Intracranial Pressure Thresholds Research Articles

Focal brain oxygen, blood flow, and intracranial pressure measurements in relation to optimal cerebral perfusion pressure.

Different paradigms for neurocritical care of traumatic brain injury (TBI) have emerged in conjunction with advanced neuromonitoring technologies and derived metrics. The priority for optimizing these metrics is not currently clear. The goal of this study was to determine whether achieving cerebral perfusion pressure (CPPopt) also improves other metrics like brain oxygenation and brain blood flow. The authors performed a retrospective analysis of high-frequency data from patients with TBI who were treated at a single center and who had partial pressure of brain oxygen (PbtO2) measurements and/or brain blood flow measurements, while also undergoing intracranial pressure (ICP) monitoring. CPPopt was not calculated or targeted during patient care, but was retrospectively computed, as was the difference between the observed CPP and CPPopt. A total of 22 patients with ICP, PbtO2, and/or brain blood flow monitoring were included in the analysis, and 245.7 days of measurements obtained every second were analyzed including 6,748,866 PbtO2 measurements, 3,296,405 blood flow measurements, and 10,264,770 ICP measurements. The data obtained every second were averaged by minute for analysis. In summative data, PbtO2 measurements peaked near CPPopt and were not improved above CPPopt. Blood flow measurements remained stable near CPPopt, decreased below it, and increased when CPP exceeded CPPopt. ICP decreased linearly with CPP without a specific relationship with CPPopt. In an inverse analysis, the percentage of CPP values at CPPopt, although significantly higher on the favorable side of contemporary treatment thresholds of PbtO2, ICP, and blood flow, was not found to be strongly correlated with the mean values of the physiological measurements obtained every minute (r = 0.27, r = 0.11, and r = 0.47 for ICP, PbtO2, and blood flow, respectively; p < 0.0001). Although CPPopt was not targeted in the patients in this study, CPPopt was a physiologically significant value based on concurrent measurements of PbtO2 and blood flow. In summative data, achievement of CPPopt was associated with optimized PbtO2 and blood flow. Conversely, the correlation between achievement of CPPopt and the mean measurement value was not strong, strengthening the significance of CPPopt. In individual patients, achieving CPPopt is not always associated with optimal PbtO2 or blood flow. Further research should explore these relationships in treatment paradigms that specifically target CPPopt. These data do not support the premise that targeting and achieving CPPopt obviates the need for concurrent PbtO2 and blood flow monitoring. Although these data suggest that targeting CPPopt may be an appropriate initial treatment strategy, they do not provide evidence that CPPopt should be targeted with highest priority.

Sex differences in the diagnostic value of optic nerve sheath diameter for assessing intracranial pressure

The optic nerve sheath diameter (ONSD) can predict elevated intracranial pressure (ICP) but it is not known whether diagnostic characteristics differ between men and women. This observational study was performed at the Karolinska University Hospital in Sweden to assess sex differences in diagnostic accuracy for ONSD. We included 139 patients (65 women), unconscious and/or sedated, with invasive ICP monitoring. Commonly used ONSD derived measurements and associated ICP measurements were collected. Linear regression analyses were performed with ICP as dependent variable and ONSD as independent variable. Area under the receiver operator characteristics curve (AUROC) analyses were performed with a threshold for elevated ICP ≥ 20 mmHg. Analyses were stratified by sex. Optimal cut-offs and diagnostic characteristics were estimated. The ONSD was associated with ICP in women. The AUROCs in women ranged from 0.70 to 0.83. In men, the ONSD was not associated with ICP and none of the AUROCs were significantly larger than 0.5. This study suggests that ONSD is a useful predictor of ICP in women but may not be so in men. If this finding is verified in further studies, this would call for a re-evaluation of the usage and interpretation of ONSD to estimate ICP.

Prediction of Intracranial Pressure in Patients with an Aneurysmal Subarachnoid Hemorrhage Using Optic Nerve Sheath Diameter via Explainable Predictive Modeling.

Background: The objective of this investigation was to formulate a model for predicting intracranial pressure (ICP) by utilizing optic nerve sheath diameter (ONSD) during endovascular treatment for an aneurysmal subarachnoid hemorrhage (aSAH), incorporating explainable predictive modeling. Methods: ONSD measurements were conducted using a handheld ultrasonography device during the course of endovascular treatment (n = 126, mean age 58.82 ± 14.86 years, and female ratio 67.46%). The optimal ONSD threshold associated with an increased ICP was determined. Additionally, the association between ONSD and ICP was validated through the application of a linear regression machine learning model. The correlation between ICP and various factors was explored through the modeling. Results: With an ICP threshold set at 20 cmH2O, 82 patients manifested an increased ICP, with a corresponding ONSD of 0.545 ± 0.08 cm. Similarly, with an ICP threshold set at 25 cmH2O, 44 patients demonstrated an increased ICP, with a cutoff ONSD of 0.553 cm. Conclusions: We revealed a robust correlation between ICP and ONSD. ONSD exhibited a significant association and demonstrated potential as a predictor of ICP in patients with an ICP ≥ 25 cmH2O. The findings suggest its potential as a valuable index in clinical practice, proposing a reference value of ONSD for increased ICP in the institution.

Evaluating the utility of quantitative pupillometry in a neuro-critical care setting for the monitoring of intracranial pressure: A prospective cohort study

IntroductionAssessment of the pupillary light reflex (PLR) is key in intensive care monitoring of neurosurgical patients, particularly for monitoring intracranial pressure (ICP). Quantitative pupillometry using a handheld pupillometer is a reliable method for PLR assessment. However, many variables are derived from such devices. We therefore aimed to assess the performance of these variables at monitoring ICP. MethodsSedated patients admitted to neurocritical care in a tertiary neurosurgical centre with invasive ICP monitoring were included. Hourly measurement of ICP, subjective pupillometry (SP) using a pen torch device, and quantitative pupillometry (QP) using a handheld pupillometer were performed. Results561 paired ICP, SP and QP pupillary observations from nine patients were obtained (1122 total pupillary observations). SP and QP had a moderate concordance for pupillary size (κ=0.62). SP performed poorly at detecting pupillary size changes (sensitivity=24%). In 40 (3.6%) observations, SP failed to detect a pupillary response whereas QP did. Moderate correlations with ICP were detected for maximum constriction velocity (MCV), dilation velocity (DV), and percentage change in pupillary diameter (%C). Discriminatory ability at an ICP threshold of >22 mmHg was moderate for MCV (AUC=0.631), DV (AUC=0.616), %C (AUC=0.602), and pupillary maximum size (AUC=0.625). ConclusionQP is superior to SP at monitoring pupillary reactivity and changes to pupillary size. Although effect sizes were moderate to weak across assessed variables, our data indicates MCV and %C as the most sensitive variables for monitoring ICP. Further study is required to validate these findings and to establish normal range cut-offs for clinical use.

Correlation between early intracranial pressure and cerebral perfusion pressure with 28-day intensive care unit mortality in patients with hemorrhagic stroke.

Hemorrhagic stroke may cause changes in intracranial pressure (ICP) and cerebral perfusion pressure (CPP), which may influence the prognosis of patients. The aim of this study was to investigate the relationship between early ICP, CPP, and 28-day mortality in the intensive care unit (ICU) of patients with hemorrhagic stroke. A retrospective study was performed using the Medical Information Mart for Intensive Care (MIMIC-IV) and the eICU Collaborative Research Database (eICU-CRD), including hemorrhagic stroke patients in the ICU with recorded ICP monitoring. The median values of ICP and CPP were collected for the first 24 h of the patient's monitoring. The primary outcome was 28-day ICU mortality. Multivariable Cox proportional hazards models were used to analyze the relationship between ICP, CPP, and 28-day ICU mortality. Restricted cubic regression splines were used to analyze nonlinear relationships. The study included 837 patients with a 28-day ICU mortality rate of 19.4%. Multivariable analysis revealed a significant correlation between early ICP and 28-day ICU mortality (HR 1.08, 95% CI 1.04-1.12, p < 0.01), whereas early CPP showed no correlation with 28-day ICU mortality (HR 1.00, 95% CI 0.98-1.01, p = 0.57), with a correlation only evident when CPP < 60 mmHg (HR 1.99, 95% CI 1.14-3.48, p = 0.01). The study also identified an early ICP threshold of 16.5 mmHg. Early ICP shows a correlation with 28-day mortality in hemorrhagic stroke patients, with a potential intervention threshold of 16.5 mmHg. In contrast, early CPP showed no correlation with patient prognosis.

Critical ICP thresholds in relation to outcome: Is 22 mmHg really the answer?

PurposeIntensive care for patients with traumatic brain injury (TBI) aims, among other tasks, at avoiding high intracranial pressure (ICP), which is perceived to worsen motor and cognitive deficits and increase mortality. International recommendations for threshold values for ICP were increased from 20 to 22 mmHg in 2016 following the findings in a study by Sorrentino et al., which were based on an observational study of patients with TBI of averaged ICP values. We aimed to reproduce their approach and validate the findings in a separate cohort.MethodsThree hundred thirty-one patients with TBI were included and categorised according to survival/death and favourable/unfavourable outcome at 6 months (based on Glasgow Outcome Score—Extended of 6–8 and 1—5, respectively). Repeated chi-square tests of survival and death (or favourable and unfavourable outcome) vs. high and low ICP were conducted with discrimination between high and low ICP sets at increasing values (integers) between 10 and 35 mmHg, using the average ICP for the entire monitoring period. The ICP limit returning the highest chi-square score was assumed to be the threshold with best discriminative ability. This approach was repeated after stratification by sex, age, and initial Glasgow Coma Score (GCS).ResultsAn ICP limit of 18 mmHg was found for both mortality and unfavourable outcome for the entire cohort. The female and the low GCS subgroups both had threshold values of 18 mmHg; for all other subgroups, the threshold varied between 16 and 30 mmHg. According to a multiple logistic regression analysis, age, initial GCS, and average ICP are independently associated with mortality and outcome.ConclusionsUsing identical methods and closely comparable cohorts, the critical thresholds for ICP found in the study by Sorrentino et al. could not be reproduced.

Intracranial Pressure-Derived Cerebrovascular Reactivity Indices and Their Critical Thresholds: A Canadian High Resolution-Traumatic Brain Injury Validation Study.

Current neurointensive care guidelines recommend intracranial pressure (ICP) and cerebral perfusion pressure (CPP) centered management for moderate-severe traumatic brain injury (TBI) because of their demonstrated associations with patient outcome. Cerebrovascular reactivity metrics, such as the pressure reactivity index (PRx), pulse amplitude index (PAx), and RAC index, have also demonstrated significant prognostic capabilities with regard to outcome. However, critical thresholds for cerebrovascular reactivity indices have only been identified in two studies conducted at the same center. In this study, we aim to determine the critical thresholds of these metrics by leveraging a unique multi-center database. The study included a total of 354 patients from the CAnadian High-Resolution TBI (CAHR-TBI) Research Collaborative. Based on 6-month Glasgow Outcome Scores, patients were dichotomized into alive versus dead and favorable versus unfavorable. Chi-square values were then computed for incrementally increasing values of each physiological parameter of interest against outcome. The values that generated the greatest chi-squares for each parameter were considered to be the thresholds with the greatest outcome discriminatory capacity. To confirm that the identified thresholds provide prognostic utility, univariate and multivariable logistical regression analyses were performed adjusting for the International Mission for Prognosis and Analysis of Clinical Trials (IMPACT) variables. Through the chi-square analysis, a lower limit CPP threshold of 60 mm Hg and ICP thresholds of 18 mm Hg and 22 mm Hg were identified for both survival and favorable outcome predictions. For the cerebrovascular reactivity metrics, different thresholds were identified for the two outcome dichotomizations. For survival prediction, thresholds of 0.35, 0.25, and 0 were identified for PRx, PAx, and RAC, respectively. For favorable outcome prediction, thresholds of 0.325, 0.20, and 0.05 were found. Univariate logistical regression analysis demonstrated that the time spent above/below thresholds were associated with outcome. Further, multivariable logistical regression analysis found that percent time above/below the identified thresholds added additional variance to the IMPACT core model for predicting both survival and favorable outcome. In this study, we were able to validate the results of the previous two works as well as to reaffirm the ICP and CPP guidelines from the Brain Trauma Foundation (BTF) and the Seattle International Severe Traumatic Brain Injury Consensus Conference (SIBICC).

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

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

Associations between intracranial pressure thresholds and multimodal monitoring in acute traumatic neural injury: a scoping review

Current moderate/severe traumatic brain injury (TBI) guidelines suggest the use of an intracranial pressure (ICP) treatment threshold of 20 mmHg or 22 mmHg. Over the past decade, the use of various cerebral physiology monitoring devices has been incorporated into neurocritical care practice and termed "multimodal monitoring." Such modalities include those that monitor systemic hemodynamics, systemic and brain oxygenation, cerebral blood flow (CBF), cerebral autoregulation, electrophysiology, and cerebral metabolism. Given that the relationship between ICP and outcomes is not yet entirely understood, a comprehensive review of the literature on the associations between ICP thresholds and multimodal monitoring is still needed. We conducted a scoping review of the literature for studies that present an objective statistical association between ICP above/below threshold and any multimodal monitoring variable. MEDLINE, BIOSIS, Cochrane library, EMBASE, Global Health, and SCOPUS were searched from inception to July 2022 for relevant articles. Full-length, peer-reviewed, original works with a sample size of ≥50 moderate-severe TBI patients were included in this study. A total of 13 articles were deemed eligible for final inclusion. The included articles were significantly heterogenous in terms of their designs, demographics, and results, making it difficult to draw any definitive conclusions. No literature describing the association between guideline-based ICP thresholds and measures of brain electrophysiology, cerebral metabolism, or direct metrics of CBF was found. There is currently little literature that presents objective statistical associations between ICP thresholds and multimodal monitoring physiology. However, overall, the literature indicates that having ICP above guideline based thresholds is associated with increased blood pressure, increased cardiac decoupling, reduced parenchymal brain oxygen tension, and impaired cerebral autoregulation, with no association with CBF velocity within the therapeutic range of ICP. There was insufficient literature to comment on other multimodal monitoring measures.

Initial neurocritical care of severe traumatic brain injury: New paradigms and old challenges.

Early neurocritical care aims to ameliorate secondary traumatic brain injury (TBI) and improve neural salvage. Increased engagement of neurosurgeons in neurocritical care is warranted as daily briefings between the intensivist and the neurosurgeon are considered a quality indicator for TBI care. Hence, neurosurgeons should be aware of the latest evidence in the neurocritical care of severe TBI (sTBI). We conducted a narrative literature review of bibliographic databases (PubMed and Scopus) to examine recent research of sTBI. This review has several take-away messages. The concept of critical neuroworsening and its possible causes is discussed. Static thresholds of intracranial pressure (ICP) and cerebral perfusion pressure may not be optimal for all patients. The use of dynamic cerebrovascular reactivity indices such as the pressure reactivity index can facilitate individualized treatment decisions. The use of ICP monitoring to tailor treatment of intracranial hypertension (IHT) is not routinely feasible. Different guidelines have been formulated for different scenarios. Accordingly, we propose an integrated algorithm for ICP management in sTBI patients in different resource settings. Although hyperosmolar therapy and decompressive craniectomy are standard treatments for IHT, there is a lack high-quality evidence on how to use them. A discussion of the advantages and disadvantages of invasive ICP monitoring is included in the study. Addition of beta-blocker, anti-seizure, and anticoagulant medications to standardized management protocols (SMPs) should be considered with careful patient selection. Despite consolidated research efforts in the refinement of SMPs, there are still many unanswered questions and novel research opportunities for sTBI care.

Closure intracranial pressure is an objective intraoperative determinant of the adequacy of surgical decompression in traumatic acute subdural haematoma: a multicentre observational study.

Acute subdural haematoma (ASDH) is associated with severe traumatic brain injury and poor outcomes. Although guidelines exist for the decompression of ASDH, the question of adequate decompression remains unanswered. The authors examined the relationship of intracranial pressure (ICP) on closure with outcomes to determine its utility in the determination of adequate ASDH decompression. A multicentre retrospective review of 105 consecutive patients with ASDH who underwent decompressive surgery was performed. Receiver operating characteristic (ROC) analysis with internal validation was performed to determine an ICP threshold for the division of patients into the inadequate and good ICP groups. Multivariable analyses were performed for both inpatient and long-term outcomes. An ICP threshold of 10mmHg was identified with a 91.5% specificity, 45.7% sensitivity, and a positive and negative predictive value of 80.8% and 68.4%. There were 26 patients (24.8%) and 79 patients (75.2%) in the inadequate and good ICP groups, respectively. After adjustment, the inadequate ICP group was associated with increased postoperative usage of mannitol (OR 14.2, p < 0.001) and barbiturates (OR 150, p = 0.001). Inadequate ICP was also associated with increased inpatient mortality (OR 24.9, p < 0.001), and a lower rate of favourable MRS at 1year (OR 0.08, p = 0.008). The complication rate was similar amongst the groups. Closure ICP is a novel, objective, and actionable intraoperative biomarker that correlates with inpatient and long-term outcomes in ASDH. Various surgical manoeuvres can be undertaken to achieve this target safely. Large-scale prospective studies should be performed to validate this ICP threshold.

Group-based trajectory modeling of intracranial pressure in patients with acute brain injury: Results from multi-center ICUs, 2008-2019.

ObjectiveThe objective of the study was to characterize the longitudinal, dynamic intracranial pressure (ICP) trajectory in acute brain injury (ABI) patients admitted to intensive care unit (ICU) and explore whether it added sights over traditional thresholds in predicting outcomes.MethodsABI patients with ICP monitoring were identified from two public databases named Medical Information Mart for the Intensive Care (MIMIC)‐IV and eICU Collaborative Research Database (eICU‐CRD). Group‐based trajectory modeling (GBTM) was employed to identify 4‐h ICP trajectories in days 0–5 post‐ICU admission. Then, logistic regression was used to compare clinical outcomes across distinct groups. To further validate previously reported thresholds, we created the receiver operating characteristic (ROC) curve in our dataset.ResultsA total of 810 eligible patients were ultimately enrolled in the study. GBTM analyses generated 6 distinct ICP trajectories, differing in the initial ICP, evolution pattern, and number/proportion of spikes >20/22 mmHg. Compared with patients in “the highest, declined then rose” trajectory, those belonging to the “lowest, stable,” “low, stable,” and “medium, stable” ICP trajectories were at lower risks of 30‐day mortality (odds ratio [OR] 0.04; 95% confidence interval [CI] 0.01, 0.21), (OR 0.04; 95% CI 0.01, 0.19), (OR 0.08; 95% CI 0.01, 0.42), respectively. ROC analysis demonstrated an unfavorable result, for example, 30‐day mortality in total cohort: an area under the curve (AUC): 0.528, sensitivity: 0.11, and specificity: 0.94.ConclusionsThis study identified three ICP trajectories associated with elevated risk, three with reduced risks for mortality during ICU hospitalization. Notably, a fixed ICP threshold should not be applied to all kinds of patients. GBTM, a granular method for describing ICP evolution and their association with clinical outcomes, may add to the current knowledge in intracranial hypertension treatment.

Intracranial Pressure as an Objective Biomarker of Decompression Adequacy in Large Territory Infarction: A Multicenter Observational Study

BackgroundDecompressive craniectomy (DC) improves the survival and functional outcomes in patients with malignant cerebral infarction. Currently, there are no objective intraoperative markers that indicates adequate decompression. We hypothesise that closure intracranial pressure (ICP) correlates with postoperative outcomes.MethodsThis is a multicentre retrospective review of all 75 DCs performed for malignant cerebral infarction. The patients were divided into inadequate ICP (iICP) and good ICP (gICP) groups based on a suitable ICP threshold determined with tiered receiver operating characteristic and association analysis. Multivariable logistic regression was performed for various postoperative outcomes.ResultsAn ICP threshold of 7 mmHg was determined, with 36 patients (48.0%) and 39 patients (52.0%) in the iICP and gICP group, respectively. After adjustment, postoperative osmotherapy usage was more likely in the iICP group (OR 6.32, p = 0.003), and when given, was given for a longer median duration (iICP, 4 days; gICP, 1 day, p = 0.003). There was no difference in complications amongst both groups. When an ICP threshold of 11 mmHg was applied, there was significant difference in the duration on ventilator (ICP ≥11 mmHg, 3–9 days, ICP <11 mmHg, 3–5 days, p = 0.023).ConclusionSurgical decompression works complementarily with postoperative medical therapy to manage progressive cerebral edema in malignant cerebral infarctions. This is a retrospective study which showed that closure ICP, a novel objective intraoperative biomarker, is able to guide the adequacy of DC in this condition. Various surgical manoeuvres can be performed to ensure that this surgical aim is accomplished.

Elevated Intracranial Pressure in Patients with Craniosynostosis by Optical Coherence Tomography.

Craniosynostosis may lead to elevated intracranial pressure, which may be implicated with impaired neurocognitive development. However, accurately measuring intracranial pressure is challenging, and patterns in craniosynostosis patients are poorly characterized. Spectral-domain optical coherence tomography may enable noninvasive assessment of intracranial pressure in pediatric patients with craniosynostosis. Pediatric patients with craniosynostosis undergoing surgical intervention between 2014 and 2019 prospectively underwent optical coherence tomographic evaluation. Intracranial pressure was directly measured intraoperatively in a subset of cases. Optical coherence tomographic parameters were compared to directly measured intracranial pressure and used for pattern assessment. Optical coherence tomography was performed in 158 subjects, among which 42 underwent direct intracranial pressure measurement during an initial cranial procedure. Maximal retinal nerve fiber layer thickness, maximal retinal thickness, and maximal anterior projection optical coherence tomographic parameters were positively correlated with intracranial pressure (p ≤ 0.001), with all parameters showing significantly higher values in patients with intracranial pressure thresholds of 15 mmHg (p < 0.001) and 20 mmHg (p ≤ 0.007). Patients with maximal retinal nerve fiber layer thickness and maximal anterior projection exceeding set thresholds in optical coherence tomography of either eye demonstrated 77.3 percent sensitivity and 95.0 percent specificity for detecting intracranial pressure above 15 mmHg, and 90.0 percent sensitivity and 81.3 percent specificity for detecting intracranial pressure above 20 mmHg. Patients with associated syndromes or multiple suture involvement and patients aged 9 months or older were significantly more likely to have elevated intracranial pressure above 15 mmHg (p ≤ 0.030) and above 20 mmHg (p ≤ 0.035). Spectral-domain optical coherence tomography can noninvasively detect elevated intracranial pressure in patients with craniosynostosis with reliable sensitivity and specificity. This technology may help guide decisions about the appropriate type and timing of surgical treatment. Diagnostic, I.

Decompressive Craniectomy After Traumatic Brain Injury: Incorporating Patient Preferences into Decision-Making

Decompressive craniectomy (DC) is highly effective in relieving intracranial hypertension; however, patient selection, intracranial pressure threshold, timing, and long-term functional outcomes are all subject to controversy. Recently, recommendations were made to update the Brain Trauma Foundation guidelines in regards to the use of DC based on the DECRA (Decompressive Craniectomy in Patients with Severe Traumatic Brain Injury) and RESCUEicp (Trial of Decompressive Craniectomy for Traumatic Intracranial Hypertension) clinical trials. Neither the updated recommendations, nor the aforementioned trials, provide a method in incorporating individualized patient or surrogate decision-maker preferences into decision making. In this manuscript, we aimed to redress the gap of not incorporating patient preferences in such value-laden decision making as in the case of DC for refractory post-traumatic intracranial hypertension. We proposed a decision aid based on principles of Decision Theory, and specifically of Expected Utility Theory. We showed that 1) early secondary DC as studied in DECRA, and based on the 1-year outcome data, is associated with decreased expected utility for all possible preference rankings of outcomes; and 2) recommending a late secondary DC versus tier-3 medical therapy, as studied in RESCUEicp, should be informed by individualized patient preference rankings of outcomes as elicited via shared decision-making. The 1-year outcomes from DECRA and RESCUEicp have served as the basis for updated guidelines. However, unaided interpretation of trial data may not be adequate for individualized decision-making; we suggest that the latter can be significantly supported by decision aids such as the one described here and based on expected utility theory.

The Relationships Among Transverse Sinus Stenosis Measured by CT Venography, Venous Trans-stenotic Pressure Gradient and Intracranial Pressure in Patients With Unilateral Venous Pulsatile Tinnitus.

ObjectivesTo assess a non-invasive means of predicting a venous trans-stenotic pressure gradient (TPG) and intracranial pressure (ICP) as opposed to invasive examinations in unilateral venous pulsatile tinnitus (PT) patients.MethodsThirty patients with unilateral venous PT who presented symptomatic-sided transverse sinus stenosis (TSS) on computed tomography venography (CTV), ipsilateral TPG measured by digital subtraction angiography (DSA) and cerebrospinal fluid (CSF) pressure measured by lumbar puncture were included. The ratio of TSS was calculated by dividing the cross-sectional areas of the maximal stenosed transverse sinus by that of the adjacent normal transverse sinus on CTV. The correlations among and predictive values of TSS, TPG, and ICP were analyzed.ResultsIn patients with unilateral venous PT, the symptomatic-sided and average bilateral TSS values were 78 ± 11 and 77 ± 9%; ICP, 230.50 ± 55.75 mmH2O; and the TPG, 9.51 ± 5.76 mmHg. The symptomatic-sided TSS was linearly and positively correlated with TPG (R2 = 0.400), and the symptomatic-sided and bilateral average TSS both showed weak correlations with ICP (R2 = 0.288, R′2 = 0.156). When the degree of TSS increased by 10%, the TPG and ICP increased by approximately 3.3 mmHg and 25.8 mmH2O, respectively. The receiver operating characteristic curve showed the optimal threshold of ipsilateral TSS for a positive TPG was 0.75, while TSS had no significant predictive value for ICP (p > 0.05). TPG and ICP also exhibited a linear positive correlation (R2 = 0.552). When ICP increased by 10 mmH2O, the TPG increased by approximately 0.77 mmHg, and the optimal threshold of ICP for a positive TPG was 227.5.ConclusionTSS, TPG, and ICP are interrelated. TSS measured by CTV can predict TPG in patients with unilateral venous PT.

Abstract P447: Intracranial Pressure and Cerebral Perfusion Pressure Monitoring in Spontaneous Intracranial Hemorrhage: A Secondary Analysis of the Mistie III Trial

Introduction: Intracerebral hemorrhage (ICH) management guidelines recommend maintaining intracranial pressure (ICP) &lt;20 and cerebral perfusion pressure (CPP) between 50-70 mmHg. We did subgroup analyses of MISTIE III trial to explore whether minimally invasive surgery (MIS) improves ICP or CPP and whether thresholds are associated with long term outcomes. Methods: MISTIE III was a randomized clinical trial including 499 patients with spontaneous ICH randomized to MIS+Alteplase or standard medical care (SMC). Primary outcomes were any threshold event of ICP &gt;20 and CPP &lt;60/70 mmHg. Secondary outcomes were poor modified Rankin Scale at one year and mortality at 30/365 days. We used multivariable models to investigate factors associated with ICP/CPP events and outcomes. Results: Of 72 patients with ICP monitored for median 92 (72-96) hours, 31 (43.1%) had at least one ICP reading &gt;20 and 52/35 (72.2/34.7%) had at least one CPP reading &lt;70/60 mmHg. Lower intraventricular hemorrhage volume and SMC group were associated with having any ICP threshold event &gt;20 and CPP event &lt;70 mmHg whereas CPP&lt;60 mmHg was associated with end of treatment (EOT) ICH volume, hydrocephalus on diagnostic CT and no prior antiplatelet agent use. On adjusted analyses, percentage of ICP readings &gt;20 were significantly less likely in patients undergoing MIS vs SMC (Coefficient -0.79, 95% Confidence Interval [CI] [(-)1.46-(-)0.11]; p=0.02). Percentage of CPP readings &lt;70 were significantly less frequent in MIS group (Coefficient -1.59 [(-)2.58-(-)0.59]; p=0.002). Patients who underwent successful MIS with EOT ICH volume &lt;15mL also had significantly lower percentage of readings at ICP&lt;20 (p=0.02), and CPP&lt;70 (p=0.05). Lower percentage of CPP readings &lt;60 mmHg was independently associated with lower mortality at 30 and 365 days (p=0.02 and 0.04) and CPP &lt;70 was associated with lower one-year mortality (p=0.04). There were no significant associations with one-year functional outcome. Conclusion: Elevated ICP and inadequate CPP are not infrequent during ICP monitoring for large ICH. Burden of low CPP events predict higher short and long term mortality, but not functional outcomes. CPP may be more significant than ICP. MIS appears to mitigate ICP and CPP threshold events.

Autonomic Nervous System Activity during Refractory Rise in Intracranial Pressure.

Refractory intracranial hypertension (RIH) is a dramatic increase in intracranial pressure (ICP) that cannot be controlled by treatment. Recent reports suggest that the autonomic nervous system (ANS) activity may be altered during changes in ICP. Our study aimed to assess ANS activity during RIH and the causal relationship between rising in ICP and autonomic activity. We reviewed retrospectively 24 multicenter (Cambridge, Tromso, Berlin) patients in whom RIH developed as a pre-terminal event after acute brain injury (ABI). They were monitored with ICP, arterial blood pressure (ABP), and electrocardiography (ECG) using ICM+ software. Parameters reflecting autonomic activity were computed in time and frequency domain through the measurement of heart rate variability (HRV) and baroreflex sensitivity (BRS). Our results demonstrated that a rise in ICP was associated to a significant rise in HRV and BRS with a higher significance level in the high-frequency HRV (p < 0.001). This increase was followed by a significant decrease in HRV and BRS above the upper-breakpoint of ICP where ICP pulse-amplitude starts to decrease whereas the mean ICP continues to rise. Temporality measured with a Granger test suggests a causal relationship from ICP to ANS. The above results suggest that a rise in ICP interacts with ANS activity, mainly interfacing with the parasympathetic-system. The ANS seems to react to the rise in ICP with a response possibly focused on maintaining the cerebrovascular homeostasis. This happens until the critical threshold of ICP is reached above which the ANS variables collapse, probably because of low perfusion of the brain and the central autonomic network.

Temporal Dynamics of ICP, CPP, PRx, and CPPopt in High-Grade Aneurysmal Subarachnoid Hemorrhage and the Relation to Clinical Outcome

BackgroundHigh intracranial pressure (ICP) and low cerebral perfusion pressure (CPP) may induce secondary brain injury following aneurysmal subarachnoid hemorrhage (aSAH). In the current study, we aimed to determine the temporal incidence of insults above/below certain ICP/CPP thresholds, the role of pressure autoregulation in CPP management (PRx and CPPopt), and the relation to clinical outcome.MethodsIn this retrospective study, 242 patients were included with aSAH, who were treated in the neurointensive care unit, Uppsala University Hospital, Sweden, 2008–2018, with ICP monitoring the first 10 days post-ictus. Data from ICP, pressure autoregulation (PRx), CPP, and CPPopt (the CPP with the lowest/optimal PRx) were analyzed the first 10 days. The percentage of good monitoring time (GMT) above/below various ICP and CPP thresholds was calculated, e.g., ICP > 20 mm Hg (%), CPP < 60 mm Hg (%), and ∆CPPopt (CPP–CPPopt) < − 10 mm Hg (%).ResultsOf the 242 patients, 63 (26%) had favorable (GOS-E 5–8) and 179 (74%) had unfavorable (GOS-E 1–4) outcome at 12 months. Higher proportion (GMT) of ICP insults above 20 mm Hg was most common the first 3 days post-ictus and was then independently associated with unfavorable outcome. CPP gradually increased throughout the 10 days post-ictus, and higher proportion of GMT with CPP < 90 mm Hg was independently associated with unfavorable outcome in the late vasospasm phase (days 6.5–10). PRx was above 0 throughout the 10 days and deteriorated in the late vasospasm phase. Higher values were then independently associated with unfavorable outcome. There was no difference in GMT of CPP deviations from CPPopt between the outcome groups.ConclusionsAvoiding intracranial hypertension early and maintaining a high CPP in the vasospasm phase when the pressure autoregulation is most disturbed may improve clinical outcome after aSAH.

Impact of duration and magnitude of raised intracranial pressure on outcome after severe traumatic brain injury: A CENTER-TBI high-resolution group study.

Magnitude of intracranial pressure (ICP) elevations and their duration have been associated with worse outcomes in patients with traumatic brain injuries (TBI), however published thresholds for injury vary and uncertainty about these levels has received relatively little attention. In this study, we have analyzed high-resolution ICP monitoring data in 227 adult patients in the CENTER-TBI dataset. Our aim was to identify thresholds of ICP intensity and duration associated with worse outcome, and to evaluate the uncertainty in any such thresholds. We present ICP intensity and duration plots to visualize the relationship between ICP events and outcome. We also introduced a novel bootstrap technique to evaluate uncertainty of the equipoise line. We found that an intensity threshold of 18 ± 4 mmHg (2 standard deviations) was associated with worse outcomes in this cohort. In contrast, the uncertainty in what duration is associated with harm was larger, and safe durations were found to be population dependent. The pressure and time dose (PTD) was also calculated as area under the curve above thresholds of ICP. A relationship between PTD and mortality could be established, as well as for unfavourable outcome. This relationship remained valid for mortality but not unfavourable outcome after adjusting for IMPACT core variables and maximum therapy intensity level. Importantly, during periods of impaired autoregulation (defined as pressure reactivity index (PRx)>0.3) ICP events were associated with worse outcomes for nearly all durations and ICP levels in this cohort and there was a stronger relationship between outcome and PTD. Whilst caution should be exercised in ascribing causation in observational analyses, these results suggest intracranial hypertension is poorly tolerated in the presence of impaired autoregulation. ICP level guidelines may need to be revised in the future taking into account cerebrovascular autoregulation status considered jointly with ICP levels.