Brain CT to Assess Intracranial Pressure in Patients with Traumatic Brain Injury

Effect of Target Temperature Management on Optic Nerve Sheath Diameter in Post-Cardiac Arrest Patients

Target Temperature Management (TTM) is a procedure used in post-cardiac arrest (CA) patients to reduce mortality and morbidity. The goal of this study was to investigate the link between intracranial pressure (ICP) and optic nerve sheath diameter (ONSD) in this patient group, which has a high mortality rate, despite TTM, and to see if ONSD may be used to predict mortality. The research was designed to be a retrospective observational study. The study comprised patients who were followed up on in a tertiary intensive care unit, had post-CA TTM, and had brain computed tomography (BCT) before and 0-6 hours after TTM. ONSD measurements were acquired from patients' BCT images recorded before and after TTM. The difference in pre-TTM ONSD and post-TTM ONSD measurements in all post-CA patients, as well as the difference in pre-TTM ONSD and post-TTM ONSD measurements in surviving and deceased patients, was compared. The study involved 33 participants. The patients' average age was 60.58-12.39 years, and 75.8% were male. Around 51.5% of the patients died. When the pre-TTM and post-TTM ONSDs of all patients were compared, there was no statistically significant difference (p = 0.856). When the percentage change (Δ) values between the post-TTM ONSD and pre-TTM ONSD and post-TTM ONSD measures of the surviving patients and the deceased patients were compared, a difference was observed (p < 0.01). Increased ICP in post-CA patients is a significant clinical issue associated with mortality and poor neurological prognosis. ONSD measurement may be useful in monitoring ICP, which may rise, despite TTM, and higher ONSD measurements may be used as an indicator for mortality in post-CA patients, who have received TTM.

Association between quantitative analysis of cerebral edema using CT imaging and neurological outcomes in cardiac arrest survivors

BACKGROUND

To determine if the density distribution proportion of Hounsfield unit (HUdp) in head computed tomography (HCT) images can be used to quantitatively measure cerebral edema in survivors of out-of-hospital cardiac arrest (OHCA).

METHODS

This retrospective observational study included adult comatose OHCA survivors who underwent HCT within 6 h (first) and 72-96 h (second), all performed using the same CT scanner. Semi-automated quantitative analysis was used to identify differences in HUdp at specific HU ranges across the intracranial component based on neurological outcome. Cerebral edema was defined as the increased displacement of the sum of HUdp values (ΔHUdp) at a specific range between two HCT scans. Poor neurological outcome was defined as cerebral performance categories 3-5 at 6 months after OHCA.

RESULTS

Twenty-three (42%) out of 55 patients had poor neurological outcome. Significant HUdp differences were observed between good and poor neurological outcomes in the second HCT scan at HU = 1-14, 23-35, and 39-56 (all P < 0.05). Only the ΔHUdp = 23-35 range showed a significant increase and correlation in the poor neurological outcome group (4.90 vs. -0.72, P < 0.001) with the sum of decreases in the other two ranges (r = 0.97, P < 0.001). Multivariate logistic regression analysis demonstrated a significant association between ΔHUdp = 23-35 range and poor neurological outcomes (adjusted OR, 1.12; 95% CI: 1.02-1.24; P = 0.02).

CONCLUSION

In this cohort study, the increased displacement in ΔHUdp = 23-35 range is independently associated with poor neurological outcome and provides a quantitative assessment of cerebral edema formation in OHCA survivors.

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.

Cardiac MR modelling of systolic and diastolic blood pressure

AIMS

Blood pressure (BP) is a crucial factor in cardiovascular health and can affect cardiac imaging assessments. However, standard outpatient cardiovascular MR (CMR) imaging procedures do not typically include BP measurements prior to image acquisition. This study proposes that brachial systolic BP (SBP) and diastolic BP (DBP) can be modelled using patient characteristics and CMR data.

METHODS

In this multicentre study, 57 patients from the PREFER-CMR registry and 163 patients from other registries were used as the derivation cohort. All subjects had their brachial SBP and DBP measured using a sphygmomanometer. Multivariate linear regression analysis was applied to predict brachial BP. The model was subsequently validated in a cohort of 169 healthy individuals.

RESULTS

Age and left ventricular ejection fraction were associated with SBP. Aortic forward flow, body surface area and left ventricular mass index were associated with DBP. When applied to the validation cohort, the correlation coefficient between CMR-derived SBP and brachial SBP was (r=0.16, 95% CI 0.011 to 0.305, p=0.03), and CMR-derived DBP and brachial DBP was (r=0.27, 95% CI 0.122 to 0.403, p=0.0004). The area under the curve (AUC) for CMR-derived SBP to predict SBP>120 mmHg was 0.59, p=0.038. Moreover, CMR-derived DBP to predict DBP>80 mmHg had an AUC of 0.64, p=0.002.

CONCLUSION

CMR-derived SBP and DBP models can estimate brachial SBP and DBP. Such models may allow efficient prospective collection, as well as retrospective estimation of BP, which should be incorporated into assessments due to its critical effect on load-dependent parameters.

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.

AI-Based Decision Support System for Traumatic Brain Injury: A Survey

Traumatic brain injury (TBI) is one of the major causes of disability and mortality worldwide. Rapid and precise clinical assessment and decision-making are essential to improve the outcome and the resulting complications. Due to the size and complexity of the data analyzed in TBI cases, computer-aided data processing, analysis, and decision support systems could play an important role. However, developing such systems is challenging due to the heterogeneity of symptoms, varying data quality caused by different spatio-temporal resolutions, and the inherent noise associated with image and signal acquisition. The purpose of this article is to review current advances in developing artificial intelligence-based decision support systems for the diagnosis, severity assessment, and long-term prognosis of TBI complications.

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.

Nanogels as Novel Nanocarrier Systems for Efficient Delivery of CNS Therapeutics

Nanogels have come out as a great potential drug delivery platform due to its prominently high colloidal stability, high drug loading, core-shell structure, good permeation property and can be responsive to environmental stimuli. Such nanoscopic drug carriers have more excellent abilities over conventional nanomaterials for permeating to brain parenchyma in vitro and in vivo. Nanogel-based system can be nanoengineered to bypass physiological barriers via non-invasive treatment, rendering it a most suitable platform for the management of neurological conditions such as neurodegenerative disorders, brain tumors, epilepsy and ischemic stroke, etc. Therapeutics of central nervous system (CNS) diseases have shown marked limited site-specific delivery of CNS by the poor access of various drugs into the brain, due to the presences of the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB). Hence, the availability of therapeutics delivery strategies is considered as one of the most major challenges facing the treatment of CNS diseases. The primary objective of this review is to elaborate the newer advances of nanogel for CNS drugs delivery, discuss the early preclinical success in the field of nanogel technology and highlight different insights on its potential neurotoxicity.

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.

Automated Detection and Screening of Traumatic Brain Injury (TBI) Using Computed Tomography Images: A Comprehensive Review and Future Perspectives

Traumatic brain injury (TBI) occurs due to the disruption in the normal functioning of the brain by sudden external forces. The primary and secondary injuries due to TBI include intracranial hematoma (ICH), raised intracranial pressure (ICP), and midline shift (MLS), which can result in significant lifetime disabilities and death. Hence, early diagnosis of TBI is crucial to improve patient outcome. Computed tomography (CT) is the preferred modality of choice to assess the severity of TBI. However, manual visualization and inspection of hematoma and its complications from CT scans is a highly operator-dependent and time-consuming task, which can lead to an inappropriate or delayed prognosis. The development of computer aided diagnosis (CAD) systems could be helpful for accurate, early management of TBI. In this paper, a systematic review of prevailing CAD systems for the detection of hematoma, raised ICP, and MLS in non-contrast axial CT brain images is presented. We also suggest future research to enhance the performance of CAD for early and accurate TBI diagnosis.

Evaluation of Intracranial Hypertension in Traumatic Brain Injury Patient: A Noninvasive Approach Based on Cranial Computed Tomography Features

BACKGROUND

Our purpose was to establish a noninvasive quantitative method for assessing intracranial pressure (ICP) levels in patients with traumatic brain injury (TBI) through investigating the Hounsfield unit (HU) features of computed tomography (CT) images.

METHODS

In this retrospective study, 47 patients with a closed TBI were recruited. Hounsfield unit features from the last cranial CT and the initial ICP value were collected. Three models were established to predict intracranial hypertension with Hounsfield unit (HU model), midline shift (MLS model), and clinical expertise (CE model) features.

RESULTS

The HU model had the highest ability to predict intracranial hypertension. In 34 patients with unilateral injury, the HU model displayed the highest performance. In three classifications of intracranial hypertension (ICP ≤ 22, 23-29, and ≥30 mmHg), the HU model achieved the highest F1 score.

CONCLUSIONS

This radiological feature-based noninvasive quantitative approach showed better performance compared with conventional methods, such as the degree of midline shift and clinical expertise. The results show its potential in clinical practice and further research.

Semi-automated Computed Tomography Volumetry as a Proxy for Intracranial Pressure in Patients with Severe Traumatic Brain Injury: Clinical Feasibility Study

INTRODUCTION

Traumatic brain injury (TBI) is associated with high mortality due to intracranial pressure (ICP). Whether computed tomography (CT) scanning of the brain within the first 24 h is indicative of intracranial hypertension is largely unknown. We assessed the feasibility of semi-automated CT segmentation in comparison with invasive ICP measurements.

RELEVANCE

CT volumetry of the brain might provide ICP data when invasive monitoring is not possible or is undesirable.

METHODS

We identified 33 patients with TBI who received a CT scan at admission and ICP monitoring within 24 h. Semi-automated segmentation of CT images in Matlab yielded cerebrospinal fluid (CSF) and intracranial volume (ICV) data. The ratio CSF/ICV × 100 (expressed as a percentage) was used as a proxy for ICP. The association between invasive ICP and the CSF/ICV ratio was evaluated using a simple linear regression model and a mono-exponential function derived from previous research in animals.

RESULTS

ICP is moderately but significantly associated with the CSF/ICV ratio (r = -0.44, p = 0.01). The mono-exponential function provided a better fit of the relationship between ICP and the CSF/ICV ratio than the linear model.

CONCLUSION

Our feasibility TBI data show that cross-sectional volumetric CT measures are associated with ICP. This non-invasive method can be used in future studies to monitor patients who are not candidates for invasive monitoring or to evaluate therapy effects objectively.

The diagnostic value of intravenous contrast computed tomography in addition to plain computed tomography in dogs with head trauma

Background

The aim of this study is to evaluate additional findings which can be detected by post-contrast computed tomography (CCT) in relation to plain CT (PCT) findings in patients presented with head trauma. Medical records of canine patients with the history of head trauma from three institutions were reviewed. PCT- and CCT-anonymized images were evaluated by a veterinary radiologist separately. From the categorized findings the following conclusions were drawn as: abnormalities were identified on (A) PCT but missed on CCT, (B) CCT but missed on PCT, (C) both PCT and CCT.

Results

Thirty-two patients were included. The results showed that findings identified on CCT or PCT (category A and B) but missed on the other series were limited to mild soft tissue and sinus changes. Overall, 61 different fracture areas, 6 injuries of the temporomandibular joint (TMJ), 4 orbital injuries, 14 nasal cavities with soft tissue density filling, 13 areas of emphysema, 4 symphysis separations, 12 intracranial hemorrhages, 6 cerebral edema, 5 cerebral midline shifts, 3 intracranial aeroceles, 3 brain herniations and 6 intraparenchymal foreign bodies (defined as an abnormal structure located within the brain: e.g. bony fragments, bullet, teeth,..) were identified on both PCT and CCT separately (category C). Severity grading was different in 50% (3/6) of the reported cerebral edema using PCT and CCT images.

Conclusion

The results showed that PCT is valuable to identify the presence of intracranial traumatic injuries and CCT is not always essential to evaluate vital traumatic changes.

Automated Measurement of Intracranial Volume Using Three-Dimensional Photography

BACKGROUND

Current methods to analyze three-dimensional photography do not quantify intracranial volume, an important metric of development. This study presents the first noninvasive, radiation-free, accurate, and reproducible method to quantify intracranial volume from three-dimensional photography.

METHODS

In this retrospective study, cranial bones and head skin were automatically segmented from computed tomographic images of 575 subjects without cranial abnormality (average age, 5 ± 5 years; range, 0 to 16 years). The intracranial volume and the head volume were measured at the cranial vault region, and their relation was modeled by polynomial regression, also accounting for age and sex. Then, the regression model was used to estimate the intracranial volume of 30 independent pediatric patients from their head volume measured using three-dimensional photography. Evaluation was performed by comparing the estimated intracranial volume with the true intracranial volume of these patients computed from paired computed tomographic images; two growth models were used to compensate for the time gap between computed tomographic and three-dimensional photography.

RESULTS

The regression model estimated the intracranial volume of the normative population from the head volume calculated from computed tomographic images with an average error of 3.81 ± 3.15 percent (p = 0.93) and a correlation (R) of 0.96. The authors obtained an average error of 4.07 ± 3.01 percent (p = 0.57) in estimating the intracranial volume of the patients from three-dimensional photography using the regression model.

CONCLUSION

Three-dimensional photography with image analysis provides measurement of intracranial volume with clinically acceptable accuracy, thus offering a noninvasive, precise, and reproducible method to evaluate normal and abnormal brain development in young children.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, V.

Cerebrospinal Fluid Volume Proportion Using Magnetic Resonance Imaging as a Predictor of Poor Neurological Outcome in Survivors of Out-of-Hospital Cardiac Arrest

We aimed to investigate the prognostic performance of the proportion of cerebrospinal fluid volume (pCSV) using brain apparent diffusion coefficient-magnetic resonance imaging (ADC-MRI) in cardiac arrest (CA) survivors. This retrospective single-cohort study comprised adult comatose CA survivors who underwent brain MRI and targeted temperature management (TTM) from March 2018 to October 2019. We calculated pCSV (pCSV0 and pCSV72 within 6 and 72 hours after return of spontaneous circulation, respectively) using an automated quantitative analysis program. The difference between pCSV0 and pCSV72 was defined as the pCSVd. Neurologic outcome 3 months after CA was assessed with the Cerebral Performance Category scale and dichotomized as good (1 or 2) or poor (3-5). Of the 73 patients included, 44 (60.3%) had a poor neurological outcome. Patients with poor outcome had significantly lower pCSV at baseline and at 72 hours, and a negative change in pCSV over time. The prognostic performance of pCSV72 and pCSVd was significantly higher compared with pCSV0 (all p < 0.001). The pCSVd showed excellent area under the curve values (0.96; 95% confidence interval 0.85-0.99) and highest sensitivity (95%) at 100% specificity. pCSV on brain ADC-MRI was associated with 3-month neurologic outcome in CA survivors. The pCSVd is a highly predictive and sensitive marker of 3-month poor neurological outcome in CA survivors treated with TTM. Multicenter prospective studies are required to determine the generalizability of these results.

Measuring intracranial pressure by invasive, less invasive or non-invasive means: limitations and avenues for improvement

Sixty years have passed since neurosurgeon Nils Lundberg presented his thesis about intracranial pressure (ICP) monitoring, which represents a milestone for its clinical introduction. Monitoring of ICP has since become a clinical routine worldwide, and today represents a cornerstone in surveillance of patients with acute brain injury or disease, and a diagnostic of individuals with chronic neurological disease. There is, however, controversy regarding indications, clinical usefulness and the clinical role of the various ICP scores. In this paper, we critically review limitations and weaknesses with the current ICP measurement approaches for invasive, less invasive and non-invasive ICP monitoring. While risk related to the invasiveness of ICP monitoring is extensively covered in the literature, we highlight other limitations in current ICP measurement technologies, including limited ICP source signal quality control, shifts and drifts in zero pressure reference level, affecting mean ICP scores and mean ICP-derived indices. Control of the quality of the ICP source signal is particularly important for non-invasive and less invasive ICP measurements. We conclude that we need more focus on mitigation of the current limitations of today's ICP modalities if we are to improve the clinical utility of ICP monitoring.

A cerebral edema monitoring system based on a new excitation source

BACKGROUND

Real-time clinical monitoring of cerebral edema (CE) is of great importance and requires continuously improved and optimized measurement hardware.

METHODS

A new excitation source with higher frequency stability and wide output power range is presented in this work. The proposed excitation source is small in size and easy to integrate. The output power range of excitation signal used is 1.5 ∼ 33 dBm with a reference signal of 9 ∼ 11 dBm, and the phase shift stability of the excitation signal and reference signal reach 10-7 within 20 min.

RESULTS

When normal saline (0.9%, 10 mL, 20 mL, 30 mL, 40 mL, and 50 mL) is injected into a human head phantom model, the magnetic induction phase shift (MIPS) changes from 252.78 ± 7.61 degrees to 252.40 ± 7.77 degrees. The MIPS signal shows a downward trend with increasing volume, indicating that MIPS can reflect the volume change of the measured object. Moreover, a more dramatic trend is visible when the solution volume increases from 0 to 10 mL and from 40 to 50 mL. This occurs where the volume increment is closer to the upper and lower sides of the over-ear sensor, where the magnetic field is strongest.

CONCLUSION

The phantom simulation experiments illustrate that the proposed MIPS detection system based on a signal source can detect the real-time progress of CE. Advantages of low cost, high precision, and high sensitivity endow this system with excellent application prospects.

Optimal timing to measure optic nerve sheath diameter as a prognostic predictor in post-cardiac arrest patients treated with targeted temperature management

AIM

We evaluated the optimal timing of optic nerve sheath diameter (ONSD) measurement to predict neurologic outcome in post-cardiac arrest patients treated with target temperature management (TTM).

METHODS

This was a prospective single-centre observational study from April 2018 to March 2019. Good outcome was defined as the Glasgow-Pittsburgh cerebral performance categories (CPC) 1 or 2, and poor outcome as a CPC between 3 and 5. ONSD was measured initially after return of spontaneous circulation (ROSC) (ONSD_initial), at 24 h (ONSD₂₄), 48 h (ONSD₄₈), and 72 h (ONSD₇₂) using ultrasonography. The receiver operating characteristic (ROC) curves and DeLong method were used to compare the values for predicting neurologic outcomes.

RESULTS

Out of the 36 patients enrolled, 18 had a good outcome. ONSD₂₄, ONSD₄₈, and ONSD₇₂ were higher in the poor outcome group. The area under ROC curve of ONSD₂₄ was 0.91 (95% confidence interval 0.77-0.98) in predicting poor neurologic outcomes. With a cut off value of 4.90 mm, ONSD₂₄ had a sensitivity of 83.3% and a specificity of 94.4% in predicting poor neurologic outcomes.

CONCLUSION

Our findings demonstrate ONSD₂₄ as a valuable tool to predict the neurologic outcome in post-cardiac arrest patients treated with TTM. Therefore, we recommend performing ONSD measurement using ultrasonography at 24 h after ROSC, rather than immediately after ROSC, to predict neurologic outcome in post-cardiac arrest patients treated with TTM.

Feasibility of Protective Ventilation During Elective Supratentorial Neurosurgery: A Randomized, Crossover, Clinical Trial

BACKGROUND

Traditional ventilation approaches, providing high tidal volumes (Vt), produce excessive alveolar distention and lung injury. Protective ventilation, employing lower Vt and positive end-expiratory pressure (PEEP), is an attractive alternative also for neuroanesthesia, when prolonged mechanical ventilation is needed. Nevertheless, protective ventilation during intracranial surgery may exert dangerous effects on intracranial pressure (ICP). We tested the feasibility of a protective ventilation strategy in neurosurgery.

MATERIALS AND METHODS

Our monocentric, double-blind, 1:1 randomized, 2×2 crossover study aimed at studying the effect size and variability of ICP in patients undergoing elective supratentorial brain tumor removal and alternatively ventilated with Vt 9 mL/kg-PEEP 0 mm Hg and Vt 7 mL/kg-PEEP 5 mm Hg. Respiratory rate was adjusted to maintain comparable end-tidal carbon dioxide between ventilation modes. ICP was measured through a subdural catheter inserted before dural opening.

RESULTS

Forty patients were enrolled; 8 (15%) were excluded after enrollment. ICP did not differ between traditional and protective ventilation (11.28±5.37, 11 [7 to 14.5] vs. 11.90±5.86, 11 [8 to 15] mm Hg; P=0.541). End-tidal carbon dioxide (28.91±2.28, 29 [28 to 30] vs. 28.00±2.17, 28 [27 to 29] mm Hg; P<0.001). Peak airway pressure (17.25±1.97, 17 [16 to 18.5] vs. 15.81±2.87, 15.5 [14 to 17] mm Hg; P<0.001) and plateau airway pressure (16.06±2.30, 16 [14.5 to 17] vs. 14.19±2.82, 14 [12.5 to 16] mm Hg; P<0.001) were higher during protective ventilation. Blood pressure, heart rate, and body temperature did not differ between ventilation modes. Dural tension was "acceptable for surgery" in all cases. ICP differences between ventilation modes were not affected by ICP values under traditional ventilation (coefficient=0.067; 95% confidence interval, -0.278 to 0.144; P=0.523).

CONCLUSIONS

Protective ventilation is a feasible alternative to traditional ventilation during elective neurosurgery.

Intracranial pressure management in patients with traumatic brain injury: an update

PURPOSE OF REVIEW

Intracranial pressure (ICP) monitoring and treatment is central in the management of traumatic brain injury. Despite 4 decades of clinical use, several aspects remain controversial, including the indications for ICP and treatment options.

RECENT FINDINGS

Two major trials tested surgical decompression and mild hypothermia as treatments for high ICP. Both were rigorous, randomized, multicenter studies, with different designs. Decompression was tested for ICP refractory to conventional treatment, whereas hypothermia was offered as an alternative to conventional medical therapy. Decompression reduced mortality, but at the expense of more disability. The hypothermia trial was stopped because of a worse outcome in the treated arm. Indications for ICP monitoring have been reviewed and new international guidelines issued. New contributions published in 2016 have dealt with computerized analysis for predicting ICP crises; noninvasive or innovative methods for measuring ICP; reassessment of standard therapeutic interventions, such as hypertonic solutions and the level of intensity of ICP therapy.

SUMMARY

Aggressive strategies for ICP control, like surgical decompression or hypothermia, carefully tested, have controversial effects on outcome. Several articles have made worthwhile contributions to important clinical issues, but with no real breakthroughs.

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.

Traumatic brain injury: Comparison between autopsy and ante-mortem CT

PURPOSE

The aim of this study was to compare pathological findings after traumatic brain injury between autopsy and ante-mortem computed tomography (CT). A second aim was to identify changes in these findings between the primary posttraumatic CT and the last follow-up CT before death.

METHODS

Through the collaboration between clinical radiology and forensic medicine, 45 patients with traumatic brain injury were investigated. These patients had undergone ante-mortem CT as well as autopsy. During autopsy, the brain was cut in fronto-parallel slices directly after removal without additional fixation or subsequent histology. Typical findings of traumatic brain injury were compared between autopsy and radiology. Additionally, these findings were compared between the primary CT and the last follow-up CT before death.

RESULTS

The comparison between autopsy and radiology revealed a high specificity (≥80%) in most of the findings. Sensitivity and positive predictive value were high (≥80%) in almost half of the findings. Sixteen patients had undergone craniotomy with subsequent follow-up CT. Thirteen conservatively treated patients had undergone a follow-up CT. Comparison between the primary CT and the last ante-mortem CT revealed marked changes in the presence and absence of findings, especially in patients with severe traumatic brain injury requiring decompression craniotomy.

CONCLUSION

The main pathological findings of traumatic brain injury were comparable between clinical ante-mortem CT examinations and autopsy. Comparison between the primary CT after trauma and the last ante-mortem CT revealed marked changes in the findings, especially in patients with severe traumatic brain injury. Hence, clinically routine ante-mortem CT should be included in the process of autopsy interpretation.