temporal agreement between markers was described by their pointwise correlation. A secondary analysis assessed the structure of covariation between marker trajectories using a bivariate linear mixed model.

RESULTS

Fifty-one patients with subarachnoid hemorrhage were included. A total of 3362 simultaneous NIRS and PbtO₂ measurements were obtained. The correlation at each measurement time ranged from - 0.25 to 0.25. The global correlation over time was - 0.026 (p = 0.130). The bivariate linear mixed model confirmed the lack of significant correlation between the PbtO₂ and NIRS measurements at follow-up. NIRS was unable to detect PbtO₂ values below 20 mm Hg (area under the receiver operating characteristic curve 0.539 [95% confidence interval 0.536-0.542]; p = 0.928), and percentage changes in NIRS were unable to detect a decrease in PbtO₂ ≥ 10% (area under the receiver operating characteristic curve 0.615 [95% confidence interval 0.614-0.616]; p < 0.001).

CONCLUSIONS

PbtO₂ and NIRS measurements were not correlated. There is no evidence that NIRS could be a substitute for PbtO₂ monitoring in patients with nontraumatic subarachnoid hemorrhage.

Effect of inotropic agents on oxygenation and cerebral perfusion in acute brain injury

Introduction

Tissue hypoxia and insufficient energy delivery is one of the mechanisms behind the occurrence of several complications in acute brain injured patients. Several interventions can improve cerebral oxygenation; however, the effects of inotropic agents remain poorly characterized.

Methods

Retrospective analysis including patients suffering from acute brain injury and monitored with brain oxygen pressure (PbtO2) catheter, in whom inotropic agents were administered according to the decision of the treating physician's decision; PbtO2 values were collected before, 1 and 2 h after the initiation of therapy from the patient data monitoring system. PbtO2 “responders” were patients with a relative increase in PbtO2 from baseline values of at least 20%.

Results

A total of 35 patients were included in this study. Most of them (31/35, 89%) suffered from non-traumatic subarachnoid hemorrhage (SAH). Compared with baseline values [20 (14–24) mmHg], PbtO2 did not significantly increase over time [19 (15–25) mmHg at 1 h and 19 (17–25) mmHg at 2 h, respectively; p = 0.052]. A total of 12/35 (34%) patients were PbtO2 “responders,” in particular if low PbtO2 was observed at baseline. A PbtO2 of 17 mmHg at baseline had a sensibility of 84% and a specificity of 91% to predict a PbtO2 responder. A significant direct correlation between changes in PbtO2 and cardiac output [r = 0.496 (95% CI 0.122 to 0.746), p = 0.01; n = 25] and a significant negative correlation between changes in PbtO2 and cerebral perfusion pressure [r = −0.389 (95% CI −0.681 to −0.010), p = 0.05] were observed.

Conclusions

In this study, inotropic administration significantly increased brain oxygenation in one third of brain injured patients, especially when tissue hypoxia was present at baseline. Future studies should highlight the role of inotropic agents in the management of tissue hypoxia in this setting.

Adult Critical Care Electroencephalography Monitoring for Seizures: A Narrative Review

Electroencephalography (EEG) is an important and relatively inexpensive tool that allows intensivists to monitor cerebral activity of critically ill patients in real time. Seizure detection in patients with and without acute brain injury is the primary reason to obtain an EEG in the Intensive Care Unit (ICU). In response to the increased demand of EEG, advances in quantitative EEG (qEEG) created an approach to review large amounts of data instantly. Finally, rapid response EEG is now available to reduce the time to detect electrographic seizures in limited-resource settings. This review article provides a concise overview of the technical aspects of EEG monitoring for seizures, clinical indications for EEG, the various available modalities of EEG, common and challenging EEG patterns, and barriers to EEG monitoring in the ICU.

Management of moderate to severe traumatic brain injury: an update for the intensivist

Traumatic brain injury (TBI) remains one of the most fatal and debilitating conditions in the world. Current clinical management in severe TBI patients is mainly concerned with reducing secondary insults and optimizing the balance between substrate delivery and consumption. Over the past decades, multimodality monitoring has become more widely available, and clinical management protocols have been published that recommend potential interventions to correct pathophysiological derangements. Even while evidence from randomized clinical trials is still lacking for many of the recommended interventions, these protocols and algorithms can be useful to define a clear standard of therapy where novel interventions can be added or be compared to. Over the past decade, more attention has been paid to holistic management, in which hemodynamic, respiratory, inflammatory or coagulation disturbances are detected and treated accordingly. Considerable variability with regards to the trajectories of recovery exists. Even while most of the recovery occurs in the first months after TBI, substantial changes may still occur in a later phase. Neuroprognostication is challenging in these patients, where a risk of self-fulfilling prophecies is a matter of concern. The present article provides a comprehensive and practical review of the current best practice in clinical management and long-term outcomes of moderate to severe TBI in adult patients admitted to the intensive care unit.

Effects of Sodium Nitroprusside Administered Via a Subdural Intracranial Catheter on the Microcirculation, Oxygenation, and Electrocortical Activity of the Cerebral Cortex in a Pig Cardiac Arrest Model

Background

Postischemic cerebral hypoperfusion has been indicated as an important contributing factor to secondary cerebral injury after cardiac arrest. We evaluated the effects of sodium nitroprusside administered via a subdural intracranial catheter on the microcirculation, oxygenation, and electrocortical activity of the cerebral cortex in the early postresuscitation period using a pig model of cardiac arrest.

Methods and Results

Twenty‐nine pigs were resuscitated with closed cardiopulmonary resuscitation after 14 minutes of untreated ventricular fibrillation. Thirty minutes after restoration of spontaneous circulation, 24 pigs randomly received either 4 mg of sodium nitroprusside (IT‐SNP group) or saline placebo (IT‐saline group) via subdural intracranial catheters and were observed for 5 hours. The same dose of sodium nitroprusside was administered intravenously in another 5 pigs. Compared with the IT‐saline group, the IT‐SNP group had larger areas under the curve for tissue oxygen tension and percent changes of arteriole diameter and number of perfused microvessels from baseline (all P<0.05) monitored on the cerebral cortex during the 5‐hour period, without severe hemodynamic instability. This group also showed faster recovery of electrocortical activity measured using amplitude‐integrated electroencephalography. Repeated‐measures analysis of variance revealed significant group–time interactions for these parameters. Intravenously administered sodium nitroprusside caused profound hypotension but did not appear to increase the cerebral parameters.

Conclusions

Sodium nitroprusside administered via a subdural intracranial catheter increased post–restoration of spontaneous circulation cerebral cortical microcirculation and oxygenation and hastened electrocortical activity recovery in a pig model of cardiac arrest. Further studies are required to determine its impact on the long‐term neurologic outcomes.

The brain in pediatric critical care: unique aspects of assessment, monitoring, investigations, and follow-up

As survival after pediatric intensive care unit (PICU) admission has improved over recent years, a key focus now is the reduction of morbidities and optimization of quality of life for survivors. Neurologic disorders and direct brain injuries are the reason for 11-16% of admissions to PICU. In addition, many critically ill children are at heightened risk of brain injury and neurodevelopmental difficulties affecting later life, e.g., complex heart disease and premature birth. Hence, assessment, monitoring and protection of the brain, using fundamental principles of neurocritical care, are crucial to the practice of pediatric intensive care medicine. The assessment of brain function, necessary to direct appropriate care, is uniquely challenging amongst children admitted to the PICU. Challenges in assessment arise in children who are unstable, or pharmacologically sedated and muscle relaxed, or who have premorbid abnormality in development. Moreover, the heterogeneity of diseases and ages in PICU patients, means that high caliber evidence is harder to accrue than in adult practice, nonetheless, great progress has been made over recent years. In this 'state of the art' paper about critically ill children, we discuss (1) patient types at risk of brain injury, (2) new standardized clinical assessment tools for age-appropriate, clinical evaluation of brain function, (3) latest evidence related to cranial imaging, non-invasive and invasive monitoring of the brain, (4) the concept of childhood 'post intensive are syndrome' and approaches for neurodevelopmental follow-up. Better understanding of these concepts is vital for taking PICU survivorship to the next level.

Challenges in the hemodynamic management of acute nontraumatic neurological injuries

PURPOSE OF REVIEW

To appraise the evidence from the literature and suggest an integrated hemodynamic approach of early and delayed phases of acute ischemic stroke (AIS), subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH).

RECENT FINDINGS

In AIS, the research aims to evaluate the optimal pressure control before, during and after the revascularization, to optimize the perfusion in the ischemic areas, minimizing the risk of hemorrhage or secondary damage to already infarcted areas. In the early phase of SAH, systemic pressure should be controlled to balance the risk of stroke, hypertension-related rebleeding, and maintenance of cerebral perfusion pressure. The late phase aims to minimize the risk of cerebral vasospasm by adapting systemic pressure and volemia to cerebral and systemic physiological hemodynamic targets. In the mild-to-moderate ICH, achieving SAP of less than 140 mmHg and greater than 110 mmHg may be considered as a beneficial target. Caution should be considered in lowering intensively SAP in severe ICH.

SUMMARY

In nontraumatic brain injuries, the hemodynamic management is strictly related to fluctuating physiology of these diseases, needing a strict control of pressure and flow variable to ensure both cerebral and systemic homeostasis.

Individualized cerebral perfusion pressure in acute neurological injury: are we ready for clinical use?

PURPOSE OF REVIEW

Individualizing cerebral perfusion pressure based on cerebrovascular autoregulation assessment is a promising concept for neurological injuries where autoregulation is typically impaired. The purpose of this review is to describe the status quo of autoregulation-guided protocols and discuss steps towards clinical use.

RECENT FINDINGS

Retrospective studies have indicated an association of impaired autoregulation and poor clinical outcome in traumatic brain injury (TBI), hypoxic-ischemic brain injury (HIBI) and aneurysmal subarachnoid hemorrhage (aSAH). The feasibility and safety to target a cerebral perfusion pressure optimal for cerebral autoregulation (CPPopt) after TBI was recently assessed by the COGITATE trial. Similarly, the feasibility to calculate a MAP target (MAPopt) based on near-infrared spectroscopy was demonstrated for HIBI. Failure to meet CPPopt is associated with the occurrence of delayed cerebral ischemia in aSAH but interventional trials in this population are lacking. No level I evidence is available on potential effects of autoregulation-guided protocols on clinical outcomes.

SUMMARY

The effect of autoregulation-guided management on patient outcomes must still be demonstrated in prospective, randomized, controlled trials. Selection of disease-specific protocols and endpoints may serve to evaluate the overall benefit from such approaches.

Neuro-oncologic Emergencies

PURPOSE OF REVIEW

Patients with brain and spine tumors are at high risk of presenting cancer-related complications at disease presentation or during active treatment and are usually related to the type and location of the lesion. Here, we discuss presentation and management of the most common emergencies affecting patients with central nervous system neoplastic lesions.

RECENT FINDINGS

Tumor-related emergencies encompass complications in patients with central nervous system neoplasms, as well as neurologic complications in patients with systemic malignancies. Brain tumor patients are at high risk of developing multiple complications such as intracranial hypertension, brain herniation, intracranial bleeding, spinal cord compression, and others. Neuro-oncologic emergencies require immediate attention and multi-disciplinary care. These emergent situations usually need rapid decision-making and management on an inpatient basis.

Intracranial Pressure Monitoring in the Intensive Care Unit for Patients with Severe Traumatic Brain Injury: Analysis of the CENTER-TBI China Registry

BACKGROUND

Although the current guidelines recommend the use of intracranial pressure (ICP) monitoring in patients with severe traumatic brain injury (sTBI), the evidence indicating benefit is limited. The present study aims to evaluate the impact of ICP monitoring on patients with sTBI in the intensive care unit (ICU).

METHODS

The patient data were obtained from the Collaborative European Neurotrauma Effectiveness Research in Traumatic Brain Injury China Registry, a prospective, multicenter, longitudinal, observational, cohort study. Patients with sTBI who were admitted to 52 ICUs across China, managed with ICP monitoring or without, were analyzed in this study. Patients with missing information on discharge survival status, Glasgow Coma Scale score on admission to hospital, and record of ICP monitoring application were excluded from the analysis. Data on demographic characteristics, injury, clinical features, treatments, survival at discharge, discharge destination, and length of stay were collected and assessed. The primary end point was survival state at discharge, and death from any cause was considered the event of interest.

RESULTS

A total of 2029 patients with sTBI were admitted to the ICU; 737 patients (36.32%) underwent ICP monitoring, and 1292 (63.68%) were managed without ICP monitoring. There was a difference between management with and without ICP monitoring on in-hospital mortality in the unmatched cohort (18.86% vs. 26.63%, p < 0.001) and the propensity-score-matched cohort (19.82% vs. 26.83%, p = 0.003). Multivariate logistic regressions also indicated that increasing age, higher injury severity score, lower Glasgow Coma Scale score, unilateral and bilateral pupillary abnormalities, systemic hypotension (SBP ≤ 90 mm Hg), hypoxia (SpO2 < 95%) on arrival at the hospital, and management without ICP monitoring were associated with higher in-hospital mortality. However, the patients without ICP monitoring had a lower length of stay in the ICU (11.79 vs. 7.95 days, p < 0.001) and hospital (25.96 vs. 21.71 days, p < 0.001), and a higher proportion of survivors were discharged to the home with better recovery in self-care.

CONCLUSIONS

Although ICP monitoring was not widely used by all of the centers participating in this study, patients with sTBI managed with ICP monitoring show a better outcome in overall survival. Nevertheless, the use of ICP monitoring makes the management of sTBI more complex and increases the costs of medical care by prolonging the patient's stay in the ICU or hospital.

Early Detection of Cerebral Herniation by Continuous Electroencephalography and Quantitative Analysis

Continuous electroencephalography (cEEG) and quantitative analysis of EEG (qEEG) are used in various circumstances such as detecting seizures, identifying acute or delayed cerebral ischemia, monitoring sedative therapy, or assessing prognosis. The authors report 2 cases: (1) Case #1 was a patient with unilateral cerebral edema and uncal herniation with asymmetric cEEG and qEEG changes detected an hour before clinical examination changes were noted and (2) Case #2 was a patient with diffuse cerebral edema and trans-tentorial herniation with symmetric cEEG and qEEG changes detected an hour before clinical examination changes were noted. These cases demonstrate the ability of cEEG and qEEG in early detection of different types of cerebral herniation. qEEG can be utilized by intensive care unit (ICU) staff not trained in EEG interpretation as a surveillance method to detect cerebral herniation, which may provide an opportunity for early intervention in high-risk patients.

Risk factors that predict delayed seizure detection on continuous electroencephalogram (cEEG) in a large sample size of critically ill patients

OBJECTIVE

Majority of seizures are detected within 24 hours on continuous EEG (cEEG). Some patients have delayed seizure detection after 24 hours. The purpose of this research was to identify risk factors that predict delayed seizure detection and to determine optimal cEEG duration for various patient subpopulations.

METHODS

We retrospectively identified all patients ≥18 years of age who underwent cEEG at Cleveland clinic during calendar year 2016. Clinical and EEG data for all patients and time to seizure detection for seizure patients were collected.

RESULTS

Twenty-four hundred and two patients met inclusion criteria. Of these, 316 (13.2%) had subclinical seizures. Sixty-five (20.6%) patients had delayed seizures detection after 24 hours. Seizure detection increased linearly till 36 hours of monitoring, and odds of seizure detection increased by 46% for every additional day of monitoring. Delayed seizure risk factors included stupor (13.2% after 48 hours, P = .031), lethargy (25.9%, P = .013), lateralized (LPDs) (27.7%, P = .029) or generalized periodic discharges (GPDs) (33.3%, P = .022), acute brain insults (25.5%, P = .036), brain bleeds (32.8%, P = .014), especially multiple concomitant bleeds (61.1%, P < .001), altered mental status (34.7%, P = .001) as primary cEEG indication, and use of antiseizure medications (27.8%, P < .001) at cEEG initiation.

SIGNIFICANCE

Given the linear seizure detection trend, 36 hours of standard monitoring appears more optimal than 24 hours especially for high-risk patients. For awake patients without epileptiform discharges, <24 hours of monitoring appears sufficient. Previous studies have shown that coma and LPDs predict delayed seizure detection. We found that stupor and lethargy were also associated with delayed seizure detection. LPDs and GPDs were associated with delayed seizures. Other delayed seizure risk factors included acute brain insults, brain bleeds especially multiple concomitant bleeds, altered mental status as primary cEEG indication, and use of ASMs at cEEG initiation. Longer cEEG (≥48 hours) is suggested for these high-risk patients.

The Relationship Between Seizures and Spreading Depolarizations in Patients with Severe Traumatic Brain Injury

BACKGROUND

Both seizures and spreading depolarizations (SDs) are commonly detected using electrocorticography (ECoG) after severe traumatic brain injury (TBI). A close relationship between seizures and SDs has been described, but the implications of detecting either or both remain unclear. We sought to characterize the relationship between these two phenomena and their clinical significance.

METHODS

We performed a post hoc analysis of a prospective observational clinical study of patients with severe TBI requiring neurosurgery at five academic neurotrauma centers. A subdural electrode array was placed intraoperatively and ECoG was recorded during intensive care. SDs, seizures, and high-frequency background characteristics were quantified offline using published standards and terminology. The primary outcome was the Glasgow Outcome Scale-Extended score at 6 months post injury.

RESULTS

There were 138 patients with valid ECoG recordings; the mean age was 47 ± 19 years, and 104 (75%) were men. Overall, 2,219 ECoG-detected seizures occurred in 38 of 138 (28%) patients in a bimodal pattern, with peak incidences at 1.7-1.8 days and 3.8-4.0 days post injury. Seizures detected on scalp electroencephalography (EEG) were diagnosed by standard clinical care in only 18 of 138 (13%). Of 15 patients with ECoG-detected seizures and contemporaneous scalp EEG, seven (47%) had no definite scalp EEG correlate. ECoG-detected seizures were significantly associated with the severity and number of SDs, which occurred in 83 of 138 (60%) of patients. Temporal interactions were observed in 17 of 24 (70.8%) patients with both ECoG-detected seizures and SDs. After controlling for known prognostic covariates and the presence of SDs, seizures detected on either ECoG or scalp EEG did not have an independent association with 6-month functional outcome but portended worse outcome among those with clustered or isoelectric SDs.

CONCLUSIONS

In patients with severe TBI requiring neurosurgery, seizures were half as common as SDs. Seizures would have gone undetected without ECoG monitoring in 20% of patients. Although seizures alone did not influence 6-month functional outcomes in this cohort, they were independently associated with electrographic worsening and a lack of motor improvement following surgery. Temporal interactions between ECoG-detected seizures and SDs were common and held prognostic implications. Together, seizures and SDs may occur along a dynamic continuum of factors critical to the development of secondary brain injury. ECoG provides information integral to the clinical management of patients with TBI.

Factors Associated With Brain Tissue Oxygenation Changes After RBC Transfusion in Acute Brain Injury Patients

OBJECTIVES

Anemia is common after acute brain injury and can be associated with brain tissue hypoxia. RBC transfusion (RBCT) can improve brain oxygenation; however, predictors of such improvement remain unknown. We aimed to identify the factors associated with PbtO2 increase (greater than 20% from baseline value) after RBCT, using a generalized mixed model.

DESIGN

This is a multicentric retrospective cohort study (2012-2020).

SETTING

This study was conducted in three European ICUs of University Hospitals located in Belgium, Switzerland, and Austria.

PATIENTS

All patients with acute brain injury who were monitored with brain tissue oxygenation (PbtO2) catheters and received at least one RBCT.

INTERVENTION

Patients received at least one RBCT. PbtO2 was recorded before, 1 hour, and 2 hours after RBCT.

MEASUREMENTS AND MAIN RESULTS

We included 69 patients receiving a total of 109 RBCTs after a median of 9 days (5-13 d) after injury. Baseline hemoglobin (Hb) and PbtO2 were 7.9 g/dL [7.3-8.7 g/dL] and 21 mm Hg (16-26 mm Hg), respectively; 2 hours after RBCT, the median absolute Hb and PbtO2 increases from baseline were 1.2 g/dL [0.8-1.8 g/dL] (p = 0.001) and 3 mm Hg (0-6 mm Hg) (p = 0.001). A 20% increase in PbtO2 after RBCT was observed in 45 transfusions (41%). High heart rate (HR) and low PbtO2 at baseline were independently associated with a 20% increase in PbtO2 after RBCT. Baseline PbtO2 had an area under receiver operator characteristic of 0.73 (95% CI, 0.64-0.83) to predict PbtO2 increase; a PbtO2 of 20 mm Hg had a sensitivity of 58% and a specificity of 73% to predict PbtO2 increase after RBCT.

CONCLUSIONS

Lower PbtO2 values and high HR at baseline could predict a significant increase in brain oxygenation after RBCT.

Acute Intracranial Hypertension During Pregnancy: Special Considerations and Management Adjustments

Pregnancy is associated with a number of pathophysiological changes (including modification of vascular resistance, increased vascular permeability, and coagulative disorders) that can lead to specific (eclampsia, preeclampsia) or not specific (intracranial hemorrhage) neurological complications. In addition to these disorders, pregnancy can affect numerous preexisting neurologic conditions, including epilepsy, brain tumors, and intracerebral bleeding from cerebral aneurysm or arteriovenous malformations. Intracranial complications related to pregnancy can expose patients to a high risk of intracranial hypertension (IHT). Unfortunately, at present, the therapeutic measures that are generally adopted for the control of elevated intracranial pressure (ICP) in the general population have not been examined in pregnant patients, and their efficacy and safety for the mother and the fetus is still unknown. In addition, no specific guidelines for the application of the staircase approach, including escalating treatments with increasing intensity of level, for the management of IHT exist for this population. Although some of basic measures can be considered safe even in pregnant patients (management of stable hemodynamic and respiratory function, optimization of systemic physiology), some other interventions, such as hyperventilation, osmotic therapy, hypothermia, barbiturates, and decompressive craniectomy, can lead to specific concerns for the safety of both mother and fetus. The aim of this review is to summarize the neurological pathophysiological changes occurring during pregnancy and explore the effects of the possible therapeutic interventions applied to the general population for the management of IHT during pregnancy, taking into consideration ethical and clinical concerns as well as the decision for the timing of treatment and delivery.

Neuromonitoring in Severe Traumatic Brain Injury: A Bibliometric Analysis

Traumatic brain injury (TBI) is the leading cause of mortality and disability among trauma-related injuries. Neuromonitoring plays an essential role in the management and prognosis of patients with severe TBI. Our bibliometric study aimed to identify the knowledge base, define the research front, and outline the social networks on neuromonitoring in severe TBI. We conducted an electronic search for articles related to neuromonitoring in severe TBI in Scopus. A descriptive analysis retrieved evidence on the most productive authors and countries, the most cited articles, the most frequently publishing journals, and the most common author's keywords. Through a three-step network extraction process, we performed a collaboration analysis among universities and countries, a cocitation analysis, and a word cooccurrence analysis. A total of 1884 records formed the basis of our bibliometric study. We recorded an increasing scientific interest in the use of neuromonitoring in severe TBI. Czosnyka, Hutchinson, Menon, Smielewski, and Stocchetti were the most productive authors. The most cited document was a review study by Maas et al. There was an extensive collaboration among universities. The most common keywords were "intracranial pressure," with an increasing interest in magnetic resonance imaging and cerebral perfusion pressure monitoring. Neuromonitoring constitutes an area of active research. The present findings indicate that intracranial pressure monitoring plays a pivotal role in the management of severe TBI. Scientific interest shifts to magnetic resonance imaging and individualized patient care on the basis of optimal cerebral perfusion pressure.

Monitoring Spinal Cord Tissue Oxygen in Patients With Acute, Severe Traumatic Spinal Cord Injuries

Objectives

To determine the feasibility of monitoring tissue oxygen tension from the injury site (psctO2) in patients with acute, severe traumatic spinal cord injuries.

Design

We inserted at the injury site a pressure probe, a microdialysis catheter, and an oxygen electrode to monitor for up to a week intraspinal pressure (ISP), spinal cord perfusion pressure (SCPP), tissue glucose, lactate/pyruvate ratio (LPR), and psctO2. We analyzed 2,213 hours of such data. Follow-up was 6-28 months postinjury.

Setting

Single-center neurosurgical and neurocritical care units.

Subjects

Twenty-six patients with traumatic spinal cord injuries, American spinal injury association Impairment Scale A-C. Probes were inserted within 72 hours of injury.

Interventions

Insertion of subarachnoid oxygen electrode (Licox; Integra LifeSciences, Sophia-Antipolis, France), pressure probe, and microdialysis catheter.

Measurements and Main Results

psctO2 was significantly influenced by ISP (psctO2 26.7 +/- 0.3 mm Hg at ISP > 10 mmHg vs psctO2 22.7 +/- 0.8 mm Hg at ISP <= 10 mm Hg), SCPP (psctO2 26.8 +/- 0.3 mm Hg at SCPP < 90 mm Hg vs psctO2 32.1 +/- 0.7 mm Hg at SCPP >= 90 mm Hg), tissue glucose (psctO2 26.8 +/- 0.4 mm Hg at glucose < 6 mM vs 32.9 +/- 0.5 mm Hg at glucose >= 6 mM), tissue LPR (psctO2 25.3 +/- 0.4 mm Hg at LPR > 30 vs psctO2 31.3 +/- 0.3 mm Hg at LPR <= 30), and fever (psctO2 28.8 +/- 0.5 mm Hg at cord temperature 37-38[degrees]C vs psctO2 28.7 +/- 0.8 mm Hg at cord temperature >= 39[degrees]C). Tissue hypoxia also occurred independent of these factors. Increasing the FIO2 by 0.48 increases psctO2 by 71.8% above baseline within 8.4 minutes. In patients with motor-incomplete injuries, fluctuations in psctO2 correlated with fluctuations in limb motor score. The injured cord spent 11% (39%) hours at psctO2 less than 5 mm Hg (< 20 mm Hg) in patients with motor-complete outcomes, compared with 1% (30%) hours at psctO2 less than 5 mm Hg (< 20 mm Hg) in patients with motor-incomplete outcomes. Complications were cerebrospinal fluid leak (5/26) and wound infection (1/26).

Conclusions

This study lays the foundation for measuring and altering spinal cord oxygen at the injury site. Future studies are required to investigate whether this is an effective new therapy.

The ICEBERG: a score and visual representation to track the severity of traumatic brain injury: design principles and preliminary results

BACKGROUND

Establishing neurological prognoses in traumatic brain injury (TBI) patients remains challenging. To help physicians in the early management of severe TBI, we have designed a visual score (ICEBERG score) including multimodal monitoring and treatment-related criteria. We evaluated the ICEBERG scores among patients with severe TBI to predict the 28-day mortality and long-term disability (Extended Glasgow Outcome Score (GOSE) at 3 years). Additionally, we made a preliminary assessment of the nurses and doctors on the uptake and reception to the use of the ICEBERG visual tool.

METHODS

This study was part of a larger prospective cohort study of 207 patients with severe TBI in the Parisian region (PariS-TBI study). The ICEBERG score included 6 variables from multimodal monitoring and treatment-related criteria: cerebral perfusion pressure (CPP), intracranial pressure (ICP), body temperature, sedation depth, arterial partial pressure of CO2 and blood osmolarity. The primary outcome measures included the ICEBERG score and its relationship with hospital mortality and GOSE.

RESULTS

The hospital mortality was 21% (45/207). The ICEBERG score baseline value and changes during the 72nd first hours were more strongly associated with TBI prognosis than the ICEBERG parameters measured individually. Interestingly, when the clinical and CT parameters at admission were combined with the ICEBERG score at 48 h using a multimodal approach, the predictive value was significantly increased (AUC = 0.92). Furthermore, comparing the ICEBERG visual representation with the traditional numerical readout revealed that changes in patient vitals were more promptly detected using ICEBERG representation (p < 0.05).

CONCLUSIONS

The ICEBERG score could represent a simple and effective method to describe severity in TBI patients, where a high score is associated with increased mortality and disability. Additionally, ICEBERG representation could enhances the recognition of unmet therapeutic goals and dynamic evolution of the patient's condition. These preliminary results must be confirmed in a prospective manner.

STUDY TYPE

Prognostic.

LEVEL OF EVIDENCE

Level III.

Perioperative management of spinal cord injury: the anesthesiologist's point of view

BACKGROUND

Traumatic spinal cord injury (SCI) is one of the most devastating events a person can experience. It may be life-threatening or result in long-term disability. This narrative review aims to delineate a systematic step-wise airways, breathing, circulation and disability (ABCD) approach to perioperative patient management during spinal cord surgery in order to fill some of the gaps in our current knowledge.

METHODS

We performed a comprehensive review of the literature regarding the perioperative management of traumatic spinal injuries from May 15, 2020, to December 13, 2020. We consulted the PubMed and Embase database libraries.

RESULTS

Videolaryngoscopy supplements the armamentarium available for airway management. Optical fiberscope use should be evaluated when intubating awake patients. Respiratory complications are frequent in the acute phase of traumatic spinal injury, with an estimated incidence of 36-83%. Early tracheostomy can be considered for expected difficult weaning from mechanical ventilation. Careful intraoperative management of administered fluids should be pursued to avoid complications from volume overload. Neuromonitoring requires investments in staff training and cooperation, but better outcomes have been obtained in centers where it is routinely applied. The prone position can cause rare but devastating complications, such as ischemic optic neuropathy; thus, the anesthetist should take the utmost care in positioning the patient.

CONCLUSIONS

A one-size fit all approach to spinal surgery patients is not applicable due to patient heterogeneity and the complexity of the procedures involved. The neurologic outcome of spinal surgery can be improved, and the incidence of complications reduced with better knowledge of patient-specific aspects and individualized perioperative management.

Safety profile of an intracranial multimodal monitoring bolt system for neurocritical care: a single-center experience

BACKGROUND

Intracranial multimodality monitoring (iMMM) is increasingly used in acute brain-injured patients; however, safety and reliability remain major concerns to its routine implementation.

METHODS

We performed a retrospective study including all patients undergoing iMMM at a single European center between July 2016 and January 2020. Brain tissue oxygenation probe (PbtO₂), alone or in combination with a microdialysis catheter and/or an 8-contact depth EEG electrode, was inserted using a triple-lumen bolt system and targeting normal-appearing at-risk brain area on the injured side, whenever possible. Surgical complications, adverse events, and technical malfunctions, directly associated with iMMM, were collected. A blinded imaging review was performed by an independent radiologist.

RESULTS

One hundred thirteen patients with 123 iMMM insertions were included for a median monitoring time of 9 [3-14] days. Of those, 93 (76%) patients had only PbtO₂ probe insertion and 30 (24%) had also microdialysis and/or iEEG monitoring. SAH was the most frequent indication for iMMM (n = 60, 53%). At least one complication was observed in 67/123 (54%) iMMM placement, corresponding to 58/113 (51%) patients. Misplacement was observed in 16/123 (13%), resulting in a total of 6/16 (38%) malfunctioning PbtO₂ catheters. Intracranial hemorrhage was observed in 14 iMMM placements (11%), of which one required surgical drainage. Five placements were complicated by pneumocephalus and 4 with bone fragments; none of these requires additional surgery. No CNS infection related to iMMM was observed. Seven (6%) probes were accidentally dislodged and 2 probes (2%) were accidentally broken. Ten PbtO₂ probes (8%) presented a technical malfunction after a median of 9 [ranges: 2-24] days after initiation of monitoring and 4 of them were replaced.

CONCLUSIONS

In this study, a high occurrence of complications related to iMMM was observed, although most of them did not require specific interventions and did not result in malfunctioning monitoring.

Evolution and Impact of the Brain Trauma Foundation Guidelines

The Brain Trauma Foundation (BTF) Guidelines for the Management of Severe Head Injury were the first clinical practice guidelines published by any surgical specialty. These guidelines have earned a reputation for rigor and have been widely adopted around the world. Implementation of these guidelines has been associated with a 50% reduction in mortality and reduced costs of patient care. Over their 25-yr history the traumatic brain injury (TBI) guidelines have been expanded, refined, and made increasingly more rigorous in conjunction with new clinical evidence and evolving methodologic standards. Here, we discuss the history and accomplishments of BTF guidelines for TBI as well as their limitations. We also discuss planned changes to future TBI guidelines intended to increase their utility and positive impact in an evolving medical landscape. Perhaps the greatest limitation of TBI guidelines now is the lack of high-quality clinical research as well as novel diagnostics and treatments with which to generate substantially new recommendations.

Optimal Cerebral Perfusion Pressure Guided by Brain Oxygen Pressure Measurement

Background: Although increasing cerebral perfusion pressure (CPP) is commonly accepted to improve brain tissue oxygen pressure (PbtO₂), it remains unclear whether recommended CPP targets (i. e., >60 mmHg) would result in adequate brain oxygenation in brain injured patients. The aim of this study was to identify the target of CPP associated with normal brain oxygenation.

Methods: Prospectively collected data including patients suffering from acute brain injury and monitored with PbtO₂, in whom daily CPP challenge using vasopressors was performed. Initial CPP target was >60 mmHg; norepinephrine infusion was modified to have an increase in CPP of at least 10 mmHg at two different steps above the baseline values. Whenever possible, the same CPP challenge was performed for the following days, for a maximum of 5 days. CPP “responders” were patients with a relative increase in PbtO₂ from baseline values > 20%.

Results: A total of 53 patients were included. On the first day of assessment, CPP was progressively increased from 73 (70–76) to 83 (80–86), and 92 (90–96) mmHg, which resulted into a significant PbtO₂ increase [from 20 (17–23) mmHg to 22 (20–24) mmHg and 24 (22–26) mmHg, respectively; p < 0.001]. Median CPP value corresponding to PbtO₂ values > 20 mmHg was 79 (74–87) mmHg, with 2 (4%) patients who never achieved such target. Similar results of CPP targets were observed the following days. A total of 25 (47%) were PbtO₂ responders during the CPP challenge on day 1, in particular if low PbtO₂ was observed at baseline.

Conclusions: PbtO₂ monitoring can be an effective way to individualize CPP values to avoid tissue hypoxia. Low PbtO₂ values at baseline can identify the responders to the CPP challenge.

Intracranial Compliance Concepts and Assessment: A Scoping Review

Background: Intracranial compliance (ICC) has been studied to complement the interpretation of intracranial pressure (ICP) in neurocritical care and help predict brain function deterioration. It has been reported that ICC is related to maintaining ICP stability despite changes in intracranial volume. However, this has not been properly translated to clinical practice. Therefore, the main objective of this scoping review was to map the key concepts of ICC in the literature. This review also aimed to characterize the relationship between ICC and ICP and systematically describe the outcomes used to assess ICC using both invasive and non-invasive measurement methods. Methods: This review included the following: (1) population: animal and humans, (2) concept of compliance or its inverse "elastance," and (3) context: neurocritical care. Therefore, literature searches without a time frame were conducted on several databases using a combination of keywords and descriptors. Results and Discussion: 43,339 articles were identified, and 297 studies fulfilled the inclusion criteria after the selection process. One hundred and five studies defined ICC. The concept was organized into three main components: physiological definition, clinical interpretation, and localization of the phenomena. Most of the studies reported the concept of compliance related to variations in volume and pressure or its inverse (elastance), primarily in the intracranial compartment. In addition, terms like "accommodation," "compensation," "reserve capacity," and "buffering ability" were used to describe the clinical interpretation. The second part of this review describes the techniques (invasive and non-invasive) and outcomes used to measure ICC. A total of 297 studies were included. The most common method used was invasive, representing 57-88% of the studies. The most commonly assessed variables were related to ICP, especially the absolute values or pulse amplitude. ICP waveforms should be better explored, along with the potential of non-invasive methods once the different aspects of ICC can be measured. Conclusion: ICC monitoring could be considered a complementary resource for ICP monitoring and clinical examination. The combination and validation of invasive/non-invasive or non-invasive measurement methods are required.

Brain Exposure to Piperacillin in Acute Hemorrhagic Stroke Patients Assessed by Cerebral Microdialysis and Population Pharmacokinetics

BACKGROUND

The broad antibacterial spectrum of piperacillin/tazobactam makes the combination suitable for the treatment of nosocomial bacterial central nervous system (CNS) infections. As limited data are available regarding piperacillin CNS exposure in patients without or with low-grade inflammation, a clinical study was conducted (1) to quantify CNS exposure of piperacillin by cerebral microdialysis and (2) to evaluate different dosing regimens in order to improve probability of target attainment (PTA) in brain.

METHODS

Ten acute hemorrhagic stroke patients (subarachnoid hemorrhage, n = 6; intracerebral hemorrhage, n = 4) undergoing multimodality neuromonitoring received 4 g piperacillin/0.5 g tazobactam every 8 h by 30-min infusions for the management of healthcare-associated pneumonia. Cerebral microdialysis was performed as part of the clinical neuromonitoring routine, and brain interstitial fluid samples were retrospectively analyzed for piperacillin concentrations after the first and after multiple doses for at least 5 days and quantified by high-performance liquid chromatography. Population pharmacokinetic modeling and Monte Carlo simulations with various doses and types of infusions were performed to predict exposure. A T_>MIC of 50% was selected as pharmacokinetic/pharmacodynamic target parameter.

RESULTS

Median peak concentrations of unbound piperacillin in brain interstitial space fluid were 1.16 (range 0.08-3.59) and 2.78 (range 0.47-7.53) mg/L after the first dose and multiple doses, respectively. A one-compartment model with a transit compartment and a lag time (for the first dose) between systemic and brain exposure was appropriate to describe the brain concentrations. Bootstrap median estimates of the parameters were: transfer rate from plasma to brain (0.32 h^-1), transfer rate from brain to plasma (7.31 h^-1), and lag time [2.70 h (coefficient of variation 19.7%)]. The simulations suggested that PTA would exceed 90% for minimum inhibitory concentrations (MICs) up to 0.5 mg/L and 1 mg/L at a dose of 12-16 and 24 g/day, respectively, regardless of type of infusion. For higher MICs, PTA dropped significantly.

CONCLUSION

Limited CNS exposure of piperacillin might be an obstacle in treating patients without general meningeal inflammation except for infections with highly susceptible pathogens. Brain exposure of piperacillin did not improve significantly with a prolongation of infusions.

Integrative Neuroinformatics for Precision Prognostication and Personalized Therapeutics in Moderate and Severe Traumatic Brain Injury

Despite changes in guideline-based management of moderate/severe traumatic brain injury (TBI) over the preceding decades, little impact on mortality and morbidity have been seen. This argues against the "one-treatment fits all" approach to such management strategies. With this, some preliminary advances in the area of personalized medicine in TBI care have displayed promising results. However, to continue transitioning toward individually-tailored care, we require integration of complex "-omics" data sets. The past few decades have seen dramatic increases in the volume of complex multi-modal data in moderate and severe TBI care. Such data includes serial high-fidelity multi-modal characterization of the cerebral physiome, serum/cerebrospinal fluid proteomics, admission genetic profiles, and serial advanced neuroimaging modalities. Integrating these complex and serially obtained data sets, with patient baseline demographics, treatment information and clinical outcomes over time, can be a daunting task for the treating clinician. Within this review, we highlight the current status of such multi-modal omics data sets in moderate/severe TBI, current limitations to the utilization of such data, and a potential path forward through employing integrative neuroinformatic approaches, which are applied in other neuropathologies. Such advances are positioned to facilitate the transition to precision prognostication and inform a top-down approach to the development of personalized therapeutics in moderate/severe TBI.

Monitoring and modifying brain oxygenation in patients at risk of hypoxic ischaemic brain injury after cardiac arrest

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2021. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2021 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from https://link.springer.com/bookseries/8901 .

Changes in endogenous daytime melatonin levels after aneurysmal subarachnoid hemorrhage - Preliminary findings from an observational cohort study

INTRODUCTION

Aneurysmal subarachnoid hemorrhage (aSAH) is associated with early and delayed brain injury due to several underlying and interrelated processes, which include inflammation, oxidative stress, endothelial, and neuronal apoptosis. Treatment with melatonin, a cytoprotective neurohormone with anti-inflammatory, anti-oxidant and anti-apoptotic effects, has been shown to attenuate early brain injury (EBI) and to prevent delayed cerebral vasospasm in experimental aSAH models. Less is known about the role of endogenous melatonin for aSAH outcome and how its production is altered by the pathophysiological cascades initiated during EBI. In the present observational study, we analyzed changes in melatonin levels during the first three weeks after aSAH.

MATERIALS AND METHODS

Daytime (from 11:00 am to 05:00 pm) melatonin levels were measured by enzyme-linked immunosorbent assay (ELISA) in serum samples obtained from 30 patients on the day of aSAH onset (d₀) and in five pre-defined time intervals during the early (d_1-4), critical (d_5-8, d_9-12, d_13-15) and late (d_16-21) phase. Perioperative daytime melatonin levels determined in 30 patients who underwent elective open aortic surgery served as a control for the acute effects of surgical treatment on melatonin homeostasis.

RESULTS

There was no difference between serum melatonin levels measured in the control patients and on the day of aSAH onset (p = 0.664). However, aSAH was associated with a sustained up-regulation that started during the critical phase (d_9-12) and progressed to the late phase (d_16-21), during which almost 80% of the patients reached daytime melatonin levels above 5 pg/ml. In addition, subgroup analyses revealed higher melatonin levels on d_5-8 in patients with a poor clinical status on admission (p = 0.031), patients with anterior communicating artery aneurysms (p = 0.040) and patients without an external ventricular drain (p = 0.018), possibly pointing to a role of hypothalamic dysfunction.

CONCLUSION

Our observations in a small cohort of patients provide first evidence for a delayed up-regulation of circulatory daytime melatonin levels after aSAH and a role of aneurysm location for higher levels during the critical phase. These findings are discussed in terms of previous results about stress-induced melatonin production and the role of hypothalamic and brainstem involvement for melatonin levels after aSAH.

Brain tissue oxygenation guided therapy and outcome in non-traumatic subarachnoid hemorrhage

Brain hypoxia can occur after non-traumatic subarachnoid hemorrhage (SAH), even when levels of intracranial pressure (ICP) remain normal. Brain tissue oxygenation (PbtO₂) can be measured as a part of a neurological multimodal neuromonitoring. Low PbtO₂ has been associated with poor neurologic recovery. There is scarce data on the impact of PbtO₂ guided-therapy on patients’ outcome. This single-center cohort study (June 2014–March 2020) included all patients admitted to the ICU after SAH who required multimodal monitoring. Patients with imminent brain death were excluded. Our primary goal was to assess the impact of PbtO₂-guided therapy on neurological outcome. Secondary outcome included the association of brain hypoxia with outcome. Of the 163 patients that underwent ICP monitoring, 62 were monitored with PbtO₂ and 54 (87%) had at least one episode of brain hypoxia. In patients that required treatment based on neuromonitoring strategies, PbtO₂-guided therapy (OR 0.33 [CI 95% 0.12–0.89]) compared to ICP-guided therapy had a protective effect on neurological outcome at 6 months. In this cohort of SAH patients, PbtO₂-guided therapy might be associated with improved long-term neurological outcome, only when compared to ICP-guided therapy.

Brain Hypoxia Is Associated With Neuroglial Injury in Humans Post-Cardiac Arrest

Supplemental Digital Content is available in the text.

Secondary brain hypoxia portends significant mortality in ischemic brain diseases; yet, our understanding of hypoxic ischemic brain injury (HIBI) pathophysiology in humans remains rudimentary.

Non-invasive Assessment of Neurovascular Coupling After Aneurysmal Subarachnoid Hemorrhage: A Prospective Observational Trial Using Retinal Vessel Analysis

Objective: Delayed cerebral ischemia (DCI) is a common complication after aneurysmal subarachnoid hemorrhage (aSAH) and can lead to infarction and poor clinical outcome. The underlying mechanisms are still incompletely understood, but animal models indicate that vasoactive metabolites and inflammatory cytokines produced within the subarachnoid space may progressively impair and partially invert neurovascular coupling (NVC) in the brain. Because cerebral and retinal microvasculature are governed by comparable regulatory mechanisms and may be connected by perivascular pathways, retinal vascular changes are increasingly recognized as a potential surrogate for altered NVC in the brain. Here, we used non-invasive retinal vessel analysis (RVA) to assess microvascular function in aSAH patients at different times after the ictus. Methods: Static and dynamic RVA were performed using a Retinal Vessel Analyzer (IMEDOS Systems GmbH, Jena) in 70 aSAH patients during the early (d_0-4), critical (d_5-15), late (d_16-23) phase, and at follow-up (f/u > 6 weeks) after the ictus. For comparison, an age-matched cohort of 42 healthy subjects was also included in the study. Vessel diameters were quantified in terms of the central retinal arterial and venous equivalent (CRAE, CRVE) and the retinal arterio-venous-ratio (AVR). Vessel responses to flicker light excitation (FLE) were quantified by recording the maximum arterial and venous dilation (MAD, MVD), the time to 30% and 100% of maximum dilation (tMAD₃₀, tMVD₃₀; tMAD, tMVD, resp.), and the arterial and venous area under the curve (AUC_art, AUC_ven) during the FLE. For subgroup analyses, patients were stratified according to the development of DCI and clinical outcomes after 12 months. Results: Vessel diameter (CRAE, CRVE) was significantly smaller in aSAH patients and showed little change throughout the whole observation period (p < 0.0001 vs. control for all time periods examined). In addition, aSAH patients exhibited impaired arterial but not venous responses to FLE, as reflected in a significantly lower MAD [2.2 (1.0-3.2)% vs. 3.6 (2.6-5.6)% in control subjects, p = 0.0016] and AUC_art [21.5 (9.4-35.8)%^*s vs. 51.4 (32.5-69.7)%^*s in control subjects, p = 0.0001] on d_0-4. However, gradual recovery was observed during the first 3 weeks, with close to normal levels at follow-up, when MAD and AUC_art amounted to 3.0 [2.0-5.0]% (p = 0.141 vs. control, p = 0.0321 vs. d_5-15) and 44.5 [23.2-61.1]%^*s (p = 0.138 vs. control, p < 0.01 vs. d_0-4 & d_5-15). Finally, patients with clinical deterioration (DCI) showed opposite changes in the kinetics of arterial responses during early and late phase, as reflected in a significantly lower tMAD₃₀ on d_0-4 [4.0 (3.0-6.8) s vs. 7.0 (5.0-8.0) s in patients without DCI, p = 0.022) and a significantly higher tMAD on d_16-23 (24.0 (21.0-29.3) s vs. 18.0 (14.0-21.0) s in patients without DCI, p = 0.017]. Conclusion: Our findings confirm and extend previous observations that aSAH results in sustained impairments of NVC in the retina. DCI may be associated with characteristic changes in the kinetics of retinal arterial responses. However, further studies will be required to determine their clinical implications and to assess if they can be used to identify patients at risk of developing DCI. Trial Registration: ClinicalTrials.gov Identifier: NCT04094155.

Neurocritical Care and Brain Monitoring

The goal of neurocritical care (NCC) is to improve the outcome of patients with neurologic insults. NCC includes the management of the primary brain injury and prevention of secondary brain injury; this is achieved with standardized clinical care for specific disorders along with neuromonitoring. Neuromonitoring uses multiple modalities, with certain modalities better suited to certain disorders. The term "multimodality monitoring" refers to using multiple modalities at the same time. This article reviews pediatric NCC, the various physiologic parameters used, especially continuous electroencephalographic monitoring.

How do we identify the crashing traumatic brain injury patient - the intensivist's view

PURPOSE OF REVIEW

Over 40% of patients with severe traumatic brain injury (TBI) show clinically significant neurological worsening within the acute admission period. This review addresses the importance of identifying the crashing TBI patient, the difficulties appreciating clinical neurological deterioration in the comatose patient and how neuromonitoring may provide continuous real-time ancillary information to detect physiologic worsening.

RECENT FINDINGS

The latest editions of the Brain Trauma Foundation's Guidelines omitted management algorithms for adult patients with severe TBI. Subsequently, three consensus-based management algorithms were published using a Delphi method approach to provide a bridge between the evidence-based guidelines and integration of the individual treatment modalities at the bedside. These consensus statements highlight the serious situation of critical deterioration requiring emergent evaluation and guidance on sedation holds to obtain a neurological examination while balancing the potential risks of inducing a stress response.

SUMMARY

One of the central tenets of neurocritical care is to detect the brain in trouble. The first and most fundamental neurological monitoring tool is the clinical exam. Ancillary neuromonitoring data may provide early physiologic biomarkers to help anticipate, prevent or halt secondary brain injury processes. Future research should seek to understand how data integration and visualization technologies may reduce the cognitive workload to improve timely detection of neurological deterioration.

The role of non-invasive brain oximetry in adult critically ill patients without primary brain injury

A primary objective in intensive care and perioperative settings is to promote an adequate supply and delivery of oxygen to tissues and organs, particularly to the brain. Cerebral near infrared spectroscopy (NIRS) is a non-invasive, continuous monitoring technique, that can be used to assess cerebral oxygenation. Using NIRS to monitor cerebral oximetry is not new, and has been in widespread use in neonates and cardiac surgery for decades. In addition, it has become common to see NIRS being used in adult and pediatric cardiac surgery, acute neurological diseases, neurosurgical procedures, vascular surgery, severe trauma and other acute medical diseases. Furthermore, recent evidence suggests a role for NIRS in the perioperative settings; detecting and preventing episodes of cerebral desaturation aiming to reduce the development of post-operative delirium. NIRS is not without its limitations; these include the risk of extra-cranial contamination, spatial limitations and skin blood flow/volume changes, as well being a measure of localized blood oxygenation underneath the sensor. However, NIRS is a non-invasive technique and can, therefore, be used in those patients without indications or justification for invasive brain monitoring; non-neurosurgical procedures such as liver transplantation, major orthopedic surgery and critically illness where the brain is at risk. The aim of this manuscript was to discuss the physical principles of NIRS and to report the current evidence regarding its use in critically ill patients without primary non-anoxic brain injury.

Surviving cardiac arrest: What happens after admission to the intensive care unit?

INTRODUCTION

Patients successfully resuscitated from cardiac arrest (CA) are admitted to the intensive care unit (ICU) for post-resuscitation care. These patients' prognosis remains dismal, with only a minority surviving to hospital discharge. Understanding the clinical factors involved in the management of these patients is essential to improve their prognosis.

OBJECTIVES

To characterize the population admitted after successful reanimation from CA, and to analyze the factors associated with their outcomes.

METHODS

We performed a retrospective descriptive study of patients admitted to an ICU after CA over a five-year period from January 2014 to December 2018. Demographic factors, CA characteristics, early management, mortality and neurologic outcomes were analyzed.

RESULTS

A total of 187 patients, median age 67 years, were admitted after CA, of whom 39% suffered out-of-hospital CA; 87% had an initial non-shockable rhythm and the most frequent presumed cause was cardiac (31%). In-hospital mortality was 63%. Significant neurologic dysfunction (cerebral performance category 3 or 4) was seen in 31% of survivors at hospital discharge. Non-immediate initiation of basic life support (BLS), higher Simplified Acute Physiology Score II score and longer relative duration of vasopressor support were independent predictors of in-hospital mortality, while shockable rhythms were associated with improved survival. Higher Glasgow coma scale at ICU discharge and shorter length of ICU stay were predictors of better neurologic outcome.

CONCLUSION

This study highlights the positive prognostic impact of shockable rhythms, and confirms the importance of immediate initiation of BLS and prompt defibrillation, supporting the need for better training both outside and inside hospitals.

Cerebrovascular pressure reactivity and intracranial pressure are associated with neurologic outcome after hypoxic-ischemic brain injury

AIM

We evaluated the association of physiological parameters measured by intracranial multimodality neuromonitoring with neurologic outcome in a consecutive series of patients with hypoxic-ischemic brain injury (HIBI).

METHODS

We retrospectively identified all patients with HIBI who underwent combined invasive intracranial pressure (ICP) and brain tissue oxygen (P_btO₂) monitoring over a 3 year period. Cerebrovascular pressure reactivity index (PRx) was calculated continuously as a surrogate of cerebral autoregulation. Favorable outcome was defined as recovery of consciousness (Glasgow Coma Scale motor score = 6). Differences in mean ICP, PRx and P_btO₂ for the entire monitoring period across outcomes were measured. Logistic regression and area under receiver operating characteristic (AUROC) curve were used to assess the association of each monitoring parameter with neurologic outcome.

RESULTS

We analyzed data from 36 patients. Most (89%) had an antecedent sudden cardiac arrest. Favorable outcome occurred in 8 (22%) patients. ICP and PRx were higher in patients with unfavorable outcome (ICP: 26 ± 4.1 mmHg vs 7.5 ± 2 mmHg, p = 0.0002; PRx: 0.51 ± 0.05 vs 0.11 ± 0.05, p < 0.0001). There was no significant difference in P_btO₂ between groups (unfavorable: 20 ± 2.4 mmHg vs favorable: 25 ± 1.5 mmHg, p = 0.12). Both ICP (AUROC 0.84, 95%CI 0.72-0.98, p = 0.003) and PRx (AUROC 0.94, 95%CI 0.85-1, p = 0.0002) discriminated between favorable and unfavorable outcome, in contrast to P_btO₂, (AUROC 0.59, 95%CI 0.39-0.78, p = 0.52). ICP > 15 mmHg, PRx > 0.2, and P_btO₂ < 18 mmHg had sensitivity/specificity of 68%/100%, 89%/88%, and 40%/100% respectively for discriminating outcomes.

CONCLUSION

Cerebrovascular pressure reactivity and intracranial pressure appear to be associated with neurologic outcome in patients with HIBI.

Invasive neuromonitoring and neurological intensive care unit management in life-threatening central nervous system infections

PURPOSE OF REVIEW

Patients with infectious diseases of the central nervous system (CNS) commonly require treatment in the intensive care unit (ICU). In a subset of patients with a life-threatening course, a more aggressive and invasive management is required. Treatment relies on the expertise of the intensivists as most recommendations are currently not based on a high level of evidence.

RECENT FINDINGS

Published data suggest that an invasive brain-focused management should be considered in life-threatening CNS infections. Brain resuscitation by adequate control of intracranial pressure (ICP) and optimization of cerebral perfusion, oxygen and glucose delivery supports the idea of personalized medicine. Recent advances in monitoring techniques help to guide clinicians to improve neurocritical care management in these patients with severe disease. Robust data on the long-term effect of decompressive craniectomy and targeted temperature management are lacking, however, these interventions can be life-saving in individual patients in the setting of a potentially fatal situation such as refractory elevated ICP.

SUMMARY

Advances in the neurocritical care management and progress in monitoring techniques in specialized neuro-ICUs may help to preserve brain function and prevent a deleterious cascade of secondary brain damage in life-threatening CNS infections.

Continuous and entirely non-invasive method for cerebrovascular reactivity assessment: technique and implications

Continuous cerebrovascular reactivity assessment in traumatic brain injury (TBI) has been limited by the need for invasive monitoring of either cerebral physiology or arterial blood pressure (ABP). This restricts the application of continuous measures to the acute phase of care, typically in the intensive care unit. It remains unknown if ongoing impairment of cerebrovascular reactivity occurs in the subacute and long-term phase, and if it drives ongoing morbidity in TBI. We describe an entirely non-invasive method for continuous assessment of cerebrovascular reactivity. We describe the technique for entirely non-invasive continuous assessment of cerebrovascular reactivity utilizing near-infrared spectroscopy (NIRS) and robotic transcranial Doppler (rTCD) technology, with details provided for NIRS. Recent advances in continuous high-frequency non-invasive ABP measurement, combined with NIRS or rTCD, can be employed to derive continuous and entirely non-invasive cerebrovascular reactivity metrics. Such non-invasive measures can be obtained during any aspect of patient care post-TBI, and even during outpatient follow-up, avoiding classical intermittent techniques and costly neuroimaging based metrics obtained only at specialized centers. This combination of technology and signal analytic techniques creates avenues for future investigation of the long-term consequences of cerebrovascular reactivity, integrating high-frequency non-invasive cerebral physiology, neuroimaging, proteomics and clinical phenotype at various stages post-injury.

Implementation of Multimodality Neurologic Monitoring Reporting in Pediatric Traumatic Brain Injury Management

Background/Objective

Multimodality neurologic monitoring (MMM) is an emerging technique for management of traumatic brain injury (TBI). An increasing array of MMM-derived biomarkers now exist that are associated with injury severity and functional outcomes after TBI. A standardized MMM reporting process has not been well described, and a paucity of evidence exists relating MMM reporting in TBI management with functional outcomes or adverse events.

Methods

Prospective implementation of standardized MMM reporting at a single pediatric intensive care unit (PICU) is described that included monitoring of intracranial pressure (ICP), cerebral oxygenation and electroencephalography (EEG). The incidence of clinical decisions made using MMM reporting is described, including timing of neuroimaging, ICP monitoring discontinuation, use of paralytic, hyperosmolar and pentobarbital therapies, neurosurgical interventions, ventilator and CPP adjustments and neurologic prognostication discussions. Retrospective analysis was performed on the association of MMM reporting with initial Glasgow Coma Scale (GCS) and Pediatric Risk of Mortality III (PRISM III) scores, duration of total hospitalization and PICU hospitalization, duration of mechanical ventilation and invasive ICP monitoring, inpatient complications, time with ICP > 20 mmHg, time with cerebral perfusion pressure (CPP) < 40 mmHg and 12-month Glasgow Outcome Scale—Extended Pediatrics (GOSE-Peds) scores. Association of outcomes with MMM reporting was investigated using the Wilcoxon rank-sum test or Fisher’s exact test, as appropriate.

Results

Eighty-five children with TBI underwent MMM over 6 years, among which 18 underwent daily MMM reporting over a 21-month period. Clinical decision-making influenced by MMM reporting included timing of neuroimaging (100.0%), ICP monitoring discontinuation (100.0%), timing of extubation trials of surviving patients (100.0%), body repositioning (11.1%), paralytic therapy (16.7%), hyperosmolar therapy (22.2%), pentobarbital therapy (33.3%), provocative cerebral autoregulation testing (16.7%), adjustments in CPP thresholds (16.7%), adjustments in PaCO2 thresholds (11.1%), neurosurgical interventions (16.7%) and neurologic prognostication discussions (11.1%). The implementation of MMM reporting was associated with a reduction in ICP monitoring duration (p = 0.0017) and mechanical ventilator duration (p = 0.0018). No significant differences were observed in initial GCS or PRISM III scores, total hospitalization length, PICU hospitalization length, total complications, time with ICP > 20 mmHg, time with CPP < 40 mmHg, use of tier 2 therapy, or 12-month GOS-E Peds scores.

Conclusion

Implementation of MMM reporting in pediatric TBI management is feasible and can be impactful in tailoring clinical decisions. Prospective work is needed to understand the impact of MMM and MMM reporting systems on functional outcomes and clinical care efficacy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12028-021-01190-8.

Surviving cardiac arrest: What happens after admission to the intensive care unit?

INTRODUCTION

Patients successfully resuscitated from cardiac arrest (CA) are admitted to the intensive care unit (ICU) for post-resuscitation care. These patients' prognosis remains dismal, with only a minority surviving to hospital discharge. Understanding the clinical factors involved in the management of these patients is essential to improve their prognosis.

OBJECTIVES

To characterize the population admitted after successful reanimation from CA, and to analyze the factors associated with their outcomes.

METHODS

We performed a retrospective descriptive study of patients admitted to an ICU after CA over a five-year period from January 2014 to December 2018. Demographic factors, CA characteristics, early management, mortality and neurologic outcomes were analyzed.

RESULTS

A total of 187 patients, median age 67 years, were admitted after CA, of whom 39% suffered out-of-hospital CA; 87% had an initial non-shockable rhythm and the most frequent presumed cause was cardiac (31%). In-hospital mortality was 63%. Significant neurologic dysfunction (cerebral performance category 3 or 4) was seen in 31% of survivors at hospital discharge. Non-immediate initiation of basic life support (BLS), higher Simplified Acute Physiology Score II score and longer relative duration of vasopressor support were independent predictors of in-hospital mortality, while shockable rhythms were associated with improved survival. Higher Glasgow coma scale at ICU discharge and shorter length of ICU stay were predictors of better neurologic outcome.

CONCLUSION

This study highlights the positive prognostic impact of shockable rhythms, and confirms the importance of immediate initiation of BLS and prompt defibrillation, supporting the need for better training both outside and inside hospitals.

Neurologic Assessment of the Neurocritical Care Patient

Sedation is a ubiquitous practice in ICUs and NCCUs. It has the benefit of reducing cerebral energy demands, but also precludes an accurate neurologic assessment. Because of this, sedation is intermittently stopped for the purposes of a neurologic assessment, which is termed a neurologic wake-up test (NWT). NWTs are considered to be the gold-standard in continued assessment of brain-injured patients under sedation. NWTs also produce an acute stress response that is accompanied by elevations in blood pressure, respiratory rate, heart rate, and ICP. Utilization of cerebral microdialysis and brain tissue oxygen monitoring in small cohorts of brain-injured patients suggests that this is not mirrored by alterations in cerebral metabolism, and seldom affects oxygenation. The hard contraindications for the NWT are preexisting intracranial hypertension, barbiturate treatment, status epilepticus, and hyperthermia. However, hemodynamic instability, sedative use for primary ICP control, and sedative use for severe agitation or respiratory distress are considered significant safety concerns. Despite ubiquitous recommendation, it is not clear if additional clinically relevant information is gleaned through its use, especially with the contemporaneous utilization of multimodality monitoring. Various monitoring modalities provide unique and pertinent information about neurologic function, however, their role in improving patient outcomes and guiding treatment plans has not been fully elucidated. There is a paucity of information pertaining to the optimal frequency of NWTs, and if it differs based on type of injury. Only one concrete recommendation was found in the literature, exemplifying the uncertainty surrounding its utility. The most common sedative used and recommended is propofol because of its rapid onset, short duration, and reduction of cerebral energy requirements. Dexmedetomidine may be employed to facilitate serial NWTs, and should always be used in the non-intubated patient or if propofol infusion syndrome (PRIS) develops. Midazolam is not recommended due to tissue accumulation and residual sedation confounding a reliable NWT. Thus, NWTs are well-tolerated in selected patients and remain recommended as the gold-standard for continued neuromonitoring. Predicated upon one expert panel, they should be performed at least one time per day. Propofol or dexmedetomidine are the main sedative choices, both enabling a rapid awakening and consistent NWT.

Goal-Directed Care Using Invasive Neuromonitoring Versus Standard of Care After Cardiac Arrest: A Matched Cohort Study

PURPOSE

Following return of spontaneous circulation after cardiac arrest, hypoxic ischemic brain injury is the primary cause of mortality and disability. Goal-directed care using invasive multimodal neuromonitoring has emerged as a possible resuscitation strategy. We evaluated whether goal-directed care was associated with improved neurologic outcome in hypoxic ischemic brain injury patients after cardiac arrest.

DESIGN

Retrospective, single-center, matched observational cohort study.

SETTING

Quaternary academic medical center.

PATIENTS

Adult patients admitted to the ICU following return of spontaneous circulation postcardiac arrest with clinical evidence of hypoxic ischemic brain injury defined as greater than or equal to 10 minutes of cardiac arrest with an unconfounded postresuscitation Glasgow Coma Scale of less than or equal to 8.

INTERVENTIONS

We compared patients who underwent goal-directed care using invasive neuromonitoring with those treated with standard of care (using both total and matched groups).

MEASUREMENTS AND MAIN RESULTS

Goal-directed care patients were matched 1:1 to standard of care patients using propensity scores and exact matching. The primary outcome was a 6-month favorable neurologic outcome (Cerebral Performance Category of 1 or 2). We included 65 patients, of whom 21 received goal-directed care and 44 patients received standard of care. The median age was 50 (interquartile range, 35-61), 48 (74%) were male, and seven (11%) had shockable rhythms. Favorable neurologic outcome at 6 months was significantly greater in the goal-directed care group (n = 9/21 [43%]) compared with the matched (n = 2/21 [10%], p = 0.016) and total (n = 8/44 [18%], p = 0.034) standard of care groups. Goal-directed care group patients had higher mean arterial pressure (p < 0.001 vs total; p = 0.0060 vs matched) and lower temperature (p = 0.007 vs total; p = 0.041 vs matched).

CONCLUSIONS

In this preliminary study of patients with hypoxic ischemic brain injury postcardiac arrest, goal-directed care guided by invasive neuromonitoring was associated with a 6-month favorable neurologic outcome (Cerebral Performance Category 1 or 2) versus standard of care. Significant work is required to confirm this finding in a prospectively designed study.

Traumatic Brain Injury Update

Traumatic brain injury is a devastating, life-changing event in most cases. After the primary brain insult, it is helpful to use evidence-based monitoring techniques to guide implementation of essential interventions to minimize secondary injury and thereby improve patient outcomes. An update on multimodal neuromonitoring is provided in this narrative review, with discussion of tools and techniques currently used in the treatment of patients with brain injury. Neuroprotective treatments, from the well-studied targeted temperature management to new potential therapeutics under investigation, such as glyburide, also are presented.

Relationship of common hemodynamic and respiratory target parameters with brain tissue oxygen tension in the absence of hypoxemia or hypotension after cardiac arrest: A post-hoc analysis of an experimental study using a pig model

Brain tissue oxygen tension (PbtO2)-guided care, a therapeutic strategy to treat or prevent cerebral hypoxia through modifying determinants of cerebral oxygen delivery, including arterial oxygen tension (PaO2), end-tidal carbon dioxide (ETCO2), and mean arterial pressure (MAP), has recently been introduced. Studies have reported that cerebral hypoxia occurs after cardiac arrest in the absence of hypoxemia or hypotension. To obtain preliminary information on the degree to which PbtO2 is responsive to changes in the common target variables for PbtO2-guided care in conditions without hypoxemia or hypotension, we investigated the relationships between the common target variables for PbtO2-guided care and PbtO2 using data from an experimental study in which the animals did not experience hypoxemia or hypotension after resuscitation. We retrospectively analyzed 170 sets of MAP, ETCO2, PaO2, PbtO2, and cerebral microcirculation parameters obtained during the 60-min post-resuscitation period in 10 pigs resuscitated from ventricular fibrillation cardiac arrest. PbtO2 and cerebral microcirculation parameters were measured on parietal cortices exposed through burr holes. Multiple linear mixed effect models were used to test the independent effects of each variable on PbtO2. Despite the absence of arterial hypoxemia or hypotension, seven (70%) animals experienced cerebral hypoxia (defined as PbtO2 <20 mmHg). Linear mixed effect models revealed that neither MAP nor ETCO2 were related to PbtO2. PaO2 had a significant linear relationship with PbtO2 after adjusting for significant covariates (P = 0.030), but it could explain only 17.5% of the total PbtO2 variance (semi-partial R2 = 0.175; 95% confidence interval, 0.086-0.282). In conclusion, MAP and ETCO2 were not significantly related to PbtO2 in animals without hypoxemia or hypotension during the early post-resuscitation period. PaO2 had a significant linear association with PbtO2, but its ability to explain PbtO2 variance was small.

Challenges and Opportunities in Multimodal Monitoring and Data Analytics in Traumatic Brain Injury

PURPOSE OF REVIEW

Increasingly sophisticated systems for monitoring the brain have led to an increase in the use of multimodality monitoring (MMM) to detect secondary brain injuries before irreversible damage occurs after brain trauma. This review examines the challenges and opportunities associated with MMM in this population.

RECENT FINDINGS

Locally and internationally, the use of MMM varies. Practical challenges include difficulties with data acquisition, curation, and harmonization with other data sources limiting collaboration. However, efforts toward integration of MMM data, advancements in data science, and the availability of cloud-based infrastructures are now affording the opportunity for MMM to advance the care of patients with brain trauma. MMM provides data to guide the precision management of patients with traumatic brain injury in real time. While challenges exist, there are exciting opportunities for MMM to live up to this promise and to drive new insights into the physiology of the brain and beyond.