Risk factors and complications of intracranial pressure monitoring with a fiberoptic device

Complications of Intracranial Multimodal Monitoring for Neurocritical Care: A Systematic Review and Meta-Analysis

Intracranial multimodal monitoring (iMMM) is increasingly used for neurocritical care. However, concerns arise regarding iMMM invasiveness considering limited evidence in its clinical significance and safety profile. We conducted a synthesis of evidence regarding complications associated with iMMM to delineate its safety profile. We performed a systematic review and meta-analysis (PROSPERO Registration Number: CRD42021225951) according to the Preferred Reporting Items for Systematic Review and Meta-Analysis and Peer Review of Electronic Search Strategies guidelines to retrieve evidence from studies reporting iMMM use in humans that mention related complications. We assessed risk of bias using the Newcastle-Ottawa Scale and funnel plots. The primary outcomes were iMMM complications. The secondary outcomes were putative risk factors. Of the 366 screened articles, 60 met the initial criteria and were further assessed by full-text reading. We included 22 studies involving 1206 patients and 1434 iMMM placements. Most investigators used a bolt system (85.9%) and a three-lumen device (68.8%), mainly inserting iMMM into the most injured hemisphere (77.9%). A total of 54 postoperative intracranial hemorrhages (pooled rate of 4%; 95% confidence interval [CI] 0-10%; I2 86%, p < 0.01 [random-effects model]) was reported, along with 46 misplacements (pooled rate of 6%; 95% CI 1-12%; I2 78%, p < 0.01) and 16 central nervous system infections (pooled rate of 0.43%; 95% CI 0-2%; I2 64%, p < 0.01). We found 6 system breakings, 18 intracranial bone fragments, and 5 cases of pneumocephalus. Currently, iMMM systems present a similar safety profile as intracranial devices commonly used in neurocritical care. Long-term outcomes of prospective studies will complete the benefit-risk assessment of iMMM in neurocritical care. Consensus-based reporting guidelines on iMMM use are needed to bolster future collaborative efforts.

A Neuro-Ophthalmologist's Guide to Advances in Intracranial Pressure Measurements

Cerebrospinal fluid disorders have a wide-ranging impact on vision, headache, cognition and a person's quality of life. Due to advances in technology and accessibility, intracranial pressure measurement and monitoring, usually managed by neurosurgeons, are being employed more widely in clinical practice. These developments are of direct importance for Ophthalmologists and Neurologists because the ability to readily measure intracranial pressure can aide management decisions. The aim of this review is to present the emerging evidence for intracranial pressure measurement methods and interpretation that is relevant to Neuro-ophthalmologists.

Electrical bioimpedance measurement and near-infrared spectroscopy in pediatric postoperative neurocritical care: a prospective observational study

Background

To investigate the clinical significance of the disturbance coefficient (DC) and regional cerebral oxygen saturation (rSO₂) as obtained through the use of electrical bioimpedance and near-infrared spectroscopy (NIRS) in pediatric neurocritical care.

Participants and methods

We enrolled 45 pediatric patients as the injury group and 70 healthy children as the control group. DC was derived from impedance analysis of 0.1 mA-50 kHz current via temporal electrodes. rSO₂ was the percentage of oxyhemoglobin measured from reflected NIR light on the forehead. DC and rSO₂ were obtained at 6, 12, 24, 48 and 72 h after surgery for the injury group and during the health screening clinic visit for the control group. We compared DC and rSO₂ between the groups, their changes over time within the injury group and their correlation with intracranial pressure (ICP), cerebral perfusion pressure (CPP), Glasgow coma scale (GCS) score, Glasgow outcome scale (GOS) score, and their ability to diagnose postoperative cerebral edema and predict poor prognosis.

Results

DC and rSO₂ were significantly lower in the injury group than in the control group. In the injury group, ICP increased over the monitoring period, while DC, CPP and rSO₂ decreased. DC was negatively correlated with ICP and positively correlated with GCS score and GOS score. Additionally, lower DC values were observed in patients with signs of cerebral edema, with a DC value of 86.5 or below suggesting the presence of brain edema in patients aged 6-16 years. On the other hand, rSO₂ was positively correlated with CPP, GCS score, and GOS score, with a value of 64.4% or below indicating a poor prognosis. Decreased CPP is an independent risk factor for decreased rSO₂.

Conclusion

DC and rSO₂ monitoring based on electrical bioimpedance and near-infrared spectroscopy not only reflect the degree of brain edema and oxygenation, but also reflect the severity of the disease and predict the prognosis of the patients. This approach offers a real-time, bedside, and accurate method for assessing brain function and detecting postoperative cerebral edema and poor prognosis.

Estimation of Physiologic Pressures: Invasive and Non-Invasive Techniques, AI Models, and Future Perspectives

The measurement of physiologic pressure helps diagnose and prevent associated health complications. From typical conventional methods to more complicated modalities, such as the estimation of intracranial pressures, numerous invasive and noninvasive tools that provide us with insight into daily physiology and aid in understanding pathology are within our grasp. Currently, our standards for estimating vital pressures, including continuous BP measurements, pulmonary capillary wedge pressures, and hepatic portal gradients, involve the use of invasive modalities. As an emerging field in medical technology, artificial intelligence (AI) has been incorporated into analyzing and predicting patterns of physiologic pressures. AI has been used to construct models that have clinical applicability both in hospital settings and at-home settings for ease of use for patients. Studies applying AI to each of these compartmental pressures were searched and shortlisted for thorough assessment and review. There are several AI-based innovations in noninvasive blood pressure estimation based on imaging, auscultation, oscillometry and wearable technology employing biosignals. The purpose of this review is to provide an in-depth assessment of the involved physiologies, prevailing methodologies and emerging technologies incorporating AI in clinical practice for each type of compartmental pressure measurement. We also bring to the forefront AI-based noninvasive estimation techniques for physiologic pressure based on microwave systems that have promising potential for clinical practice.

Can a new noninvasive method for assessment of intracranial pressure predict intracranial hypertension and prognosis?

PURPOSE

Individuals with TBI are at risk of intracranial hypertension (ICH), and monitoring of intracranial pressure (ICP) is usually indicated. However, despite many new noninvasive devices, none is sufficiently accurate and effective for application in clinical practice, particularly in the management of TBIs. This study aimed to compare the noninvasive Brain4Care system (nICP) with invasive ICP (iICP) curve parameters in their ability to predict ICH and functional prognosis in severe TBI.

METHODS

Observational, descriptive-analytical, and prospective study of 22 patients between 2018 and 2021, simultaneously monitored with nICP and iICP. The independent variables evaluated were the presence of ICH and functional prognoses. The dependent variables were the P2/P1 pressure ratio metrics, time to peak (TTP), and TTP × P2/P1.

RESULTS

We found a good nonlinear correlation between iICP and nICP waveforms, despite a moderate Pearson's linear correlation. The noninvasive parameters of P2/P1, P2/P1 × TTP, and TTP were not associated with outcomes or ICH. The nICP P2/P1 ratio showed sensitivity/specificity/accuracy (%) of 100/0/56.3, respectively for 1-month outcomes and 77.8/22.2/50 for 6-month outcomes. The nICP TTP ratio had values of 100/0/56.3 for 1-month and 99.9/42.9/72.2 for 6-month outcomes. The nICP P2/P1 × TTP values were 100/0/56.3 for 1-month outcomes and 81.8/28.6/61.1 for 6-month outcomes.

CONCLUSION

Brain4Care's noninvasive method showed low specificity and accuracy and cannot be used as the sole means of monitoring ICP in patients with severe TBI. Future studies with a larger sample of patients with P2 > P1 and new nICP curve parameters are warranted.

Accuracy of Intracranial Pressure Monitoring-Single Centre Observational Study and Literature Review

Intracranial hypertension and adequacy of brain blood flow are primary concerns following traumatic brain injury. Intracranial pressure (ICP) monitoring is a critical diagnostic tool in neurocritical care. However, all ICP sensors, irrespective of design, are subject to systematic and random measurement inaccuracies that can affect patient care if overlooked or disregarded. The wide choice of sensors available to surgeons raises questions about performance and suitability for treatment. This observational study offers a critical review of the clinical and experimental assessment of ICP sensor accuracy and comments on the relationship between actual clinical performance, bench testing, and manufacturer specifications. Critically, on this basis, the study offers guidelines for the selection of ICP monitoring technologies, an important clinical decision. To complement this, a literature review on important ICP monitoring considerations was included. This study utilises illustrative clinical and laboratory material from 1200 TBI patients (collected from 1992 to 2019) to present several important points regarding the accuracy of in vivo implementation of contemporary ICP transducers. In addition, a thorough literature search was performed, with sources dating from 1960 to 2021. Sources considered to be relevant matched the keywords: "intraparenchymal ICP sensors", "fiberoptic ICP sensors", "piezoelectric strain gauge sensors", "external ventricular drains", "CSF reference pressure", "ICP zero drift", and "ICP measurement accuracy". Based on single centre observations and the 76 sources reviewed in this paper, this material reports an overall anticipated measurement accuracy for intraparenchymal transducers of around ± 6.0 mm Hg with an average zero drift of <2.0 mm Hg. Precise ICP monitoring is a key tenet of neurocritical care, and accounting for zero drift is vital. Intraparenchymal piezoelectric strain gauge sensors are commonly implanted to monitor ICP. Laboratory bench testing results can differ from in vivo observations, revealing the shortcomings of current ICP sensors.

Fiber-Optic Intracranial Pressure Monitoring System Using Wi-Fi-An In Vivo Study

BACKGROUND

Continuous invasive monitoring of intracranial pressure (ICP) is essential in neurocritical care for surveillance and management of raised ICP. Fluid-based systems and strain gauge microsensors remain the current standard. In the past few decades, several studies with wireless monitoring were developed aiming to reduce invasiveness and complications.

OBJECTIVE

To describe a novel Wi-Fi fiber-optic device for continuous ICP monitoring using smartphone in a swine model.

METHODS

Two ICP sensors (wireless prototype and wire-based reference) were implanted in the cerebral parenchyma of a swine model for a total of 120 minutes of continuous monitoring. Every 5 minutes, jugular veins compression was performed to evaluate ICP changes. The experimentation was divided in 3 phases for comparison and analysis.

RESULTS

Phase 1 showed agreement in ICP changes for both sensors during jugular compression and releasing, with a positive and strong Spearman correlation (r = 0.829, P < .001). Phase 2 started after inversion of the sensors in the burr holes; there was a positive and moderately weak Spearman correlation (r = 0.262, P < .001). For phase 3, the sensors were returned to the first burr holes; the prototype behaved similarly to the reference sensor, presenting a positive and moderately strong Spearman correlation (r = 0.669, P < .001).

CONCLUSION

A Wi-Fi ICP monitoring system was demonstrated in a comprehensive and feasible way. It was possible to observe, using smartphone, an adequate correlation regarding ICP variations. Further adaptations are already being developed.

Postprocedural Complications of External Ventricular Drains: A Meta-Analysis Evaluating the Absolute Risk of Hemorrhages, Infections, and Revisions

BACKGROUND

External ventricular drain (EVD) insertion is often a lifesaving procedure frequently used in neurosurgical emergencies. It is routinely done at the bedside in the neurocritical care unit or in the emergency room. However, there are infectious and noninfectious complications associated with this procedure. This meta-analysis sought to evaluate the absolute risk associated with EVD hemorrhages, infections, and revisions. The secondary purpose was to identify and characterize risk factors for EVD complications.

METHODS

We searched the MEDLINE (PubMed) database for "external ventricular drain," "external ventricular drain" + "complications" or "Hemorrhage" or "Infection" or "Revision" irrespective of publication year. Estimates from individual studies were combined using a random effects model, and 95% confidence intervals (CIs) were calculated with maximum likelihood specification. To investigate heterogeneity, the t2 and I2 tests were utilized. To evaluate for publication bias, a funnel plot was developed.

RESULTS

There were 260 total studies screened from our PubMed literature database search, with 176 studies selected for full-text review, and all of these 176 studies were included in the meta-analysis as they met the inclusion criteria. A total of 132,128 EVD insertions were reported, with a total of 130,609 participants having at least one EVD inserted. The pooled absolute risk (risk difference) and percentage of the total variability due to true heterogeneity (I2) for hemorrhagic complication was 1236/10,203 (risk difference: -0.63; 95% CI: -0.66 to -0.60; I2: 97.8%), infectious complication was 7278/125,909 (risk difference: -0.65; 95% CI: -0.67 to -0.64; I2: 99.7%), and EVD revision was 674/4416 (risk difference: -0.58; 95% CI: -0.65 to -0.51; I2: 98.5%). On funnel plot analysis, we had a variety of symmetrical plots, and asymmetrical plots, suggesting no bias in larger studies, and the lack of positive effects/methodological quality in smaller studies.

CONCLUSIONS

In conclusion, these findings provide valuable information regarding the safety of one of the most important and most common neurosurgical procedures, EVD insertion. Implementing best-practice standards is recommended in order to reduce EVD-related complications. There is a need for more in-depth research into the independent risk factors associated with these complications, as well as confirmation of these findings by well-structured prospective studies.

Optic nerve sheath diameter, intensive care unit admission and COVID-19-related-in-hospital mortality

BACKGROUND

Hypoxia and hypercapnia due to acute pulmonary failure in patients with coronavirus disease 2019 (COVID-19) can increase the intracranial pressure (ICP). ICP correlated with the optic nerve sheath diameter (ONSD) on ultrasonography and is associated with a poor prognosis.

AIM

We investigated the capability of ONSD measured during admission to the intensive care unit (ICU) in patients with critical COVID-19 in predicting in-hospital mortality.

METHODS

A total of 91 patients enrolled in the study were divided into two groups: survivor (n = 48) and nonsurvivor (n = 43) groups. ONSD was measured by ultrasonography within the first 3 h of ICU admission.

RESULTS

The median ONSD was higher in the nonsurvivor group than in the survivor group (5.95 mm vs. 4.15 mm, P < 0.001). The multivariate Cox proportional hazard regression analysis between ONSD and in-hospital mortality (contains 26 covariates) was significant (adjusted hazard ratio, 4.12; 95% confidence interval, 1.46-11.55; P = 0.007). The ONSD cutoff for predicting mortality during ICU admission was 5 mm (area under the curve, 0.985; sensitivity, 98%; and specificity, 90%). The median survival of patients with ONSD >5 mm (43%; n = 39) was lower than those with ONSD ≤5 mm (57%; n = 52) (11.5 days vs. 13.2 days; log-rank test P = 0.001).

CONCLUSIONS

ONSD ultrasonography during ICU admission may be an important, cheap and easy-to-apply method that can be used to predict mortality in the early period in patients with critical COVID-19.

Non-Invasive Assessment of Intracranial Hypertension in Patients with Traumatic Brain Injury Using Computed Tomography Radiomic Features: A Pilot Study

This study aimed to assess intracranial hypertension in patients with traumatic brain injury non-invasively using computed tomography (CT) radiomic features. Fifty patients from the primary cohort were enrolled in this study. The clinical data, pre-operative cranial CT images, and initial intracranial pressure readings were collected and used to develop a prediction model. Data of 20 patients from another hospital were used to validate the model. Clinical features including age, sex, midline shift, basilar cistern status, and ventriculocranial ratio were measured. Radiomic features-i.e., 18 first-order and 40 second-order features- were extracted from the CT images. LASSO method was used for features filtration. Multi-variate logistic regression was used to develop three prediction models with clinical (CF model), first-order (FO model), and second-order features (SO model). The SO model achieved the most robust ability to predict intracranial hypertension. Internal validation showed that the C-statistic of the model was 0.811 (95% confidence interval [CI]: 0.691-0.931) with the bootstrapping method. The Hosmer Lemeshow test and calibration curve also showed that the SO model had excellent performance. The external validation results showed a good discrimination with an area under the curve of 0.725 (95% CI: 0.500-0.951). Although the FO model was inferior to the SO model, it had better prediction ability than the CF model. The study shows that the radiomic features analysis, especially second-order features, can be used to evaluate intracranial hypertension non-invasively compared with conventional clinical features, given its potential for clinical practice and further research.

Theory for a non-invasive diagnostic biomarker for craniospinal diseases

Monitoring intracranial pressure (ICP) and craniospinal compliance (CC) is frequently required in the treatment of patients suffering from craniospinal diseases. However, current approaches are invasive and cannot provide continuous monitoring of CC. Dynamic exchange of blood and cerebrospinal fluid (CSF) between cranial and spinal compartments due to cardiac action transiently modulates the geometry and dielectric properties of the brain. The resulting impedance changes can be measured and might be usable as a non-invasive CC surrogate. A numerically robust and computationally efficient approach based on the reciprocity theorem was developed to compute dynamic impedance changes resulting from small geometry and material property changes. The approach was successfully verified against semi-analytical benchmarks, before being combined with experimental brain pulsation data to study the information content of the impedance variation. The results indicate that the measurable signal is dominated by the pulsatile displacement of the cortical brain surface, with minor contributions from the ventricular surfaces and from changes in brain perfusion. Different electrode setups result in complementary information. The information content from the investigated three electrode pairs was employed to successfully infer subject-specific brain pulsation and motion features. This suggests that non-invasive CC surrogates based on impedance monitoring could be established.

The Impact of Nursing Education on Emergency Bedside External Ventricular Drain Insertion for Patients With Acute Hydrocephalus

Objectives Acute hydrocephalus is a neurosurgical emergency that requires immediate intervention. With emergency external ventricular drain (EVD) insertion and management, such rapid intervention can be a safe bedside procedure. Nurses play an integral role in patient management. Thus, this study aims to assess the knowledge, attitudes, and practices of nurses from different departments regarding bedside EVD insertion in patients with acute hydrocephalus. Methods EVD and intracranial pressure (ICP) monitoring competency checklists were developed, and a quasi-experimental, single-group, pre/post-test study was conducted at a university hospital in Jeddah, Saudi Arabia, in January 2018 during an educational program. The neurosurgery team determined program efficacy using pre/post-questionnaires. All attendees who agreed to fill in the pre- and post-survey and whose data were complete were included in the study. Results Of the 140 nurses who participated in the study, the data of 101 were analyzed. Knowledge level improved significantly between the pre- and post-test; for example, when asked about administering antibiotics before EVD insertion, the pre-test correct response rate of 65% increased to 94% in the post-test (p<0.001), and 98% considered the session informative. However, the attitude toward bedside EVD insertion did not change after the teaching sessions. Conclusion This study emphasizes the importance of ongoing nursing education, hands-on training, and strict adherence to an EVD insertion checklist to achieve successful bedside management of patients with acute hydrocephalus.

Optic Nerve Sheath Diameter Ultrasound: A Non-Invasive Approach to Evaluate Increased Intracranial Pressure in Critically Ill Pediatric Patients

Early diagnosis of increased intracranial pressure (ICP) is crucial for prompt diagnosis and treatment of intracranial hypertension in critically ill pediatric patients, preventing secondary brain damage and mortality. Although the placement of an external ventricular drain coupled to an external fluid-filled transducer remains the gold standard for continuous ICP monitoring, other non-invasive approaches are constantly being improved and can provide reliable estimates. The use of point-of-care ultrasound (POCUS) for the assessment of ICP has recently become widespread in pediatric emergency and critical care settings, representing a valuable extension of the physical examination. The aim of this manuscript is to review and discuss the basic principles of ultra-sound measurement of the optic nerve sheath diameter (ONSD) and summarize current evidence on its diagnostic value in pediatric patients with ICP. There is increasing evidence that POCUS measurement of the ONSD correlates with ICP, thus appearing as a useful extension of the physical examination in pediatrics, especially in emergency medicine and critical care settings for the initial non-invasive assessment of patients with suspected raised ICP. Its role could be of value even to assess the response to therapy and in the follow-up of patients with diagnosed intracranial hypertension if invasive ICP monitoring is not available. Further studies on more homogeneous and extensive study populations should be performed to establish ONSD reference ranges in the different pediatric ages and to define cut-off values in predicting elevated ICP compared to invasive ICP measurement.

Pulsatile tympanic membrane displacement is associated with cognitive score in healthy subjects

To test the hypothesis that pulsing of intracranial pressure has an association with cognition, we measured cognitive score and pulsing of the tympanic membrane in 290 healthy subjects. This hypothesis was formed on the assumptions that large intracranial pressure pulses impair cognitive performance and tympanic membrane pulses reflect intracranial pressure pulses. 290 healthy subjects, aged 20-80 years, completed the Montreal Cognitive Assessment Test. Spontaneous tympanic membrane displacement during a heart cycle was measured from both ears in the sitting and supine position. We applied multiple linear regression, correcting for age, heart rate, and height, to test for an association between cognitive score and spontaneous tympanic membrane displacement. Significance was set at P < 0.0125 (Bonferroni correction.) A significant association was seen in the left supine position (p = 0.0076.) The association was not significant in the right ear supine (p = 0.28) or in either ear while sitting. Sub-domains of the cognitive assessment revealed that executive function, language and memory have been primarily responsible for this association. In conclusion, we have found that spontaneous pulses of the tympanic membrane are associated with cognitive performance and believe this reflects an association between cognitive performance and intracranial pressure pulses.

A Novel Noninvasive Technique for Intracranial Pressure Waveform Monitoring in Critical Care

BACKGROUND

We validated a new noninvasive tool (B4C) to assess intracranial pressure waveform (ICPW) morphology in a set of neurocritical patients, correlating the data with ICPW obtained from invasive catheter monitoring.

MATERIALS AND METHODS

Patients undergoing invasive intracranial pressure (ICP) monitoring were consecutively evaluated using the B4C sensor. Ultrasound-guided manual internal jugular vein (IJV) compression was performed to elevate ICP from the baseline. ICP values, amplitudes, and time intervals (P2/P1 ratio and time-to-peak [TTP]) between the ICP and B4C waveform peaks were analyzed.

RESULTS

Among 41 patients, the main causes for ICP monitoring included traumatic brain injury, subarachnoid hemorrhage, and stroke. Bland-Altman's plot indicated agreement between the ICPW parameters obtained using both techniques. The strongest Pearson's correlation for P2/P1 and TTP was observed among patients with no cranial damage (r = 0.72 and 0.85, respectively) to the detriment of those who have undergone craniotomies or craniectomies. P2/P1 values of 1 were equivalent between the two techniques (area under the receiver operator curve [AUROC], 0.9) whereas B4C cut-off 1.2 was predictive of intracranial hypertension (AUROC 0.9, p < 000.1 for ICP > 20 mmHg).

CONCLUSION

B4C provided biometric amplitude ratios correlated with ICPW variation morphology and is useful for noninvasive critical care monitoring.

Noninvasive intracranial pressure monitoring methods: a critical review

BACKGROUND

Intracranial pressure (ICP) monitoring has been used for decades in management of various neurological conditions. The gold standard for measuring ICP is a ventricular catheter connected to an external strain gauge, which is an invasive system associated with a number of complications. Despite its limitations, no noninvasive ICP monitoring (niICP) method fulfilling the technical requirements for replacing invasive techniques has yet been developed, not even in cases requiring only ICP monitoring without cerebrospinal fluid (CSF) drainage.

OBJECTIVES

Here, we review the current methods for niICP monitoring.

METHODS

The different methods and approaches were grouped according to the mechanism used for detecting elevated ICP or its associated consequences.

RESULTS

The main approaches reviewed here were: physical examination, brain imaging (magnetic resonance imaging, computed tomography), indirect ICP estimation techniques (fundoscopy, tympanic membrane displacement, skull elasticity, optic nerve sheath ultrasound), cerebral blood flow evaluation (transcranial Doppler, ophthalmic artery Doppler), metabolic changes measurements (near-infrared spectroscopy) and neurophysiological studies (electroencephalogram, visual evoked potential, otoacoustic emissions).

CONCLUSION

In terms of accuracy, reliability and therapeutic options, intraventricular catheter systems still remain the gold standard method. However, with advances in technology, noninvasive monitoring methods have become more relevant. Further evidence is needed before noninvasive methods for ICP monitoring or estimation become a more widespread alternative to invasive techniques.

Novel Algorithm for Automated Optic Nerve Sheath Diameter Measurement Using a Clustering Approach

INTRODUCTION

Using ultrasound to measure optic nerve sheath diameter (ONSD) has been shown to be a useful modality to detect elevated intracranial pressure. However, manual assessment of ONSD by a human operator is cumbersome and prone to human errors. We aimed to develop and test an automated algorithm for ONSD measurement using ultrasound images and compare it to measurements performed by physicians.

MATERIALS AND METHODS

Patients were recruited from the Neurological Intensive Care Unit. Ultrasound images of the optic nerve sheath from both eyes were obtained using an ultrasound unit with an ocular preset. Images were processed by two attending physicians to calculate ONSD manually. The images were processed as well using a novel computerized algorithm that automatically analyzes ultrasound images and calculates ONSD. Algorithm-measured ONSD was compared with manually measured ONSD using multiple statistical measures.

RESULTS

Forty-four patients with an average/Standard Deviation (SD) intracranial pressure of 14 (9.7) mmHg were recruited and tested (with a range between 1 and 57 mmHg). A t-test showed no statistical difference between the ONSD from left and right eyes (P > 0.05). Furthermore, a paired t-test showed no significant difference between the manually and algorithm-measured ONSD with a mean difference (SD) of 0.012 (0.046) cm (P > 0.05) and percentage error of difference of 6.43% (P = 0.15). Agreement between the two operators was highly correlated (interclass correlation coefficient = 0.8, P = 0.26). Bland-Altman analysis revealed mean difference (SD) of 0.012 (0.046) (P = 0.303) and limits of agreement between -0.1 and 0.08. Receiver Operator Curve analysis yielded an area under the curve of 0.965 (P < 0.0001) with high sensitivity and specificity.

CONCLUSION

The automated image-analysis algorithm calculates ONSD reliably and with high precision when compared to measurements obtained by expert physicians. The algorithm may have a role in computer-aided decision support systems in acute brain injury.

Blunt and Penetrating Severe Traumatic Brain Injury

Severe traumatic brain injury is a common problem. Current practices focus on the importance of early resuscitation, transfer to high-volume centers, and provider expertise across multiple specialties. In the emergency department, patients should receive urgent intracranial imaging and consideration for tranexamic acid. Close observation in the intensive care unit environment helps identify problems, such as seizure, intracranial pressure crisis, and injury progression. In addition to traditional neurologic examination, patients benefit from use of intracranial monitors. Monitors gather physiologic data on intracranial and cerebral perfusion pressures to help guide therapy. Brain tissue oxygenation monitoring and cerebromicrodialysis show promise in studies.

Real-Time Intraoperative Pressure Monitoring to Avoid Surgically Induced Localized Brain Injury Using a Miniaturized Piezoresistive Pressure Sensor

Neurosurgical procedures often cause damage to the brain tissue at the periphery from surgical manipulations. Especially during retraction, a large amount of pressure could be applied on the brain surface, which can damage it, leading to brain herniation, which can be fatal for patients. To resolve this issue, we have developed a pressure sensor that can be used to monitor the applied pressure during surgery for intraoperative care. This device was tested on a rodent model to create a superficial surgically induced damage profile for three different applied pressures (30, 50, and 70 mmHg) and compared to a standard intracranial pressure monitoring system. Magnetic resonance imaging has been performed after surgical procedures to detect the herniation caused by applied pressure. To evaluate the damage to brain cells and tissue rupture, histological analysis was performed using hematoxylin and eosin staining. A scoring system was developed to understand the severity of the surgically induced brain injury, which will help neurosurgeons to limit the pressure to an optimum point without causing damage.

Assessment of Bacterial Colonization of Intracranial Pressure Transducers: A Prospective Study

OBJECTIVES

Cerebral infections related to the presence of an intraparenchymal intracranial pressure transducer (ICPT) are rare. We assessed the incidence of ICPT-related infections and colonization using culture, molecular biology, and electron microscopy.

METHODS

All consecutive patients in a neurosurgical intensive care unit who had an ICPT inserted between March 2017 and February 2018 were prospectively included. Presence of colonization on the ICPTs was assessed after removal using culture, scanning electron microscopy (SEM), and next-generation sequencing (NGS).

RESULTS

Fifty-three ICPTs (53 patients), indwelling for a median of 4 (range 3-7) days, were studied. Median patient follow-up was 3 months. SEM, microbial culture, and NGS were performed for 91%, 79%, and 72% of ICPTs, respectively; 28 ICPTs (53%) were assessed using all three techniques. No patient developed ICPT-related infection. Microbial cultures were positive for two of the ICPTs (5%); colonization was identified on all ICPTs using NGS and SEM. Mature biofilm was observed on 35/48 (73%) of ICPTs. A median of 10 (8-12) operational taxonomic units were identified for each ICPT, most being of environmental origin. There was no association between biofilm maturity and antimicrobial treatment or duration of ICPT insertion. Antimicrobial treatment was associated with decreased alpha and beta-diversity (p = 0.01).

CONCLUSIONS

We observed no ICPT-related cerebral infections although colonization was identified on all ICPTs using NGS and SEM. Mature biofilm was the main bacterial lifestyle on the ICPTs.

Complications of elective intracranial pressure monitoring in adult hydrocephalus

Continuous invasive monitoring of intracranial pressure (ICP) can be used in the diagnosis and management of various types of chronic cerebrospinal fluid (CSF) circulation disorders, such as hydrocephalus, shunt dysfunction and idiopathic intracranial hypertension. The risk profile and incidence of adverse events of this surgical procedure in this patient population is not well established. We aimed to investigate and describe the risks of ICP monitoring in adult patients with chronic CSF circulation disorders. We analysed 152 patients undergoing continuous ICP monitoring between 2010 and 2019, mainly for idiopathic normal pressure hydrocephalus. The average duration of ICP monitoring was 17 h 51 min. We observed no major adverse events, such as symptomatic intracranial haemorrhage, intracranial infection, or persistent neurological deficit. Minor complications were seen in 7% of patients and included accidental removal of the ICP probe in 4 patients, inability to remove the probe requiring surgical removal in 2 patients and single generalised seizures in 2 patients. In summary, the risk of serious adverse events and complications from invasive ICP monitoring in chronic CSF circulation disorders in adult patients appears to be low.

Intracranial pressure monitoring: Gold standard and recent innovations

Intracranial pressure monitoring (ICP) is based on the doctrine proposed by Monroe and Kellie centuries ago. With the advancement of technology and science, various invasive and non-invasive modalities of monitoring ICP continue to be developed. An ideal monitor to track ICP should be easy to use, accurate, reliable, reproducible, inexpensive and should not be associated with infection or haemorrhagic complications. Although the transducers connected to the extra ventricular drainage continue to be Gold Standard, its association with the likelihood of infection and haemorrhage have led to the search for alternate non-invasive methods of monitoring ICP. While Camino transducers, Strain gauge micro transducer based ICP monitoring devices and the Spiegelberg ICP monitor are the emerging technology in invasive ICP monitoring, optic nerve sheath diameter measurement, venous opthalmodynamometry, tympanic membrane displacement, tissue resonance analysis, tonometry, acoustoelasticity, distortion-product oto-acoustic emissions, trans cranial doppler, electro encephalogram, near infra-red spectroscopy, pupillometry, anterior fontanelle pressure monitoring, skull elasticity, jugular bulb monitoring, visual evoked response and radiological based assessment of ICP are the non-invasive methods which are assessed against the gold standard.

Automated Optic Nerve Sheath Diameter Measurement Using Super-pixel Analysis

The optic nerve is a part of the central nervous system surrounded by cerebrospinal fluid and is encased in a sheath. Changes to the cerebrospinal fluid due to injury, tumor rupture and so on can increase intracranial pressure (ICP) and can result in changes in the sheath diameter. Measuring the changes in the sheath can be done through ultrasound imaging with which the optic nerve sheath diameter can be measured. Since this approach is non-invasive, it would reduce the cost for patients and healthcare if sheath diameter could be used as a predictor of increase in ICP. However, the manual measurement of the nerve sheath diameter is very time consuming and could be affected by human errors. In this paper we propose an image processing approach in which the optic nerve sheath diameter is measured automatically. In our proposed method, we first denoise images and then detect the region of interest using a simple line integral method. After that by analyzing super-pixels we measure the diameter. We compared the results of the proposed method with manual measurements from two experts. The average percentage of error between the proposed method and the experts' measurements did not substantially differ from the error between the two experts.

Optic Nerve Sheath Diameter Correlation with Elevated Intracranial Pressure Determined via Ultrasound

Background

The early detection of elevated intracranial pressure (ICP) can not only prevent mortality but also aid in more aggressive management. Brain computed tomography (CT) is a mainstay modality in detecting elevated ICP, but the feasibility of using brain CTs to detect elevated ICP in critically ill patients is limited, especially for patients who require high levels of inotropic support. The optic nerve sheath is a direct extension of the brain meninges. Therefore, the elevation of ICP is directly transmitted to the sheath. Measuring the optic nerve sheath diameter (ONSD) through ultrasound (US) is a bedside, noninvasive means to detect elevated ICP. The goal of this study was to assess the correlation of ONSD with elevated ICP as measured via US in an intensive care unit (ICU).

Methods

We conducted a six-month prospective, single-center, observational study of mass effect stroke patients aged 18 to 65 years who had a traumatic brain injury (TBI) and were admitted to the ICU. Patients with chronic hydrocephalus, extensive local orbit trauma, a pre-existing ocular disease affecting the optic nerve and/or orbital cavity, hyperthyroidism with exophthalmos, and facial trauma affecting the orbits and/or eyeballs were excluded. We measured the ONSD at the entry of optic nerve into the globe using two-dimensional (2D) US.

Results

One hundred patients were included in the study. Forty-nine patients had diffuse cerebral edema detected on CT scan correlating with increased ONSD notable via bedside US. The mean ONSD related to CT-detectable elevated ICP was 0.61 cm. The sensitivity for the ONSD cut-off value of ≥5.8 mm was 94% (95% confidence interval [CI], 84.05% to 98.79%), and the specificity was 96.08% (95% CI, 86.7% to 99.52%).The positive predictive value was 92.08% (95% CI, 86.28% to 98.96%), and the negative predictive value was 94.23% (95% CI, 84.47% to 98.00%).

Conclusion

The greatest accuracy in ONSD was found with a cut-off of >0.58 cm in patients with positive CT brain findings. Therefore, US can be used as an initial screening test when physicians suspect a patient has elevated ICP.

[Intracranial pressure monitoring in polytrauma patients with traumatic brain injury]

BACKGROUND

The monitoring of intracranial pressure (ICP) represents a cornerstone in the intensive care of patients with traumatic brain injury (TBI) and the industry provides various technical solutions to this end. Decompressive craniectomy can be an option if conservative measures fail to reduce excessive ICP.

OBJECTIVE

To examine the pathophysiology of ICP in trauma, the management of polytrauma involving TBI, and the indications for decompressive craniectomy; and to compare the different monitoring systems and their complications.

MATERIAL AND METHODS

A retrospective analysis of TBI patients between 2010 and 2016 was performed. Relevant publications are discussed, particularly those relating to the indications for monitoring and its influence on polytrauma management.

RESULTS

Between 2010 and 2016, 106 patients with closed TBI and a mean age of 65.9 years received a total of 120 ICP monitors, most of which were parenchyma devices (111/120), followed by intraventricular catheters (8/120), and one combined system (1/120). Of these patients, 27.4% had sustained polytrauma, whilst 33% regularly used anticoagulants. ICP monitors were removed after 8.5 days on an average and the mean ICU stay was 20 days. Probe insertion was combined with craniectomy in 69.8% patients. Probe-related complications, most commonly involving malfunction, were seen in 6.6%. The duration of monitoring was significantly related to polytrauma (p ≤ 0.001) and age <60 (p = 0.03). ICU stay was also significantly related to polytrauma (p = 0.02) and monitoring complications (p ≤ 0.001). Mortality was related to anticoagulant medication (p = 0.01) and age <60 (p = 0.03).

CONCLUSIONS

ICP monitoring is one of the most important tools in TBI treatment. The course and outcome of these severe injuries is affected by polytrauma, age, and the use of anticoagulants.

Cerebral Oxygenation in Traumatic Brain Injury: Can a Non-Invasive Frequency Domain Near-Infrared Spectroscopy Device Detect Changes in Brain Tissue Oxygen Tension as Well as the Established Invasive Monitor?

The cost and highly invasive nature of brain monitoring modality in traumatic brain injury patients currently restrict its utility to specialist neurological intensive care settings. We aim to test the abilities of a frequency domain near-infrared spectroscopy (FD-NIRS) device in predicting changes in invasively measured brain tissue oxygen tension. Individuals admitted to a United Kingdom specialist major trauma center were contemporaneously monitored with an FD-NIRS device and invasively measured brain tissue oxygen tension probe. Area under the curve receiver operating characteristic (AUROC) statistical analysis was utilized to assess the predictive power of FD-NIRS in detecting both moderate and severe hypoxia (20 and 10 mm Hg, respectively) as measured invasively. Sixteen individuals were prospectively recruited to the investigation. Severe hypoxic episodes were detected in nine of these individuals, with the NIRS demonstrating a broad range of predictive abilities (AUROC 0.68-0.88) from relatively poor to good. Moderate hypoxic episodes were detected in seven individuals with similar predictive performance (AUROC 0.576-0.905). A variable performance in the predictive powers of this FD-NIRS device to detect changes in brain tissue oxygen was demonstrated. Consequently, this enhanced NIRS technology has not demonstrated sufficient ability to replace the established invasive measurement.

Multimodality Monitoring in Neurocritical Care: Decision-Making Utilizing Direct And Indirect Surrogate Markers

Substantial progress has been made to create innovative technology that can monitor the different physiological characteristics that precede the onset of secondary brain injury, with the ultimate goal of intervening prior to the onset of irreversible neurological damage. One of the goals of neurocritical care is to recognize and preemptively manage secondary neurological injury by analyzing physiologic markers of ischemia and brain injury prior to the development of irreversible damage. This is helpful in a multitude of neurological conditions, whereby secondary neurological injury could present including but not limited to traumatic intracranial hemorrhage and, specifically, subarachnoid hemorrhage, which has the potential of progressing to delayed cerebral ischemia and monitoring postneurosurgical interventions. In this study, we examine the utilization of direct and indirect surrogate physiologic markers of ongoing neurologic injury, including intracranial pressure, cerebral blood flow, and brain metabolism.

Complications following intracranial pressure monitoring in children: a 6-year single-center experience

OBJECTIVE Intracranial pressure (ICP) monitoring is an important tool in the neurosurgeon's armamentarium and is used for a wide range of indications. There are many different ICP monitors available, of which fiber-optic intraparenchymal devices are very popular. Here, the authors document their experience performing ICP monitoring from 2005 to 2015 and specifically complication rates following insertion of the Microsensor ICP monitor. METHODS A retrospective case series review of all patients who underwent ICP monitoring over a 10-year period from 2005 to 2015 was performed. RESULTS There were 385 separate operations with an overall complication rate of 8.3% (32 of 385 cases). Hardware failure occurred in 4.2% of cases, the CSF leakage rate was 3.6%, the postoperative hemorrhage rate was 0.5%, and there was 1 case of infection (0.3% of cases). Only patients with hardware problems required further surgery as a result of their complications, and no patient had any permanent morbidity or mortality from the procedure. Younger patients (p = 0.001) and patients with pathologically high ICP (13% of patients with high ICP vs 6.5% of patients with normal ICP; p = 0.04) were significantly more likely to have complications. There was no significant difference in the complication rates between general neurosurgical patients and craniofacial patients (7.6% vs 8.8%, respectively; p = 0.67). CONCLUSIONS Intraparenchymal ICP monitoring is a safe procedure associated with low complications and morbidity in the pediatric craniofacial and neurosurgical population and should be offered to appropriate patients to assess ICP with the reassurance of the safety record reported in this study.

Intracranial Pressure Monitoring-Review and Avenues for Development

Intracranial pressure (ICP) monitoring is a staple of neurocritical care. The most commonly used current methods of monitoring in the acute setting include fluid-based systems, implantable transducers and Doppler ultrasonography. It is well established that management of elevated ICP is critical for clinical outcomes. However, numerous studies show that current methods of ICP monitoring cannot reliably define the limit of the brain's intrinsic compensatory capacity to manage increases in pressure, which would allow for proactive ICP management. Current work in the field hopes to address this gap by harnessing live-streaming ICP pressure-wave data and a multimodal integration with other physiologic measures. Additionally, there is continued development of non-invasive ICP monitoring methods for use in specific clinical scenarios.

Temporising an extradural haematoma by intraosseous needle craniostomy in the District General Hospital by non-neurosurgical doctors - A case report

We report the case of a 69-year-old man admitted to the emergency department of a UK district general hospital with an extradural haematoma following closed head injury. He deteriorated rapidly before transfer to the regional neurosurgical centre and was treated with decompression of the extradural haematoma through an EZ-IO™ intraosseous needle in our department, with telephone guidance from the neurosurgeon. We believe this to be the first reported use of this technique in a district general hospital.

Invasive and noninvasive means of measuring intracranial pressure: a review

Measurement of intracranial pressure (ICP) can be invaluable in the management of critically ill patients. Cerebrospinal fluid is produced by the choroid plexus in the brain ventricles (a set of communicating chambers), after which it circulates through the different ventricles and exits into the subarachnoid space around the brain, where it is reabsorbed into the venous system. If the fluid does not drain out of the brain or get reabsorbed, the ICP increases, which may lead to brain damage or death. ICP elevation accompanied by dilatation of the cerebral ventricles is termed hydrocephalus, whereas ICP elevation accompanied by normal or small ventricles is termed idiopathic intracranial hypertension.

OBJECTIVE

We performed a comprehensive literature review on how to measure ICP invasively and noninvasively.

APPROACH

This review discusses the advantages and disadvantages of current invasive and noninvasive approaches.

MAIN RESULTS

Invasive methods remain the most accurate at measuring ICP, but they are prone to a variety of complications including infection, hemorrhage and neurological deficits. Ventricular catheters remain the gold standard but also carry the highest risk of complications, including difficult or incorrect placement. Direct telemetric intraparenchymal ICP monitoring devices are a good alternative. Noninvasive methods for measuring and evaluating ICP have been developed and classified in five broad categories, but have not been reliable enough to use on a routine basis. These methods include the fluid dynamic, ophthalmic, otic, and electrophysiologic methods, as well as magnetic resonance imaging, transcranial Doppler ultrasonography (TCD), cerebral blood flow velocity, near-infrared spectroscopy, transcranial time-of-flight, spontaneous venous pulsations, venous ophthalmodynamometry, optical coherence tomography of retina, optic nerve sheath diameter (ONSD) assessment, pupillometry constriction, sensing tympanic membrane displacement, analyzing otoacoustic emissions/acoustic measure, transcranial acoustic signals, visual-evoked potentials, electroencephalography, skull vibrations, brain tissue resonance and the jugular vein.

SIGNIFICANCE

This review provides a current perspective of invasive and noninvasive ICP measurements, along with a sense of their relative strengths, drawbacks and areas for further improvement. At present, none of the noninvasive methods demonstrates sufficient accuracy and ease of use while allowing continuous monitoring in routine clinical use. However, they provide a realizable ICP measurement in specific patients especially when invasive monitoring is contraindicated or unavailable. Among all noninvasive ICP measurement methods, ONSD and TCD are attractive and may be useful in selected settings though they cannot be used as invasive ICP measurement substitutes. For a sufficiently accurate and universal continuous ICP monitoring method/device, future research and developments are needed to integrate further refinements of the existing methods, combine telemetric sensors and/or technologies, and validate large numbers of clinical studies on relevant patient populations.

Temporising extradural haematoma by craniostomy using an intraosseous needle

We report a novel application of intraosseous needle drainage, alleviating raised intracranial pressure due to extradural haematoma. The potential application of this technique in preventing secondary brain injury and herniation during transfer to a neurosurgical unit is discussed.

Intracranial Multimodality Monitoring for Delayed Cerebral Ischemia

Management of patients with aneurysmal subarachnoid hemorrhage focuses on prevention of rebleeding by early treatment of the aneurysm, as well as detection and management of neurologic and medical complications. Early detection of delayed cerebral ischemia and management of modifiable contributing causes such as vasospasm take a central role, with the goal of preventing irreversible cerebral injury. In efforts to prevent delayed cerebral ischemia, multimodality monitoring has emerged as a promising tool in detecting subclinical physiologic changes before infarction occurs. However, there has been much variability in the utilization of this technology. Recent consensus guidelines discuss the role of multimodality monitoring in acute brain injury. In this review, we evaluate these guidelines and the utility of each modality of multimodality monitoring in aneurysmal subarachnoid hemorrhage.

Neurologic Complications in the Intensive Care Unit

Complications involving the central and peripheral nervous system are frequently encountered in critically ill patients. All components of the neuraxis can be involved including the brain, spinal cord, peripheral nerves, neuromuscular junction, and muscles. Neurologic complications adversely impact outcome and length of stay. These complications can be related to underlying critical illness, pre-existing comorbid conditions, and commonly used and life-saving procedures and medications. Familiarity with the myriad neurologic complications that occur in the intensive care unit can facilitate their timely recognition and treatment. Additionally, awareness of treatment-related neurologic complications may inform decision-making, mitigate risk, and improve outcomes.

Safety profile and probe placement accuracy of intraspinal pressure monitoring for traumatic spinal cord injury: Injured Spinal Cord Pressure Evaluation study

OBJECTIVE

A novel technique for monitoring intraspinal pressure and spinal cord perfusion pressure in patients with traumatic spinal cord injury was recently described. This is analogous to monitoring intracranial pressure and cerebral perfusion pressure in patients with traumatic brain injury. Because intraspinal pressure monitoring is a new technique, its safety profile and impact on early patient care and long-term outcome after traumatic spinal cord injury are unknown. The object of this study is to review all patients who had intraspinal pressure monitoring to date at the authors' institution in order to define the accuracy of intraspinal pressure probe placement and the safety of the technique.

METHODS

At the end of surgery to fix spinal fractures, a pressure probe was inserted intradurally to monitor intraspinal pressure at the injury site. Postoperatively, CT scanning was performed within 48 hours and MRI at 2 weeks and 6 months. Neurointensive care management and complications were reviewed. The American Spinal Injury Association Impairment Scale (AIS) grade was determined on admission and at 2 to 4 weeks and 12 to 18 months postoperation.

RESULTS

To date, 42 patients with severe traumatic spinal cord injuries (AIS Grades A–C) had undergone intraspinal pressure monitoring. Monitoring started within 72 hours of injury and continued for up to a week. Based on postoperative CT and MRI, the probe position was acceptable in all patients, i.e., the probe was located at the site of maximum spinal cord swelling. Complications were probe displacement in 1 of 42 patients (2.4%), CSF leakage that required wound resuturing in 3 of 42 patients (7.1%), and asymptomatic pseudomeningocele that was diagnosed in 8 of 42 patients (19.0%). Pseudomeningocele was diagnosed on MRI and resolved within 6 months in all patients. Based on the MRI and neurological examination results, there were no serious probe-related complications such as meningitis, wound infection, hematoma, wound breakdown, or neurological deterioration. Within 2 weeks postoperatively, 75% of patients were extubated and 25% underwent tracheostomy. Norepinephrine was used to support blood pressure without complications. Overall, the mean intraspinal pressure was around 20 mm Hg, and the mean spinal cord perfusion pressure was around 70 mm Hg. In laminectomized patients, the intraspinal pressure was significantly higher in the supine than lateral position by up to 18 mm Hg after thoracic laminectomy and 8 mm Hg after cervical laminectomy. At 12 to 18 months, 11.4% of patients had improved by 1 AIS grade and 14.3% by at least 2 AIS grades.

CONCLUSIONS

These data suggest that after traumatic spinal cord injury intradural placement of the pressure probe is accurate and intraspinal pressure monitoring is safe for up to a week. In patients with spinal cord injury who had laminectomy, the supine position should be avoided in order to prevent rises in intraspinal pressure.

Non-invasive assessment of intracranial pressure

Monitoring of intracranial pressure (ICP) is invaluable in the management of neurosurgical and neurological critically ill patients. Invasive measurement of ventricular or parenchymal pressure is considered the gold standard for accurate measurement of ICP but is not always possible due to certain risks. Therefore, the availability of accurate methods to non-invasively estimate ICP has the potential to improve the management of these vulnerable patients. This review provides a comparative description of different methods for non-invasive ICP measurement. Current methods are based on changes associated with increased ICP, both morphological (assessed with magnetic resonance, computed tomography, ultrasound, and fundoscopy) and physiological (assessed with transcranial and ophthalmic Doppler, tympanometry, near-infrared spectroscopy, electroencephalography, visual-evoked potentials, and otoacoustic emissions assessment). At present, none of the non-invasive techniques alone seem suitable as a substitute for invasive monitoring. However, following the present analysis and considerations upon each technique, we propose a possible flowchart based on the combination of non-invasive techniques including those characterizing morphologic changes (e.g., repetitive US measurements of ONSD) and those characterizing physiological changes (e.g., continuous TCD). Such an integrated approach, which still needs to be validated in clinical practice, could aid in deciding whether to place an invasive monitor, or how to titrate therapy when invasive ICP measurement is contraindicated or unavailable.

Brain Multimodality Monitoring: Updated Perspectives

The challenges posed by acute brain injury (ABI) involve the management of the initial insult in addition to downstream inflammation, edema, and ischemia that can result in secondary brain injury (SBI). SBI is often subclinical, but can be detected through physiologic changes. These changes serve as a surrogate for tissue injury/cell death and are captured by parameters measured by various monitors that measure intracranial pressure (ICP), cerebral blood flow (CBF), brain tissue oxygenation (PbtO2), cerebral metabolism, and electrocortical activity. In the ideal setting, multimodality monitoring (MMM) integrates these neurological monitoring parameters with traditional hemodynamic monitoring and the physical exam, presenting the information needed to clinicians who can intervene before irreversible damage occurs. There are now consensus guidelines on the utilization of MMM, and there continue to be new advances and questions regarding its use. In this review, we examine these recommendations, recent evidence for MMM, and future directions for MMM.

Invasive Neuromonitoring

Advances in technology have resulted in a plethora of invasive neuromonitoring options for practitioners to manage while caring for the complex needs of the critical care patient. Although many types of invasive neuromonitoring are available to the practitioner, intraparenchymal monitors and external ventricular devices are used most frequently in the clinical setting and are the focus of this article. In addition, multimodality monitoring has been noted to confer a survival benefit in patients with this complex type of invasive neuromonitoring and is discussed as well.

Multimodality Neuromonitoring in Pediatric Neurocritical Care: Review of the Current Resources

Brain insults in children represent a daily challenge in neurocritical care. Having a constant grasp on various parameters in the pediatric injured brain may affect the patient's outcome. Currently, new advances provide clinicians with the ability to utilize several modalities to monitor brain function. This multi-modal approach allows real-time information, leading to faster responses in management and furthermore avoiding secondary insults in the injured brain.

Intracranial pressure monitoring: fundamental considerations and rationale for monitoring

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. In large part critical care for TBI is focused on the identification and management of secondary brain injury. This requires effective neuromonitoring that traditionally has centered on intracranial pressure (ICP). The purpose of this paper is to review the fundamental literature relative to the clinical application of ICP monitoring in TBI critical care and to provide recommendations on how the technique maybe applied to help patient management and enhance outcome. A PubMed search between 1980 and September 2013 identified 2,253 articles; 244 of which were reviewed in detail to prepare this report and the evidentiary tables. Several important concepts emerge from this review. ICP monitoring is safe and is best performed using a parenchymal monitor or ventricular catheter. While the indications for ICP monitoring are well established, there remains great variability in its use. Increased ICP, particularly the pattern of the increase and ICP refractory to treatment is associated with increased mortality. Class I evidence is lacking on how monitoring and management of ICP influences outcome. However, a large body of observational data suggests that ICP management has the potential to influence outcome, particularly when care is targeted and individualized and supplemented with data from other monitors including the clinical examination and imaging.

Effects and Clinical Characteristics of Intracranial Pressure Monitoring-Targeted Management for Subsets of Traumatic Brain Injury: An Observational Multicenter Study

OBJECTIVES

To evaluate the efficacy of traumatic brain injury management guided by intracranial pressure monitoring and to explore the specific subgroups for which intracranial pressure monitoring might be significantly associated with improved outcomes based on a classification of the various traumatic brain injury pathophysiologies using the clinical features and CT scans.

DESIGN

Retrospective observational multicenter study.

SETTING

Twenty-two hospitals (16 level I trauma centers and six level II trauma centers) in nine provinces in China.

PATIENTS

Moderate or severe traumatic brain injury patients who were more than 14 years old.

INTERVENTIONS

Intracranial pressure monitoring.

MEASUREMENTS AND MAIN RESULTS

All data were collected by physicians from medical records. The 6-month mortality and favorable outcome were assessed with the Glasgow Outcome Scale Extended score. An intracranial pressure monitor was inserted into 838 patients (58.1%). The mean duration of intracranial pressure monitoring was 4.44 ± 3.65 days. The significant predictors of intracranial pressure monitoring included the mechanism of injury, a Glasgow Coma Scale score of 9-12 at admission that dropped to a score of 3-8 within 24 hours after injury, a Marshall CT classification of III-IV, the presence of a major extracranial injury, subdural hematoma, intraparenchymal lesions, trauma center level, and intracranial pressure monitoring utilization of hospital. The intracranial pressure monitoring and no intracranial pressure monitoring groups did not significantly differ in terms of complications. For the total sample, the placement of intracranial pressure monitoring was not associated with either 6-month mortality (16.9% vs 20.5%; p = 0.086) or 6-month unfavorable outcome (49.4% vs 45.8%; p = 0.175). For patients with a Glasgow Coma Scale score of 3-8 at admission, intracranial pressure monitoring was also not significantly associated with 6-month mortality (20.9% vs 26.0%; p = 0.053) or an unfavorable outcome (56.9% vs 55.5%; p = 0.646). Multivariate logistic regression analyses showed that intracranial pressure monitoring resulted in a significantly lower 6-month mortality for patients who had a Glasgow Coma Scale score of 3-5 at admission (adjusted odds ratio, 0.57; 95% CI, 0.36-0.90; adjusted p = 0.016), those who had a Glasgow Coma Scale score of 9-12 at admission that dropped to 3-8 within 24 hours after injury (adjusted odds ratio, 0.28; 95% CI, 0.08-0.96; adjusted p = 0.043), and those who had a probability of death at 6 months greater than 0.6 (adjusted odds ratio, 0.55; 95% CI, 0.32-0.94; adjusted p = 0.029).

CONCLUSIONS

There were multiple differences between the intracranial pressure monitoring and no intracranial pressure monitoring groups regarding patient characteristics, injury severity, characteristics of CT scan, and hospital type. Intracranial pressure monitoring in conjunction with intracranial pressure-targeted therapies is significantly associated with lower mortality in some special traumatic brain injury subgroups. The prospective randomized controlled trials specifically investigating these subgroups will be required to further characterize the effects of intracranial pressure monitoring on behavioral outcomes in patients with traumatic brain injury.

Optical Fibre Pressure Sensors in Medical Applications

This article is focused on reviewing the current state-of-the-art of optical fibre pressure sensors for medical applications. Optical fibres have inherent advantages due to their small size, immunity to electromagnetic interferences and their suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based pressure sensors, together with being lightweight and flexible, mean that they are minimally invasive for many medical applications and, thus, particularly suited to in vivo measurement. This means that the sensor can be placed directly inside a patient, e.g., for urodynamic and cardiovascular assessment. This paper presents an overview of the recent developments in optical fibre-based pressure measurements with particular reference to these application areas.

Characteristics of intracranial pressure (ICP) waves and ICP in children with treatment-responsive hydrocephalus

BACKGROUND

One important goal of modern treatment of pediatric hydrocephalus is to normalize the intracranial pressure (ICP) and ICP volume reserve capacity to optimize normal brain development. Better knowledge of the characteristics of ICP waves/ICP in pediatric hydrocephalus may provide new insight into the mechanisms behind modern hydrocephalus treatment. The aim of the present work was to characterize the ICP waves/ICP in children with either communicating or non-communicating hydrocephalus who improved clinically after surgery. The hydrocephalic children not treated surgically following ICP monitoring served as reference patients.

METHODS

The patient material includes all children with hydrocephalus and no previous surgical treatment who underwent diagnostic ICP wave/ICP monitoring during the period 2002-2011. We retrieved the information about the patients from the patient records and the digitally stored ICP waveforms. The ICP wave characteristics amplitude, rise time and rise time coefficient and the mean ICP were determined in the patients treated surgically for their hydrocephalus. The findings were compared with findings in children not treated surgically after ICP monitoring who served as reference patients.

RESULTS

The patient material includes 58 patients. Thirty-one (53%) were treated surgically after ICP monitoring, of whom all improved clinically. As compared to the reference patients, patients treated surgically presented with increased ICP wave amplitudes (MWA) and mean ICP. Alterations were comparable in communicating and non-communicating hydrocephalus. We found no apparent association between the ICP wave/ICP scores and presence of symptoms, indices of ventricular size or age.

CONCLUSIONS

Children with either communicating or non-communicating hydrocephalus improving clinically after surgery presented with elevated MWA and mean ICP. In particular, the levels of MWA were raised to a magnitude seen when intracranial compliance is impaired. Hence, the present observations may support the idea that improvement of intracranial compliance can be an important mechanism by which shunts work in pediatric hydrocephalus.

Intracranial pressure monitoring in pediatric and adult patients with hydrocephalus and tentative shunt failure: a single-center experience over 10 years in 146 patients

OBJECT In patients with hydrocephalus and shunts, lasting symptoms such as headache and dizziness may be indicative of shunt failure, which may necessitate shunt revision. In cases of doubt, the authors monitor intracranial pressure (ICP) to determine the presence of over- or underdrainage of CSF to tailor management. In this study, the authors reviewed their experience of ICP monitoring in shunt failure. The aims of the study were to identify the complications and impact of ICP monitoring, as well as to determine the mean ICP and characteristics of the cardiac-induced ICP waves in pediatric versus adult over- and underdrainage. METHODS The study population included all pediatric and adult patients with hydrocephalus and shunts undergoing diagnostic ICP monitoring for tentative shunt failure during the 10-year period from 2002 to 2011. The patients were allocated into 3 groups depending on how they were managed following ICP monitoring: no drainage failure, overdrainage, or underdrainage. While patients with no drainage failure were managed conservatively without further actions, over- or underdrainage cases were managed with shunt revision or shunt valve adjustment. The ICP and ICP wave scores were determined from the continuous ICP waveforms. RESULTS The study population included 71 pediatric and 75 adult patients. There were no major complications related to ICP monitoring, but 1 patient was treated for a postoperative superficial wound infection and another experienced a minor bleed at the tip of the ICP sensor. Following ICP monitoring, shunt revision was performed in 74 (51%) of 146 patients, while valve adjustment was conducted in 17 (12%) and conservative measures without any actions in 55 (38%). Overdrainage was characterized by a higher percentage of episodes with negative mean ICP less than -5 to -10 mm Hg. The ICP wave scores, in particular the mean ICP wave amplitude (MWA), best differentiated underdrainage. Neither mean ICP nor MWA levels showed any significant association with age. CONCLUSIONS In this cohort of pediatric and adult patients with hydrocephalus and tentative shunt failure, the risk of ICP monitoring was very low, and helped the authors avoid shunt revision in 49% of the patients. Mean ICP best differentiated overdrainage, which was characterized by a higher percentage of episodes with negative mean ICP less than -5 to -10 mm Hg. Underdrainage was best characterized by elevated MWA values, indicative of impaired intracranial compliance.