Invasive Intracranial Pressure Measurement Research Articles

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

Targeting single monitoring modalities such as intracranial pressure (ICP) or cerebral perfusion pressure alone has shown to be insufficient in improving outcome after traumatic brain injury (TBI). Multimodality monitoring (MMM) allows for a more complete description of brain function and for individualized management. Transcranial Doppler (TCD) represents the gold standard for continuous cerebral blood flow velocity assessment, but requires high levels skill and time. In TBI, the practical aspects of conducting extended TCD monitoring sessions have yet to be evaluated. Patients with acute moderate-to-severe TBI admitted to the neurocritical care unit between March 2022 and December 2023 receiving invasive ICP measurements were evaluated for inclusion. Exclusion criteria included trauma incompatible with TCD monitoring and if MMM was unwarranted. Daily MMM sessions (in addition to regular monitoring) were performed using TCD (Delica EMS 9D System or the DWL Doppler Box) for ≤5 d. Quantitative and qualitative feasibility, safety, and quality metrics were assessed. Of 74 patients, 36 (75% male; mean age, 44 ± 17 y) were included. Common reasons for exclusion were skull fractures (n = 12) and decompressive craniectomy (n = 9). We acquired 88 recordings (mean, 275 ± 88 min). Overall monitoring times increased, and set-up times decreased. Physiologic variables (including ICP/brain temperature) did not change with TCD application. A single adverse event (dislodging of a microdialysis catheter) occurred. Implementing extended TCD monitoring in MMM protocols is feasible and safe. Considering these results, inclusion of long-term TCD as part of the MMM is strongly encouraged to allow for in-depth description and direct evaluation of hemodynamic changes after TBI.

Dimensions of Arachnoid Bulk Ratio: A Superior Optic Nerve Sheath Index for Intracranial Pressure.

Background Discrepancies in the literature regarding optimal optic nerve sheath diameter (ONSD) cutoffs for intracranial pressure (ICP) necessitate alternative neuroimaging parameters to improve clinical management. Purpose To evaluate the diagnostic accuracy of the dimensions of the perineural subarachnoid space to the optic nerve sheath ratio, measured using US, in predicting increased ICP. Materials and Methods In a prospective cohort study from April 2022 to December 2023, patients with suspected increased ICP underwent optic nerve US to determine the dimensions of arachnoid bulk (DAB) ratio and ONSD before invasive ICP measurement. Correlation between the parameters and ICP, as well as diagnostic accuracy, was assessed using area under the receiver operating characteristic curve (AUC) analysis. Results A total of 30 participants were included (mean age, 39 years ± 14 [SD]; 24 female). The DAB ratio and ONSD were significantly larger in participants with increased ICP (38% [0.16 of 0.42] and 14% [0.82 of 6.04 mm], respectively; P < .001). The DAB ratio showed a stronger correlation with ICP than ONSD (rs = 0.87 [P < .001] vs rs = 0.61 [P < .001]). The DAB ratio and ONSD optimal cutoffs for increased ICP were 0.5 and 6.5 mm, respectively, and the ratio had higher sensitivity (100% vs 92%) and specificity (94% vs 83%) compared with ONSD. Moreover, the DAB ratio better predicted increased ICP than ONSD, with a higher AUC (0.98 [95% CI: 0.95, 1.00] vs 0.86 [95% CI: 0.71, 0.95], P = .047). Conclusion An imaging ratio was proposed to predict ICP based on the relative anatomy of the cerebrospinal fluid space, demonstrating more accurate diagnosis of increased ICP and a strong correlation with ICP values, suggesting its potential utility as a neuroimaging marker in clinical settings. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Shepherd in this issue.

Ultrasound-guided initial diagnosis and follow-up of pediatric idiopathic intracranial hypertension

BackgroundIdiopathic intracranial hypertension in children often presents with non-specific symptoms found in conditions such as hydrocephalus. For definite diagnosis, invasive intracranial pressure measurement is usually required. Ultrasound (US) of the optic nerve sheath diameter provides a non-invasive method to assess intracranial pressure. Transtemporal US allows imaging of the third ventricle and thus assessment for hydrocephalus.ObjectiveTo investigate whether the combination of US optic nerve sheath and third ventricle diameter can be used as a screening tool in pediatric idiopathic intracranial hypertension to indicate elevated intracranial pressure and exclude hydrocephalus as an underlying pathology. Further, to analyze whether both parameters can be used to monitor treatment outcome.Materials and methodsWe prospectively included 36 children with idiopathic intracranial hypertension and 32 controls. Using a 12-Mhz linear transducer and a 1–4-Mhz phased-array transducer, respectively, optic nerve sheath and third ventricle diameters were determined initially and during the course of treatment.ResultsIn patients, the mean optic nerve sheath diameter was significantly larger (6.45±0.65 mm, controls: 4.96±0.32 mm) and the mean third ventricle diameter (1.69±0.65 mm, controls: 2.99±1.31 mm) was significantly smaller compared to the control group, P<0.001. Optimal cut-off values were 5.55 mm for the optic nerve sheath and 1.83 mm for the third ventricle diameter.ConclusionsThe combined use of US optic nerve sheath and third ventricle diameter is an ideal non-invasive screening tool in pediatric idiopathic intracranial hypertension to indicate elevated intracranial pressure while ruling out hydrocephalus. Treatment can effectively be monitored by repeated US, which also reliably indicates relapse.

Diagnostic accuracy of optic nerve sheath diameter on ultrasound for the detection of increased intracranial pressure in patients with traumatic brain injury: A systematic review and meta‑analysis.

The timely diagnosis and treatment of elevated intracranial pressure (ICP) reduces morbidity rates and prevents mortality. The aim of the present systematic review and meta-analysis was to determine the diagnostic accuracy of optic nerve sheath diameter (ONSD) vs. standard invasive ICP measurements in patients with traumatic brain injury (TBI). The PubMed, Embase, Web of Science and Cochrane Library databases were systematically searched for studies including adult patients with TBI with suspected elevated ICP, and the sonographic ONSD measurements were compared with those from a standard invasive method. The quality of the studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool by two independent authors. A bivariate random effects model was used to summarize the pooled sensitivity, specificity and diagnostic odds ratio (DOR). A total of eight prospective studies with 222 patients with TBI were included. The pooled sensitivity was 0.82 [95% confidence interval (CI), 0.75-0.88], the specificity was 0.82 (95% CI, 0.71-0.90) and the DOR was 17.75 (95% CI, 7.02-44.83) with partial evidence of heterogeneity. The accuracy of the area under the summary ROC was 0.87. An ultrasound-determined elevated ICP has reasonable performance indicators with high sensitivity and specificity in patients with TBI. As such, this method may be a useful complementary monitoring tool in acute care.

What We Know About Intracranial Hypertension in Children With Syndromic Craniosynostosis.

A scoping review of literature about mechanisms leading to intracranial hypertension (ICH) in syndromic craniosynostosis (sCS) patients, followed by a narrative synopsis of whether cognitive and behavioral outcome in sCS is more related to genetic origins, rather than the result of ICH. The scoping review comprised of a search of keywords in EMBASE, MEDLINE, Web of science, Cochrane Central Register of Trials, and Google scholar databases. Abstracts were read and clinical articles were selected for full-text review and data were extracted using a structured template. A priori, the authors planned to analyze mechanistic questions about ICH in sCS by focusing on 2 key aspects, including (1) the criteria for determining ICH and (2) the role of component factors in the Monro-Kellie hypothesis/doctrine leading to ICH, that is, cerebral blood volume, cerebrospinal fluid (CSF), and the intracranial volume. Of 1893 search results, 90 full-text articles met criteria for further analysis. (1) Invasive intracranial pressure measurements are the gold standard for determining ICH. Of noninvasive alternatives to determine ICH, ophthalmologic ones like fundoscopy and retinal thickness scans are the most researched. (2) The narrative review shows how the findings relate to ICH using the Monro-Kellie doctrine. Development of ICH is influenced by different aspects of sCS: deflection of skull growth, obstructive sleep apnea, venous hypertension, obstruction of CSF flow, and possibly reduced CSF absorption. Problems in cognition and behavior are more likely because of genetic origin. Cortical thinning and problems in visual function are likely the result of ICH.

332 Estimation of Intracranial Pressure Using Non-Invasive Monitor and Machine Learning

INTRODUCTION: Several non-invasive technologies have attempted to utilize surrogate markers of cerebral hemodynamics to infer intracranial pressure (ICP). Successful clinical application of these methods have been limited by hesitancy to rely upon surrogate data and inferences about ICP, in lieu of directly measured ICP. One newer method utilizes a mechanical extensometer to detect subtle, dynamic skull deformations can yield a non-invasive ICP waveform. This data has been validated to provide important information about intracranial dynamics, including inferences on the cerebral compliance. This method does not provide an absolute intracranial pressure and thus questions about clinical application remain. METHODS: High frequency (326 Hz) arterial blood pressure, non-invasive and invasive ICP measurements were collected from 5 patients. Samples were collected over 30 minutes. The first 15 minutes were used for training and last 15 minutes were used for testing. Facebook Prophet was used to perform signal analysis and forecasting. Switch-point analysis tools were also used to identify shifts in ICP measurements. RESULTS: Model per patient was generated from the 5 patients. Trend and seasonality analysis were then performed using Facebook Prophet modeling. Arterial blood pressure and non-invasive measurement were used as regressor to invasive intracranial pressure measurement. Mean absolute error of the testing samples of all models ranged from 0.8–2.4 mmHg. CONCLUSIONS: More closely and reliably estimating invasive intracranial pressure measurement from non-invasive measurements and arterial blood pressure is feasible using sequence analysis and machine learning. This will aid the clinical applicability of non-invasive monitoring and perhaps provide the pathway to replacing invasive measurement altogether. Further study of the applications of this clinical tool is warranted with the goal of intervening early to improve neurologic outcomes following acute brain injuries.

Ultrasonographic measurement of the optic nerve sheath diameter to detect intracranial hypertension: an observational study

ObjectivesTo evaluate the ultrasonographic measurement of optic nerve sheath diameter (ONSD) as a predictor of intracranial hypertension as compared to the invasive measurement of intracranial pressure (ICP).DesignCross-sectional observational study.SettingIntensive Care Unit (ICU) of two tertiary university hospitals in Montevideo, Uruguay.PatientsWe included 56 adult patients, over 18 years of age, who required sedation, mechanical ventilation, and invasive ICP monitoring as a result of a severe acute neurologic injury (traumatic or non-traumatic) and had a Glascow Coma Score (GCS) equal to or less than 8 on admission to the ICU.InterventionsUltrasonographic measurement of ONSD to detect intracranial hypertension.Measurements and main resultsIn our study, a logistic regression model was performed in which it was observed that the variable ONSD is statistically significant with a p value of 0.00803 (< 0.05). This model estimates and predicts the probability that a patient will have an ICP greater than 20 mmHg. From the analysis of the cut-off points, it is observed that a value of 5.7 mm of ONSD maximizes the sensitivity (92.9%) of the method (a greater number of individuals with ICP > 20 mmHg are correctly identified).ConclusionsIn sedated neurocritical patients, with structural Acute Brain Injury, the ONSD measurement correlates with the invasive measurement of ICP. It was observed that with ONSD values less than 5.7 mm, the probability of being in the presence of ICP above 20 mmHg is very low, while for ONSD values greater than 5.7 mm, said probability clearly increases.

Optic Nerve Ultrasound Evaluation in Children: A Review.

Managing patients with neurocritical illness requires monitoring and treating elevated intracranial pressure (ICP), especially in cases in children. In terms of precise and real-time measurements, invasive ICP measurements are presently the gold standard for the initial diagnosis and follow-up ICP assessments. As a rapid and non-invasive way to detect elevated ICP, point-of-care ultrasonography (POCUS) of optic nerve sheath diameter (ONSD) has been proposed. The utility of bedside POCUS of ONSD to detect elevated ICP with excellent diagnostic test accuracy in adults has already been demonstrated. Nonetheless, data on the relationship between POCUS of ONSD and ICP in children are scarce. Therefore, the purpose of this review is to point out the most recent findings from the pediatric published literature and briefly discuss what was assessed with ONSD ultrasound examination, and also to describe and discuss the diagnostic procedures available for optic nerve ultrasound appraisal. A search of the medical databases PubMed and Scopus was carried out. The terms such as "ocular ultrasonography", "ICP assessment", "children", "point-of-care ultrasound", and "POCUS" were searched. In conclusion, the use of the standardized A-scan technique coupled with the B-scan technique should be suggested to provide data that are as accurate, precise, repeatable, and objective as possible.

Assessment of a Non-Invasive Brain Pulse Monitor to Measure Intra-Cranial Pressure Following Acute Brain Injury.

Intracranial pressure (ICP) monitoring requires placing a hole in the skull through which an invasive pressure monitor is inserted into the brain. This approach has risks for the patient and is expensive. We have developed a non-invasive brain pulse monitor that uses red light to detect a photoplethysmographic (PPG) signal arising from the blood vessels on the brain's cortical surface. The brain PPG and the invasive ICP waveform share morphological features which may allow measurement of the intracranial pressure. We enrolled critically ill patients with an acute brain injury with invasive ICP monitoring to assess the new monitor. A total of 24 simultaneous invasive ICP and brain pulse monitor PPG measurements were undertaken in 12 patients over a range of ICP levels. The waveform morphologies were similar for the invasive ICP and brain pulse monitor PPG approach. Both methods demonstrated a progressive increase in the amplitude of P2 relative to P1 with increasing ICP levels. An automated algorithm was developed to assess the PPG morphological features in relation to the ICP level. A correlation was demonstrated between the brain pulse waveform morphology and ICP levels, R2=0.66,P < 0.001. The brain pulse monitor's PPG waveform demonstrated morphological features were similar to the invasive ICP waveform over a range of ICP levels, these features may provide a method to measure ICP levels. ACTRN12620000828921.

In Vitro Evaluation of a Non-Invasive Photoplethysmography Based Intracranial Pressure Sensor

Intracranial pressure (ICP) is an important measurement in the treatment of Traumatic Brain Injury (TBI). Currently, ICP can only be measured invasively, which exposes patients to operative risk and can only be performed by neurosurgeons. Hence, there is a significant need for a non-invasive ICP technology. This paper describes the evaluation of a novel non-invasive intracranial pressure (nICP) monitor which uses the Photoplethysmogram (PPG) to measure the ICP. The monitor was evaluated in an in vitro model that simulated cerebral haemodynamics and allowed the controlled manipulation of ICP. A number of features from the PPG were extracted and utilised in a machine learning model to estimate ICP. Three separate measurements in which the ICP was varied were performed, and the estimated ICP (nICP) was compared with reference (invasive) ICP measurements. The ICP estimated by the nICP monitor was highly correlated with reference ICP measurements (Pearson’s correlation coefficient between 0.95 and 0.98). The nICP monitor also showed a low Root Mean Square Error from the reference ICP measure (3.12, 1.48, and 1.45 mmHg). Analysis of agreement by Bland and Altman also revealed good agreement between the two techniques. The optical nICP monitor was able to estimate the ICP non-invasively from an in vitro model simulating intracranial hypertension. The non-invasive ICP monitor showed very promising results which can set the base for further investigations. This work contributes significantly to the quest for non-invasive ICP monitoring in Traumatic Brain Injury (TBI), and paves the way for further research in this field.

Analysis of dynamic changes in optic nerve sheath diameter (ONSD) with ultrasound in post-craniotomy patients: Trends and correlation with computed tomography ONSD and Glasgow coma scale in post-operative period.

Intracranial pressure (ICP) monitoring in patients with intracranial tumors undergoing craniotomy is usually done in perioperative period in intensive care unit. Invasive measurement of ICP, though considered as the gold standard, has its own limitations such as availability of expertise, equipment, and associated complications. Period of raised ICP in post-operative period may impact patient outcomes. Post-craniotomy computed tomography (CT) assessment is done routinely and may need to be repeated if indicated during post-operative stay. Utility of sonographic serial optic nerve sheath diameter (ONSD) assessment in post-operative monitoring of patients who have undergone elective craniotomy was explored in this study. The primary objective of the study was to measure the dynamic change in ONSD as compared to baseline pre-operative measurement in the first 3 postoperative days after elective craniotomy. The secondary objective of the study was to evaluate correlation between ONSD value with Glasgow Coma Scale (GCS) and post-operative CT findings. In this prospective, observational, and cohort study, we studied adult patients undergoing craniotomy for intracranial tumors. GCS assessment and sonographic measurement of ONSD were done preoperatively, immediate post-operative period, and 12, 24, and 48 h after surgery. CT scan to detect raised ICP was done at 24 h post-operative. Correlation of ONSD with GCS at respective period and correlation of CT scan finding with respective ONSD assessment were evaluated. A total of 57 patients underwent elective craniotomy for intracranial tumors. Significant difference was observed in ONSD value depending on time of measurement perioperatively (χ2 = 78.9, P = 0.00). There was initial increase in the first 12 h followed by decrease in ONSD in the next 48 h. Negative correlation was observed between baseline ONSD and 12 h GCS (ρ = -0.345, P = 0.013). There was significant change in GCS scores based on the status of ONSD (raised or normal) at 12 h after surgery (P = 0.014). Significant correlation between USG ONSD and CT ONSD was observed (ρ = 0.928, P = 0.000). Optimal cutoff value of ONSD to detect raised ICP with reference to CT signs was 4.8 mm with 80% sensitivity and 95% specificity. ONSD undergoes dynamic changes, correlates with CT scan, and has good diagnostic accuracy to detect raised ICP post-craniotomy for intracranial tumors. It may serve as a useful tool in monitoring in resource-limited setup.

A simplified cranial cavity model to understand the relationship between intracranial pressure and dural sinus pressure.

Although accurate intracranial pressure (ICP) monitoring is essential for the diagnosis and treatment of severe brain diseases, current methods are performed invasively. Therefore, a safe and less invasive ICP measurement is required. The purpose of our study was to develop a simplified cranial cavity model for a better understanding of the relationship between the ICP and the pressure measurement within the dural venous sinus (DVS) to support the validity of using sinus pressure as the surrogate of the ICP. The in-house cranial cavity model had three components: the brain part, the DVS part, and the subarachnoid space (SAS) part. Pressure in other parts was measured when the pressure in the SAS part and, separately, brain part was increased from 0 (baseline) to 50 mmHg at intervals of 10 mmHg. When the pressure in the SAS part was increased from 10 to 50 mmHg at 10 mmHg interval, pressures of both the brain and DVS parts increased without significant difference (all P > 0.05). However, pressures in both the SAS and DVS parts differed while the pressure in the brain part was increased. The pressures in both parts showed about 70% of the increase in the brain part. Nevertheless, the pressures in the SAS and DVS parts were not significantly different (P > 0.05). A simplified in-house cranial cavity model was developed consisting of three compartments to represent the actual intracranial spaces. The pressure measurement within the DVS was feasible to use as a surrogate for the ICP measurement.

Predictive Value of Optic Nerve Sheath Diameter for Diagnosis of Intracranial Hypertension in Children With Severe Brain Injury.

Background and AimsIntracranial Hypertension (ICH) is a life-threatening complication of brain injury. The invasive measurement of intracranial pressure (ICP) remains the gold standard to diagnose ICH. Measurement of Optic Nerve Sheath Diameter (ONSD) using ultrasonography is a non-invasive method for detecting ICH. However, data on paediatric brain injury are scarce. The aim of the study was to determine the performance of the initial ONSD measurement to predict ICH occurring in children with severe brain injury and to describe the ONSD values in a control group.MethodsIn this cross-sectional study, ONSD was measured in children aged 2 months-17 years old with invasive ICP monitoring: before placement of ICP probe and within the 60 min after, and then daily during 3 days. ONSD was also measured in a control group.ResultsNinety-nine patients were included, of whom 97 were analysed, with a median (IQR) age of 8.7 [2.3–13.6] years. The median (IQR) PIM 2 score was 6.6 [4.4–9.7] and the median (IQR) PELOD score was 21 [12–22]. Aetiologies of brain injury were trauma (n = 72), infection (n = 17) and stroke (n = 8). ICH occurred in 65 children. The median (IQR) ONSD was 5.58 mm [5.05–5.85]. ONSD performed poorly when it came to predicting ICH occurrence within the first 24 h (area under the curve, 0.58). There was no significant difference between the ONSD of children who presented with ICH within the first 24 h and the other children, with a median (IQR) of 5.6 mm [5.1–5.9] and 5.4 mm [4.9–5.8], respectively. Infants aged less than 2 years had a median (IQR) ONSD of 4.9 mm [4.5–5.2], significantly different from children aged more than 2 years, whose median ONSD was 5.6 mm [5.2–5.9]. Age, aetiology or ICP levels did not change the results. Thirty-one controls were included, with a median age of 3.7 (1.2–8.8) years. The median (IQR) of their ONSD measurement was 4.5 mm [4.1–4.8], significantly lower than the patient group.ConclusionIn a paediatric severe brain injury population, ONSD measurement could not predict the 24 h occurrence of ICH. Severity of patients, timing and conditions of measurements may possibly explain these results.

Can Quantitative Pupillometry be used to Screen for Elevated Intracranial Pressure? A Retrospective Cohort Study

BackgroundElevated intracranial pressure (ICP) is a serious complication in brain injury. Because of the risks involved, ICP is not monitored in all patients at risk. Noninvasive screening tools to identify patients with elevated ICP are needed. Anisocoria, abnormal pupillary size, and abnormal pupillary light reflex are signs of high ICP, but manual pupillometry is arbitrary and subject to interrater variability. We have evaluated quantitative pupillometry as a screening tool for elevated ICP.MethodsWe performed a retrospective observational study of the association between Neurological Pupil index (NPi), measured with the Neuroptics NPi-200 pupillometer, and ICP in patients routinely monitored with invasive ICP measurement in the intensive care unit. We performed a nonparametric receiver operator curve analysis for ICP ≥ 20 mm Hg with NPi as a classification variable. We performed a Youden analysis for the optimal NPi cutoff value and recorded sensitivity and specificity for this cutoff value. We also performed a logistic regression with elevated ICP as the dependent variable and NPi as the independent variable.ResultsWe included 65 patients with invasive ICP monitoring. A total of 2,705 measurements were analyzed. Using NPi as a screening tool for elevated ICP yielded an area under receiver operator curve of 0.72. The optimal mean NPi cutoff value to rule out elevated ICP was ≥ 3.9. The probability of elevated ICP decreased with increasing NPi, with an odds ratio of 0.55 (0.50, 0.61).ConclusionsScreening with NPi may inform high stakes clinical decisions by ruling out elevated ICP with a high degree of certainty. It may also aid in estimating probabilities of elevated ICP. This can help to weigh the risks of initiating invasive ICP monitoring against the risks of not doing so. Because of its ease of use and excellent interrater reliability, we suggest further studies of NPi as a screening tool for elevated ICP.

Zero retinal vein pulsation amplitude extrapolated model in non-invasive intracranial pressure estimation

Intracranial pressure (ICP) includes the brain, optic nerve, and spinal cord pressures; it influences blood flow to those structures. Pathological elevation in ICP results in structural damage through various mechanisms, which adversely affects outcomes in traumatic brain injury and stroke. Currently, invasive procedures which tap directly into the cerebrospinal fluid are required to measure this pressure. Recent fluidic engineering modelling analogous to the ocular vascular flow suggests that retinal venous pulse amplitudes are predictably influenced by downstream pressures, suggesting that ICP could be estimated by analysing this pulse signal. We used this modelling theory and our photoplethysmographic (PPG) retinal venous pulse amplitude measurement system to measure amplitudes in 30 subjects undergoing invasive ICP measurements by lumbar puncture (LP) or external ventricular drain (EVD). We estimated ICP from these amplitudes using this modelling and found it to be accurate with a mean absolute error of 3.0 mmHg and a slope of 1.00 (r = 0.91). Ninety-four percent of differences between the PPG and invasive method were between − 5.5 and + 4.0 mmHg, which compares favourably to comparisons between LP and EVD. This type of modelling may be useful for understanding retinal vessel pulsatile fluid dynamics and may provide a method for non-invasive ICP measurement.

A recurrent machine learning model predicts intracranial hypertension in neurointensive care patients.

The evolution of intracranial pressure (ICP) of critically ill patients admitted to a neurointensive care unit (ICU) is difficult to predict. Besides the underlying disease and compromised intracranial space, ICP is affected by a multitude of factors, many of which are monitored on the ICU, but the complexity of the resulting patterns limits their clinical use. This paves the way for new machine learning techniques to assist clinical management of patients undergoing invasive ICP monitoring independent of the underlying disease.An institutional cohort (ICP-ICU) of patients with invasive ICP monitoring (n = 1346) was used to train recurrent machine learning models to predict the occurrence of ICP increases of ≥22 mmHg over a long (>2 h) time period in the upcoming hours. External validation was performed on patients undergoing invasive ICP measurement in two publicly available datasets [Medical Information Mart for Intensive Care (MIMIC, n = 998) and eICU Collaborative Research Database (n = 1634)].Different distances (1–24 h) between prediction time point and upcoming critical phase were evaluated, demonstrating a decrease in performance but still robust AUC-ROC with larger distances (24 h AUC-ROC: ICP-ICU 0.826 ± 0.0071, MIMIC 0.836 ± 0.0063, eICU 0.779 ± 0.0046, 1 h AUC-ROC: ICP-ICU 0.982 ± 0.0008, MIMIC 0.965 ± 0.0010, eICU 0.941 ± 0.0025). The model operates on sparse hourly data and is stable in handling variable input lengths and missingness through its nature of recurrence and internal memory. Calculation of gradient-based feature importance revealed individual underlying decisions for our long short time memory-based model and thereby provided improved clinical interpretability.Recurrent machine learning models have the potential to be an effective tool for the prediction of ICP increases with high translational potential.

Comparing ultrasonographic optic nerve sheath diameter to head computed tomography scan to predict intracranial pressure elevation.

Introduction:Intracranial hypertension is an emergency condition that needs to be recognized as soon as possible. Lumbar puncture, the gold standard diagnostic procedure for intracranial hypertension, is contraindicated in some conditions while brain imaging procedures may be too difficult to be performed on critically ill patients. To solve this problem, this study aims to assess an alternative method to detect intracranial hypertension by measuring optic nerve sheath diameter using ocular ultrasound and optic nerve sheath diameter difference in each etiology.Methods:This cross-sectional study was conducted at the Emergency Department of Dr Iskak Tulungagung General Hospital. Sixty-nine patients who visited the emergency room for the first onset of intracranial pathology were included for optic nerve sheath diameter measurement by ultrasound. Subjects were divided into elevated and non-elevated intracranial pressure groups based on head computed tomography scan findings. The optic nerve sheath diameter results were compared and analyzed.Result:There were 29 subjects in the elevated intracranial pressure group and 40 subjects in the non-elevated intracranial pressure group. The mean of optic nerve sheath diameter in the elevated and non-elevated intracranial pressure groups was 0.63 ± 0.06 and 0.57 ± 0.06 cm, respectively (p = 0.000). Based on receiver operating characteristics analysis, 0.58 cm was the most optimal cut-off value.Conclusion:Ultrasonographic optic nerve sheath diameter can be used to predict elevated intracranial pressure in suspected patients who are contraindicated to invasive intracranial pressure measurement or critically ill. There were significant differences between elevated and non-elevated intracranial pressure groups in stroke and trauma subjects.

Correlations between optic nerve sheath diameters measured using computed tomography and elevated intracranial pressure levels

BackgroundIncreased intracranial pressure (ICP) is commonly encountered in neurosurgery. Invasive external ventricular drainage is the gold standard ICP monitoring method. Higher ICPs enlarge the optic nerve sheath diameter (ONSD). Currently, few data describing correlations between ONSDs measured using computed tomography and ICPs. This manuscript describes a study that aimed to evaluate associations between the ICP and the ONSD measured using head CT, and to determine the ability of the ONSD to predict intracranial hypertension. ObjectivesWe aimed to study correlations between ONSDs and ICPs in patients who underwent ventricular shunting procedures, and to determine ONSD cutoff values that represent ICPs >15 mmHg and >20 mmHg, together with their sensitivities, specificities, negative predictive values (NPVs), and positive predictive values (PPVs). MethodsThe patients’ charts, operative notes, and brain computed tomography (CT) findings were reviewed retrospectively. The ONSDs were measured at 3 mm behind the globes on axial CT images from 102 patients who underwent ventricular shunting. Intraoperative ICP data were collected. ResultsA total of 102 patients were enrolled, comprising 93 (91.2%) without and 9 (8.8%) with traumatic brain injuries. Their mean age was 56.95 years (SD 17.01 years). The most common diagnoses were spontaneous intracerebral hemorrhages (ICH) with or without hydrocephalus (30 [29.4%]) and aneurysmal subarachnoid hemorrhages (SAH) (19 [18.6%]). The mean preoperative ONSD was 4.875 mm (SD 0.96 mm). The ONSD correlated significantly with the ICP levels (p < 0.001). An ONSD cutoff value of 5.125 mm predicted an ICP >15 mmHg (sensitivity: 94.7%; specificity: 90.6%; PPV: 85.7%; NPV: 96.7%). An ONSD cutoff value of 5.35 mm corresponded with an ICP >20 mmHg (sensitivity: 94.7%; specificity: 84.3%; PPV: 58.1 %; NPV: 98.6%). The ONSD decreased significantly to within the normal range (4.17 mm [standard deviation (SD) 0.60 mm]; p < 0.001) at 27 days (SD 14.70 days) postoperatively. ConclusionsCT-determined ONSDs correlated strongly with invasive ICP measurements. An ONSD of 5.35 mm, which corresponded with an ICP >20 mmHg, could become a noninvasive, alternative indicator for ICP level.

Optical Detection of Intracranial Pressure and Perfusion Changes in Neonates With Hydrocephalus

To demonstrate that a novel noninvasive index of intracranial pressure (ICP) derived from diffuse optics-based techniques is associated with intracranial hypertension. We compared noninvasive and invasive ICP measurements in infants with hydrocephalus. Infants born term and preterm were eligible for inclusion if clinically determined to require cerebrospinal fluid (CSF) diversion. Ventricular size was assessed preoperatively via ultrasound measurement of the fronto-occipital (FOR) and frontotemporal (FTHR) horn ratios. Invasive ICP was obtained at the time of surgical intervention with a manometer. Intracranial hypertension was defined as invasive ICP ≥15mmHg. Diffuse optical measurements of cerebral perfusion, oxygen extraction, and noninvasive ICP were performed preoperatively, intraoperatively, and postoperatively. Optical and ultrasound measures were compared with invasive ICP measurements, and their change in values after CSF diversion were obtained. We included 39 infants, 23 with intracranial hypertension. No group difference in ventricular size was found by FOR (P=.93) or FTHR (P=.76). Infants with intracranial hypertension had significantly higher noninvasive ICP (P=.02) and oxygen extraction fraction (OEF) (P=.01) compared with infants without intracranial hypertension. Increased cerebral blood flow (P=.005) and improved OEF (P<.001) after CSF diversion were observed only in infants with intracranial hypertension. Noninvasive diffuse optical measures (including a noninvasive ICP index) were associated withintracranial hypertension. The findings suggest that impaired perfusion from intracranial hypertension was independentof ventricular size. Hemodynamic evidence of the benefits of CSF diversion was seen in infants with intracranial hypertension. Noninvasive optical techniques hold promise for aiding the assessment of CSF diversion timing.

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

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 24h is indicative of intracranial hypertension is largely unknown. We assessed the feasibility of semi-automated CT segmentation in comparison with invasive ICP measurements. CT volumetry of the brain might provide ICP data when invasive monitoring is not possible or is undesirable. We identified 33 patients with TBI who received a CT scan at admission and ICP monitoring within 24h. 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. 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. 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.