Transcranial Doppler: a stethoscope for the brain-neurocritical care use

Feasibility and Safety of Integrating Extended TCD Assessments in a Full Multimodal Neuromonitoring Protocol After Traumatic Brain Injury

OBJECTIVE

Targeting single monitoring modalities such as intracranial pressure (ICP) or cerebral perfusion pressure alone has shown to be insufficient in improving outcome after traumatic brain injury (TBI). Multimodality monitoring (MMM) allows for a more complete description of brain function and for individualized management. Transcranial Doppler (TCD) represents the gold standard for continuous cerebral blood flow velocity assessment, but requires high levels skill and time. In TBI, the practical aspects of conducting extended TCD monitoring sessions have yet to be evaluated.

METHODS

Patients with acute moderate-to-severe TBI admitted to the neurocritical care unit between March 2022 and December 2023 receiving invasive ICP measurements were evaluated for inclusion. Exclusion criteria included trauma incompatible with TCD monitoring and if MMM was unwarranted. Daily MMM sessions (in addition to regular monitoring) were performed using TCD (Delica EMS 9D System or the DWL Doppler Box) for ≤5 d. Quantitative and qualitative feasibility, safety, and quality metrics were assessed.

RESULTS

Of 74 patients, 36 (75% male; mean age, 44 ± 17 y) were included. Common reasons for exclusion were skull fractures (n = 12) and decompressive craniectomy (n = 9). We acquired 88 recordings (mean, 275 ± 88 min). Overall monitoring times increased, and set-up times decreased. Physiologic variables (including ICP/brain temperature) did not change with TCD application. A single adverse event (dislodging of a microdialysis catheter) occurred.

CONCLUSION

Implementing extended TCD monitoring in MMM protocols is feasible and safe. Considering these results, inclusion of long-term TCD as part of the MMM is strongly encouraged to allow for in-depth description and direct evaluation of hemodynamic changes after TBI.

Transcranial Doppler Ultrasound and Concussion-Supplemental Symptoms with Physiology: A Systematic Review

Sport-related concussion (SRC) can impair the cerebrovasculature both acutely and chronically. Transcranial Doppler (TCD) ultrasound assessment has the potential to illuminate the mechanisms of impairment and provide an objective evaluation of SRC. The current systematic review investigated studies employing TCD ultrasound assessment of intracranial arteries across three broad categories of cerebrovascular regulation: neurovascular coupling (NVC), cerebrovascular reactivity (CVR), and dynamic cerebral autoregulation (dCA). The current review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD42021275627). The search strategy was applied to PubMed, as this database indexes all biomedical journals. Original articles on TCD for athletes with medically diagnosed SRC were included. Title/abstract and full-text screening were completed by three authors. Two authors completed data extraction and risk of bias using the Methodological Index for Non-Randomized Studies and Scottish Intercollegiate Guideline Network checklists. Of the 141 articles identified, 14 met the eligibility criteria. One article used an NVC challenge, eight assessed CVR, and six investigated dCA. Methodologies varied widely among studies, and results were heterogeneous. There was evidence of cerebrovascular impairment in all three domains roughly 2 days post-SRC, but the magnitude and recovery of these impairments were not clear. There was evidence that clinical symptom resolution occurred before cerebrovascular function, indicating that physiological deficits may persist despite clinical recovery and return to play. Collectively, this emphasizes an opportunity for the use of TCD to illuminate the cerebrovascular deficits caused by SRC. It also highlights that there is need for consistent methodological rigor when employing TCD in a SRC population.

Hemodynamic Stroke: Emerging Concepts, Risk Estimation, and Treatment

Ischemic stroke can arise from the sudden occlusion of a brain-feeding artery by a clot (embolic), or local thrombosis. Hemodynamic stroke occurs when blood flow does not sufficiently meet the metabolic demand of a brain region at a certain time. This discrepancy between demand and supply can occur with cerebropetal arterial occlusion or high-grade stenosis but also arises with systemic conditions reducing blood pressure. Treatment of hemodynamic stroke is targeted toward increasing blood flow to the affected area by either systemically or locally enhancing perfusion. Thus, blood pressure is often maintained above normal values, and extra-intracranial flow augmentation bypass surgery is increasingly considered. Still, current evidence supporting the superiority of pressure or flow increase over conservative measures is limited. However, methods assessing hemodynamic impairment and identifying patients at risk of hemodynamic stroke are rapidly evolving. Sophisticated models incorporating clinical and imaging factors have been suggested to aid patient selection. In this narrative review, we provide current state-of-the-art knowledge about hemodynamic stroke, tools for assessment, and treatment options.

Laparoscopic Median Arcuate Ligament Release During Gastric Tube Reconstruction in Subtotal Esophagectomy for a Patient With Esophageal Cancer Complicated by Median Arcuate Ligament Syndrome: A Case Report

A 74-year-old man was diagnosed with squamous cell carcinoma of the lower thoracic esophagus following an upper gastrointestinal endoscopy during a health check-up, which revealed a type 0-IIc tumor. Biopsy confirmed squamous cell carcinoma, with suspicion of submucosal invasion. The patient was referred to our department. Contrast-enhanced computed tomography of the chest and abdomen showed no apparent lymph node or distant metastasis. Severe stenosis at the origin of the celiac artery, likely due to the median arcuate ligament, was observed. No abdominal symptoms were noted at rest or after meals, leading to the diagnosis of thoracic esophageal cancer with asymptomatic median arcuate ligament syndrome. Subsequently, laparoscopic median arcuate ligament release was performed during gastric tube reconstruction in subtotal esophagectomy.

Pathlength-selective, interferometric diffuse correlation spectroscopy (PaLS-iDCS)

Diffuse correlation spectroscopy (DCS) is an optical method that offers non-invasive assessment of blood flow in tissue through the analysis of intensity fluctuations in diffusely backscattered coherent light. The non-invasive nature of the technique has enabled several clinical applications for deep tissue blood flow measurements, including cerebral blood flow monitoring as well as tumor blood flow mapping. While a promising technique, in measurement configurations targeting deep tissue hemodynamics, the standard DCS implementations suffer from insufficient signal-to-noise ratio (SNR), depth sensitivity, and sampling rate, limiting their utility. In this work, we present an enhanced DCS method called pathlength-selective, interferometric DCS (PaLS-iDCS), which improves upon both the sensitivity of the measurement to deep tissue hemodynamics and the SNR of the measurement using pathlength-specific coherent gain. Through interferometric detection, PaLS-iDCS can provide time-of-flight (ToF) specific blood flow information without the use of expensive time-tagging electronics and low-jitter detectors. The new technique is compared to time-domain DCS (TD-DCS), another enhanced DCS method able to resolve photon ToF in tissue, through Monte Carlo simulation, phantom experiments, and human subject measurements. PaLS-iDCS consistently demonstrates improvements in SNR (>2x) for similar measurement conditions (same photon ToF), and the SNR improvements allow for measurements at extended photon ToFs, which have increased sensitivity to deep tissue hemodynamics (~50% increase). Further, like TD-DCS, PaLS-iDCS allows direct estimation of tissue optical properties from the sampled ToF distribution without the need for a separate spectroscopic measurement. This method offers a relatively straightforward way to allow DCS systems to make robust measurements of blood flow with greatly enhanced sensitivity to deep tissue hemodynamics, enabling further applications of this non-invasive technology.

Head-to-toe bedside ultrasound for adult patients on extracorporeal membrane oxygenation

Bedside ultrasound represents a well-suited diagnostic and monitoring tool for patients on extracorporeal membrane oxygenation (ECMO) who may be too unstable for transport to other hospital areas for diagnostic tests. The role of ultrasound, however, starts even before ECMO initiation. Every patient considered for ECMO should have a thorough ultrasonographic assessment of cardiac and valvular function, as well as vascular anatomy without delaying ECMO cannulation. The role of pre-ECMO ultrasound is to confirm the indication for ECMO, identify clinical situations for which ECMO is not indicated, rule out contraindications, and inform the choice of ECMO configuration. During ECMO cannulation, the use of vascular and cardiac ultrasound reduces the risk of complications and ensures adequate cannula positioning. Ultrasound remains key for monitoring during ECMO support and troubleshooting ECMO complications. For instance, ultrasound is helpful in the assessment of drainage insufficiency, hemodynamic instability, biventricular function, persistent hypoxemia, and recirculation on venovenous (VV) ECMO. Lung ultrasound can be used to monitor signs of recovery on VV ECMO. Brain ultrasound provides valuable diagnostic and prognostic information on ECMO. Echocardiography is essential in the assessment of readiness for liberation from venoarterial (VA) ECMO. Lastly, post decannulation ultrasound mainly aims at identifying post decannulation thrombosis and vascular complications. This review will cover the role of head-to-toe ultrasound for the management of adult ECMO patients from decision to initiate ECMO to the post decannulation phase.

Cerebrovascular and cardiovascular autonomic regulation in sickle cell patients with white matter lesions

BACKGROUND AND PURPOSE

White matter lesions (WMLs) are frequent in sickle cell disease (SCD), with a prevalence described to be as high as 53% by age 30. Cerebrovascular regulation and cardiovascular autonomic regulation, more specifically the sympatho-vagal balance, can be altered in SCD. In this study the association between WMLs, cerebrovascular regulation and sympatho-vagal balance was assessed in SCD patients.

METHODS AND RESULTS

Sickle cell disease patients with no history of stroke were prospectively evaluated for cerebrovascular reactivity using the breath-holding test (BHT), the sympatho-vagal balance (ratio low frequency/high frequency [HF]) using heart rate variability parameters and cerebral autoregulation in the time domain using correlation index Mx, and arterial cerebral compliance based on continuous assessment of cerebral blood flow velocities using transcranial Doppler ultrasound and arterial blood pressure with photo-plethysmography. WMLs were assessed with magnetic resonance imaging using Fazekas score grading and the presence of lacunes. Forty-one patients (F/M 25/16) were included. Median age was 37.5 years (19-65). Twenty-nine (70.7%) patients had SS genotype. Eleven patients had WMLs (26.8%). Patients with WMLs were significantly older (p < 0.001), had a lower HF (p < 0.005) and an impaired cerebral arterial compliance (p < 0.014). The receiver operating curve for the regression model including age and HF showed a higher area under the curve compared to age alone (0.946 vs. 0.876). BHT and Mx did not significantly differ between the two groups.

CONCLUSIONS

Lower parasympathetic activity and impaired cerebral arterial compliance were associated with WMLs in adults with SCD. This could potentially yield to a better understanding of pathophysiological parameters leading to premature cerebrovascular ageing in SCD.

Noninvasive Neuromonitoring Modalities in Children Part I: Pupillometry, Near-Infrared Spectroscopy, and Transcranial Doppler Ultrasonography

BACKGROUND

Noninvasive neuromonitoring in critically ill children includes multiple modalities that all intend to improve our understanding of acute and ongoing brain injury.

METHODS

In this article, we review basic methods and devices, applications in clinical care and research, and explore potential future directions for three noninvasive neuromonitoring modalities in the pediatric intensive care unit: automated pupillometry, near-infrared spectroscopy, and transcranial Doppler ultrasonography.

RESULTS

All three technologies are noninvasive, portable, and easily repeatable to allow for serial measurements and trending of data over time. However, a paucity of high-quality data supporting the clinical utility of any of these technologies in critically ill children is currently a major limitation to their widespread application in the pediatric intensive care unit.

CONCLUSIONS

Future prospective multicenter work addressing major knowledge gaps is necessary to advance the field of pediatric noninvasive neuromonitoring.

Validation of the Openwater wearable optical system: cerebral hemodynamic monitoring during a breath hold maneuver

Bedside cerebral blood flow (CBF) monitoring has the potential to inform and improve care for acute neurologic diseases, but technical challenges limit the use of existing techniques in clinical practice. Here we validate the Openwater optical system, a novel wearable headset that uses laser speckle contrast to monitor microvascular hemodynamics. We monitored 25 healthy adults with the Openwater system and concurrent transcranial Doppler (TCD) while performing a breath-hold maneuver to increase CBF. Relative blood flow (rBF) was derived from the changes in speckle contrast, and relative blood volume (rBV) was derived from the changes in speckle average intensity. A strong correlation was observed between beat-to-beat optical rBF and TCD-measured cerebral blood flow velocity (CBFv), R=0.79; the slope of the linear fit indicates good agreement, 0.87 (95% CI:0.83-0.92). Beat-to-beat rBV and CBFv were strongly correlated, R=0.72, but as expected the two variables were not proportional; changes in rBV were smaller than CBFv changes, with linear fit slope of 0.18 (95% CI:0.17-0.19). Further, strong agreement was found between rBF and CBFv waveform morphology and related metrics. This first in vivo validation of the Openwater optical system highlights its potential as a cerebral hemodynamic monitor, but additional validation is needed in disease states.

Higher critical closing pressure is independently associated with enlarged basal ganglia perivascular spaces

Objective

This study aimed to explore the association between cerebral hemodynamic parameters focused on the critical closing pressure (CCP) and enlarged perivascular spaces (EPVS).

Methods

Cerebral blood velocity in the middle cerebral artery (MCAv) and non-invasive continuous blood pressure (NIBP) were measured using a transcranial Doppler (TCD) and Finometer, followed by the calculation of cerebral hemodynamic parameters including CCP, resistance area product (RAP), pulsatility index (PI), and pulse pressure (PP). EPVS were graded separately in the basal ganglia (BG) and centrum semiovale (CSO), using a visual semiquantitative ordinal scale. Patients with EPVS >10 were classified into the severe BG-EPVS group and severe CSO-EPVS group, and the remainder into the mild BG-EPVS group and the mild CSO-EPVS group. Spearman's correlation and binary logistic regression analysis were performed to analyze the relationship between hemodynamic parameters and BG-EPVS and CSO-EPVS, respectively.

Results

Overall, 107 patients were enrolled. The severe BG-EPVS group had higher CCP, mean arterial blood pressure (MABP), systolic blood pressure (SBP), and diastolic blood pressure (DBP) than that in the mild BG-EPVS group (p < 0.05). There was no statistical difference in hemodynamic parameters between the severe CSO-EPVS group and the mild CSO-EPVS group. Spearman's correlation analysis showed that CCP was positively associated with BG-EPVS (rho = 0.331, p < 0.001) and CSO-EPVS (rho = 0.154, p = 0.044). The binary logistic regression analysis showed that CCP was independently associated with severe BG-EPVS (p < 0.05) and not with CSO-EPVS (p > 0.05) after adjusting for confounders.

Conclusion

CCP representing cerebrovascular tension was independently associated with BG-EPVS.

Stiffness pulsation of the human brain detected by non-invasive time-harmonic elastography

Introduction: Cerebral pulsation is a vital aspect of cerebral hemodynamics. Changes in arterial pressure in response to cardiac pulsation cause cerebral pulsation, which is related to cerebrovascular compliance and cerebral blood perfusion. Cerebrovascular compliance and blood perfusion influence the mechanical properties of the brain, causing pulsation-induced changes in cerebral stiffness. However, there is currently no imaging technique available that can directly quantify the pulsation of brain stiffness in real time. Methods: Therefore, we developed non-invasive ultrasound time-harmonic elastography (THE) technique for the real-time detection of brain stiffness pulsation. We used state-of-the-art plane-wave imaging for interleaved acquisitions of shear waves at a frequency of 60 Hz to measure stiffness and color flow imaging to measure cerebral blood flow within the middle cerebral artery. In the second experiment, we used cost-effective lineby-line B-mode imaging to measure the same mechanical parameters without flow imaging to facilitate future translation to the clinic. Results: In 10 healthy volunteers, stiffness increased during the passage of the arterial pulse wave from 4.8% ± 1.8% in the temporal parenchyma to 11% ± 5% in the basal cisterns and 13% ± 9% in the brain stem. Brain stiffness peaked in synchrony with cerebral blood flow at approximately 180 ± 30 ms after the cardiac R-wave. Line-by-line THE provided the same stiffness values with similar time resolution as high-end plane-wave THE, demonstrating the robustness of brain stiffness pulsation as an imaging marker. Discussion: Overall, this study sets the background and provides reference values for time-resolved THE in the human brain as a cost-efficient and easy-touse mechanical biomarker associated with cerebrovascular compliance.

Transcranial Doppler Remote Positioning System with Virtual Reality Integration for Vestibular Studies

Transcranial doppler (TCD) ultrasound probes are an invaluable tool in cerebral blood flow (CBF) studies. Their operation demands maintaining consistent pose on the subject throughout the experimental protocol. However, the displacement of the TCD probe during vestibular studies is common and substantially prolongs the experiment or even terminates it. This is a significant challenge for integrating motion-based vestibular studies with CBF investigations. In response, a mechatronics system is designed to allow remote repositioning of the TCD probe during data collection experiments while the subject is wearing a head mounted virtual reality (VR) display and seated in a vestibular disorientation device. This paper presents the design, prototype, and operation of this mechatronics apparatus.Clinical Relevance- The mechatronics apparatus of this paper can enable motion-based vestibular studies that entail the use of CBF velocity measurement and head-mounted virtual reality display.

Follow-Up by Transcranial Doppler After Rupture of a Giant Intracranial Aneurysm

Giant intracranial aneurysms (GIA) are rare and manifest primarily through subarachnoid hemorrhage (SAH), cerebral ischemia, or progressive symptoms of mass effect. Transcranial Doppler (TCD) can be used to monitor cerebral vasospasm after treatment of intracranial aneurysm allowing the adjustment of therapeutics and avoiding complications. The authors present a clinical case of a patient with a ruptured intracranial giant aneurysm in which TCD was essential to monitor vasospasm and intracranial hypertension (IH). A 53-year-old male was admitted due to a sudden headache and impaired consciousness, left hemiparesis, and dysarthria. Cerebral CT scan and CT angiography at admission showed a giant aneurysm of the right middle cerebral artery (MCA) with extensive and diffuse intraventricular SAH of Fisher grade IV and Hunt and Hess grade 4. Clipping, placement of an intracranial pressure sensor, and external ventricular drain (EVD) were performed on the same day, with difficulty in preserving the M2 branch and complicated by postoperative extensive right MCA ischemia. On day three of hospitalization, TCD revealed an increased pulsatility index (>1.5) with clinical deterioration leading to re-intervention for a decompressive craniectomy. On day six, a TCD follow-up was performed to monitor blood flow complications, and particularly vasospasm, showing a severe increase in middle blood flow velocity (MBFV) in the right MCA of 205 cm/s and Lindegaard Index > 6. Daily surveillance by TCD was maintained to guide clinical management since the attempt to withdraw the EVD led to clinical deterioration with subsequent worsening of vasospasm. Improvement occurred after surgery as ventriculoperitoneal shunt insertion was performed. TCD had a major role in the clinical orientation of SAH as well as in intracranial pressure management and was decisive to establish long-term treatment.

Second- and Third-Tier Therapies for Severe Traumatic Brain Injury

Intracranial hypertension is a common finding in patients with severe traumatic brain injury. These patients need treatment in the intensive care unit, where intracranial pressure monitoring and, whenever possible, multimodal neuromonitoring can be applied. A three-tier approach is suggested in current recommendations, in which higher-tier therapies have more significant side effects. In this review, we explain the rationale for this approach, and analyze the benefits and risks of each therapeutic modality. Finally, we discuss, based on the most recent recommendations, how this approach can be adapted in low- and middle-income countries, where available resources are limited.

Point-of-Care Ultrasound in Neurology - Report of the EAN SPN/ESNCH/ERcNsono Neuro-POCUS Working Group

In the last decade, ultrasound examination in neurology has been undergoing a significant expansion of its modalities. In parallel, there is an increasing demand for rapid and high-quality diagnostics in various acute diseases in the prehospital setting, the emergency room, intensive care unit, and during surgical or interventional procedures. Due to the growing need for rapid answers to clinical questions, there is particular demand for diagnostic ultrasound imaging. The Neuro-POCUS working group, a joint project by the European Academy of Neurology Scientific Panel Neurosonology, the European Society of Neurosonology and Cerebral Hemodynamics, and the European Reference Centers in Neurosonology (EAN SPN/ESNCH/ERcNsono Neuro-POCUS working group), was given the task of creating a concept for point-of-care ultrasound in neurology called "Neuro-POCUS". We introduce here a new ultrasound examination concept called point-of-care ultrasound in neurology (Neuro-POCUS) designed to streamline conclusive imaging outside of the ultrasound center, directly at the bedside. The aim of this study is to encourage neurologists to add quick and disease-oriented Neuro-POCUS to accompany the patient in the critical phase as an adjunct not a substitution for computed tomography, magnetic resonance imaging, or standard comprehensive neurosonology examination. Another goal is to avoid unwanted complications during imaging-free periods, ultimately resulting in advantages for the patient.

Association Between Post-procedure Cerebral Blood Flow Velocity and Severity of Brain Edema in Acute Ischemic Stroke With Early Endovascular Therapy

Objectives

We aimed to investigate the association between post-procedure cerebral blood flow velocity (CBFV) and severity of brain edema in patients with acute ischemic stroke (AIS) who received early endovascular therapy (EVT).

Methods

We retrospectively included patients with AIS who received EVT within 24 h of onset between February 2016 and November 2021. Post-procedure CBFV of the middle cerebral artery was measured in the affected and the contralateral hemispheres using transcranial Doppler ultrasound. The severity of brain edema was measured using the three-level cerebral edema grading from the Safe Implementation of Thrombolysis in Stroke-Monitoring Study, with grades 2–3 indicating severe brain edema. The Association between CBFV parameters and severity of brain edema was analyzed.

Results

A total of 101 patients (mean age 64.2 years, 65.3% male) were included, of whom 56.3% (57/101) suffered brain edema [grade 1, 23 (22.8%); grade 2, 10 (9.9%); and grade 3, 24 (23.8%)]. Compared to patients with non-severe brain edema, patients with severe brain edema had lower affected/contralateral ratios of systolic CBFV (median 1 vs. 1.2, P = 0.020) and mean CBFV (median 0.9 vs. 1.3, P = 0.029). Multivariate logistic regression showed that severe brain edema was independently associated with affected/contralateral ratios of systolic CBFV [odds ratio (OR) = 0.289, 95% confidence interval (CI): 0.069–0.861, P = 0.028] and mean CBFV (OR = 0.278, 95% CI: 0.084–0.914, P = 0.035) after adjusting for potential confounders.

Conclusion

Post-procedure affected/contralateral ratio of CBFV may be a promising predictor of brain edema severity in patients with AIS who received early EVT.

Automated Pupillometry as an Assessment Tool for Intracranial Hemodynamics in Septic Patients

Impaired cerebral autoregulation (CA) may increase the risk of brain hypoperfusion in septic patients. Sepsis dysregulates the autonomic nervous system (ANS), potentially affecting CA. ANS function can be assessed through the pupillary light reflex (PLR). The aim of this prospective, observational study was to investigate the association between CA and PLR in adult septic patients. Transcranial Doppler was used to assess CA and calculate estimated cerebral perfusion pressure (eCPP) and intracranial pressure (eICP). An automated pupillometer (AP) was used to record Neurological Pupil Index (NPi), constriction (CV) and dilation (DV) velocities. The primary outcome was the relationship between AP-derived variables with CA; the secondary outcome was the association between AP-derived variables with eCPP and/or eICP. Among 40 included patients, 21 (53%) had impaired CA, 22 (55%) had low eCPP (<60 mmHg) and 15 (38%) had high eICP (>16 mmHg). DV was lower in patients with impaired CA compared to others; DV predicted impaired CA with area under the curve, AUROC= 0.78 [95% Confidence Interval, CI 0.63−0.94]; DV < 2.2 mm/s had sensitivity 85% and specificity 69% for impaired CA. Patients with low eCPP or high eICP had lower NPi values than others. NPi was correlated with eCPP (r = 0.77, p < 0.01) and eICP (r = −0.87, p < 0.01). Automated pupillometry may play a role to assess brain hemodynamics in septic patients.

Diffusion-Weighted Imaging Image Combined with Transcranial Doppler Ultrasound in the Diagnosis of Patients with Cerebral Infarction and Vertigo

This study aimed at exploring the application value of diffusion-weighted imaging (DWI) combined with transcranial Doppler (TCD) in the diagnosis of patients with cerebral infarction and vertigo (CI + V). In this article, using a retrospective case-control study, 100 CI + V patients (CI + V group) were examined by DWI combined with TCD. Seventy cases of noncerebral infarction with vertigo (control group) who were hospitalized at the same time were collected for clinical data analysis and comprehensive evaluation of each index. The results showed that in patients with CI + V, the abnormal rate of blood vessels was proportional to the size of the lesion, and the abnormal rate of blood vessels in the large-area infarction group (97%) was much higher than that of the small-area infarct group (62%) and the lacunar infarction group (51%). The overall abnormal rate of blood vessels in the CI + V group (71%) was greatly higher than that in the control group (15%), showing a statistically and extremely great difference (P < 0.01). In short, DWI can effectively extract lesion-related data, and combined with TCD examination, the clinical diagnosis of CI + V can be more accurately performed, which had a positive impact on the clinical work of CI + V. This work provided some reference for the clinical effective diagnosis method of CI + V.

A Standardized Multimodal Neurological Monitoring Protocol-Guided Cerebral Protection Therapy for Venoarterial Extracorporeal Membrane Oxygenation Supported Patients

Background

The main objective of this study was to investigate the role of a multimodal neurological monitoring (MNM)-guided protocol in the precision identification of neural impairment and long-term neurological outcomes in venoarterial extracorporeal membrane oxygenation (VA-ECMO) supported patients.

Methods

We performed a cohort study that examined adult patients who underwent VA-ECMO support in our center between February 2010 and April 2021. These patients were retrospectively assigned to the “with MNM group” and the “without MNM group” based on the presence or absence of MNM-guided precision management. The differences in ECMO-related characteristics, evaluation indicators (precision, sensitivity, and specificity) of the MNM-guided protocol, and the long-term outcomes of the surviving patients were measured and compared between the two groups.

Results

A total of 63 patients with VA-ECMO support were retrospectively assigned to the without MNM group (n = 35) and the with MNM group (n = 28). The incidence of neural impairment in the without MNM group was significantly higher than that in the with MNM group (82.1 vs. 54.3%, P = 0.020). The MNM group exhibited older median ages [52.5 (39.5, 65.3) vs. 31 (26.5, 48.0), P = 0.008], a higher success rate of ECMO weaning (92.8 vs. 71.4%, P = 0.047), and a lower median duration of building ECMO [40.0 (35.0, 52.0) vs. 58.0 (48.0, 76.0), P = 0.025] and median ECMO duration days [5.0 (4.0, 6.2) vs. 7.0 (5.0, 10.5), P = 0.018] than the group without MNM. The MNM-guided protocol exhibited a higher precision rate (82.1 vs. 60.0%), sensitivity (95.7 vs. 78.9%), and specificity (83.3 vs. 37.5%) in identifying neural impairment in VA-ECMO support patients. There were significant differences in the long-term outcomes of survivors at 1, 3 and 6 months after discharge between the two groups (P < 0.05). However, the results showed no significant differences in ICU length of stay (LOS), hospital LOS, survival to discharge, or 28-day mortality between the two groups (P > 0.05).

Conclusion

The MNM-guided protocol is conducive to guiding intensivists in the improvement of cerebral protection therapy for ECMO-supported patients to detect and treat potential neurologic impairment promptly, and then improving long-term neurological outcomes after discharge.

Playing a musical instrument increases blood flow in the middle cerebral artery

Purpose

Studies using functional magnetic resonance imaging and positron-emission tomography suggest that many regions of the brain are activated by such complex muscle activity. Although these studies demonstrated relative increases in blood flow in some brain regions with increased neural activity, whether or not the absolute value of cerebral blood flow increases has yet to be elucidated. It also remains unknown whether playing musical instruments affects cerebral blood flow. The aim of this study was to determine the impact of playing a musical instrument on blood flow velocity in the middle cerebral artery (MCAv) by using Doppler ultrasound to measure absolute values of arterial flow velocity.

Methods

Thirteen musicians performed three pieces of music with different levels of difficulty: play for the first time (FS), music in practice (PR) and already mastered (MS) on either piano or violin. MCAv was recorded continuously from 10 min before until 10 min after playing. Associations between the cerebral blood flow response and blood pressure and gas-exchange variables were examined.

Results

PR and MS significantly increased the MCAv. The blood pressure increased significantly in performances of all difficulty levels except for MS. There were no significant changes in exhaled gas variables during the performance.

Conclusion

These findings suggest that playing a musical instrument increases MCAv, and that this change is influenced by the difficulty of the performance.

Transcranial Doppler as a screening test to exclude intracranial hypertension in brain-injured patients: the IMPRESSIT-2 prospective multicenter international study

Background

Alternative noninvasive methods capable of excluding intracranial hypertension through use of transcranial Doppler (ICPtcd) in situations where invasive methods cannot be used or are not available would be useful during the management of acutely brain-injured patients. The objective of this study was to determine whether ICPtcd can be considered a reliable screening test compared to the reference standard method, invasive ICP monitoring (ICPi), in excluding the presence of intracranial hypertension.

Methods

This was a prospective, international, multicenter, unblinded, diagnostic accuracy study comparing the index test (ICPtcd) with a reference standard (ICPi), defined as the best available method for establishing the presence or absence of the condition of interest (i.e., intracranial hypertension). Acute brain-injured patients pertaining to one of four categories: traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), intracerebral hemorrhage (ICH) or ischemic stroke (IS) requiring ICPi monitoring, were enrolled in 16 international intensive care units. ICPi measurements (reference test) were compared to simultaneous ICPtcd measurements (index test) at three different timepoints: before, immediately after and 2 to 3 h following ICPi catheter insertion. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated at three different ICPi thresholds (> 20, > 22 and > 25 mmHg) to assess ICPtcd as a bedside real-practice screening method. A receiver operating characteristic (ROC) curve analysis with the area under the curve (AUC) was used to evaluate the discriminative accuracy and predictive capability of ICPtcd.

Results

Two hundred and sixty-two patients were recruited for final analysis. Intracranial hypertension (> 22 mmHg) occurred in 87 patients (33.2%). The total number of paired comparisons between ICPtcd and ICPi was 687. The NPV was elevated (ICP > 20 mmHg = 91.3%, > 22 mmHg = 95.6%, > 25 mmHg = 98.6%), indicating high discriminant accuracy of ICPtcd in excluding intracranial hypertension. Concordance correlation between ICPtcd and ICPi was 33.3% (95% CI 25.6–40.5%), and Bland–Altman showed a mean bias of -3.3 mmHg. The optimal ICPtcd threshold for ruling out intracranial hypertension was 20.5 mmHg, corresponding to a sensitivity of 70% (95% CI 40.7–92.6%) and a specificity of 72% (95% CI 51.9–94.0%) with an AUC of 76% (95% CI 65.6–85.5%).

Conclusions and relevance

ICPtcd has a high NPV in ruling out intracranial hypertension and may be useful to clinicians in situations where invasive methods cannot be used or not available.

Trial registration: NCT02322970.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03978-2.

Cerebral Pulsatility Index and In-Hospital Mortality in Chinese Patients with Traumatic Brain Injury: A Retrospective Cohort Study

There are limited studies on the relationship between the vascular transcranial Doppler (TCD) pulsatility index (PI) and in-hospital mortality in patients with traumatic brain injury (TBI). To address this issue, we conducted this study to explore whether, in newly diagnosed Chinese TBI patients, the PI is an independent predictor of the in-hospital mortality rate after adjusting for other covariates. This study is a retrospective cohort study. From 24 March 2019 to 24 January 2020, we recruited 144 Chinese patients with newly diagnosed TBI from a Chinese hospital. The independent variable was the PI, and the dependent variable was in-hospital mortality in TBI patients. The relationship between the PI and in-hospital mortality in TBI patients was nonlinear and had an inflection point of 1.11. In the multivariate analysis, after adjusting for potential confounders, the effect sizes and confidence intervals per additional 0.1 units on the left and right sides of the inflection point were 4.09 (1.30–12.83) and 1.42 (0.93–2.17). The relationship between the PI and in-hospital mortality was nonlinear. The PI was positively related with in-hospital mortality when the PI was less than 1.11.

The Utility of a Point-of-Care Transcranial Doppler Ultrasound Management Algorithm on Outcomes in Pediatric Asphyxial Out-of-Hospital Cardiac Arrest – An Exploratory Investigation

Background

Transcranial Doppler ultrasound is a sensitive, real time tool used for monitoring cerebral blood flow; it could provide additional information for cerebral perfusion in cerebral resuscitation during post cardiac arrest care. The aim of the current study was to evaluate the utility of a point-of-care transcranial Doppler ultrasound management algorithm on outcomes in pediatric asphyxial out-of-hospital cardiac arrest.

Methods

This retrospective cohort study was conducted in two tertiary pediatric intensive care units between January 2013 and June 2018. All children between 1 month and 18 years of age with asphyxial out-of-hospital cardiac arrest and a history of at least 3 min of chest compressions, who were treated with therapeutic hypothermia and survived for 12 h or more after the return of circulation were eligible for inclusion.

Results

Twenty-one patients met the eligibility criteria for the study. Sixteen (76.2%) of the 21 children were male, and the mean age was 2.8 ± 4.1 years. Seven (33.3%) of the children had underlying disorders. The overall 1-month survival rate was 52.4%. Twelve (57.1%) of the children received point-of-care transcranial Doppler ultrasound. The 1-month survival rate was significantly higher (p = 0.03) in the point-of-care transcranial Doppler ultrasound group (9/12, 75%) than in the non-point-of-care transcranial Doppler ultrasound group (2/9, 22.2%).

Conclusions

Point-of-care transcranial Doppler ultrasound group was associated with a significantly better 1-month survival rate compared with no point-of-care transcranial Doppler ultrasound group in pediatric asphyxial out-of-hospital cardiac arrest.

McKeown esophagectomy with concomitant median arcuate ligament release in a case of esophageal cancer with celiac artery stenosis

BACKGROUND

The celiac artery stenosis due to compression by median arcuate ligament (MAL) has been reported in many cases of pancreaticoduodenectomy, but not in cases of esophagectomy. Recently, the celiac artery stenosis due to MAL or arteriosclerosis has been reported to be associated with the gastric tube necrosis or anastomotic leakage following Ivor-Lewis esophagectomy. Herein, we present the first reported case of esophageal cancer with celiac artery stenosis due to compression by the MAL successfully treated by McKeown esophagectomy and gastric tube reconstruction following prophylactic MAL release.

CASE PRESENTATION

A 72-year-old female patient was referred to our department for esophagectomy. The patient had received two courses of neoadjuvant chemotherapy with 5-FU and cisplatin for T2N0M0 squamous cell carcinoma of the middle esophagus. Preoperative contrast-enhanced computed tomography (CECT) showed celiac artery stenosis due to compression by the MAL. The development of collateral arteries around the pancreatic head was observed without evidence of aneurysm formation. The patient reported no abdominal symptoms. After robot-assisted esophagectomy with mediastinal lymphadenectomy, gastric mobilization, supra-pancreatic lymphadenectomy, and preparation of the gastric tube were performed under laparotomy. Subsequently, the MAL was cut, and released to expose the celiac artery. Improved celiac artery blood flow was confirmed by decreased pulsatility index on intraoperative Doppler sonography. The operation was completed with the cervical esophagogastric anastomosis following cervical lymphadenectomy. Postoperative CECT on postoperative day 7 demonstrated increased celiac artery patency. The patient had an uncomplicated postoperative course thereafter.

CONCLUSIONS

Prophylactic MAL release may be considered in patients with celiac artery stenosis due to compression by the MAL on preoperative CECT for esophagectomy.

Arterial and Venous Cerebral Blood Flow Velocities and Their Correlation in Healthy Volunteers and Traumatic Brain Injury Patients

BACKGROUND

Few studies have explored the cerebral venous compartment or the correlation between venous and arterial cerebral blood flows. We aimed to correlate cerebral blood flow velocities in the arterial (middle cerebral artery) and venous (straight sinus) compartments in healthy volunteers and traumatic brain injury (TBI) patients. In addition, we determined the normative range of these parameters.

MATERIALS AND METHODS

A total of 122 healthy volunteers and 95 severe TBI patients of both sexes were included and stratified into 3 age groups as follows: group 1 (aged, 18 to 44 y); group 2 (aged, 45 to 64 y); group 3 (older than 65 y). Transcranial Doppler systolic cerebral blood flow velocity, diastolic cerebral blood flow velocity, and mean cerebral blood flow velocity (FVs, FVd, FVm, respectively) were measured in the middle cerebral artery and peak cerebral venous blood flow velocity (FVVs) was measured in the straight sinus. The arteriovenous correlation was assessed on the basis of a positive relationship between FVs and FVVs.

RESULTS

There was an arteriovenous correlation (FVs vs. FVVs) in healthy volunteers (R=0.39, P<0.0001). We found no arteriovenous correlation in the TBI cohort overall, but FVs and FVVs were correlated in age group 1 (R=0.28, P=0.05) and in males (R=0.29, P=0.01). In healthy volunteers, FVs and FVm were significantly higher in males compared with females; and FVs, FVm, FVd, FVVs all increased across the age spectrum. There were no significant differences in any of these parameters in TBI patients.

CONCLUSIONS

There are age and sex differences in arterial and venous cerebral blood flow velocities in healthy volunteers. Arteriovenous correlation is present in healthy volunteers but absent in TBI patients.

Role of imaging in early diagnosis of acute ischemic stroke: a literature review

Stroke is a serious health condition that is responsible for more than 5% of total deaths. Near 20% of patients experiencing stroke die every year, resulting in the stroke being at the top of the list of preventable causes of death. Once an acute stroke is suspected, a golden hour of less than an hour is available to prevent the undesirable consequences. Since neuroimaging is mandatory in the diagnosis of stroke, the proper use of neuroimaging could help saving time and planning the right treatment for the patient. Some of the available imaging methods help us with rapid results, while others benefit us from a more accurate diagnosis. Hereby, we aim to provide a clinical review of the advantages and disadvantages of different available neuroimaging methods in approaching acute stroke to help clinicians choose the best method according to the settings.

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.

Utility of Transcranial Doppler in Moderate and Severe Traumatic Brain Injury: A Narrative Review of Cerebral Physiologic Metrics

Since its creation in the 1980s, transcranial Doppler (TCD) has provided a method of non-invasively monitoring cerebral physiology and has become an invaluable tool in neurocritical care. In this narrative review, we examine the role TCD has in the management of the moderate and severe traumatic brain injury (TBI) patient. We examine the principles of TCD and the ways in which it has been applied to gain insight into cerebral physiology following TBI, as well as explore the clinical evidence supporting these applications. Its usefulness as a tool to non-invasively determine intracranial pressure, detect post-traumatic vasospasm, predict patient outcome, and assess the state of cerebral autoregulation are all explored.

Arterial and Venous Cerebral Blood Flow Velocities in Healthy Volunteers

Transcranial Doppler ultrasound (TCD) enables assessment of brain hemodynamics through insonation of cerebral arteries and veins. Few studies have investigated whether the normal ranges of flow velocities in both arterial and venous compartments may be affected by age and sex.The purpose of this study was to determine the normal blood flow velocities across different sex and age subgroups in a cohort of healthy volunteers by studying the middle cerebral arteries (MCAs) and the straight sinus (SS).A total of 122 healthy volunteers undergoing preanesthetic assessment were recruited at Galliera Hospital in Genoa, Italy. The cohort was stratified for sex (males and females) and for age (18-44 years, 45-64 years, and ≥65 years). Data on systolic, diastolic, and mean flow velocities (FVs, FVd, and FVm, respectively) in the MCA and peak venous flow velocity in the SS (FVVs) were collected from each volunteer.The arterial FVs and FVm were significantly higher in males than in females; FVs, FVm, FVd, and FVVs increased across the age spectrum, especially in the elderly female population.Our findings suggest that there are differences in cerebrovascular flow velocities due to age and sex, which may be correlated to hormonal variations during the lifespan.

Management of intracranial hypertension following traumatic brain injury: a best clinical practice adoption proposal for intracranial pressure monitoring and decompressive craniectomy. Joint statements by the Traumatic Brain Injury Section of the Italian Society of Neurosurgery (SINch) and the Neuroanesthesia and Neurocritical Care Study Group of the Italian Society of Anesthesia, Analgesia, Resuscitation and Intensive Care (SIAARTI)

No robust evidence is provided by literature regarding the management of intracranial hypertension following severe traumatic brain injury (TBI). This is mostly due to the lack of prospective randomized controlled trials (RCTs), the presence of studies containing extreme heterogeneously collected populations and controversial considerations about chosen outcome. A scientific society should provide guidelines for care management and scientific support for those areas for which evidence-based medicine has not been identified. However, RCTs in severe TBI have failed to establish intervention effectiveness, arising the need to make greater use of tools such as Consensus Conferences between experts, which have the advantage of providing recommendations based on experience, on the analysis of updated literature data and on the direct comparison of different logistic realities. The Italian scientific societies should provide guidelines following the national laws ruling the best medical practice. However, many limitations do not allow the collection of data supporting high levels of evidence for intracranial pressure (ICP) monitoring and decompressive craniectomy (DC) in patients with severe TBI. This intersociety document proposes best practice guidelines for this subsetting of patients to be adopted on a national Italian level, along with joint statements from "TBI Section" of the Italian Society of Neurosurgery (SINch) endorsed by the Neuroanesthesia and Neurocritical Care Study Group of the Italian Society of Anesthesia, Analgesia, Resuscitation and Intensive Care (SIAARTI). Presented here is a recap of recommendations on management of ICP and DC supported a high level of available evidence and rate of agreement expressed by the assemblies during the more recent consensus conferences, where members of both groups have had a role of active participants and supporters. The listed recommendations have been sent to a panel of experts consisting of the 107 members of the "TBI Section" of the SINch and the 111 members of the Neuroanesthesia and Neurocritical Care Study Group of the SIAARTI. The aim of the survey was to test a preliminary evaluation of the grade of predictable future adherence of the recommendations following this intersociety proposal. The following recommendations are suggested as representing best clinical practice, nevertheless, adoption of local multidisciplinary protocols regarding thresholds of ICP values, drug therapies, hemostasis management and perioperative care of decompressed patients is strongly recommended to improve treatment efficiency, to increase the quality of data collection and to provide more powerful evidence with future studies. Thus, for this future perspective a rapid overview of the role of the multimodal neuromonitoring in the optimal severe TBI management is also provided in this document. It is reasonable to assume that the recommendations reported in this paper will in future be updated by new observations arising from future trials. They are not binding, and this document should be offered as a guidance for clinical practice through an intersociety agreement, taking in consideration the low level of evidence.

Role of Ultrasound in Neurocritical Care

Bedside point of care ultrasound has acquired an extremely significant role in diagnosis and management of neurocritical care, just as it has in other specialties. Easy availability and increasing expertise have allowed the intensivists to use it in a wide array of situations, such as confirming clinical findings as well as for interventional and prognostic purposes. At present, the clinical applications of ultrasonography (USG) in a neurosurgical patient include estimation of elevated intracranial pressure (ICP), assessment of cerebral blood flow (CBF) and velocities, diagnosis of intracranial mass lesion and midline shifts, and examination of pupils, apart from the systemic applications. Transcranial sonography has also found use in the diagnosis of the cerebral circulatory arrest. An increasing number of clinicians are now relying on the use of ultrasound in the neurointensive care unit for neurological as well as non-neurological indications. These uses include the diagnosis of shock, respiratory failure, deep vein thrombosis and performing bedside procedures.

Transcranial Doppler Combined With Quantitative Electroencephalography Brain Function Monitoring for Estimating the Prognosis of Patients With Posterior Circulation Cerebral Infarction

Posterior circulation cerebral infarction (PCCI) can lead to deceased infratentorial cerebral blood flow (CBF) and metabolism. Neural activity is closely related to regional cerebral blood flow both spatially and temporally. Transcranial Doppler (TCD) combined with quantitative electroencephalography (QEEG) is a technique that evaluates neurovascular coupling and involves synergy between the metabolic and vascular systems. This study aimed to monitor brain function using TCD-QEEG and estimate the efficacy of TCD-QEEG for predicting the prognosis of patients with PCCI. We used a TCD-QEEG recording system to perform quantitative brain function monitoring; we recorded the related clinical variables simultaneously. The data were analyzed using a Cox proportional hazards regression model. Receiver-operating characteristic (ROC) curve analysis was used to evaluate the cut-off for the diastolic flow velocity (VD) and (delta + theta)/(alpha + beta) ratio (DTABR). The area under the ROC curve (AUROC) was calculated to assess the predictive validity of the study variables. Forty patients (aged 63.7 ± 9.9 years; 30 men) were assessed. Mortality at 90 days was 40%. The TCD indicators of VD [hazard ratio (HR) 0.168, confidence interval (CI) 0.047-0.597, p = 0.006] and QEEG indicators of DTABR (HR 12.527, CI 1.637-95.846, p = 0.015) were the independent predictors of the clinical outcomes. The AUROC after combination of VD and DTABR was 0.896 and showed better predictive accuracy than the Glasgow Coma Scale score (0.75), VD (0.76), and DTABR (0.781; all p < 0.05). TCD-QEEG provides a good understanding of the coupling mechanisms in the brain and can improve our ability to predict the prognosis of patients with PCCI.

Transcranial sonographic assessment of the third ventricle in neuro-ICU patients to detect hydrocephalus: a diagnostic reliability pilot study

Background

Transcranial sonography is a point-of-care tool recommended in intensive care units (ICU) to monitor brain injured patients. Objectives of the study was to assess feasibility and reliability of the third ventricle (V3) diameter measurement using transcranial sonography (TCS) compared to brain computed-tomography (CT), the gold standard measurement, and to measure the TCS learning curve. Design: prospective study, in a 16-bed neurological ICU in an academic hospital. Every consecutive brain injured adult patient, who required a brain CT and TCS monitoring were included. The V3 diameter was blindly measured by TCS and CT. Intraclass correlation coefficient (ICC) and Bland–Altman plot were used to assess the reliability and agreement between TCS and CT V3 measurements. Diagnosis performance of the V3 diameter using TCS to detect hydrocephalus was measured. Absolute difference between V3 measurement by residents and experts was measured consecutively to assess the learning curve.

Results

Among the 100 patients included in the study, V3 diameter could be assessed in 87 patients (87%) from at least one side of the skull. Both temporal windows were available in 70 patients (70%). The ICC between V3 diameter measured by TCS and CT was 0.90 [95% CI 0.84–0.93] on the right side, and 0.92 [0.88–0.95] on the left side. In Bland–Altman analysis, mean difference, standard deviation, 95% limits of agreement were 0.36, 1.52, − 2.7 to 3.3 mm, respectively, on the right side; 0.25, 1.47, − 2.7 to 3.1 mm, respectively, on the left side. Among the 35 patients with hydrocephalus, V3 diameters could be measured by TCS in 31 patients (89%) from at least one side. Hydrocephalus was, respectively, excluded, confirmed, or inconclusive using TCS in 35 (40%), 25 (29%) and 27 (31%) of the 87 assessable patients. After 5 measurements, every resident reached a satisfactory measurement compared to the expert operator.

Conclusion

TCS allows rapid, simple and reliable V3 diameter measurement compared with the gold standard in neuro-ICU patients. Aside from sparing irradiating procedures and transfers to the radiology department, it may especially increase close patient monitoring to detect clinically occult hydrocephalus earlier. Further studies are needed to measure the potential clinical benefit of this method.

Trial registration: ClinicalTrials.gov ID: NCT02830269.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00857-x.

Brain Ultrasonography Consensus on Skill Recommendations and Competence Levels Within the Critical Care Setting

BACKGROUND

To report a consensus on the different competency levels for the elaboration of skill recommendations in performing brain ultrasonography within the neurocritical care setting.

METHODS

Four brain ultrasound experts, supported by a methodologist, performed a preselection of indicators and skills based on the current literature and clinical expertise. An international panel of experts was recruited and subjected to web-based questionnaires according to a Delphi method presented in three separate rounds. A pre-defined threshold of agreement was established on expert subjective opinions, > 84% of votes was set to support a strong recommendation and > 68% for a weak recommendation. Below these thresholds, no recommendation reached.

RESULTS

We defined four different skill levels (basic, basic-plus, pre-advanced, advanced). Twenty-five experts participated to the full process. After four rounds of questions, two items received a strong recommendation in the basic skill category, three in the advanced, twelve in the basic-plus, and seven in the pre-advanced. Two items in the pre-advanced category received a weak recommendation and three could not be collocated and were excluded from the list.

CONCLUSIONS

Results from this consensus permitted stratification of the different ultrasound examination skills in four levels with progressively increasing competences. This consensus can be useful as a guide for beginners in brain ultrasonography and for the development of specific training programs within this field.

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.

[Clinical efficacy of restrictive fluid management in patients with severe traumatic brain injury]

OBJECTIVE

To investigate the effects of restrictive fluid management in patients with severe traumatic brain injury (sTBI).

METHODS

Between January, 2019 and June, 2020, we randomly assigned 51 postoperative patients (stay in the ICU of no less than 7 days) with sTBI into treatment group (n=25) with restrictive fluid management and the control group (n=26) with conventional fluid management. The data of optic nerve sheath diameter (ONSD), middle cerebral artery pulsatility index (MAC- PI), neuron-specific enolase (NSE) level, inferior vena cava (IVC) diameter, Glascow Coma Scale (GCS) score, mean arterial blood pressure, heart rate, and fluid balance of the patients were collected at ICU admission and at 1, 3 and 7 days after ICU admission, and the duration of mechanical ventilation, ICU stay, and 28-day mortality were recorded.

RESULTS

The cumulative fluid balance of the two groups were positive on day 1 and negative on days 3 and 7 after ICU admission; at the same time points, the patients in the treatment group had significantly greater negative fluid balance than those in the control group (P < 0.05). In both of the groups, the ONSD and MCA-PI values were significantly higher on day 1 than the baseline (P < 0.05), reached the peak levels on day 3, and decreased on day 7; at the same time point, these values were significantly lower in the treatment group than in the control group (P < 0.05). No significant difference was found in NSE level on day 1 between the two groups (P>0.05); on day 3, NSE level reached the peak level and was significantly higher in the control group (P < 0.05); on day 7, NSE level was lowered the level of day 1 in the treatment group but remained higher than day 1 level in the control group. The 28-day mortality rate did not differ significantly between the two groups (16.00% vs 23.08%, P>0.05); the duration of mechanical ventilation, length of ICU stay, and the number of tracheotomy were all significantly shorter or lower in the treatment group than in the control group (P < 0.05).

CONCLUSIONS

Restrictive fluid management can reduce cerebral edema and improve the prognosis but does not affect the 28-day mortality of patients with sTBI.

Transcranial Doppler-derived indices of cerebrovascular haemodynamics are independent of depth and angle of insonation

Continuous measurement of cerebral blood flow velocity (CBFV) of the middle cerebral artery (MCA) using transcranial Doppler (TCD) and arterial blood pressure (ABP) monitoring enables assessment of cerebrovascular haemodynamics. Further indices describing cerebrovascular function can be calculated from ABP and CBFV, such as the mean index (Mxa) of cerebrovascular autoregulation, the 'time constant of the cerebral arterial bed' (tau), the 'critical closing pressure' (CrCP) and a 'non-invasive estimator of ICP' (nICP). However, TCD is operator-dependent and changes in angle and depth of MCA insonation result in different readings of CBFV. The effect of differing CBFV readings on the calculated secondary indices remains unknown. The aim of this study was to investigate variation in angle and depth of MCA insonation on these secondary indices. In eight patients continuous ABP and ipsilateral CBFV monitoring was performed using two different TCD probes, resulting in four simultaneous CBFV readings at different angles and depths per patient. From all individual recordings, the K-means clustering algorithm was applied to the four simultaneous longitudinal measurements. The average ratios of the between-clusters, sum-of-squares and total sum-of-squares were significantly higher for CBFV than for the indices Mxa, tau and CrCP (p < 0.001, p = 0.007 and p = 0.016) but not for nICP (p = 0.175). The results indicate that Mxa, tau and CrCP seemed to be not affected by depth and angle of TCD insonation, whereas nICP was.

Hypertonic Saline for Moderate Traumatic Brain Injury: A Scoping Review of Impact on Neurological Deterioration

Hypertonic saline (HTS) is a commonly administered agent for intracranial pressure (ICP) control in traumatic brain injury (TBI). The literature on its use is mainly in moderate/severe TBI where invasive ICP monitoring is present. The role of HTS in patients with moderate TBI (mTBI) outside of the intensive care unit (ICU) setting remains unclear. The goal of this scoping review was to provide an overview of the available literature on HTS administration in patients with mTBI without ICP monitoring, assessing its impact on outcome and transitions in care. We performed a scoping systematic review of the literature of MEDLINE, Embase, Scopus, BIOSIS, and the Cochrane Databases from inception to July 31, 2020. We searched for those published articles documenting the administration of HTS in patients with mTBI with recorded functional outcome or transitions in hospital care. A two-step review process was conducted in accordance with methodology outlined in the Cochrane Handbook for Systematic Reviews of Interventions. There were many studies with combined moderate/severe TBI populations. However, most failed to document subgroup analysis for patients with mTBI. Our search strategy identified only one study that documented the administration of HTS in mTBI in which subgroup analysis for mTBI and outcomes were provided. This retrospective cohort study assessed patients with mTBI who did/did not receive prophylactic HTS, finding that those not receiving HTS demonstrated a deterioration in Glasgow Coma Scale (GCS) score in the first 48 h. However, the HTS group did demonstrate a trend to longer hospital stay and pneumonia. Our scoping review identified a significant gap in knowledge surrounding the use of HTS for patients with mTBI without invasive ICP monitoring. The limited identified literature suggests prophylactic administration prevents clinical deterioration, although this is based on a single study with data available for mTBI sub-analysis. Further studies on HTS in non-monitored patients with mTBI are required.

Cerebral ischemia detection using artificial intelligence (CIDAI)-A study protocol

BACKGROUND

The onset of cerebral ischemia is difficult to predict in patients with altered consciousness using the methods available. We hypothesize that changes in Heart Rate Variability (HRV), Near-Infrared Spectroscopy (NIRS), and Electroencephalography (EEG) correlated with clinical data and processed by artificial intelligence (AI) can indicate the development of imminent cerebral ischemia and reperfusion, respectively. This study aimed to develop a method that enables detection of imminent cerebral ischemia in unconscious patients, noninvasively and with the support of AI.

METHODS

This prospective observational study will include patients undergoing elective surgery for carotid endarterectomy and patients undergoing acute endovascular embolectomy for cerebral arterial embolism. HRV, NIRS, and EEG measurements and clinical information on patient status will be collected and processed using machine learning. The study will take place at Sahlgrenska University Hospital, Gothenburg, Sweden. Inclusion will start in September 2020, and patients will be included until a robust model can be constructed. By analyzing changes in HRV, EEG, and NIRS measurements in conjunction with cerebral ischemia or cerebral reperfusion, it should be possible to train artificial neural networks to detect patterns of impending cerebral ischemia. The analysis will be performed using machine learning with long short-term memory artificial neural networks combined with convolutional layers to identify patterns consistent with cerebral ischemia and reperfusion.

DISCUSSION

Early signs of cerebral ischemia could be detected more rapidly by identifying patterns in integrated, continuously collected physiological data processed by AI. Clinicians could then be alerted, and appropriate actions could be taken to improve patient outcomes.

Multimodal non-invasive assessment of intracranial hypertension: an observational study

BACKGROUND

Although placement of an intra-cerebral catheter remains the gold standard method for measuring intracranial pressure (ICP), several non-invasive techniques can provide useful estimates. The aim of this study was to compare the accuracy of four non-invasive methods to assess intracranial hypertension.

METHODS

We reviewed prospectively collected data on adult intensive care unit (ICU) patients with traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), or intracerebral hemorrhage (ICH) in whom invasive ICP monitoring had been initiated and estimates had been simultaneously collected from the following non-invasive indices: optic nerve sheath diameter (ONSD), pulsatility index (PI), estimated ICP (eICP) using transcranial Doppler, and the neurological pupil index (NPI) measured using automated pupillometry. Intracranial hypertension was defined as an invasively measured ICP > 20 mmHg.

RESULTS

We studied 100 patients (TBI = 30; SAH = 47; ICH = 23) with a median age of 52 years. The median invasively measured ICP was 17 [12-25] mmHg and intracranial hypertension was present in 37 patients. Median values from the non-invasive techniques were ONSD 5.2 [4.8-5.8] mm, PI 1.1 [0.9-1.4], eICP 21 [14-29] mmHg, and NPI 4.2 [3.8-4.6]. There was a significant correlation between all the non-invasive techniques and invasive ICP (ONSD, r = 0.54; PI, r = 0.50; eICP, r = 0.61; NPI, r = - 0.41-p < 0.001 for all). The area under the curve (AUC) to estimate intracranial hypertension was 0.78 [CIs = 0.68-0.88] for ONSD, 0.85 [95% CIs 0.77-0.93] for PI, 0.86 [95% CIs 0.77-0.93] for eICP, and 0.71 [95% CIs 0.60-0.82] for NPI. When the various techniques were combined, the highest AUC (0.91 [0.84-0.97]) was obtained with the combination of ONSD with eICP.

CONCLUSIONS

Non-invasive techniques are correlated with ICP and have an acceptable accuracy to estimate intracranial hypertension. The multimodal combination of ONSD and eICP may increase the accuracy to estimate the occurrence of intracranial hypertension.

Optic nerve sheath diameter ultrasonography at admission as a predictor of intracranial hypertension in traumatic brain injured patients: a prospective observational study

OBJECTIVE

Intracranial hypertension and impaired cerebral autoregulation are common causes of secondary injuries in patients with traumatic brain injury (TBI). The primary outcome of this study was to assess whether a noninvasive method to estimate intracranial pressure (ICP) based on the ultrasonography of the optic nerve sheath diameter (ONSD) measured at the time of neurocritical care unit (NCCU) admission is correlated with the mean ICP during NCCU stay. Secondary outcomes were to assess whether ONSD is correlated with the dose of ICP > 20 mm Hg and impaired autoregulation during NCCU stay and with instantaneous ICP and whether ONSD is associated with NCCU mortality.

METHODS

This prospective observational monocentric study included adults with severe TBI. ONSD was measured at NCCU admission, immediately after invasive ICP insertion. ONSD-predicted noninvasive ICP (nICPONSD) was calculated according the formula: nICPONSD = 5 × ONSD - 14 (nICPONSD in mm Hg, ONSD in mm). Autoregulation was measured using the pressure reactivity index (PRx).

RESULTS

In total, 100 patients were included in this study. ONSD was significantly correlated with mean ICP (r = 0.46, p < 0.0001), with mean PRx (r = 0.21, p = 0.04), and with the dose of ICP > 20 mm Hg during NCCU stay (r = 0.49, p < 0.0001). Admission nICPONSD was shown to be significantly correlated with instantaneous ICP (r = 0.85, p < 0.001). ONSD at admission was significantly correlated with NCCU mortality (p = 0.02).

CONCLUSIONS

ONSD measured at NCCU admission can give important information about patients at risk of developing intracranial hypertension and impaired autoregulation. ONSD examination could be useful to screen patients at admission to determine who would benefit from further invasive ICP monitoring.

Clinical Applications of Ultrasonography in Neurocritically Ill Patients

Ultrasonography is part of the multimodal monitoring of the neurocritical patient. Through transcranial color Doppler ultrasound, carotid-color Doppler ultrasound, and ocular ultrasound it is possible to diagnose and monitor a multitude of pathological conditions, such as cerebrovascular events, vasospasm, Terson syndrome, carotid atheromatosis, and brain death. Furthermore, these techniques enable the monitoring of the intracranial pressure, the cerebral perfusion pressure, and the midline deviation, which allows us to understand the patient's neurocritical pathology at their bedside, in a noninvasive way. Although none of these tools have yet been shown to improve patient prognosis, the dissemination of knowledge and management of neurovascular ultrasonography could significantly improve the comprehensive management of neurocritical patients.

Transcranial Doppler Ultrasound During Critical Illness in Children: Survey of Practices in Pediatric Neurocritical Care Centers

OBJECTIVES

The scope of transcranial Doppler ultrasound in the practice of pediatric neurocritical care is unknown. We have surveyed pediatric neurocritical care centers on their use of transcranial Doppler and analyzed clinical management practices.

DESIGN

Electronic-mail recruitment with survey of expert centers using web-based questionnaire.

SETTING

Survey of 43 hospitals (31 United States, 12 international) belonging to the Pediatric Neurocritical Care Research Group.

PATIENTS

None.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A 67% (29/43) hospital-response rate. Of these centers, 27 reported using transcranial Doppler in the PICU; two hospitals opted out due to lack of transcranial Doppler availability/use. The most common diagnoses for using transcranial Doppler in clinical care were intracranial/subarachnoid hemorrhage (20 hospitals), arterial ischemic stroke (14 hospitals), and traumatic brain injury (10 hospitals). Clinical studies were carried out and interpreted by credentialed individuals in 93% (25/27) and 78% (21/27) of the centers, respectively. A written protocol for performance of transcranial Doppler in the PICU was available in 30% (8/27 hospitals); of these, two of eight hospitals routinely performed correlation studies to validate results. In 74% of the centers (20/27), transcranial Doppler results were used to guide clinical care: that is, when to obtain a neuroimaging study (18 hospitals); how to manipulate cerebral perfusion pressure with fluids/vasopressors (13 hospitals); and whether to perform a surgical intervention (six hospitals). Research studies were also commonly performed for a range of diagnoses.

CONCLUSIONS

At least 27 pediatric neurocritical care centers use transcranial Doppler during clinical care. In the majority of centers, studies are performed and interpreted by credentialed personnel, and findings are used to guide clinical management. Further studies are needed to standardize these practices.

Cerebral Blood Flow in Low Intracranial Pressure Headaches-What is Known?

Headaches attributed to low cerebrospinal fluid (CSF) pressure are described as orthostatic headaches caused by spontaneous or secondary low CSF pressure or CSF leakages. Regardless of the cause, CFS leaks may lead to intracranial hypotension (IH) and influence cerebral blood flow (CBF). When CSF volume decreases, a compensative increase in intracranial blood volume and cerebral vasodilatation occurs. Sinking of the brain and traction on pain-sensitive structures are thought to be the causes of orthostatic headaches. Although there are many studies concerning CBF during intracranial hypertension, little is known about CBF characteristics during low intracranial pressure. The aim of this review is to examine the relationship between CBF, CSF, and intracranial pressure in headaches assigned to low CSF pressure.