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

PURPOSE: Individuals with TBI are at risk of intracranial hypertension (ICH), and monitoring of intracranial pressure (ICP) is usually indicated. However, despite many new noninvasive devices, none is sufficiently accurate and effective for application in clinical practice, particularly in the management of TBIs. This study aimed to compare the noninvasive Brain4Care system (nICP) with invasive ICP (iICP) curve parameters in their ability to predict ICH and functional prognosis in severe TBI. METHODS: Observational, descriptive-analytical, and prospective study of 22 patients between 2018 and 2021, simultaneously monitored with nICP and iICP. The independent variables evaluated were the presence of ICH and functional prognoses. The dependent variables were the P2/P1 pressure ratio metrics, time to peak (TTP), and TTP × P2/P1. RESULTS: We found a good nonlinear correlation between iICP and nICP waveforms, despite a moderate Pearson's linear correlation. The noninvasive parameters of P2/P1, P2/P1 × TTP, and TTP were not associated with outcomes or ICH. The nICP P2/P1 ratio showed sensitivity/specificity/accuracy (%) of 100/0/56.3, respectively for 1-month outcomes and 77.8/22.2/50 for 6-month outcomes. The nICP TTP ratio had values of 100/0/56.3 for 1-month and 99.9/42.9/72.2 for 6-month outcomes. The nICP P2/P1 × TTP values were 100/0/56.3 for 1-month outcomes and 81.8/28.6/61.1 for 6-month outcomes. CONCLUSION: Brain4Care's noninvasive method showed low specificity and accuracy and cannot be used as the sole means of monitoring ICP in patients with severe TBI. Future studies with a larger sample of patients with P2 > P1 and new nICP curve parameters are warranted.

Creatinine Clearance in Acute Brain Injury: A Comparison of Methods.

BACKGROUND: Currently, the measurement of glomerular filtration rate is very complex and costly, so its daily evaluation is performed using endogenous markers, of which creatinine is the most frequently used. It allows the estimation of glomerular filtration rate by means of its clearance or by formulas based on its serum and urine concentration. Augmented renal clearance (ARC) is frequent among critically ill patients and is defined as creatinine clearance (CrCl) > 130 ml/min/1.73 m2. The aim of this study was to compare measured CrCl (MCC) and estimated CrCl obtained with the Cockcroft-Gault formula (CG), the Modification of Diet in Renal Disease Study equation (MDRD), and the Chronic Kidney Disease Epidemiology Collaboration formula (CKD-EPI) in patients with severe traumatic brain injury and nontraumatic subarachnoid hemorrhage. The second aim was to assess the incidence of ARC in this population of neurocritical patients. METHODS: This was a prospective, observational, single center study from a cohort of 74 patients admitted to the neurocritical intensive care unit due to traumatic brain injury or subarachnoid hemorrhage. Serum creatinine (at 7 a.m.) and a 6-h urine collection were analyzed, and CrCl was measured and estimated by using CG, MDRD, and CKD-EPI. The intraclass correlation coefficient (ICC) was evaluated for each pair, and Bland-Altman plots were used to assess clinical significance. RESULTS: Among 74 patients, the median age was 53 (interquartile range [IQR] 36-65), and the median Glasgow Coma Scale score at admission was 6. The median MCC at admission was 176 (IQR 135-214). The medians of CG, MDRD and CKD-EPI were, respectively, 129 ml/min/1.73 m2 (IQR 95-176), 158 (IQR 115-202), and 116 (97-132). An ICC was applied to evaluate the correlation between MCC and estimated methods and showed a weak correlation between MCC and estimated CrCl obtained with the three different methods. The strongest ICC statistical correlation was found between MCC and MDRD, and the weakest correlation was found between MCC and CKD-EPI. Bland-Altman plots showed that differences between each pair were not clinically acceptable. ARC was present in 78% of measurements, using MCC. A weak correlation was observed between MCC and calculated CrCl. CG, MDRD, and CKD-EPI overestimated MCC when MCC ≤ 130 ml/min/1.73 m2 and underestimated it when MCC > 130 ml/min/1.73 m2. CONCLUSIONS: In this population, there was a weak statistical correlation between measured and estimated methods. In patients with ARC, formulas underestimated MCC. MCC should probably be the preferred methodology for renal function assessment in the clinical setting to better adjust drug dosage and guarantee drug effectiveness.

Monitoring cerebrovascular reactivity in pediatric traumatic brain injury: comparison of three methods.

PURPOSE: To study three different methods of monitoring cerebral autoregulation in children with severe traumatic brain injury. METHODS: Prospective cohort study of all children admitted to the pediatric intensive care unit at a university-affiliated hospital with severe TBI over a 4-year period to study three different methods of monitoring cerebral autoregulation: pressure-reactivity index (PRx), transcranial Doppler derived mean flow velocity index (Mx), and near-infrared spectroscopy derived cerebral oximetry index (COx). RESULTS: Twelve patients were included in the study, aged 5 months to 17 years old. An empirical regression analyzing dependence of PRx on cerebral perfusion pressure (CPP) displayed the classic U-shaped distribution, with low PRx values (< 0.3) reflecting intact auto-regulation, within the CPP range of 50-100 mmHg. The optimal CPP was 75-80 mmHg for PRx and COx. The correlation coefficients between the three indices were as follows: PRx vs Mx, r = 0.56; p < 0.0001; PRx vs COx, r = 0.16; p < 0.0001; and COx vs Mx, r = 0.15; p = 0.022. The mean PRx with a cutoff value of 0.3 predicted correctly long-term outcome (p = 0.015). CONCLUSIONS: PRx seems to be the most robust index to access cerebrovascular reactivity in children with TBI and has promising prognostic value. Optimal CPP calculation is feasible with PRx and COx.

Monitoring of Cerebrovascular Reactivity in Intracerebral Hemorrhage and Its Relation with Survival.

INTRODUCTION: Neuromonitoring analysis for intracerebral hemorrhage (ICH) is still rare, especially regarding vascular reactivity patterns. Our goal was to analyze neuromonitoring data and 28-day mortality for ICH patients. METHODS: Neuromonitoring records were retrospectively reviewed from a cohort of ICH patients admitted to a neurocritical care unit between 2013 and 2016. Variables considered were intracranial pressure (ICP), cerebral perfusion pressure (CPP), optimal CPP, and pressure reactivity index (PRx), as well as ICP dose, PRx dose, and time percentage above critical value (T%abv). Information regarding demographics, surgical drainage, external ventricular drain placement, and 28-day mortality was recorded. Statistical analysis was performed using the t-test and Kaplan-Meier curves. RESULTS: Forty-six patients were analyzed, with a mean of 263 ± 173 h of signal records and a median length of stay in the intensive care unit of 22 (interquartile range of 13) days. The mean age was 62.6 ± 11.8 years old, and 24 (52%) of the patients were male. Patients who died within 28 day (37.0%) had significantly higher mean ICP, PRx, ICP dose, PRx dose, and T%abv. Although their mean ICP was under 20 mmHg, they presented PRx > 0.25, indicating impaired cerebrovascular reactivity (0.30 ± 0.26). Also, patients with PRx > 0.25 had a lower survival rate, with a proportion of 14% at 28 days, as opposed to 85% of those with PRx < 0.25 (p < 0.001). CONCLUSION: The data suggest that autoregulation indexes are associated with 28-day mortality for ICH patients.

Brain Multimodal Monitoring in Severe Acute Brain Injury: Is It Relevant to Patient Outcome and Mortality?

INTRODUCTION: Advanced multimodal monitoring (MMM) of the brain is recommended as a tool to manage severe acute brain injury in intensive care units (ICUs) and prevent secondary lesions. The aim of this study was to determine if MMM has implications for patient outcome and mortality. METHODS: We analyzed data on 389 patients admitted with a subarachnoid hemorrhage (SAH) or traumatic brain injury (TBI) to two general ICUs and one neurocritical care ICU (NCCU) between March 2014 and October 2016, and their subsequent outcomes. RESULTS: The study population consisted of 259 males and 130 females. Group 1, which comprised 69 patients with MMM admitted to the NCCU, was compared with group 2, which comprised patients managed without MMM. With the exceptions of the Simplified Acute Physiology Score (SAPS II) and Glasgow Coma Scale (GCS) scores, there were no differences between the two groups. Group 1 had significantly better outcomes at ICU discharge, at 28 days, and at 3 months, and also had a lower mortality rate (P < 0.05). When outcomes were adjusted for SAPS II scores, patients who had MMM had better outcomes (odds ratios 0.215 at ICU discharge, 0.234 at 28 days, 0.338 at 3 months, and 0.474 at 6 months) but no difference in mortality. CONCLUSION: Use of MMM in patients with SAH or TBI is associated with better outcomes and should be considered in the management of these patients.

Comparison of Waveforms Between Noninvasive and Invasive Monitoring of Intracranial Pressure.

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

Plateau Waves of Intracranial Pressure and Multimodal Brain Monitoring.

The aim of this study was to describe multimodal brain monitoring characteristics during plateau waves of intracranial pressure (ICP) in patients with head injury, using ICM+ software for continuous recording. Plateau waves consist of an abrupt elevation of ICP above 40 mmHg for 5-20 min. This is a prospective observational study of patients with head injury who were admitted to a neurocritical care unit and who developed plateau waves. We analyzed 59 plateau waves that occurred in 8 of 18 patients (44 %). At the top of plateau waves arterial blood pressure remained almost constant, but cerebral perfusion pressure, cerebral blood flow, brain tissue oxygenation, and cerebral oximetry decreased. After plateau waves, patients with a previously better autoregulation status developed hyperemia, demonstrated by an increase in cerebral blood flow and brain oxygenation. Pressure and oxygen cerebrovascular reactivity indexes (pressure reactivity index and ORxshort) increased significantly during the plateau wave as a sign of disruption of autoregulation. Bedside multimodal brain monitoring is important to characterize increases in ICP and give differential diagnoses of plateau waves, as management of this phenomenon differs from that of regular ICP.

Validation of a New Minimally Invasive Intracranial Pressure Monitoring Method by Direct Comparison with an Invasive Technique.

In this chapter we present in vivo experiments with a new minimally invasive method of monitoring intracranial pressure (ICP). Strain gauge deformation sensors are externally glued onto the exposed skull. The signal from these sensors is amplified, filtered, and sent to a computer with appropriate software for analysis and data storage. Saline infusions into the spinal channel of rats were performed to produce ICP changes, and minimally invasive ICP and direct Codman intraparenchymal ICP were simultaneously acquired in six animals. The similarity between the invasive and minimally invasive methods in response to ICP increase was assessed using Pearson's correlation coefficient. It demonstrated good agreement between the two measures < r > = 0.8 ± 0.2, with a range of 0.31-0.99.

Validation of a New Noninvasive Intracranial Pressure Monitoring Method by Direct Comparison with an Invasive Technique.

The search for a completely noninvasive intracranial pressure (ICPni) monitoring technique capable of real-time digitalized monitoring is the Holy Grail of brain research. If available, it may facilitate many fundamental questions within the range of ample applications in neurosurgery, neurosciences and translational medicine, from pharmaceutical clinical trials, exercise physiology, and space applications. In this work we compare invasive measurements with noninvasive measurements obtained using the proposed new noninvasive method. Saline was infused into the spinal channel of seven rats to produce ICP changes and the simultaneous acquisition of both methods was performed. The similarity in the invasive and noninvasive methods of ICP monitoring was calculated using Pearson's correlation coefficients (r). Good agreement between measures < r > = 0.8 ± 0.2 with a range 0.28-0.96 was shown.

Clinical and Physiological Events That Contribute to the Success Rate of Finding "Optimal" Cerebral Perfusion Pressure in Severe Brain Trauma Patients.

OBJECTIVE: Recently, a concept of an individually targeted level of cerebral perfusion pressure that aims to restore impaired cerebral vasoreactivity has been advocated after traumatic brain injury. The relationship between cerebral perfusion pressure and pressure reactivity index normally is supposed to have a U-shape with its minimum interpreted as the value of "optimal" cerebral perfusion pressure. The aim of this study is to investigate the relation between the absence of the optimal cerebral perfusion pressure curve and physiological variables, clinical factors, and interventions. DESIGN: Retrospective analysis of prospectively collected data. SETTING: Neurocritical care units in two university centers. PATIENTS: Between May 2012 and December 2013, a total of 48 traumatic brain injury patients were studied with real-time annotation of predefined clinical events. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: All patients had continuous monitoring of arterial blood pressure, intracranial pressure, and cerebral perfusion pressure, with real-time calculations of pressure reactivity index and optimal cerebral perfusion pressure using ICM+ software (Cambridge Enterprise, University of Cambridge, Cambridge, UK). Selected clinical events were inserted on a daily basis, including changes in physiological variables, sedativeanalgesic drugs, vasoactive drugs, and medical/surgical therapies for intracranial hypertension. The collected data were divided into 4-hour periods, with the primary outcome being absence of the optimal cerebral perfusion pressure curve. For every period, mean values (± SDs) of arterial blood pressure, intracranial pressure, pressure reactivity index, and other physiological variables were calculated; clinical events were organized using predefined scales. In 28% of all 1,561 periods, an optimal cerebral perfusion pressure curve was absent. A generalized linear mixed model with binary logistic regression was fitted. Absence of slow arterial blood pressure waves (odds ratio, 2.7; p < 0.001), higher pressure reactivity index values (odds ratio, 2.9; p < 0.001), lower amount of sedative-analgesic drugs (odds ratio, 1.9; p = 0.03), higher vasoactive medication dose (odds ratio, 3.2; p = 0.02), no administration of maintenance neuromuscular blockers (odds ratio, 1.7; p < 0.01), and following decompressive craniectomy (odds ratio, 1.8; p < 0.01) were independently associated with optimal cerebral perfusion pressure curve absence. CONCLUSIONS: This study identified six factors that were independently associated with absence of optimal cerebral perfusion pressure curves.

Kidney-brain link in traumatic brain injury patients? A preliminary report.

BACKGROUND: Kidney hyperfiltration with augmented renal clearance is frequently observed in patients with traumatic brain injury. The aim of this study is to report preliminary findings about the relationship between brain autoregulation impairment, estimated kidney glomerular filtration rate and outcome in critically ill patients after severe traumatic brain injury. METHODS: Data collected from a cohort of 18 consecutive patients with severe traumatic brain injury managed with ICP monitoring in a Neurocritical Care Unit, were retrospectively analyzed. Early morning blood tests were performed for routine chemistry assessments and we analyzed creatinine and estimated creatinine clearance, osmolarity, and sodium. Daily norepinephrine dose, protein intake, and water balance were documented. Time average of brain monitoring data (intracranial pressure, cerebral perfusion pressure, and cerebrovascular reactivity pressure index--PRx) were calculated for 6 h before blood sample tests. Patient outcome was evaluated using Glasgow outcome scale at 6-month follow-up, considering nonfatal outcome if GOS ≥ 3 and fatal outcome if GOS < 3. Multiple linear regression models were used to study the crude and adjusted effects of the above variables on PRx throughout time. RESULTS: A total of 199 complete daily observations from 18 adult consecutive multiple trauma patients with severe traumatic brain injury were analyzed. At hospital admission, the median post-resuscitation Glasgow coma score was 6 (range 3-12), mean SAPSII score was 44.65 with predicted mortality of 36 %. Hospital mortality rate was 27 % and median GOS at 6 month after discharge was 3. Creatinine clearance (CrCl) was found to have a negative correlation with PRx (Pearson correlation--0.82), with statistically significant crude (p < 0.001) and adjusted (p = 0.001) effects. For each increase of 10 ml/min in CrCl (estimated either by the Cockcroft-Gault or by Modification of Diet in Renal Disease Study equations) a mean decrease in PRx of approximately 0.01 was expected. Amongst possible confounders only norepinephrine was shown to have a significant effect. Mean PRx value for outcome fatal status was greater than mean PRx for nonfatal status (p < 0.05), regardless of the model used for the CrCl estimation. CONCLUSIONS: Better cerebral autoregulation evaluated with cerebrovascular PRx is significantly correlated with augmented renal clearance in TBI patients and associates with better outcome.

Increased blood glucose is related to disturbed cerebrovascular pressure reactivity after traumatic brain injury.

BACKGROUND: Increased blood glucose and impaired pressure reactivity (PRx) after traumatic brain injury (TBI) are both known to correlate with unfavorable patient outcome. However, the relationship between these two variables is unknown. METHODS: To test the hypothesis that increased blood glucose leads to increased PRx, we retrospectively analyzed data from 86 traumatic brain injured patients admitted to the Neurocritical Care Unit. Data analyzed included arterial glucose concentration, intracranial pressure (ICP), cerebral perfusion pressure (CPP) and end-tidal CO2. PRx was calculated as the moving correlation coefficient between averaged (10 seconds) arterial blood pressure and ICP. One arterial glucose concentration and one time-aligned PRx value were obtained for each patient, during each day until the fifth day after ictus. RESULTS: Mean arterial glucose concentrations during the first 5 days since ictus were positively correlated with mean PRx (Pearson correlation coefficient = 0.25, p = 0.02). The correlation was strongest on the first day after injury (Pearson correlation coefficient = 0.47, p = 0.008). CONCLUSION: Our preliminary findings indicate that increased blood glucose may impair cerebrovascular reactivity, potentially contributing to a mechanistic link between increased blood glucose and poorer outcome after TBI.

Optimal Cerebral Perfusion Pressure Management at Bedside: A Single-Center Pilot Study.

BACKGROUND: Guidelines recommend cerebral perfusion pressure (CPP) values of 50-70 mmHg and intracranial pressure lower than 20 mmHg for the management of acute traumatic brain injury (TBI). However, adequate individual targets are still poorly addressed, since patients have different perfusion thresholds. Bedside assessment of cerebral autoregulation may help to optimize individual CPP-guided treatment. OBJECTIVE: To assess staff compliance and outcome impact of a new method of autoregulation-guided treatment (CPPopt) based on continuous evaluation of cerebrovascular reactivity (PRx). METHODS: Prospective pilot study of severe TBI adult patients managed with continuous multimodal brain monitoring in a single Neurocritical Care Unit (NCCU). Every minute CPPopt was automatically estimated, based on the previous 4-h window, as the CPP with the lowest PRx indicating the best cerebrovascular pressure reactivity. Patients were managed with CPPopt targets whenever possible and otherwise CPP was managed following general/international guidelines. In addition, other offline CPPopt estimates were calculated using cerebral oximetry (COx-CPPopt), brain tissue oxygenation (ORxs-CPPopt), and cerebral blood flow (CBFx-CPPopt). RESULTS: Eighteen patients with a total multimodal brain monitoring time of 5,520 h were enrolled. During the total monitoring period, 11 patients (61 %) had a CPPopt U-shaped curve, 5 patients (28 %) had either ascending or descending curves, and only 2 patients (11 %) had no fitted curve. Real CPP correlated significantly with calculated CPPopt (r = 0.83, p < 0.0001). Preserved autoregulation was associated with greater Glasgow coma score on admission (p = 0.01) and better outcome (p = 0.01). We demonstrated that patients with the larger discrepancy (>10 mm Hg) between real CPP and CPPopt more likely have had adverse outcome (p = 0.04). Comparison between CPPopt and the other estimates revealed similar limits of precision. The lowest bias (-0.1 mmHg) was obtained with COx-CPPopt (NIRS). CONCLUSION: Targeted individual CPP management at the bedside using cerebrovascular pressure reactivity seems feasible. Large deviation from CPPopt seems to be associated with adverse outcome. The COx-CPPopt methodology using non-invasive CO (NIRS) warrants further evaluation.

Pressures, flow, and brain oxygenation during plateau waves of intracranial pressure.

BACKGROUND: Plateau waves are common in traumatic brain injury. They constitute abrupt increases of intracranial pressure (ICP) above 40 mmHg associated with a decrease in cerebral perfusion pressure (CPP). The aim of this study was to describe plateau waves characteristics with multimodal brain monitoring in head injured patients admitted in neurocritical care. METHODS: Prospective observational study in 18 multiple trauma patients with head injury admitted to Neurocritical Care Unit of Hospital Sao Joao in Porto. Multimodal systemic and brain monitoring of primary variables [heart rate, arterial blood pressure, ICP, CPP, pulse amplitude, end tidal CO2, brain temperature, brain tissue oxygenation pressure, cerebral oximetry (CO) with transcutaneous near-infrared spectroscopy and cerebral blood flow (CBF)] and secondary variables related to cerebral compensatory reserve and cerebrovascular reactivity were supported by dedicated software ICM+ ( www.neurosurg.cam.ac.uk/icmplus) . The compiled data were analyzed in patients who developed plateau waves. RESULTS: In this study we identified 59 plateau waves that occurred in 44% of the patients (8/18). During plateau waves CBF, cerebrovascular resistance, CO, and brain tissue oxygenation decreased. The duration and magnitude of plateau waves were greater in patients with working cerebrovascular reactivity. After the end of plateau wave, a hyperemic response was recorded in 64% of cases with increase in CBF and brain oxygenation. The magnitude of hyperemia was associated with better autoregulation status and low oxygenation levels at baseline. CONCLUSIONS: Multimodal brain monitoring facilitates identification and understanding of intrinsic vascular brain phenomenon, such as plateau waves, and may help the adequate management of acute head injury at bed side.

Lung Injury Risk in Traumatic Brain Injury Managed With Optimal Cerebral Perfusion Pressure Guided-Therapy.

Introduction: Management of traumatic brain injury (TBI) has to counterbalance prevention of secondary brain injury without systemic complications, namely lung injury. The potential risk of developing acute respiratory distress syndrome (ARDS) leads to therapeutic decisions such as fluid balance restriction, high PEEP and other lung protective measures, that may conflict with neurologic outcome. In fact, low cerebral perfusion pressure (CPP) may induce secondary ischemic injury and mortality, but disproportionate high CPP may also increase morbidity and worse lung compliance and hypoxia with the risk of developing ARDS and fatal outcome. The evaluation of cerebral autoregulation at bedside and individualized (optimal CPP) CPPopt-guided therapy, may not only be a relevant measure to protect the brain, but also a safe measure to avoid systemic complications. Aim of the study: We aimed to study the safety of CPPopt-guided-therapy and the risk of secondary lung injury association with bad outcome. Methods and results: Single-center retrospective analysis of 92 severe TBI patients admitted to the Neurocritical Care Unit managed with CPPopt-guided-therapy by PRx (pressure reactivity index). During the first 10 days, we collected data from blood gas, ventilation and brain variables. Evolution along time was analyzed using linear mixed-effects regression models. 86% were male with mean age 53±21 years. 49% presented multiple trauma and 21% thoracic trauma. At hospital admission, median GCS was 7 and after 3-months GOS was 3. Monitoring data was CPP 86±7mmHg, CPP-CPPopt -2.8±10.2mmHg and PRx 0.03±0.19. The average PFratio (PaO2/FiO2) was 305±88 and driving pressure 15.9±3.5cmH2O. PFratio exhibited a significant quadratic dependence across time and PRx and driving pressure presented significant negative association with PFRatio. CPP and CPPopt did not present significant effect on PFratio (p=0.533; p=0.556). A significant positive association between outcome and the difference CPP-CPPopt was found. Conclusion: Management of TBI using CPPopt-guided-therapy was associated with better outcome and seems to be safe regarding the development of secondary lung injury.

Neurocritical care management supported by multimodal brain monitoring after acute brain injury.

OBJECTIVE: To evaluate the association between different intensive care units and levels of brain monitoring with outcomes in acute brain injury. METHODS: Patients with traumatic brain injury and subarachnoid hemorrhage admitted to intensive care units were included. Neurocritical care unit management was compared to general intensive care unit management. Patients managed with multimodal brain monitoring and optimal cerebral perfusion pressure were compared with general management patients. A good outcome was defined as a Glasgow outcome scale score of 4 or 5. RESULTS: Among 389 patients, 237 were admitted to the neurocritical care unit, and 152 were admitted to the general intensive care unit. Neurocritical care unit management patients had a lower risk of poor outcome (OR = 0.228). A subgroup of 69 patients with multimodal brain monitoring (G1) was compared with the remaining patients (G2). In the G1 and G2 groups, 59% versus 23% of patients, respectively, had a good outcome at intensive care unit discharge; 64% versus 31% had a good outcome at 28 days; 76% versus 50% had a good outcome at 3 months (p < 0.001); and 77% versus 58% had a good outcome at 6 months (p = 0.005). When outcomes were adjusted by SAPS II severity score, using good outcome as the dependent variable, the results were as follows: for G1 compared to G2, the OR was 4.607 at intensive care unit discharge (p < 0.001), 4.22 at 28 days (p = 0.001), 3.250 at 3 months (p = 0.001) and 2.529 at 6 months (p = 0.006). Patients with optimal cerebral perfusion pressure management (n = 127) had a better outcome at all points of evaluation. Mortality for those patients was significantly lower at 28 days (p = 0.001), 3 months (p < 0.001) and 6 months (p = 0.001). CONCLUSION: Multimodal brain monitoring with autoregulation and neurocritical care unit management were associated with better outcomes and should be considered after severe acute brain injury.

Multiscale Information Decomposition of Long Memory Processes: Application to Plateau Waves of Intracranial Pressure.

Traumatic Brain Injury (TBI) patients present high levels of physical stress, which in some situations can manifest as Plateau Wave (PW) episodes. This intense stress phenomenon can be evidenced by Heart Rate Variability (HRV). Thus, the multivariate and simultaneous analysis of cardio-cerebrovascular oscillations, involving the RR intervals, mean arterial pressure (MAP) and the amplitude of intracranial pressure (AMP), will be useful to understand the interconnections between body signals, allowing the interpretation of the combined activity of pathophysiological mechanisms. In this work, the multiscale representation of the Transfer Entropy (TE) and of its decomposition in the network of these three interacting processes is obtained, based on a Vector AutoRegressive Fractionally Integrated (VARFI) framework for Gaussian processes. This method allows to assess directed interactions and to quantify the information flow accounting for the simultaneous presence of short-term dynamics and long-range correlations. The results show that the baseline RR, but not MAP can provide information about the possibility of a PW arising. During PW, the long-term correlations highlight synergistic interactions between MAP and AMP processes on RR. The multiscale decomposition of the information along with the incorporation of the long term correlations allowed a better description of HRV during PW, highlighting the fact that the HRV mirrors this cerebrovascular phenomena.

The Importance of the Temporary Clip Removal Phase on Exposure to Hypoxia: On-Line Measurement of Temporal Lobe Oxygen Levels During Surgery for Middle Cerebral Artery Aneurysms.

BACKGROUND: Most studies concerning intraoperative temporary arterial occlusion overlook the period between and after clip placement. OBJECTIVE: To analyze the brain tissue oxygen tension through the process by which anterograde arterial blood flow is re-established after temporary clipping (TR). METHODS: In this prospective observational study, patients who presented to surgery for middle cerebral artery aneurysms were continuously monitored with ICM+, to obtain temporal (downstream) PbtO2 levels while M1 segment temporary clips were applied and removed. PbtO2 changes were analyzed and compared with the clipping phase, and measures of exposure to hypoxia were defined and assessed during both phases and used in a model to test the impact of extending them. RESULTS: Eighty-six TRs (20 patients) were recorded. The mean acquired amount of time per clip release (CR) event was 336.7 seconds. Temporary clip removal produced specifically shaped, highly individual PbtO2 curves that correlated with their corresponding clipping phase events but developing slower and less consistently. The CR phase was responsible for greater cumulative exposure to hypoxia than the clip application phase through the first and second minutes of each. In our model, the duration of the TR phase was mostly responsible for the total exposure to hypoxia, and longer CR phases reduced the mean exposure to hypoxia. CONCLUSION: During the clip removal phase, the brain tissue is still exposed to oxygen levels that are significantly below the baseline, reverting through a singular, dynamic process. Therefore, it must be regarded by surgeons with the same degree of attention as its counterpart.

Treatment of Cerebral Vasospasm With Continuous Intra-Arterial Nimodipine: A Case Report.

Aneurysmal subarachnoid hemorrhage (aSAH) is an important cause of death and disability, not just due to the initial event, but also because of the delayed complications. Cerebral vasospasm (CV) stands out as a serious complication, with high prevalence and association with permanent neurologic impairment. The treatment of CV includes non-invasive measures, like oral nimodipine and induced hypertension, but also invasive measures. Endovascular rescue treatment (ERT), with intra-arterial approaches, is linked with improvement of cerebral perfusion and thus associated with a better outcome. There are several, widely studied substances used in intra-arterial approaches, none showing clear superiority over the others. The main issues with these substances are the adverse systemic effects and the recurrence of CV, due to the short duration of action. Recent studies suggest that the use of continuous infusion of nimodipine, instead of bolus injection, may be related to better outcomes. The authors present a case of severe refractory vasospasm successfully treated with continuous intra-arterial nimodipine infusion. A 23-year-old female was admitted with aSAH, Fischer IV, and Hunt Hess 5. A brain CT scan showed an extensive and diffuse subarachnoid hemorrhage causing ill-defined hypodensity of the brainstem, bilateral hemispheric hypodensities, and alterations compatible with diffuse cerebral edema. The cerebral angiography revealed an aneurysm in the emergence of the left posterior communicating artery. Coil target detachment was performed with partial occlusion of the aneurysm. On the fifth day of hospitalization, transcranial Doppler (TCD) ultrasonography revealed hemodynamic signs suggestive of vasospasm. Cerebral angiography performed later showed vasospasm of the terminal segment of the left internal carotid artery (ICA) and the A1 and M1 segments. Intra-arterial verapamil was instilled, with angiographic control showing a slight increase in the caliber of these segments. On the 13th day of hospitalization, the patient maintained sonographic evidence of vasospasm in the left ICA and middle cerebral artery (MCA). Selective catheterization of the left ICA was performed with a microcatheter at the level of the petrous segment and continuous infusion of 1 mg/h intra-arterial nimodipine was started. A progressive improvement was documented after the beginning of the continuous infusion of intra-arterial nimodipine, which was maintained for five days, and angiographic control revealed improvement of vasospasm in the terminal portion of the ICA as well as in the A1 and M1 segments. Long-term continuous intra-arterial nimodipine infusion is a promising technique for the treatment of refractory CV and may be considered in selected cases.