Multimodal neurologic monitoring

Altered levels of transthyretin in human cerebral microdialysate after subarachnoid haemorrhage using proteomics; a descriptive pilot study

BACKGROUND

Subarachnoid haemorrhage (SAH) is one of the most severe forms of stroke in which delayed cerebral ischemia is one of the major complications. Neurointensive care aims at preventing and treating such complications and identification of biomarkers of early signs of ischemia might therefore be helpful.

METHODS

We aimed at describing proteome profile in cerebral microdialysate in four patients with aneurysmal SAH using two dimensional gel electrophoresis in combination with mass spectrometry in search for new biomarkers for delayed cerebral ischemia and to investigate if there were temporal fluctuations in those biomarkers over time after aneurysmal bleed.

RESULTS

The results showed transthyretin in nine different proteoforms (1001, 1102, 2101, 3101, 4101, 4102, 5001, 5101, 6101) in cerebral microdialysate samples from four patients having sustained SAH. Several proteoforms show highly differing levels and pooled analysis of all samples showed varying optical density related to time from aneurysmal bleed, indicating a temporal evolution.

CONCLUSIONS

Transthyretin proteoforms have not earlier been shown in cerebral microdialysate after SAH and we describe differing levels based on proteoform as well as time from subarachnoid bleed. Transthyretin is well known to be synthetized in choroid plexus, whilst intraparenchymal synthesis remains controversial. The results need to be confirmed in larger studies in order to further describe transthyretin.

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.

Intensive Care Admission and Management of Patients With Acute Ischemic Stroke: A Cross-sectional Survey of the European Society of Intensive Care Medicine

BACKGROUND

No specific recommendations are available regarding the intensive care management of critically ill acute ischemic stroke (AIS) patients, and questions remain regarding optimal ventilatory, hemodynamic, and general intensive care unit (ICU) therapeutic targets in this population. We performed an international survey to investigate ICU admission criteria and management of AIS patients.

METHODS

An electronic questionnaire including 25 items divided into 3 sections was available on the European Society of Intensive Care Medicine Web site between November 1, 2019 and March 30, 2020 and advertised through the neurointensive care (NIC) section newsletter. This survey was emailed directly to the NIC members and was endorsed by the European Society of Intensive Care Medicine.

RESULTS

There were 214 respondents from 198 centers, with response rate of 16.5% of total membership (214/1296). In most centers (67%), the number of AIS patients admitted to respondents' hospitals in 2019 was between 100 and 300, and, among them, fewer than 50 required ICU admission per hospital. The most widely accepted indication for ICU admission criteria was a requirement for intubation and mechanical ventilation. A standard protocol for arterial blood pressure (ABP) management was utilized by 88 (58%) of the respondents. For patients eligible for intravenous thrombolysis, the most common ABP target was <185/110 mm Hg (n=77 [51%]), whereas for patients undergoing mechanical thrombectomy it was ≤160/90 mm Hg (n=79 [54%]). The preferred drug for reducing ABP was labetalol (n=84 [55.6%]). Other frequently used therapeutic targets included: blood glucose 140 to 180 mg/dL (n=65 [43%]) maintained with intravenous insulin infusion in most institutions (n=110 [72.4%]); enteral feeding initiated within 2 to 3 days from stroke onset (n=142 [93.4%]); oxygen saturation (SpO2) >95% (n=80 [53%]), and tidal volume 6 to 8 mL/kg of predicted body weight (n=135 [89%]).

CONCLUSIONS

The ICU management of AIS, including therapeutic targets and clinical practice strategies, importantly varies between centers. Our findings may be helpful to define future studies and create a research agenda regarding the ICU therapeutic targets for AIS patients.

IRIS: A Modular Platform for Continuous Monitoring and Caretaker Notification in the Intensive Care Unit

OBJECTIVE

New approaches are needed to interpret large amounts of physiologic data continuously recorded in the ICU. We developed and prospectively validated a versatile platform (IRIS) for real-time ICU physiologic monitoring, clinical decision making, and caretaker notification.

METHODS

IRIS was implemented in the neurointensive care unit to stream multimodal time series data, including EEG, intracranial pressure (ICP), and brain tissue oxygenation (PbtO2), from ICU monitors to an analysis server. IRIS was applied for 364 patients undergoing continuous EEG, 26 patients undergoing burst suppression monitoring, and four patients undergoing intracranial pressure and brain tissue oxygen monitoring. Custom algorithms were used to identify periods of elevated ICP, compute burst suppression ratios (BSRs), and detect faulty or disconnected EEG electrodes. Hospital staff were notified of clinically relevant events using our secure API to route alerts through a password-protected smartphone application.

RESULTS

Sustained increases in ICP and concordant decreases in PbtO2 were reliably detected using user-defined thresholds and alert throttling. BSR trends computed by the platform correlated highly with manual neurologist markings (r2 0.633-0.781; p < 0.0001). The platform identified EEG electrodes with poor signal quality with 95% positive predictive value, and reduced latency of technician response by 93%.

CONCLUSION

This study validates a flexible real-time platform for monitoring and interpreting ICU data and notifying caretakers of actionable results, with potential to reduce the manual burden of continuous monitoring services on care providers.

SIGNIFICANCE

This work represents an important step toward facilitating translational medical data analytics to improve patient care and reduce health care costs.

Current Status of Neurosurgical and Neurointensive Care Units in Korea : A Brief Report on Nationwide Survey Results

Objective

The purpose of this study is identify the operation status of the neurosurgical care units (NCUs) in neurosurgical residency training hospitals nationwide and determine needed changes by comparing findings with those obtained from the Korean Neurosurgical Society (KNS) and Korean Society of Neurointensive Care Medicine (KNIC) survey of 2010.

Method

This survey was conducted over 1 year in 86 neurosurgical residency training hospitals and two neurosurgery specialist hospitals and focused on the following areas : 1) the current status of the infrastructure and operating systems of NCUs in Korea, 2) barriers to installing neurointensivist team systems, 3) future roles of the KNS and KNIC, and 4) a handbook for physicians and practitioners in NCUs. We compared and analyzed the results of this survey with those from a KNIC survey of 2010.

Results

Seventy seven hospitals (87.5%) participated in the survey. Nineteen hospitals (24.7%) employed a neurointensivist or faculty member; Thirty seven hospitals (48.1%) reported high demand for neurointensivists, and 62 hospitals (80.5%) stated that the mandatory deployment of a neurointensivist improved the quality of patient care. Forty four hospitals (57.1%) believed that hiring neurointensivist would increase hospital costs, and in response to a question on potential earnings declines. In terms of potential solutions to these problems, 70 respondents (90.9%) maintained that additional fees were necessary for neurointensivists’ work, and 64 (83.1%) answered that direct support was needed of the personnel expenses for neurointensivists.

Conclusion

We hope the results of this survey will guide successful implementation of neurointensivist systems across Korea.

Flavin Adenine Dinucleotide Fluorescence as an Early Marker of Mitochondrial Impairment During Brain Hypoxia

Multimodal continuous bedside monitoring is increasingly recognized as a promising option for early treatment stratification in patients at risk for ischemia during neurocritical care. Modalities used at present are, for example, oxygen availability and subdural electrocorticography. The assessment of mitochondrial function could be an interesting complement to these modalities. For instance, flavin adenine dinucleotide (FAD) fluorescence permits direct insight into the mitochondrial redox state. Therefore, we explored the possibility of using FAD fluorometry to monitor consequences of hypoxia in brain tissue in vitro and in vivo. By combining experimental results with computational modeling, we identified the potential source responsible for the fluorescence signal and gained insight into the hypoxia-associated metabolic changes in neuronal energy metabolism. In vitro, hypoxia was characterized by a reductive shift of FAD, impairment of synaptic transmission and increasing interstitial potassium [K⁺]_o. Computer simulations predicted FAD changes to originate from the citric acid cycle enzyme α-ketoglutarate dehydrogenase and pyruvate dehydrogenase. In vivo, the FAD signal during early hypoxia displayed a reductive shift followed by a short oxidation associated with terminal spreading depolarization. In silico, initial tissue hypoxia followed by a transient re-oxygenation phase due to glucose depletion might explain FAD dynamics in vivo. Our work suggests that FAD fluorescence could be readily used to monitor mitochondrial function during hypoxia and represents a potential diagnostic tool to differentiate underlying metabolic processes for complementation of multimodal brain monitoring.

Multimodal neurocritical monitoring

Neurocritical monitoring is important in caring for patients in the neurological intensive care unit. Although clinical neurologic examination is standard for neurocritical monitoring, changes found during the examination are often late signs and insufficient to detect and prevent secondary brain injury. Therefore, various neuromonitoring tools have been developed to monitor different physiologic parameters, such as cerebral oxygenation, cerebral blood flow, cerebral pressure, cerebral autoregulation, cerebral electric activity, and cerebral metabolism. In this review, we have discussed current commonly used neurocritical monitoring tools. No single monitor is sufficient and perfect for neurocritical monitoring. Multimodal neurocritical monitoring is the current trend. However, the lack of common formatting standards and uncertainty of improvement in patients' outcomes warrant further studies of multimodal neurocritical monitoring. Nevertheless, multimodal neurocritical monitoring considers individual pathophysiological variations in patients or their injuries and allows clinicians to tailor individualized management decisions.

Current Status and Recommendations in Multimodal Neuromonitoring

Every patient in neurocritical care evolves through two phases. Acute pathologies are addressed first. These include trauma, hemorrhagic or ischemic stroke, or neuroinfection. Soon after, the concentration shifts to identifying secondary pathologies like fever, seizures, and ischemia, which may exacerbate the brain injury. Frequent bedside examinations are not sufficient for timely detection and prevention of secondary brain injury (SBI) as per the International Multidisciplinary Consensus Conference on Multimodality Monitoring in Neurocritical Care. Multimodality monitoring (MMM) can help in tailoring treatment decisions to prevent such a brain injury. Multimodal neuromonitoring involves data-guided therapeutic interventions by employing various tools and data integration to understand brain physiology. Monitors provide real-time information on cerebral hemodynamics, oxygenation, metabolism, and electrophysiology. The monitors may be invasive/noninvasive and global/regional. We have reviewed such technologies in this write-up. Novel themes like bioinformatics, clinical research, and device development will also be discussed.

Big data in status epilepticus

Status epilepticus care and treatment are already being touched by the revolution in data science. New approaches designed to leverage the tremendous potential of "big data" in the clinical sphere are enabling researchers and clinicians to extract information from sources such as administrative claims data, the electronic medical health record, and continuous physiologic monitoring data streams. Algorithmic methods of data extraction also offer potential to fuse multimodal data (including text-based documentation, imaging data, and time-series data) to improve patient assessment and stratification beyond the manual capabilities of individual physicians. Still, the potential of data science to impact the diagnosis, treatment, and minute-to-minute care of patients with status epilepticus is only starting to be appreciated. In this brief review, we discuss how data science is impacting the field and draw examples from the following three main areas: (1) analysis of insurance claims from large administrative datasets to evaluate the impact of continuous electroencephalogram (EEG) monitoring on clinical outcomes; (2) natural language processing of the electronic health record to find, classify, and stratify patients for prognostication and treatment; and (3) real-time systems for data analysis, data reduction, and multimodal data fusion to guide therapy in real time. While early, it is our hope that these examples will stimulate investigators to leverage data science, computer science, and engineering methods to improve the care and outcome of patients with status epilepticus and other neurological disorders. This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".

A Patient-Independent Significance Test by Means of False-Positive Rates in Selected Correlation Analysis of Brain Multimodal Monitoring Data

Recently, we introduced a mathematical toolkit called selected correlation analysis (sca) that reliably detects negative and positive correlations between arterial blood pressure (ABP) and intracranial pressure (ICP) data, recorded during multimodal monitoring, in a time-resolved way. As has been shown with the aid of a mathematical model of cerebral perfusion, such correlations reflect impaired autoregulation and reduced intracranial compliance in patients with critical neurological diseases. Sca calculates a Fourier transform-based index called selected correlation (sc) that reflects the strength of correlation between the input data and simultaneously an index called mean Hilbert phase difference (mhpd) that reflects the phasing between the data. To reliably detect pathophysiological conditions during multimodal monitoring, some thresholds for the abovementioned indexes sc and mhpd have to be established that assign predefined significance levels to that thresholds. In this paper, we will present a method that determines the rate of false positives for fixed pairs of thresholds (lsc, lmhpd). We calculate these error rates as a function of the predefined thresholds for each individual out of a patient cohort of 52 patients in a retrospective way. Based on the deviation of the individual error rates, we subsequently determine a globally valid upper limit of the error rate by calculating the predictive interval. From this predictive interval, we deduce a globally valid significance level for appropriate pairs of thresholds that allows the application of sca to every future patient in a prospective, bedside fashion.

Multimodality Neuromonitoring in Adult Traumatic Brain Injury: A Narrative Review

Neuromonitoring plays an important role in the management of traumatic brain injury. Simultaneous assessment of cerebral hemodynamics, oxygenation, and metabolism allows an individualized approach to patient management in which therapeutic interventions intended to prevent or minimize secondary brain injury are guided by monitored changes in physiologic variables rather than generic thresholds. This narrative review describes various neuromonitoring techniques that can be used to guide the management of patients with traumatic brain injury and examines the latest evidence and expert consensus guidelines for neuromonitoring.

Cerebral Oximetry for Detecting High-mortality Risk Patients with Cryptococcal Meningitis

Background

Cryptococcus is the commonest cause of adult meningitis in Africa, with 50%–70% experiencing increased intracranial pressure. Cerebral oximetry is a noninvasive near-infrared spectroscopy technology to monitor percent regional cerebral tissue oxygenation (rSO₂). We assessed if cerebral oximetry predicts meningitis mortality.

Methods

We performed cerebral oximetry within 14 days of cryptococcal meningitis diagnosis on 121 Ugandans from April 2016 to September 2017. We evaluated baseline rSO₂ association with mortality by multivariable logistic regression and correlation with other clinical factors. We compared groups formed by initial rSO₂ <30% vs ≥30% for longitudinal change with mixed effects models. We measured change in %rSO₂ before and after lumbar puncture (LP).

Results

The median initial rSO₂ (interquartile range) was 36% (29%–42%), and it was <30% in 29% (35/121). For 30-day mortality, the unadjusted odds ratio (per 5% increase in rSO₂) was 0.73 (95% confidence interval [CI], 0.58 to 0.91; P = .005). Those with initial rSO₂ <30% had 3.4 (95% CI, 1.5 to 8.0) higher odds of 30-day mortality than those with initial rSO₂ ≥30%. Hemoglobin correlated with initial rSO₂ (rho = .54; P < .001), but rSO₂ did not correlate with pulse oximetry, intracranial pressure, cerebral perfusion pressure, or quantitative cerebrospinal fluid culture, and rSO₂ was unchanged pre/post–lumbar punctures. The longitudinal rSO₂ measurements change was 15% (95% CI, 12% to 18%) lower in the group with initial rSO₂ <30%.

Conclusions

Individuals with cryptococcal meningitis and low cerebral oximetry (rSO₂ < 30%) have high mortality. Cerebral oximetry may be useful as a prognostic marker of mortality. Targeted interventions to improve rSO₂ should be tested in trials to try to decrease mortality in meningitis.