Advances in Intracranial Pressure Monitoring and Its Significance in Managing Traumatic Brain Injury. Int J Mol Sci. 2015;16:28979-28997. [PMID: 26690122 PMCID: PMC4691093 DOI: 10.3390/ijms161226146]

Acute intracranial hemorrhage during the installation of the LICOX microdialysis system: A case report

Neuro-monitoring is widely employed for the evaluation of intubated patients in the intensive care unit with stroke, severe head trauma, subarachnoid hemorrhage and/or hepatic encephalopathy. The present study reports the case of a patient with acute intracranial hemorrhage following the insertion of neuromonitoring catheters, which required surgical management. The patient was a 14-year-old male who sustained a severe traumatic brain injury and underwent a right-sided hemicraniectomy. During the installation of the neuromonitoring catheters, an acute hemorrhage was noted with a rapidly elevating intracranial pressure. A craniotomy was performed to identify and coagulate the injured cortical vessel. As demonstrated herein, the thorough evaluation of the clotting profile of the patient, a meticulous surgical technique and obtaining a post-insertion computed tomography scan may minimize the risk of any neuromonitoring-associated hemorrhagic complications.

Utility of intracranial pressure monitoring as a diagnostic tool in pediatric ventriculomegaly

OBJECTIVE

Intracranial pressure (ICP) monitoring is commonly utilized for identifying pathologic ICP in cases of traumatic brain injury; however, its utility in hydrocephalic children has not been elucidated. Although patients with typical (pressure-active) hydrocephalus present with clear signs and/or symptoms and the need for cerebrospinal fluid (CSF) diversion is often clear, others may have arrested or pressure-compensated hydrocephalus with pathologic ICP elevation masked by ambiguous signs or are completely asymptomatic. Without treatment these pathologic ICP elevations may affect neurologic development or crescendo over time leading to neurological decline. The purpose of this study is to investigate the utility of ICP monitoring as a diagnostic tool in this relatively common patient population and identify ventriculomegaly patients with and without pathologic ICP, thus improving accuracy of identifying those with and without surgical needs.

METHODS

36 patients (≤ 17 years old) underwent 41 inpatient ICP recording sessions between 2016 and 2022 and were retrospectively reviewed. This included patients with a history of severe, nonprogressive ventriculomegaly and normal fundoscopic examinations lacking traditional signs and symptoms concerning for elevated ICP. Nighttime pathological plateau waves were defined as sustained elevations of ICP ≥ 2x baseline for a duration of ≥ 5 minutes.

RESULTS

The mean age of patients was 5.5 years old (range 0-17 years old). 46.3% of patients had prior endoscopic third ventriculostomy (ETV), 14.6% had prior ventriculoperitoneal shunt (VPS), and 39% were without prior surgical intervention. Roughly half (51.2%) of patients had congenital ventriculomegaly while other patients had ventriculomegaly due to other pathologies such as germinal matrix hemorrhage/intraventricular hemorrhage (GMH/IVH) (29.3%), stroke (4.9%), cerebral infections/meningitis (2.4%), or unknown etiology (12.2%). The average procedure time was 19.1 ± 10.5 minutes, and mean length of stay was 2.8 ± 0.7 days. Pathologic ICP was demonstrated in 12 cases (29.3%), 4 (33.3%) of which were asymptomatic. Pathologic ICP was found in 7 of 19 (36.8%) in the prior ETV group, 1 of 6 (16.7%) in prior shunt group, and 4 of 16 (25%) in the non-surgical group (p = 0.649). Among those with pathologic ICP, 6 (50%) cases received an ETV, 5 (41.7%) cases underwent VPS placement, and 1 (8.3%) case underwent a VPS revision. There were no infectious complications or cases of hemorrhage. 4 patients required repositioning of the ICP monitor due to dislodgement.

CONCLUSION

Inpatient ICP monitoring is a safe and effective diagnostic tool for evaluating the presence of pathologic ICP in severe, persistent non-progressive ventriculomegaly. The use of ICP monitoring may aid in identifying patients with pressure-compensated hydrocephalus who demonstrate pathologic ICP where surgical intervention may be warranted, while preventing unnecessary CSF diversion in those without pathology.

Development of a predictive nomogram for 28-day mortality risk in non-traumatic or post-traumatic subarachnoid hemorrhage patients

OBJECTIVE

Subarachnoid hemorrhage (SAH) is associated with high rates of mortality and permanent disability. At present, there are few definite clinical tools to predict prognosis in SAH patients. The current study aims to develop and assess a predictive nomogram model for estimating the 28-day mortality risk in both non-traumatic or post-traumatic SAH patients.

METHODS

The MIMIC-III database was searched to select patients with SAH based on ICD-9 codes. Patients were separated into non-traumatic and post-traumatic SAH groups. Using LASSO regression analysis, we identified independent risk factors associated with 28-day mortality and incorporated them into nomogram models. The performance of each nomogram was assessed by calculating various metrics, including the area under the curve (AUC), net reclassification improvement (NRI), integrated discrimination improvement (IDI), and decision curve analysis (DCA).

RESULTS

The study included 999 patients with SAH, with 631 in the non-traumatic group and 368 in the post-traumatic group. Logistic regression analysis revealed critical independent risk factors for 28-day mortality in non-traumatic SAH patients, including gender, age, glucose, platelet, sodium, BUN, WBC, PTT, urine output, SpO2, and heart rate and age, glucose, PTT, urine output, and body temperature for post-traumatic SAH patients. The prognostic nomograms outperformed the commonly used SAPSII and APSIII systems, as evidenced by superior AUC, NRI, IDI, and DCA results.

CONCLUSION

The study identified independent risk factors associated with the 28-day mortality risk and developed predictive nomogram models for both non-traumatic and post-traumatic SAH patients. The nomogram holds promise in guiding prognosis improvement strategies for patients with SAH.

Reliability and performance of the IRRAflow® system for intracranial lavage and evacuation of hematomas-A technical note

BACKGROUND

Intraventricular hemorrhage (IVH) is a severe condition with poor outcomes and high mortality. IRRAflow® (IRRAS AB) is a new technology introduced to accelerate IVH clearance by minimally invasive wash-out. The IRRAflow® system performs active and controlled intracranial irrigation and aspiration with physiological saline, while simultaneously monitoring and maintaining a stable intracranial pressure (ICP). We addressed important aspects of the device implementation and intracranial lavage.

METHOD

To allow versatile investigation of multiple device parameters, we designed an ex vivo lab setup. We evaluated 1) compatibility between the IRRAflow® catheter and the Silverline f10 bolt (Spiegelberg), 2) the physiological and hydrodynamic effects of varying the IRRAflow® settings, 3) the accuracy of the IRRAflow® injection volumes, and 4) the reliability of the internal ICP monitor of the IRRAflow®.

RESULTS

The IRRAflow® catheter was not compatible with Silverline bolt fixation, which was associated with leakage and obstruction. Design space exploration of IRRAflow® settings revealed that appropriate settings included irrigation rate 20 ml/h with a drainage bag height at 0 cm, irrigation rate 90 ml/h with a drainage bag height at 19 cm and irrigation rate 180 ml/h with a drainage bag height at 29 cm. We found the injection volume performed by the IRRAflow® to be stable and reliable, while the internal ICP monitor was compromised in several ways. We observed a significant mean drift difference of 3.16 mmHg (variance 0.4, p = 0.05) over a 24-hour test period with a mean 24-hour drift of 3.66 mmHg (variance 0.28) in the pressures measured by the IRRAflow® compared to 0.5 mmHg (variance 1.12) in the Raumedic measured pressures.

CONCLUSION

Bolting of the IRRAflow® catheter using the Medtronic Silverline® bolt is not recommendable. Increased irrigation rates are recommendable followed by a decrease in drainage bag level. ICP measurement using the IRRAflow® device was unreliable and should be accompanied by a control ICP monitor device in clinical settings.

"NeuroVanguard": a contemporary strategy in neuromonitoring for severe adult brain injury patients

Severe acute brain injuries, stemming from trauma, ischemia or hemorrhage, remain a significant global healthcare concern due to their association with high morbidity and mortality rates. Accurate assessment of secondary brain injuries severity is pivotal for tailor adequate therapies in such patients. Together with neurological examination and brain imaging, monitoring of systemic secondary brain injuries is relatively straightforward and should be implemented in all patients, according to local resources. Cerebral secondary injuries involve factors like brain compliance loss, tissue hypoxia, seizures, metabolic disturbances and neuroinflammation. In this viewpoint, we have considered the combination of specific noninvasive and invasive monitoring tools to better understand the mechanisms behind the occurrence of these events and enhance treatment customization, such as intracranial pressure monitoring, brain oxygenation assessment and metabolic monitoring. These tools enable precise intervention, contributing to improved care quality for severe brain injury patients. The future entails more sophisticated technologies, necessitating knowledge, interdisciplinary collaboration and resource allocation, with a focus on patient-centered care and rigorous validation through clinical trials.

The current status of noninvasive intracranial pressure monitoring: A literature review

Elevated intracranial pressure (ICP) is a life-threatening condition that must be promptly diagnosed. However, the gold standard methods for ICP monitoring are invasive, time-consuming, and they involve certain risks. To address these risks, many noninvasive approaches have been proposed. This study undertakes a literature review of the existing noninvasive methods, which have reported promising results. The experimental base on which they are established, however, prevents their application in emergency conditions and thus none of them are capable of replacing the traditional invasive methods to date. On the other hand, contemporary methods leverage Machine Learning (ML) which has already shown unprecedented results in several medical research areas. That said, only a few publications exist on ML-based approaches for ICP estimation, which are not appropriate for emergency conditions due to their restricted capability of employing the medical imaging data available in intensive care units. The lack of such image-based ML models to estimate ICP is attributed to the scarcity of annotated datasets requiring directly measured ICP data. This ascertainment highlights an active and unexplored scientific frontier, calling for further research and development in the field of ICP estimation, particularly leveraging the untapped potential of ML techniques.

Hippo cell signaling and HS-proteoglycans regulate tissue form and function, age-dependent maturation, extracellular matrix remodeling, and repair

This review examined how Hippo cell signaling and heparan sulfate (HS)-proteoglycans (HSPGs) regulate tissue form and function. Despite being a nonweight-bearing tissue, the brain is regulated by Hippo mechanoresponsive cell signaling pathways during embryonic development. HS-proteoglycans interact with growth factors, morphogens, and extracellular matrix components to regulate development and pathology. Pikachurin and Eyes shut (Eys) interact with dystroglycan to stabilize the photoreceptor axoneme primary cilium and ribbon synapse facilitating phototransduction and neurotransduction with bipolar retinal neuronal networks in ocular vision, the primary human sense. Another HSPG, Neurexin interacts with structural and adaptor proteins to stabilize synapses and ensure specificity of neural interactions, and aids in synaptic potentiation and plasticity in neurotransduction. HSPGs also stabilize the blood-brain barrier and motor neuron basal structures in the neuromuscular junction. Agrin and perlecan localize acetylcholinesterase and its receptors in the neuromuscular junction essential for neuromuscular control. The primary cilium is a mechanosensory hub on neurons, utilized by YES associated protein (YAP)-transcriptional coactivator with PDZ-binding motif (TAZ) Hippo, Hh, Wnt, transforming growth factor (TGF)-β/bone matrix protein (BMP) receptor tyrosine kinase cell signaling. Members of the glypican HSPG proteoglycan family interact with Smoothened and Patched G-protein coupled receptors on the cilium to regulate Hh and Wnt signaling during neuronal development. Control of glycosyl sulfotransferases and endogenous protease expression by Hippo TAZ YAP represents a mechanism whereby the fine structure of HS-proteoglycans can be potentially modulated spatiotemporally to regulate tissue morphogenesis in a similar manner to how Hippo signaling controls sialyltransferase expression and mediation of cell-cell recognition, dysfunctional sialic acid expression is a feature of many tumors.

A pilot clinical study to estimate intracranial pressure utilising cerebral photoplethysmograms in traumatic brain injury patients

PURPOSE

In this research, a non-invasive intracranial pressure (nICP) optical sensor was developed and evaluated in a clinical pilot study. The technology relied on infrared light to probe brain tissue, using photodetectors to capture backscattered light modulated by vascular pulsations within the brain's vascular tissue. The underlying hypothesis was that changes in extramural arterial pressure could affect the morphology of recorded optical signals (photoplethysmograms, or PPGs), and analysing these signals with a custom algorithm could enable the non-invasive calculation of intracranial pressure (nICP).

METHODS

This pilot study was the first to evaluate the nICP probe alongside invasive ICP monitoring as a gold standard. nICP monitoring occurred in 40 patients undergoing invasive ICP monitoring, with data randomly split for machine learning. Quality PPG signals were extracted and analysed for time-based features. The study employed Bland-Altman analysis and ROC curve calculations to assess nICP accuracy compared to invasive ICP data.

RESULTS

Successful acquisition of cerebral PPG signals from traumatic brain injury (TBI) patients allowed for the development of a bagging tree model to estimate nICP non-invasively. The nICP estimation exhibited 95% limits of agreement of 3.8 mmHg with minimal bias and a correlation of 0.8254 with invasive ICP monitoring. ROC curve analysis showed strong diagnostic capability with 80% sensitivity and 89% specificity.

CONCLUSION

The clinical evaluation of this innovative optical nICP sensor revealed its ability to estimate ICP non-invasively with acceptable and clinically useful accuracy. This breakthrough opens the door to further technological refinement and larger-scale clinical studies in the future.

TRIAL REGISTRATION

NCT05632302, 11th November 2022, retrospectively registered.

Estimating intracranial parameters using an inverse mathematical model with viscoelastic elements that closely predicts complex ICP morphologies

The quantitative relationship between arterial blood pressure (ABP) and intracranial pressure (ICP) waveforms has not been adequately explained. We hypothesized that the ICP waveform results from interferences between propagating and reflected pressure waves occurring in the cranium following the initiating arterial waveform. To demonstrate cranial effects on interferences between waves and generation of an ICP waveform morphology, we modified our previously reported mathematical model to include viscoelastic elements that affect propagation velocity. Using patient data, we implemented an inverse model methodology to generate simulated ICP waveforms in response to given ABP waveforms. We used an open database of traumatic brain injury patients and studied 65 pairs of ICP and ABP waveforms from 13 patients (five pairs from each). Incorporating viscoelastic elements into the model resulted in model-generated ICP waveforms that very closely resembled the measured waveforms with a 16-fold increase in similarity index relative to the model with only pure elasticity elements. The mean similarity index for the pure elasticity model was 0.06 ± 0.12 SD, compared to 0.96 ± 0.28 SD for the model with viscoelastic components. The normalized root mean squared error (NRMSE) improved substantially for the model with viscoelastic elements compared to the model with pure elastic elements (NRMSE of 2.09% ± 0.62 vs. 15.2% ± 4.8, respectively). The ability of the model to generate complex ICP waveforms indicates that the model may indeed reflect intracranial dynamics. Our results suggest that the model may allow the estimation of intracranial biomechanical parameters with potential clinical significance. It represents a first step in the estimation of inaccessible intracranial parameters.

Applications of flexible electronics related to cardiocerebral vascular system

Ensuring accessible and high-quality healthcare worldwide requires field-deployable and affordable clinical diagnostic tools with high performance. In recent years, flexible electronics with wearable and implantable capabilities have garnered significant attention from researchers, which functioned as vital clinical diagnostic-assisted tools by real-time signal transmission from interested targets in vivo. As the most crucial and complex system of human body, cardiocerebral vascular system together with heart-brain network attracts researchers inputting profuse and indefatigable efforts on proper flexible electronics design and materials selection, trying to overcome the impassable gulf between vivid organisms and rigid inorganic units. This article reviews recent breakthroughs in flexible electronics specifically applied to cardiocerebral vascular system and heart-brain network. Relevant sensor types and working principles, electronics materials selection and treatment methods are expounded. Applications of flexible electronics related to these interested organs and systems are specially highlighted. Through precedent great working studies, we conclude their merits and point out some limitations in this emerging field, thus will help to pave the way for revolutionary flexible electronics and diagnosis assisted tools development.

Idiopathic intracranial hypertension: a step change in understanding the disease mechanisms

The understanding of idiopathic intracranial hypertension (IIH) has evolved over the past few years. Previously, IIH was considered a disease exclusively affecting the neuro-ophthalmic axis, characterized by raised intracranial pressure, headache and papilloedema, and resulting in the risk of severe and permanent visual loss and life-changing disabling headaches. Recent advances have begun to redefine IIH as a probable metabolic disease involving a range of systemic manifestations. More than 95% of individuals affected by the disease are women of reproductive age with obesity. The incidence is rapidly rising and parallels the escalating worldwide obesity rates. Contemporary insights identify associations with insulin resistance, type 2 diabetes and a twofold increased risk of cardiovascular disease in excess of that driven by obesity alone. Adipose distribution in people with IIH, like that in other metabolic diseases, is preferentially centripetal and is associated with changes in intracranial pressure. Evidence now demonstrates adipose tissue dysfunction in people with IIH, involving transcriptional and metabolic priming for lipogenesis and weight gain. Hormonal perturbations are also observed, including a unique phenotype of androgen excess that promotes cerebrospinal fluid secretion. Knowledge of these additional disease features is driving research into novel therapeutic targets and altering the approach to multidisciplinary care.

Noninvasive neuromonitoring with rheoencephalography: a case report

Cerebral blood flow (CBF) autoregulation (AR) can be monitored using invasive modalities, such as intracranial pressure (ICP) and arterial blood pressure (ABP) to calculate the CBF AR index (PRx). Monitoring PRx can reduce the extent of secondary brain damage in patients. Rheoencephalography (REG) is an FDA-approved non-invasive method to measure CBF. REGx, a CBF AR index, is calculated from REG and arm bioimpedance pulse waves. Our goal was to test REG for neuromonitoring. 28 measurement sessions were performed on 13 neurocritical care patients. REG/arm bioimpedance waveforms were recorded on a laptop using a bioimpedance amplifier and custom-built software. The same program was used for offline data processing. Case #1: The patient's mean REGx increased from - 0.08 on the first day to 0.44 on the second day, indicating worsening intracranial compliance (ICC) (P < 0.0001, CI 0.46-0.58). Glasgow Coma Scale (GCS) was 5 on both days. Case #2: REGx decreased from 0.32 on the first recording to 0.07 on the last (P = 0.0003, CI - 0.38 to - 0.12). GCS was 7 and 14, respectively. Case #3: Within a 36-minute recording, REGx decreased from 0.56 to - 0.37 (P < 0.0001, 95%, CI - 1.10 to - 0.76). Central venous pressure changed from 14 to 9 mmHg. REG pulse wave morphology changed from poor ICC to good ICC morphology. Bioimpedance recording made it possible to quantify the active/passive status of CBF AR, indicate the worsening of ICC, and present it in real time. REGx can be a suitable, non-invasive alternative to PRx for use in head-injured patients.

Prognostic predictive value of intracranial pressure and cerebral oxygen metabolism monitoring in patients with spontaneous intracerebral hemorrhage

OBJECTIVE

Our study aimed to investigate the predictive value of intracranial pressure (ICP) and cerebral oxygen metabolism monitoring in the postoperative prognosis of patients with spontaneous intracerebral hemorrhage (SICH).

METHODS

The clinical data of 55 patients with SICH treated by neurosurgery were analyzed retrospectively. These patients were divided into two groups based on postoperative Glasgow Outcome Scale (GOS) scores, i.e., the poor prognosis group (GOS I-III) and the good prognosis group (GOS IV and V). Next, the ICP and cerebral oxygen metabolism indexes, such as brain temperature (BT), cerebral perfusion pressure (CPP), internal jugular venous oxygen saturation (SjvO2), and arterial partial pressure of carbon dioxide (PaCO2), were recorded after the operation. Further, the prognostic differences between the two groups were compared, and the predictive values were evaluated using the receiver operating characteristic curve (ROC) and area under the curve (AUC).

RESULTS

The results showed that the average ICP and BT in the good prognosis group were lower than those in the poor prognosis group. However, the CPP and SjvO2 in the good prognosis group were higher than those in the poor prognosis group. Moreover, the incidence of low PaCO2 in the poor prognosis group was higher than that in the good prognosis group.

CONCLUSIONS

Our results demonstrated that the average ICP, BT, CPP, SjvO2, and arterial PaCO2 may reflect the changes in brain function and cerebral blood flow, which are significantly correlated with the prognosis of patients. Further, our findings indicated that the combined postoperative ICP levels with cerebral oxygen metabolism indexes could guide clinical treatments and predict prognosis.

Implantable Intracranial Pressure Sensor with Continuous Bluetooth Transmission via Mobile Application

Hydrocephalus is a clinical disorder caused by excessive cerebrospinal fluid (CSF) buildup in the ventricles of the brain, often requiring permanent CSF diversion via an implanted shunt system. Such shunts are prone to failure over time; an ambulatory intracranial pressure (ICP) monitoring device may assist in the detection of shunt failure without an invasive diagnostic workup. Additionally, high resolution, noninvasive intracranial pressure monitoring will help in the study of diseases such as normal pressure hydrocephalus (NPH) and idiopathic intracranial hypertension (IIH). We propose an implantable, continuous, rechargeable ICP monitoring device that communicates via Bluetooth with mobile applications. The design requirements were met at the lower ICP ranges; the obtained error fell within the idealized ±2 mmHg margin when obtaining pressure values at or below 20 mmHg. The error was slightly above the specified range at higher ICPs (±10% from 20-100 mmHg). The system successfully simulates occlusions and disconnections of the proximal and distal catheters, valve failure, and simulation of A and B ICP waves. The mobile application accurately detects the ICP fluctuations that occur in these physiologic states. The presented macro-scale prototype is an ex-vivo model of an implantable, rechargeable ICP monitoring system that has the potential to measure clinically relevant ICPs and wirelessly provide accessible and continuous data to aid in the workup of shunt failure.

Intracranial Pressure Monitoring and Treatment Thresholds in Acute Neural Injury: A Narrative Review of the Historical Achievements, Current State, and Future Perspectives

Since its introduction in the 1960s, intracranial pressure (ICP) monitoring has become an indispensable tool in neurocritical care practice and a key component of the management of moderate/severe traumatic brain injury (TBI). The primary utility of ICP monitoring is to guide therapeutic interventions aimed at maintaining physiological ICP and preventing intracranial hypertension. The rationale for such ICP maintenance is to prevent secondary brain injury arising from brain herniation and inadequate cerebral blood flow. There exists a large body of evidence indicating that elevated ICP is associated with mortality and that aggressive ICP control protocols improve outcomes in severe TBI patients. Therefore, current management guidelines recommend a cerebral perfusion pressure (CPP) target range of 60-70 mm Hg and an ICP threshold of >20 or >22 mm Hg, beyond which therapeutic intervention should be initiated. Though our ability to achieve these thresholds has drastically improved over the past decades, there has been little to no change in the mortality and morbidity associated with moderate-severe TBI. This is a result of the "one treatment fits all" dogma of current guideline-based care that fails to take individual phenotype into account. The way forward in moderate-severe TBI care is through the development of continuously derived individualized ICP thresholds. This narrative review covers the topic of ICP monitoring in TBI care, including historical context/achievements, current monitoring technologies and indications, treatment methods, associations with patient outcome and multi-modal cerebral physiology, present controversies surrounding treatment thresholds, and future perspectives on personalized approaches to ICP-directed therapy.

Mobilization phases in traumatic brain injury

Mobilization in traumatic brain injury (TBI) have shown the improvement of length of stay, infection, long term weakness, and disability. Primary damage as a result of trauma's direct effect (skull fracture, hematoma, contusion, laceration, and nerve damage) and secondary damage caused by trauma's indirect effect (microvasculature damage and pro-inflammatory cytokine) result in reduced tissue perfusion & edema. These can be facilitated through mobilization, but several precautions must be recognized as mobilization itself may further deteriorate patient's condition. Very few studies have discussed in detail regarding mobilizing patients in TBI cases. Therefore, the scope of this review covers the detail of physiological effects, guideline, precautions, and technique of mobilization in patients with TBI.

A review of invasive intracranial pressure monitoring following surgery for hypertensive cerebral hemorrhage

Hypertensive cerebral hemorrhage, the most common prevalent of spontaneous cerebral hemorrhage, poses a significant threat to patient mortality and morbidity, while therapeutic options remain limited, making the disease a burden not only for patients' families but also a major challenge for national healthcare systems. The elevation of intracranial pressure subsequent to hypertensive cerebral hemorrhage is a critical contributor to mortality. However, it often manifests before the onset of clinical symptoms, which are typically atypical, leading to delayed treatment and irreversible consequences for the patient. Hence, early detection of intracranial pressure variations can aid in timely, efficient, and precise treatment, reducing patient mortality. Invasive intracranial pressure monitoring enables real-time, accurate monitoring of intracranial pressure changes, providing clinicians with therapeutic guidance and overcoming the limitations of empirical treatment. This article aims to review the use of invasive intracranial pressure monitoring in postoperative hypertensive cerebral hemorrhage and hopes to contribute to clinical and scientific research.

Multimodal and autoregulation monitoring in the neurointensive care unit

Given the complexity of cerebral pathology in patients with acute brain injury, various neuromonitoring strategies have been developed to better appreciate physiologic relationships and potentially harmful derangements. There is ample evidence that bundling several neuromonitoring devices, termed "multimodal monitoring," is more beneficial compared to monitoring individual parameters as each may capture different and complementary aspects of cerebral physiology to provide a comprehensive picture that can help guide management. Furthermore, each modality has specific strengths and limitations that depend largely on spatiotemporal characteristics and complexity of the signal acquired. In this review we focus on the common clinical neuromonitoring techniques including intracranial pressure, brain tissue oxygenation, transcranial doppler and near-infrared spectroscopy with a focus on how each modality can also provide useful information about cerebral autoregulation capacity. Finally, we discuss the current evidence in using these modalities to support clinical decision making as well as potential insights into the future of advanced cerebral homeostatic assessments including neurovascular coupling.

Current status and outlook for the management of intracranial hypertension after traumatic brain injury: decompressive craniectomy, therapeutic hypothermia, and barbiturates

INTRODUCTION

Increased intracranial pressure (ICP) has been associated with poor neurological outcomes and increased mortality in patients with severe traumatic brain injury (TBI). Traditionally, ICP-lowering therapies are administered using an escalating approach, with more aggressive options reserved for patients showing no response to first-tier interventions, or with refractory intracranial hypertension.

DEVELOPMENT

The therapeutic value and the appropriate timing for the use of rescue treatments for intracranial hypertension have been a subject of constant debate in literature. In this review, we discuss the main management options for refractory intracranial hypertension after severe TBI in adults. We intend to conduct an in-depth revision of the most representative randomised controlled trials on the different rescue treatments, including decompressive craniectomy, therapeutic hypothermia, and barbiturates. We also discuss future perspectives for these management options.

CONCLUSIONS

The available evidence appears to show that mortality can be reduced when rescue interventions are used as last-tier therapy; however, this benefit comes at the cost of severe disability. The decision of whether to perform these interventions should always be patient-centred and made on an individual basis. The development and integration of different physiological variables through multimodality monitoring is of the utmost importance to provide more robust prognostic information to patients facing these challenging decisions.

Clinical translation of noninvasive intracranial pressure sensing with diffuse correlation spectroscopy

OBJECTIVE

Intracranial pressure (ICP) is an important therapeutic target in many critical neuropathologies. The current tools for ICP measurements are invasive; hence, these are only selectively applied in critical cases where the benefits surpass the risks. To address the need for low-risk ICP monitoring, the authors developed a noninvasive alternative.

METHODS

The authors recently demonstrated noninvasive quantification of ICP in an animal model by using morphological analysis of microvascular cerebral blood flow (CBF) measured with diffuse correlation spectroscopy (DCS). The current prospective observational study expanded on this preclinical study by translating the method to pediatric patients. Here, the CBF features, along with mean arterial pressure (MAP) and heart rate (HR) data, were used to build a random decision forest, machine learning model for estimation of ICP; the results of this model were compared with those of invasive monitoring.

RESULTS

Fifteen patients (mean age ± SD [range] 9.8 ± 5.1 [0.3-17.5] years; median age [interquartile range] 11 [7.4] years; 10 males and 5 females) who underwent invasive neuromonitoring for any purpose were enrolled. Estimated ICP (ICPest) very closely matched invasive ICP (ICPinv), with a root mean square error (RMSE) of 1.01 mm Hg and 95% limit of agreement of ≤ 1.99 mm Hg for ICPinv 0.01-41.25 mm Hg. When the ICP range (ICPinv 0.01-29.05 mm Hg) was narrowed on the basis of the sample population, both RMSE and limit of agreement improved to 0.81 mm Hg and ≤ 1.6 mm Hg, respectively. In addition, 0.3% of the test samples for ICPinv ≤ 20 mm Hg and 5.4% of the test samples for ICPinv > 20 mm Hg had a limit of agreement > 5 mm Hg, which may be considered the acceptable limit of agreement for clinical validity of ICP sensing. For the narrower case, 0.1% of test samples for ICPinv ≤ 20 mm Hg and 1.1% of the test samples for ICPinv > 20 mm Hg had a limit of agreement > 5 mm Hg. Although the CBF features were crucial, the best prediction accuracy was achieved when these features were combined with MAP and HR data. Lastly, preliminary leave-one-out analysis showed model accuracy with an RMSE of 6 mm Hg and limit of agreement of ≤ 7 mm Hg.

CONCLUSIONS

The authors have shown that DCS may enable ICP monitoring with additional clinical validation. The lower risk of such monitoring would allow ICP to be estimated for a wide spectrum of indications, thereby both reducing the use of invasive monitors and increasing the types of patients who may benefit from ICP-directed therapies.

Mechanical Complications of External Ventricular and Lumbar Drains

BACKGROUND

External ventricular drain (EVD) and lumbar drain insertion are 2 of the most commonly performed neurosurgical procedures worldwide for acute hydrocephalus. Mechanical complications, such as obstruction or cerebrospinal fluid (CSF) leakage, are often seen and may contribute toward significant patient morbidity. Different CSF drainage methods are advocated to reduce the incidence of complications, but evidence regarding comparative effectiveness is limited.

METHODS

In this single-center prospective cohort study, the incidence of mechanical complications and associated interventional factors, including choice of drain, collecting system, and location, were studied in patients requiring CSF diversion for acute hydrocephalus. Univariate analyses were performed to explore trends within the data, followed by a repeated-measures mixed-effects regression to determine the independent influence of drain device on mechanical failure.

RESULTS

Sixty-one patients required CSF diversion between January 2020 and March 2021, via 3 different drain types (lumbar drain, tunneled, and bolted EVD) and 2 collection systems (LiquoGuard 7 and AccuDrain), performed in either theater or intensive care. Twenty-one patients (39%) experienced a mechanical complication, with blockage being the most common. Multivariate analyses showed that bolted EVDs (odds ratio, 0.08; confidence interval, 0.01-0.58) and LiquoGuards (OR, 0.23; CI, 0.08-0.69) were significantly associated with fewer mechanical complications compared with tunneled EVDs and gravity-based collection systems, respectively (P ≤ 0.01).

DISCUSSION

Drain device has an influence on the occurrence of EVD-related complications. These preliminary findings suggest that choosing bolted EVDs and motor-assisted drainage can reduce drain-associated mechanical failure. A randomized controlled trial comparing drain devices is required to confirm these findings.

Decision Support Tool to Judiciously Assign High-Frequency Neurologic Examinations in Traumatic Brain Injury

INTRODUCTION

Traumatic brain injury (TBI) management includes serial neurologic examinations to assess for changes dictating neurosurgical interventions. We hypothesized hourly examinations are overassigned. We conducted a decision tree analysis to determine an algorithm to judiciously assign hourly examinations.

METHODS

A retrospective cohort study of 1022 patients with TBI admitted to a Level 1 trauma center from January 1, 2019, to December 31, 2019, was conducted. Patients with penetrating TBI or immediate or planned interventions and those with nonsurvivable injuries were excluded. Patients were stratified by whether they underwent an unplanned intervention (e.g., craniotomy or invasive intracranial monitoring). Univariate analysis identified factors for inclusion in chi-square automatic interaction detection technique, classifying those at risk for unplanned procedures.

RESULTS

A total of 830 patients were included, 287 (35%) were assigned hourly (Q1) examinations, and 17 (2%) had unplanned procedures, with 16 of 17 (94%) on Q1 examinations. Patients requiring unplanned procedures were more likely to have mixed intracranial hemorrhage pattern (82% versus 39%; P = 0.001), midline shift (35% versus 14%; P = 0.023), an initial poor neurologic examination (Glasgow Comas Scale ≤8, 77% versus 14%; P < 0.001), and be intubated (88% versus 17%; P < 0.001). Using chi-square automatic interaction detection, the decision tree demonstrated low-risk (2% misclassification) and excellent discrimination (area under the curve = 0.915, 95% confidence interval 0.844-0.986; P < 0.001) of patients at risk of an unplanned procedure. By following the algorithm, 167 fewer patients could have been assigned Q1 examinations, resulting in an estimated 6012 fewer examinations.

CONCLUSIONS

Using a 4-factor algorithm can optimize the assignment of neuro examinations and substantially reduce neuro examination burden without sacrificing patient safety.

Lawrence K, Tachtsidis I, Tong Y, Torricelli A, Urner T, Wabnitz H, Wolf M, Wolf U, Xu S, Yang C, Yodh AG, Yücel MA, Zhou W. Optical imaging and spectroscopy for the study of the human brain: status report

This report is the second part of a comprehensive two-part series aimed at reviewing an extensive and diverse toolkit of novel methods to explore brain health and function. While the first report focused on neurophotonic tools mostly applicable to animal studies, here, we highlight optical spectroscopy and imaging methods relevant to noninvasive human brain studies. We outline current state-of-the-art technologies and software advances, explore the most recent impact of these technologies on neuroscience and clinical applications, identify the areas where innovation is needed, and provide an outlook for the future directions.

Brain Tissue Damage Induced by Multimodal Neuromonitoring In Situ during MRI after Severe Traumatic Brain Injury: Incidence and Clinical Relevance

Both neuromonitoring and early magnetic resonance imaging (MRI) provide crucial information for treatment management and prognosis in patients with severe traumatic brain injury (sTBI). So far, neuromonitoring in situ impedes the routine implementation of MRI due to safety concerns. We aimed to evaluate the brain tissue damage induced by inserted neuromonitoring devices and its clinical relevance. Nineteen patients with sTBI and being exposed to at least one MRI with neuromonitoring in situ and one follow-up MRI after neuromonitoring removal were analyzed. All MRIs were reviewed for specific tissue damage. Three females and sixteen males (aged 20–74 years, mean 42.8 years) with an initial median GCS of 5 (range 3–8) were analyzed. No lesion was observed in six patients (31.6%), whereas another six patients (31.6%) demonstrated a detectable probe trajectory. Probe-related tissue damage was visible in seven patients (36.8%) with the size of the lesion prone to further enlarge with increasing cumulative duration of MRI examinations. Upon interdisciplinary evaluation, the lesions were not considered clinically relevant. Neuromonitoring probes in situ during MRI examinations may cause local brain tissue damage, yet without any clinical implications if placed correctly. Therefore, indications must be strictly based on joint decision from all involved disciplines.

In-Vitro Demonstration of Ultra-Reliable, Wireless and Batteryless Implanted Intracranial Sensors Operated on Loci of Exceptional Points

Vital signal monitoring, such as pulse, respiration rate, intra-organ and intra-vascular pressure, can provide important information for determination of clinic diagnosis, treatments, and surgical protocols. Nowadays, micromachined bioimplants, equipped with antennas for converting bio-signals to modulated radio transmissions, may allow remote continuous monitoring of patients' vital signs. Yet, current passive biotelemetry techniques usually suffer from poor signal reproducibility and robustness in light of inevitable misalignment between transmitting and receiving antennas. Here, we seek to address this long-existing challenge and to robustly acquire information from a passive wireless intracranial pressure (or brain pressure) sensor by introducing a novel, high-performance biotelemetry system. In spite of variable inductive links, this biotelemetry system may have absolute accuracy by leveraging the uniqueness of loci of exceptional points (EPs) in non-Hermitian radio-frequency (RF) electronic systems with parity-time (PT) symmetry. Our in-vitro experimental demonstration shows that the proposed intracranial (ICP) monitoring system can provide a sub-mmHg resolution in the ICP range of 0-20 mmHg and ultra-robust wireless data acquisition against the misalignment-induced weakening of inductive link. Our results could provide a practical pathway toward reliable, real-time wireless monitoring of ICP, and other vital signals generated by bio-implants and wearables.

Preliminary evaluation of a non-invasive device for monitoring intracranial pressure waveforms in dogs

OBJECTIVES

The objective of this study was to compare waveforms obtained with a new device for the non-invasive monitoring of intracranial pressure (ICP) in dogs with and without neurological disease.

MATERIALS AND METHODS

This prospective study was conducted on both neurologically normal dogs and dogs with neurological diseases. First, non-invasive ICP waveforms were recorded in normal dogs using the Braincare® BcMM 2000 monitor while the dogs were under general anaesthesia induced for procedures unrelated to this study. The dogs were positioned in lateral recumbency, and the sensor was placed over the skin of the parietal region. Secondly, non-invasive ICP waveforms were monitored in dogs with brain and spinal disease until waveforms with characteristic peaks were acquired. All the recorded signals were amplified, filtered and digitalized, by the device, and then transferred to a computer for analysis.

RESULTS

Normal pulse waveforms indicating normal brain complacency were observed in eight neurologically normal dogs. In six dogs with brain disease, abnormal pulse waveforms were observed suggesting increased ICP and decreased brain complacency. Four dogs with spinal disease undergoing myelography, had normal waveforms before contrast medium injection and abnormal pulse waveforms during contrast medium injection, indicating a potential increase in ICP.

CLINICAL SIGNIFICANCE

Based on these preliminary observations, this method was capable of detecting abnormal pulse waveforms that suggested increased ICP.

Precision-Microfabricated Fiber-Optic Probe for Intravascular Pressure and Temperature Sensing

Small form-factor sensors are widely used in minimally invasive intravascular diagnostic procedures. Manufacturing complexities associated with miniaturizing current fiber-optic probes, particularly for multi-parameter sensing, severely constrain their adoption outside of niche fields. It is especially challenging to rapidly prototype and iterate upon sensor designs to optimize performance for medical devices. In this work, a novel technique to construct a microscale extrinsic fiber-optic sensor with a confined air cavity and sub-micron geometric resolution is presented. The confined air cavity is enclosed between a 3 μm thick pressure-sensitive distal diaphragm and a proximal temperature-sensitive plano-convex microlens segment unresponsive to changes in external pressure. Simultaneous pressure and temperature measurements are possible through optical interrogation via phase-resolved low-coherence interferometry (LCI). Upon characterization in a simulated intravascular environment, we find these sensors capable of detecting pressure changes down to 0.11 mmHg (in the range of 760 to 1060 mmHg) and temperature changes of 0.036 °C (in the range 34 to 50 °C). By virtue of these sensitivity values suited to intravascular physiological monitoring, and the scope of design flexibility enabled by the precision-fabricated photoresist microstructure, it is envisaged that this technique will enable construction of a wide range of fiber-optic sensors for guiding minimally invasive medical procedures.

Comparison of Waveforms Between Noninvasive and Invasive Monitoring of Intracranial Pressure

Intracranial pressure (ICP) is an important invasive monitoring parameter in management of patients with acute brain injury and compromised compliance. This study aimed to compare waveforms obtained from standard ICP monitoring and noninvasive ICP monitoring (nICP) methods.We analyzed continuous arterial blood pressure (ABP) waves, ICP (with standard monitoring), and nICP recorded simultaneously. All signal recordings were sliced into data chunks, each 1 min in duration, and from the mean pulse, we determined the time to peak (Tp) and the ratio between tidal and percussion waves (P2/P1). We also calculated the Isomap projection of the pulses into a bidimensional space-K1 and K2. The defined nICP and ICP parameters were compared using a unilateral Wilcoxon-Mann-Whitney test. The Pearson correlation coefficient and normalized mutual information were used to verify the association between parameters.In total, 1504 min of monitoring from ten patients were studied. Nine of the patients were male. The mean age of the patients was 58.4 ± 10.4 years, and they had an initial Glasgow Coma Scale of 9 ± 4, a mean Simplified Acute Physiology Score (SAPS II) of 45.6, and an intensive care unit stay of 44 ± 45 days. With the exception of Tp, all parameters showed a weak linear association but presented a strong nonlinear association.Mutual information analysis and a bigger sample size would be helpful to build more refined models and to improve understanding of the waveform relationships.

Non-invasive detection of intracranial pressure related to the optic nerve

Intracranial pressure (ICP) is associated with a variety of diseases. Early diagnosis and the timely intervention of elevated ICP are effective means to clinically reduce the morbidity and mortality of some diseases. The detection and judgment of reduced ICP are beneficial to glaucoma doctor and neuro ophthalmologist to diagnose optic nerve disease earlier. It is important to evaluate and monitor ICP clinically. Although invasive ICP detection is the gold standard, it can have complications. Most non-invasive ICP tests are related to the optic nerve and surrounding tissues due to their anatomical characteristics. Ultrasound, magnetic resonance imaging, transcranial Doppler, papilledema on optical coherence tomography, visual evoked potential, ophthalmodynamometry, the assessment of spontaneous retinal venous pulsations, and eye-tracking have potential for application. Although none of these methods can completely replace invasive technology; however, its repeatable, low risk, high accuracy, gradually attracted people's attention. This review summarizes the non-invasive ICP detection methods related to the optic nerve and the role of the diagnosis and prognosis of neurological disorders and glaucoma. We discuss the advantages and challenges and predict possible areas of development in the future.

Large-Volume Intrathecal Administrations: Impact on CSF Pressure and Safety Implications

The increasing number of studies demonstrates the high potency of the intrathecal (IT) route for the delivery of biopharmaceuticals to the central nervous system (CNS). Our earlier data exhibited that both the infused volume and the infusion rate can regulate the initial disposition of the administered solute within the cerebrospinal fluid (CSF). This disposition is one of key factors in defining the subsequent transport of the solute to its intended target. On the other hand, fast additions of large volumes of liquid to the CSF inevitably raise the CSF pressure [a.k.a. intracranial pressure (ICP)], which may in turn lead to adverse reactions if the physiologically delimited threshold is exceeded. While long-term biological effects of elevated ICP (hydrocephalus) are known, the safety thresholds pertaining to short-term ICP elevations caused by IT administrations have not yet been characterized. This study aimed to investigate the dynamics of ICP in rats and non-human primates (NHPs) with respect to IT infusion rates and volumes. The safety regimes were estimated and analyzed across species to facilitate the development of translational large-volume IT therapies. The data revealed that the addition of a liquid to the CSF raised the ICP in a rate and volume-dependent manner. At low infusion rates (<0.12 ml/min in rats and <2 ml/min in NHPs), NHPs and rats displayed similar tolerance patterns. Specifically, safe accommodations of such added volumes were mainly facilitated by the accelerated pressure-dependent CSF drainage into the blood, with I stabilizing at different levels below the safety threshold of 28 ± 4 mm Hg in rats and 50 ± 5 mm Hg in NHPs. These ICPs were safely tolerated for extended durations (of at least 2–25 min). High infusion rates (including boluses) caused uncompensated exponential ICP elevations rapidly exceeding the safety thresholds. Their tolerance was species-dependent and was facilitated by the compensatory role of the varied components of craniospinal compliance while not excluding the possibility of other contributing factors. In conclusion, large volumes of liquids can safely be delivered via IT routes provided that ICP is monitored as a safety factor and cross-species physiological differences are accounted for.

Reference values for intracranial pressure and lumbar cerebrospinal fluid pressure: a systematic review

BACKGROUND

Although widely used in the evaluation of the diseased, normal intracranial pressure and lumbar cerebrospinal fluid pressure remain sparsely documented. Intracranial pressure is different from lumbar cerebrospinal fluid pressure. In addition, intracranial pressure differs considerably according to the body position of the patient. Despite this, the current reference values do not distinguish between intracranial and lumbar cerebrospinal fluid pressures, and body position-dependent reference values do not exist. In this study, we aim to establish these reference values.

METHOD

A systematic search was conducted in MEDLINE, EMBASE, CENTRAL, and Web of Sciences. Methodological quality was assessed using an amended version of the Joanna Briggs Quality Appraisal Checklist. Intracranial pressure and lumbar cerebrospinal fluid pressure were independently evaluated and subdivided into body positions. Quantitative data were presented with mean ± SD, and 90% reference intervals.

RESULTS

Thirty-six studies were included. Nine studies reported values for intracranial pressure, while 27 reported values for the lumbar cerebrospinal fluid pressure. Reference values for intracranial pressure were -  5.9 to 8.3 mmHg in the upright position and 0.9 to 16.3 mmHg in the supine position. Reference values for lumbar cerebrospinal fluid pressure were 7.2 to 16.8 mmHg and 5.7 to 15.5 mmHg in the lateral recumbent position and supine position, respectively.

CONCLUSIONS

This systematic review is the first to provide position-dependent reference values for intracranial pressure and lumbar cerebrospinal fluid pressure. Clinically applicable reference values for normal lumbar cerebrospinal fluid pressure were established, and are in accordance with previously used reference values. For intracranial pressure, this study strongly emphasizes the scarcity of normal pressure measures, and highlights the need for further research on the matter.

BIIB093 (intravenous glibenclamide) for the prevention of severe cerebral edema

Background:

Vasogenic edema in the setting of acute ischemic stroke can be attributed to the opening of transient receptor potential 4 channels, which are expressed in the setting of injury and regulated by sulfonylurea receptor 1 (SUR1) proteins. Glibenclamide, also known as glyburide, RP-1127, Cirara, and BIIB093, is a second-generation sulfonylurea that binds SUR1 at potassium channels and may significantly reduce cerebral edema following stroke, as evidenced by recent clinical trials. This review provides a comprehensive analysis of clinical considerations of glibenclamide use and current patient outcomes when administered in the setting of acute ischemic stroke to reduce severe edema.

Methods:

National databases (MEDLINE, EMBASE, Cochrane, and Google scholar databases) were searched to identify studies that reported on the clinical outcomes of glibenclamide administered immediately following acute ischemic stroke.

Results:

The pharmacological mechanism of glibenclamide was reviewed in depth as well as the known indications and contraindications to receiving treatment. Eight studies were identified as having meaningful clinical outcome data, finding statistically significant differences in glibenclamide treatment groups ranging from matrix metalloproteinase-9 serum levels, midline shift, modified Rankin Scores, National Institute of Health Stroke Score, and mortality endpoints.

Conclusion:

Studies analyzing the GAMES-Pilot and GAMES-PR trials suggest that glibenclamide has a moderate, however, measurable effect on intermediate biomarkers and clinical endpoints. Meaningful conclusions are limited by the small sample size of patients studied.

Improved spatial memory, neurobehavioral outcomes, and neuroprotective effect after progesterone administration in ovariectomized rats with traumatic brain injury: Role of RU486 progesterone receptor antagonist

OBJECTIVES

The contribution of classic progesterone receptors (PR) in interceding the neuroprotective efficacy of progesterone (P4) on the prevention of brain edema and long-time behavioral disturbances was assessed in traumatic brain injury (TBI).

MATERIALS AND METHODS

Female Wistar rats were ovariectomized and apportioned into 6 groups: sham, TBI, oil, P4, vehicle, and RU486. P4 or oil was injected following TBI. The antagonist of PR (RU486) or DMSO was administered before TBI. The brain edema and destruction of the blood-brain barrier (BBB) were determined. Intracranial pressure (ICP), cerebral perfusion pressure (CPP), and beam walk (BW) task were evaluated previously and at various times post-trauma. Long-time locomotor and cognitive consequences were measured one day before and on days 3, 7, 14, and 21 after the trauma.

RESULTS

RU486 eliminated the inhibitory effects of P4 on brain edema and BBB leakage (P<0.05, P<0.001, respectively). RU486 inhibited the decremental effect of P4 on ICP as well as the increasing effect of P4 on CPP (P<0.001) after TBI. Also, RU486 inhibited the effect of P4 on the increase in traversal time and reduction in vestibulomotor score in the BW task (P<0.001). TBI induced motor, cognitive, and anxiety-like disorders, which lasted for 3 weeks after TBI; but, P4 prevented these cognitive and behavioral abnormalities (P<0.05), and RU486 opposed this P4 effect (P<0.001).

CONCLUSION

The classic progesterone receptors have neuroprotective effects and prevent long-time behavioral and memory deficiency after brain trauma.

Challenges of Delirium Management in Patients with Traumatic Brain Injury: From Pathophysiology to Clinical Practice

Traumatic brain injury (TBI) can initiate a very complex disease of the central nervous system (CNS), starting with the primary pathology of the inciting trauma and subsequent inflammatory and CNS tissue response. Delirium has long been regarded as an almost inevitable consequence of moderate to severe TBI, but more recently has been recognized as an organ dysfunction syndrome with potentially mitigating interventions. The diagnosis of delirium is independently associated with prolonged hospitalization, increased mortality and worse cognitive outcome across critically ill populations. Investigation of the unique problems and management challenges of TBI patients is needed to reduce the burden of delirium in this population. In this narrative review, possible etiologic mechanisms behind post-traumatic delirium are discussed, including primary injury to structures mediating arousal and attention and secondary injury due to progressive inflammatory destruction of the brain parenchyma. Other potential etiologic contributors include dysregulation of neurotransmission due to intravenous sedatives, seizures, organ failure, sleep cycle disruption or other delirium risk factors. Delirium screening can be accomplished in TBI patients and the presence of delirium portends worse outcomes. There is evidence that multi-component care bundles including an analgesia-prioritized sedation algorithm, regular spontaneous awakening and breathing trials, protocolized delirium assessment, early mobility and family engagement can reduce the burden of ICU delirium. The aim of this review is to summarize the approach to delirium in TBI patients with an emphasis on pathogenesis and management. Emerging CNS-active drug therapies that show promise in preclinical studies are highlighted.

Telemetric intracranial pressure monitoring: our experience with 22 patients investigated for intracranial hypertension

INTRODUCTION

We present the application of the Raumedic^® P-tel telemetric device that monitors Intracranial Pressure (ICP) over long periods, in 22 patients, with suspected intracranial hypertension.

METHODS

A telemetric device (Raumedic^®, Neurovent^® P-tel) was surgically implanted in 22 patients aged between 21 and 65 years. Among the patients, the inconclusive diagnosis of benign intracranial hypertension was set in 10, the possible diagnosis of postoperative hydrocephalus in 3, and the possible diagnosis of aqueduct stenosis in 2. Additionally, shunt malfunction and Normal Pressure Hydrocephalus (NPH) were investigated in 1 and 3 patients, respectively. Finally, 3 patients presented ventricular dilatation of unknown origin. All the individuals underwent a 3-day ICP recording within the nursing unit. Three more recordings were obtained over a period of 2-6 months at the outpatient base.

RESULTS

Analysis of the data excluded the diagnosis of intracranial hypertension in 12 patients. Elevated ICP values were confirmed in 10 patients. Subsequently, 7 of them underwent shunts' implantation, while 2 refused further neurosurgical treatment and 1 was treated with acetazolamide. Additionally, 1 patient who demonstrated normal ICP values, thus confirmed with NPH, underwent VP shunt implantation, while another 2 with similar characteristics refused further surgery. In our series the overall clinical complication rate after P-tel implantation was insignificant.

CONCLUSIONS

The telemetric device is safely implanted via a rather simple procedure. In selected patients, it could provide long-term ICP recordings, which are necessary to confirm diagnosis and guide to the appropriate treatment.

Changes in intracranial pressure and pulse wave amplitude during postural shifts

BACKGROUND

Monitoring of intracranial pressure (ICP) and ICP pulse wave amplitude (PWA) is an integrated part of neurosurgery. An increase in ICP usually leads to an increase in PWA. These findings have yet to be replicated during the positional shift from supine to upright, where we only know that ICP decreases. Our main aim is to clarify whether the positional shift also results in a change in pulse wave amplitude.

METHOD

Our database was retrospectively reviewed for subjects having had a standardized investigation of positional ICP. In all subjects, mean ICP and PWA were determined with both an automatic and a manual method and compared using Student's t test. Finally, ICP and PWA were tested for correlation in both in supine and upright position.

RESULTS

The study included 29 subjects. A significant change in ICP (Δ14.1 mmHg, p < 0.01) and no significant change in PWA (Δ0.4 mmHg, p = 0.06) were found. Furthermore, a linear correlation between ICP and PWA was found in both supine and upright positions (p < 0.01).

CONCLUSIONS

We found that during the positional shift from supine to upright, ICP is reduced while PWA remains unaffected. This indicates that the pressure-volume curve is shifted downward according to a hydrostatic pressure offset, while the slope of the curve does not change. In addition, the correlation between ICP and PWA in both supine and upright position validates the previous research on the matter.

Fluctuations in intracranial pressure can be estimated non-invasively using near-infrared spectroscopy in non-human primates

Intracranial pressure (ICP) is typically measured invasively through a sensor placed inside the brain or a needle inserted into the spinal canal, limiting the patient population on which this assessment can be performed. Currently, non-invasive methods are limited due to lack of sensitivity and thus only apply to extreme cases of increased ICP, instead of use in general clinical practice. We demonstrate a novel application for near-infrared spectroscopy (NIRS) to accurately estimate ICP changes over time. Using a non-human primate (Rhesus Macaque) model, we collected optical data while we induced ICP oscillations at multiple ICP levels obtained by manipulating the height of a fluid column connected via a catheter to the lateral ventricle. Hemodynamic responses to ICP changes were measured at the occipital pole and compared to changes detected by a conventional intraparenchymal ICP probe. We demonstrate that hemoglobin concentrations are highly correlated with induced ICP oscillations and that this response is frequency dependent. We translated the NIRS data into non-invasive ICP measurements via a fitted non-parametric transfer function, demonstrating a match in both magnitude and time alignment with an invasively measured reference. Our results demonstrate that NIRS has the potential for non-invasive ICP monitoring.

Current status and outlook for the management of intracranial hypertension after traumatic brain injury: decompressive craniectomy, therapeutic hypothermia, and barbiturates

INTRODUCTION

Increased intracranial pressure has been associated with poor neurological outcomes and increased mortality in patients with severe traumatic brain injury. Traditionally, intracranial pressure-lowering therapies are administered using an escalating approach, with more aggressive options reserved for patients showing no response to first-tier interventions, or with refractory intracranial hypertension.

DEVELOPMENT

The therapeutic value and the appropriate timing for the use of rescue treatments for intracranial hypertension have been a subject of constant debate in literature. In this review, we discuss the main management options for refractory intracranial hypertension after severe traumatic brain injury in adults. We intend to conduct an in-depth revision of the most representative randomised controlled trials on the different rescue treatments, including decompressive craniectomy, therapeutic hypothermia, and barbiturates. We also discuss future perspectives for these management options.

CONCLUSIONS

The available evidence appears to show that mortality can be reduced when rescue interventions are used as last-tier therapy; however, this benefit comes at the cost of severe disability. The decision of whether to perform these interventions should always be patient-centred and made on an individual basis. The development and integration of different physiological variables through multimodality monitoring is of the utmost importance to provide more robust prognostic information to patients facing these challenging decisions.

Repeatability of ultrasound examination of the optic nerve sheath diameter in the adult cat: comparison between healthy cats and cats suffering from presumed intracranial hypertension

OBJECTIVES

The objectives of this study were to test: (1) the repeatability of ultrasonographic examination of the optic nerve sheath diameter (ONSD) in the cat; (2) the association between the ONSD and age, sex and body weight in healthy cats; and (3) the difference in the ONSD between healthy cats and those suffering from presumed intracranial hypertension (ICH).

METHODS

This study had a prospective, blinded, observational cross-sectional study design. Two groups of animals were considered: healthy cats (group A) and cats with a diagnosis of presumed ICH (group B). The ONSD was evaluated, measured and compared between the two groups via an ultrasonographic transpalpebral approach. Repeatability of the procedure was evaluated through the intraclass correlation coefficient (ICC). Data were statistically compared using the Student's t-test and linear regression analysis.

RESULTS

A strong inter- and intraobserver ICC indicating good repeatability was observed. The interobserver ICC was 0.965 (P  <0.05) for the right eye and 0.956 (P  <0.05) for the left eye. The intraobserver ICC was 0.988 (P  <0.05) and 0.984 (P  <0.05) for the right and left eyes, respectively. In healthy cats the mean ± SD ONSD was 1.23 ± 0.11 mm (range 1-1.47 mm) and 1.23 ± 0.10 (range 1-1.4 mm) for right and left eyes, respectively. The ONSD was not related to sex or weight; a weak relationship was observed with age. In group B, the mean ONSD was 1.68 ± 0.13 mm (range 1.5-1.9 mm) and 1.61 ± 0.15 mm (range 1.4-1.9 mm) for the right and left eyes, respectively. In group B, the ONSD was statistically significantly larger than in group A, the healthy cats (P  <0.001).

CONCLUSIONS AND RELEVANCE

The transpalpebral ultrasonographic technique is a non-invasive, feasible and reproducible method to measure ONSD both in healthy cats and in cats suffering from suspected ICH.

A Power-Efficient Bridge Readout Circuit for Implantable, Wearable, and IoT Applications

A power-efficient bridge-to-digital sensing interface is proposed, which also offers immunity against power supply noise. The interface utilizes duty-cycling to reduce the static power consumption of resistive bridge sensors, which are commonly used in implantable, wearable, and internet of things (IoT) applications, such as intracranial pressure (ICP) sensing and blood pressure (BP) monitoring. The proposed interface uses a revised version of the pseudo-pseudo differential (PPD) topology with the ping-pong technique to reduce the complexity of traditional fully-differential counterparts. A proof-of-concept prototype has been fabricated in 0.35-μm CMOS and occupies an active area of 0.48 mm2. It achieves 9.13 effective number of bits (ENOB) at 3.72 kHz sampling rate and improvement of more than 50 dB in the power supply rejection ratio (PSRR) by employing the ping-pong technique. It reduces the power consumption of a 5-kΩ Wheatstone bridge by 99.6% compared to a traditional interface, down to 2.53 μw at 1.8 V supply. The functionality of the system has also been demonstrated in an experimental setup in conjunction with an embedded resistive bridge pressure sensor.

Kouzani A, Mosadegh B, Gharaie S. Blood Pressure Sensors: Materials, Fabrication Methods, Performance Evaluations and Future Perspectives

Advancements in materials science and fabrication techniques have contributed to the significant growing attention to a wide variety of sensors for digital healthcare. While the progress in this area is tremendously impressive, few wearable sensors with the capability of real-time blood pressure monitoring are approved for clinical use. One of the key obstacles in the further development of wearable sensors for medical applications is the lack of comprehensive technical evaluation of sensor materials against the expected clinical performance. Here, we present an extensive review and critical analysis of various materials applied in the design and fabrication of wearable sensors. In our unique transdisciplinary approach, we studied the fundamentals of blood pressure and examined its measuring modalities while focusing on their clinical use and sensing principles to identify material functionalities. Then, we carefully reviewed various categories of functional materials utilized in sensor building blocks allowing for comparative analysis of the performance of a wide range of materials throughout the sensor operational-life cycle. Not only this provides essential data to enhance the materials' properties and optimize their performance, but also, it highlights new perspectives and provides suggestions to develop the next generation pressure sensors for clinical use.

Extending existing recommended military casualty evacuation timelines will likely increase morbidity and mortality: a UK consensus statement

INTRODUCTION

Future conflicts may have limited use of aviation-based prehospital emergency care for evacuation. This will increase the likelihood of extended evacuation timelines and an extended hold at a forward hospital care facility following the completion of damage control surgery or acute medical interventions.

METHODS

A three-round Delphi Study was undertaken using a panel comprising 44 experts from the UK armed forces including clinicians, logisticians, medical planners and commanders. The panel was asked to consider the effect of an extended hold at Deployed Hospital Care (Forward) from the current 2-hour timeline to +4, +8, +12 and +24 hours on a broad range of clinical and logistical issues. Where 75% of respondents had the same opinion, consensus was accepted. Areas where consensus could not be achieved were used to identify future research priorities.

RESULTS

Consensus was reached that increasing timelines would increase the personnel, logistics and equipment support required to provide clinical care. There is a tipping point with a prolonged hold over 8 hours, after which the greatest number of clinical concerns emerge. Additional specialties of surgeons other than general and orthopaedic surgeons will likely be required with holds over 24 hours, and robust telemedicine would not negate this requirement.

CONCLUSIONS

Retaining acute medical emergencies at 4 hours, and head injuries was considered a particular risk. This could potentially be mitigated by an increased forward capacity of some elements of medical care and availability of a CT scanner and intracranial pressure monitoring at over 12 hours. Any efforts to mitigate the effects of prolonged timelines will come at the expense of an increased logistical burden and a reduction in mobility. Ultimately the true effect of prolonged timelines can only be answered by close audit and analysis of clinical outcomes during future operations with an extended hold.

Intracranial Pressure Monitoring-Aided Management Associated with Favorable Outcomes in Patients with Hypertension-Related Spontaneous Intracerebral Hemorrhage

To investigate the effect of intracranial pressure (ICP) monitoring on the functional outcome of patients with hypertension-related spontaneous intracerebral hemorrhage (ICH). We included 196 patients with Glasgow Coma Scale (GCS) scores of 3-12 in this observational study, of which 103 underwent ICP monitors. Binary and ordinal regression analyses were used to estimate the effect of ICP monitoring on the functional outcome. The rate of adverse events, blood pressure control, and length of hospitalization were compared between the two groups. ICP monitoring had a significant impact on the clinical outcome of patients by shifting the Extended Glasgow Outcome Scale (GOS-E) scores in a favorable direction (p = 0.027) and reducing mortality at discharge (p = 0.004) and 6 months later (p = 0.02). The rate of favorable outcome at 6 months was higher in the ICP-monitored group (p = 0.03). However, subgroup analysis showed that no relationship between ICP monitoring and clinical outcome was found for patients with GCS scores of 3-8. For patients with GCS scores of 9-12, the distribution of GOS-E scores at 6 months shifted in a favorable direction in the ICP-monitored group (p = 0.001). The rate of favorable outcome at 6 months was higher in the ICP-monitored group (p = 0.01). The mortality at discharge and 6 months later was also lower in the ICP-monitored group. Thus, our study supports the value of ICP monitoring in hypertension-related ICH patients with GCS scores of 3-12, especially those with GCS scores of 9-12.

Estimating intracranial pressure using pulsatile cerebral blood flow measured with diffuse correlation spectroscopy

Measuring intracranial pressure (ICP) is necessary for the treatment of severe head injury but measurement systems are highly invasive and introduce risk of infection and complications. We developed a non-invasive alternative for quantifying ICP using measurements of cerebral blood flow (CBF) by diffuse correlation spectroscopy. The recorded cardiac pulsation waveform in CBF undergoes morphological changes in response to ICP changes. We used the pulse shape to train a randomized regression forest to estimate the underlying ICP and demonstrate in five non-human primates that DCS-based estimation can explain over 90% of the variance in invasively measured ICP.

Evaluation of a New Catheter for Simultaneous Intracranial Pressure Monitoring and Cerebral Spinal Fluid Drainage: A Pilot Study

OBJECTIVES

Intracranial pressure (ICP) monitoring is a common practice when treating intracranial pathology with risk of elevated ICP. External ventricular drain (EVD) insertion is a standard approach for both monitoring ICP and draining cerebrospinal fluid (CSF). However, the conventional EVD cannot serve these two purposes simultaneously because it cannot accurately measure ICP and its pulsatile waveform while the EVD is open to CSF drainage. A new Integra^® Camino^® FLEX Ventricular Catheter (Integra Lifesciences, County Offaly, Ireland) with a double-lumen construction has been recently introduced into the market, and it can monitor ICP waveforms even during CSF drainage. The aim of this study was to evaluate and validate this new FLEX catheter for ICP monitoring in a neurological intensive care unit.

METHODS

Six patients with 34 EVD open/close episodes were retrospectively analyzed. Continuous ICP was detected in two ways: through the FLEX sensor at the tip (ICP_f) and through a fluid-coupled manometer within the FLEX catheter, functioning as a conventional EVD (ICP_e). The morphologies of ICP_f and ICP_e pulses were extracted using Morphological Clustering and Analysis of ICP algorithm, an algorithm that has been validated in previous publications. The mean ICP and waveform shapes of ICP pulses detected through the two systems were compared. Bland-Altman plots were used to assess the agreement of the two systems.

RESULTS

A significant linear relationship existed between mean ICP_f and mean ICP_e, which can be described as: mICP_f = 0.81 × mICP_e + 1.67 (r = 0.79). The Bland-Altman plot revealed that no significant difference existed between the two ICPs (average of [ICP_e-ICP_f] was - 1.69 mmHg, 95% limits of agreement: - 7.94 to 4.56 mmHg). The amplitudes of the landmarks of ICP pulse waveforms from the two systems showed strong, linear relationship (r ranging from 0.89 to 0.94).

CONCLUSIONS

This study compared a new FLEX ventricular catheter with conventional fluid-coupled manometer for ICP waveform monitoring. Strong concordance in ICP value and waveform morphology between the two systems indicates that this catheter can be used for reliability for both clinical and research applications.

Nursing Interventions for Patients with Intracranial Hypertension: Integrative Literature Review

Objective: the study sought to identify, in national and international publications, the principal Nursing interventions aimed at patients with intracranial hypertension. Materials and Method: integrative literature review with search in LILACS, PubMed, Scopus, Web of Science, Cinahal, and Google Scholar databases, from 2013 to 2018. Results: the sample was comprised of seven articles fulfilling the inclusion criteria. Two thematic categories were established for the Nursing interventions aimed at patients with intracranial hypertension: cognitive skills and clinical reasoning, necessary to control neuro-physiological parameters and prevent intracranial hypertension, and evidence-based practices to improve care for neuro-critical patients. Conclusions: intracranial hypertension is an event of great clinical impact, whose complications can be minimized and control through specific Nursing interventions that encompass control of neuro-physiological and hemodynamic parameters and prevention of increased intracranial pressure related with the performance of procedures by the Nursing staff.