Intracranial Pressure Variability Research Articles

Optic nerve sheath diameter and eyeball transverse diameter in severe head injury and its correlation with intracranial pressure

BackgroundGold standard for determining intracranial pressure (ICP), intraventricular catheter, is invasive with associated risks. Non-invasive investigations like magnetic resonance imaging and ultrasonography have demonstrated correlation between optic nerve sheath diameter (ONSD) and raised ICP. However, computed tomography (CT) is accessible and less operator-dependent. Literature shows variable results regarding correlations between ICP and ONSD on CT. The study aimed to investigate correlations between raised ICP and ONSD, eyeball transverse diameter (ETD), and ONSD/ETD ratios on CT scan(s) of severe head injuries. MethodsA retrospective review of a three-year prospectively-maintained database of severe traumatic head injuries in patients who had ICP measurements and CT scans was conducted. Glasgow Coma Score (GCS), ICP, ONSD 3 mm and 9 mm behind the globe, ETD, ONSD/ETD ratios, CT Marshall Grade, and Glasgow Outcome Score (GOS) were recorded. Statistical analysis assessed correlations between ICP and CT measurements. ResultsSeventy-four patients were assessed; mortality rate: 36.5 %. Assault (48.6 %) and pedestrian-vehicle collisions (21.6 %) were the most common mechanisms. CT Marshall Grade correlated significantly with 3 mm and 9 mm ONSD, ONSD/ETD ratios, GCS, and GCS motor score, which correlated significantly with GOS. No significant correlation was found between ICP and ONSD, ETD or ONSD/ETD ratios. Marshall Grade was not significantly associated with ICP measurements but correlated with injury severity. ConclusionsUnlike previous studies, our study not only investigated the correlation between ICP and single variables (ONSD and ETD) but also the ONSD/ETD ratios. No correlations were observed between raised ICP and ONSD, ETD or ONSD/ETD ratio on CT in neurotrauma patients.

The role of intracranial pressure variability as a predictor of intracranial hypertension and mortality in critically ill patients.

Intracranial pressure (ICP) monitoring is a widely utilized and essential tool for tracking neurosurgical patients, but there are limitations to the use of a solely ICP-based paradigm for guiding management. It has been suggested that ICP variability (ICPV), in addition to mean ICP, may be a useful predictor of neurological outcomes, as it represents an indirect measure of intact cerebral pressure autoregulation. However, the current literature regarding the applicability of ICPV shows conflicting associations between ICPV and mortality. Thus, the authors aimed to investigate the effect of ICPV on intracranial hypertensive episodes and mortality using the eICU Collaborative Research Database version 2.0. The authors extracted from the eICU database 1,815,676 ICP readings from 868 patients with neurosurgical conditions. ICPV was computed using two methods: the rolling standard deviation (RSD) and the absolute deviation from the rolling mean (DRM). An episode of intracranial hypertension was defined as at least 25 minutes of ICP > 22 mm Hg in any 30-minute window. The effects of mean ICPV on intracranial hypertension and mortality were computed using multivariate logistic regression. A recurrent neural network with long short-term memory was used for time-series predictions of ICP and ICPV to prognosticate future episodes of intracranial hypertension. A higher mean ICPV was significantly associated with intracranial hypertension using both ICPV definitions (RSD: aOR 2.82, 95% CI 2.07-3.90, p < 0.001; DRM: aOR 3.93, 95% CI 2.77-5.69, p < 0.001). ICPV was significantly associated with mortality in patients with intracranial hypertension (RSD: aOR 1.28, 95% CI 1.04-1.61, p = 0.026, DRM: aOR 1.39, 95% CI 1.10-1.79, p = 0.007). In the machine learning models, both definitions of ICPV achieved similarly good results, with the best F1 score of 0.685 ± 0.026 and an area under the curve of 0.980 ± 0.003 achieved with the DRM definition over 20 minutes. ICPV may be useful as an adjunct for the prognostication of intracranial hypertensive episodes and mortality in neurosurgical critical care as part of neuromonitoring. Further research on predicting future intracranial hypertensive episodes with ICPV may help clinicians react expediently to ICP changes in patients.

Intracranial and Blood Pressure Variability and In-Hospital Outcomes in Intracranial Device-Monitored Patients with Spontaneous Intracerebral Hemorrhage.

Spontaneous intracerebral hemorrhage (sICH) is a major health concern and has high mortality rates up to 52%. Despite a decrease in its incidence, fatality rates remain unchanged; understanding and preventing of factors associated with mortality and treatments for theseare needed. Blood pressure variability (BPV) has been shown to be a potential modifiable factor associated with clinical outcomes in patients with traumatic intracerebral hemorrhage and sICH. Few data are available on the effect of intracranial pressure (ICP) variability (ICPV) and outcomes in patients with sICH. The goal of our study was to investigate the association between ICPV and BPV during the first 24h of intensive care unit (ICU) admission and external ventricular drain (EVD) placement, and mortality in patients with sICH who were monitored with an EVD. We conducted a single-center retrospective study of adult patients admitted to an ICU with a diagnosis of sICH who required EVD placement during hospitalization. We excluded patients with ICH secondary to other pathological conditions such as trauma, underlying malignancy, or arteriovenous malformation. Blood pressure and ICP measurements were collected and recorded hourly during the first 24h of ICU admission and EVD placement, respectively. Measures of variability used were standard deviation (SD) and successive variation (SV). Primary outcome of interest was in-hospital mortality, and secondary outcomes were hematoma expansion and discharge home (a surrogate for good functional outcome at discharge). Descriptive statistics and multivariable logistic regressions were performed. We identified 179 patients with sICH who required EVD placement. Of these, 52 (29%) patients died, 121 (68%) patients had hematoma expansion, and 12 (7%) patients were discharged home. Patient's mean age (± SD) was 56 (± 14), and 87 (49%) were women. The mean opening ICP (± SD) was 21 (± 8) and median ICH score (interquartile range) was 2 (2-3). Multivariable logistic regression found an association between ICP-SV and ICP-SD and hematoma expansion (odds ratio 1.6 [1.03-2.30], p = 0.035 and odds ratio 0.77 [0.63-0.93] p = 0.009, respectively). Our study found an association between ICPV and hematoma expansion in patients with sICH monitored with an EVD. Measures of ICPV relating to rapid changes in ICP (ICP-SV) were associated with a higher odds of hematoma expansion, whereas measures relating to tight control of ICP (ICP-SD) were associated with a lower odds of hematoma expansion. One measure of BPV, sytolic blood pressure maximum-minimum (SBPmax-min), was found to be weakly associated with discharge home (a surrogate for good functional outcome at hospital discharge). More research is needed to support these findings.

The Role of Intracranial Pressure Variability as a Predictor for Intracranial Hypertension and Mortality in Critically Ill Patients

The Role of Intracranial Pressure Variability as a Predictor for Intracranial Hypertension and Mortality in Critically Ill Patients

Higher intracranial pressure variability is associated with lower cerebrovascular resistance in aneurysmal subarachnoid hemorrhage

Higher intracranial pressure variability (ICPV) has been associated with a more favorable cerebral energy metabolism, lower rate of delayed ischemic neurologic deficits, and more favorable outcome in aneurysmal subarachnoid hemorrhage (aSAH). We have hypothesized that higher ICPV partly reflects more compliant and active cerebral vessels. In this study, the aim was to further test this by investigating if higher ICPV was associated with lower cerebrovascular resistance (CVR) and higher cerebral blood flow (CBF) after aSAH. In this observational study, 147 aSAH patients were included, all of whom had been treated in the Neurointensive Care (NIC) Unit, Uppsala, Sweden, 2012–2020. They were required to have had ICP monitoring and at least one xenon-enhanced computed tomography (Xe-CT) scan to study cortical CBF within the first 2 weeks post-ictus. CVR was defined as the cerebral perfusion pressure in association with the Xe-CT scan divided by the concurrent CBF. ICPV was defined over three intervals: subminute (ICPV-1m), 30-min (ICPV-30m), and 4 h (ICPV-4h). The first 14 days were divided into early (days 1–3) and vasospasm phase (days 4–14). In the vasospasm phase, but not in the early phase, higher ICPV-4h (β = − 0.19, p < 0.05) was independently associated with a lower CVR in a multiple linear regression analysis and with a higher global cortical CBF (r = 0.19, p < 0.05) in a univariate analysis. ICPV-1m and ICPV-30m were not associated with CVR or CBF in any phase. This study corroborates the hypothesis that higher ICPV, at least in the 4-h interval, is favorable and may reflect more compliant and possibly more active cerebral vessels.

Intracranial Pressure Variability: A New Potential Metric of Cerebral Ischemia and Energy Metabolic Dysfunction in Aneurysmal Subarachnoid Hemorrhage?

It was recently reported that lower intracranial pressure variability (ICPV) is associated with delayed ischemic neurological deficits and unfavorable outcomes in patients with aneurysmal subarachnoid hemorrhage (aSAH). In this study, we aimed to determine whether lower ICPV also correlated with worse cerebral energy metabolism after aSAH. A total of 75 aSAH patients treated in the neurointensive care unit at Uppsala University Hospital, Sweden between 2008 and 2018 and with both intracranial pressure and cerebral microdialysis (MD) monitoring during the first 10 days after ictus were included in this retrospective study. ICPV was calculated with a bandpass filter limited to intracranial pressure slow waves with a wavelength of 55 to 15 seconds. Cerebral energy metabolites were measured hourly with MD. The monitoring period was divided into 3 phases; early (days 1 to 3), early vasospasm (days 4 to 6.5), and late vasospasm (days 6.5 to 10). Lower ICPV was associated with lower MD-glucose in the late vasospasm phase, lower MD-pyruvate in the early vasospasm phases, and higher MD-lactate-pyruvate ratio (LPR) in the early and late vasospasm phases. Lower ICPV was associated with poor cerebral substrate supply (LPR >25 and pyruvate <120 µM) rather than mitochondrial failure (LPR >25 and pyruvate >120 µM). There was no association between ICPV and delayed ischemic neurological deficit, but lower ICPV in both vasospasm phases correlated with unfavorable outcomes. Lower ICPV was associated with an increased risk for disturbed cerebral energy metabolism and worse clinical outcomes in aSAH patients, possibly explained by a vasospasm-related decrease in cerebral blood volume dynamics and cerebral ischemia.

Transient Increases in Intracranial Pressure After Soccer Heading

Objective To evaluate whether intracranial pressure (ICP) continued to stay elevated in trained athletes 24 hours after soccer heading. Methods Eight male subjects (21.7±1.7 years) were recruited from the UCSD soccer team to participate in the study. Baseline ICP and cardiovascular variables were recorded, and measurements were repeated after subjects underwent the heading trial. Acoustical evoked tympanic membrane displacement was used to estimate ICP, where decreasing volume displacement (-Vm) is associated with an increase in ICP. Mean arterial pressure (MAP) and heart rate (HR) were measured through the volume-clamp method. The heading trial consisted of 6 repeated headers of a soccer ball kicked from 32 meters away into a regulation goal. Follow up measurements of ICP, MAP, and HR were recorded 24 hours after heading trial. Measurements were taken in three randomized positions: 15° head-up tilt (HUT), 0° supine, -15° head-down tilt (HDT). Results At 15° HUT, baseline mean Vm was 37.81±133.21 nL, -20.82±158.27 nL immediately after heading trial (P=0.0482, paired t test), and 27.20±140.61 nL at 24 hours post soccer heading (P=0.1738, paired t test), corresponding to a significant increase in ICP immediately after the heading trial that then returns to baseline levels after 24 hours. At 0° supine, baseline mean Vm was -46.19±178.50 nL, -84.27±183.55 nL after heading trial (P=0.0321, paired t test) and -62.90±135.44 nL at 24 hours post soccer heading (P=0.5048, paired t test), corresponding to the same trend observed in the 15° HUT position. At -15° HDT, mean Vm was -148.48±196.07 nL at baseline, -187.02±186.19 nL after heading trial (P=0.1176, paired t test), and -151.10±174.86 nL at 24 hours post soccer heading (P=0.9329), corresponding to no significant increase in ICP at either time point. MAP and HR did not significantly change at any point after soccer heading. Discussions ICP significantly increased after soccer heading at 15° HUT and 0° supine but returned to baseline levels after 24 hours. ICP at -15° HDT, MAP, and HR did not significantly change immediately after soccer heading or 24 hours after soccer heading. While these results demonstrate a mild increase in ICP that subsides after 24 hours, athletes may experience these transient increases in ICP continuously for extended periods of time during their entire athletic careers. These cycles of increased ICP may result in a state of intermittent but persistently altered cerebral blood flow, which may suggest a health risk of participating in head contact sports such as soccer.

Low intracranial pressure variability is associated with delayed cerebral ischemia and unfavorable outcome in aneurysmal subarachnoid hemorrhage

PurposeHigh intracranial pressure variability (ICPV) is associated with favorable outcome in traumatic brain injury, by mechanisms likely involving better cerebral blood flow regulation. However, less is known about ICPV in aneurysmal subarachnoid hemorrhage (aSAH). In this study, we investigated the explanatory variables for ICPV in aSAH and its association with delayed cerebral ischemia (DCI) and clinical outcome.MethodsIn this retrospective study, 242 aSAH patients, treated at the neurointensive care, Uppsala, Sweden, 2008–2018, with ICP monitoring the first ten days post-ictus were included. ICPV was evaluated on three time scales: (1) ICPV-1 m—ICP slow wave amplitude of wavelengths between 55 and 15 s, (2) ICPV-30 m—the deviation from the mean ICP averaged over 30 min, and (3) ICPV-4 h—the deviation from the mean ICP averaged over 4 h. The ICPV measures were analyzed in the early phase (day 1–3), in the early vasospasm phase (day 4–6.5), and the late vasospasm phase (day 6.5–10).ResultsHigh ICPV was associated with younger age, reduced intracranial pressure/volume reserve (high RAP), and high blood pressure variability in multiple linear regression analyses for all ICPV measures. DCI was associated with reduced ICPV in both vasospasm phases. High ICPV-1 m in the post-ictal early phase and the early vasospasm phase predicted favorable outcome in multiple logistic regressions, whereas ICPV-30 m and ICPV-4 h in the late vasospasm phase had a similar association.ConclusionsHigher ICPV may reflect more optimal cerebral vessel activity, as reduced values are associated with an increased risk of DCI and unfavorable outcome after aSAH.

Epidural Oscillating Cardiac-Gated Intracranial Implant Modulates Cerebral Blood Flow.

We have previously reported a method and device capable of manipulating ICP pulsatility while minimally effecting mean ICP. To test the hypothesis that different modulations of the intracranial pressure (ICP) pulse waveform will have a differential effect on cerebral blood flow (CBF). Using an epidural balloon catheter attached to a cardiac-gated oscillating pump, 13 canine subjects underwent ICP waveform manipulation comparing different sequences of oscillation in successive animals. The epidural balloon was implanted unilaterally superior to the Sylvian sulcus. Subjects underwent ICP pulse augmentation, reduction and inversion protocols, directly comparing time segments of system activation and deactivation. ICP and CBF were measured bilaterally along with systemic pressure and heart rate. CBF was measured using both thermal diffusion, and laser doppler probes. The activation of the cardiac-gate balloon implant resulted in an ipsilateral/contralateral ICP pulse amplitude increase with augmentation (217%/202% respectively, P<.0005) and inversion (139%/120%, P<.0005). The observed changes associated with the ICP mean values were smaller, increasing with augmentation (23%/31%, P<.0001) while decreasing with inversion (7%/11%, P=.006/.0003) and reduction (4%/5%, P<.0005). CBF increase was observed for both inversion and reduction protocols (28%/7.4%, P<.0001/P=.006 and 2.4%/1.3%, P<.0001/P=.003), but not the augmentation protocol. The change in CBF was correlated with ICP pulse amplitude and systolic peak changes and not with change in mean ICP or systemic variables (heart rate, arterial blood pressure). Cardiac-gated manipulation of ICP pulsatility allows the study of intracranial pulsatile dynamics and provides a potential means of altering CBF.

Effect of Body Position on Intraocular Pressure (IOP), Intracranial Pressure (ICP), and Translaminar Pressure (TLP) Via Continuous Wireless Telemetry in Nonhuman Primates (NHPs).

PurposeRecent retrospective clinical studies and animal experiments have suggested that cerebrospinal fluid pressure (CSFP) is important in glaucoma, acting through the translaminar pressure (TLP = IOP − CSFP), which directly affects the optic nerve head. In this study, IOP and intracranial pressure (ICP; a surrogate of CSFP) were measured at various body positions to quantify the determinants of TLP.MethodsWe have developed an implantable wireless pressure telemetry system based on a small piezoelectric sensor with low temporal drift. Telemetry transducers were placed in the anterior chamber to measure IOP and in the brain parenchyma at eye height to measure ICP. IOP was calibrated against anterior cannulation manometry, and ICP/CSFP was calibrated against an intraparenchymal Codman ICP Express microsensor. We measured IOP, ICP, and TLP = IOP − ICP continuously at 200 Hz in three male nonhuman primates (NHPs) in three trials; pressures were then averaged for 30 seconds per body position. Relative change of IOP, ICP, and TLP from the supine (baseline) position to the seated, standing, and inverted positions were quantified.ResultsTLP changed significantly and instantaneously from the supine to seated (+14 mm Hg), supine to standing (+13 mm Hg) and supine to inverted (−12 mm Hg) positions (P < 0.05). There was no significant TLP change for supine to prone. ICP showed greater relative change than IOP.ConclusionsTLP change due to body position change is driven more by ICP/CSFP than IOP. IOP, ICP, and TLP variability, coupled with telemetry, should allow us to test the hypotheses that IOP, ICP, or TLP fluctuations contribute independently to glaucoma onset or progression.

Intracranial Pressure After Soccer Heading

OBJECTIVETo evaluate the effect of soccer heading on intracranial pressure (ICP) in trained athletes.METHODSEight subjects (all male, 21.7±1.7 years) were recruited from the UC San Diego soccer team. ICP and cardiovascular variables were recorded before and after 6 repeats of heading a soccer ball kicked from 35 yards away, into a goal. ICP was estimated non‐invasively from acoustical evoked tympanic membrane displacement (Vm), where a more negative volume displacement is correlated with higher ICP. Mean arterial pressure (MAP), heart rate (HR; Nexfin, Netherlands), and ICP were recorded in three different postures, 15° head up tilt (HUT), 0° supine, −15° head down tilt (HDT), in a randomized order.RESULTSMean Vm at 15° HUT was 37.81±133.21 nL at baseline and −20.82±158.27 nL immediately post soccer heading (P=0.0482, paired t test), analogous to an increased ICP. At 0° supine, mean Vm was −46.19±178.50 nL at baseline and −84.27±183.55 nL after impact (P=0.0321, paired t test). At −15° HDT, mean Vm was −148.48±196.07 nL at baseline and −187.02±186.19 nL immediately post soccer heading (P=0.1176, paired t test). MAP and HR did not significantly change between the baseline and post soccer heading measurements.DISCUSSIONAfter repeated soccer ball heading, ICP significantly increased at 15° HUT and 0° supine, while ICP at −15° HDT, MAP and HR did not significantly change. The relative increase in ICP associated with HDT is comparable to previously described trends. Although the measurement technique currently employed does not provide an absolute ICP baseline, the technique has been established as useful in evaluating relative changes. Under that interpretation, these results reflect what may be an elevated ICP related to soccer heading impacts. Accordingly, the results of this study suggest a potential health risk of participation in head contact sports.Support or Funding InformationNASA (80NSSC19K0020) and Novo Nordic Foundation (NNF16OC0019196)Soccer Heading Increases Intracranial Pressure at Head Up Tilt and Supine PositionsVolume displacement of tympanic membrane (Vm), measured non‐invasively from acoustical evoked tympanic membrane displacement, indicated an increase in intracranial pressure (ICP) after soccer heading at 15° head up tilt (HUT) and 0° supine (n = 8, paired t test, *P &lt; 0.05). No significant increase in ICP at −15° head down tilt (HDT) was observed after soccer heading.Figure 1

Intracranial pressure variability: relation to clinical outcome, intracranial pressure\u2013volume index, cerebrovascular reactivity and blood pressure variability

It was recently found in traumatic brain injury (TBI) that ICP variability (ICPV) predicted favorable outcome. We hypothesized that ICPV may depend on intracranial compliance, unstable blood pressure and cerebral vasomotion. In this study, we aimed to further investigate the explanatory variables for ICPV and its relation to outcome. Data from 362 TBI patients were retrospectively analyzed day 2 to 5 post-injury. ICPV was evaluated in three ways. First, variability in the sub-minute time interval (similar to B waves) was calculated as the amplitude of the ICP slow waves using a bandpass filter, limiting the analysis to oscillations of 55 to 15 s (ICP AMP 55–15). The second and third ICPV measures were calculated as the deviation from the mean ICP averaged over 30 min (ICPV-30m) and 4 h (ICPV-4h), respectively. All ICPV measures were associated with a reduced intracranial pressure/volume state (high ICP and RAP) and high blood pressure variability in multiple linear regression analyses. Higher ICPV was associated with better pressure reactivity in the univariate, but not the multiple analyses. All ICPV measures were associated with favorable outcome in univariate analysis, but only ICP AMP 55–15 and ICPV-30m did so in the multiple logistic regression analysis. Higher ICPV can be explained by a reduced intracranial compliance and variations in cerebral blood volume due to the vessel response to unstable blood pressure. As ICP AMP 55–15 and ICPV-30m independently predicted favorable outcome, it may represent general cerebral vessel activity, associated with better cerebral blood flow regulation and less secondary insults.

The Acute Phase of Experimental Subarachnoid Hemorrhage: Intracranial Pressure Dynamics and Their Effect on Cerebral Blood Flow and Autoregulation.

Clinical presentation and neurological outcome in subarachnoid hemorrhage (SAH) is highly variable. Aneurysmal SAH (aSAH) is hallmarked by sudden increase of intracranial pressure (ICP) and acute hypoperfusion contributing to early brain injury (EBI) and worse outcome, while milder or non-aneurysmal SAH with comparable amount of blood are associated with better neurological outcome, possibly due to less dramatic changes in ICP. Acute pressure dynamics may therefore be an important pathophysiological aspect determining neurological complications and outcome. We investigated the influence of ICP variability on acute changes after SAH by modulating injection velocity and composition in an experimental model of SAH. Five hundred microliters of arterial blood (AB) or normal saline (NS) were injected intracisternally over 1 (AB1, NS1), 10 (AB10, NS10), or 30min (AB30) with monitoring for 6h (n= 68). Rapid blood injection resulted in highest ICP peaks (AB1 median 142.7mmHg [1.Q 116.7-3.Q 230.6], AB30 33.42mmHg [18.8-38.3], p< 0.001) and most severe hypoperfusion (AB1 16.6% [11.3-30.6], AB30 44.2% [34.8-59.8]; p< 0.05). However, after 30min, all blood groups showed comparable ICP elevation and prolonged hypoperfusion. Cerebral autoregulation was disrupted initially due to the immediate ICP increase in all groups except NS10; only AB1, however, resulted in sustained impairment of autoregulation, as well as early neuronal cell loss. Rapidity and composition of hemorrhage resulted in characteristic hyperacute hemodynamic changes, with comparable hypoperfusion despite different ICP ranges. Only rapid ICP increase was associated with pronounced and early, but sustained disruption of cerebral autoregulation, possibly contributing to EBI.

Intracranial Pressure Trajectories: A Novel Approach to Informing Severe Traumatic Brain Injury Phenotypes.

Intracranial pressure in traumatic brain injury is dynamic and influenced by factors like injury patterns, treatments, and genetics. Existing studies use time invariant summary intracranial pressure measures thus potentially losing critical information about temporal trends. We identified longitudinal intracranial pressure trajectories in severe traumatic brain injury and evaluated whether they predicted outcome. We further interrogated the model to explore whether ABCC8 polymorphisms (a known cerebraledema regulator) differed across trajectory groups. Prospective observational cohort. Single-center academic medical center. Four-hundred four severe traumatic brain injury patients. None. We used group-based trajectory modeling to identify hourly intracranial pressure trajectories in days 0-5 post traumatic brain injury incorporating risk factor adjustment (age, sex, Glasgow Coma Scale 6score, craniectomy, primary hemorrhage pattern). We compared 6-month outcomes (Glasgow Outcome Scale, Disability Rating Scale, mortality) and ABCC8 tag-single-nucleotide polymorphisms associated with cerebral edema (rs2237982, rs7105832) across groups. Regression models determined whether trajectory groups predicted outcome. A six trajectory group model best fit the data, identifying cohorts differing in initial intracranial pressure, evolution, and number/proportion of spikes greater than 20 mm Hg. There were pattern differences in age, hemorrhage type, and craniectomy rates. ABCC8 polymorphisms differed across groups. GOS (p = 0.006), Disability Rating Scale (p = 0.001), mortality (p < 0.0001), and rs2237982 (p = 0.035) differed across groups. Unfavorable outcomes were surprisingly predicted by both low intracranial pressure trajectories and sustained intracranial hypertension. Intracranial pressure variability differed across groups (p < 0.001) and may reflect preserved/impaired intracranial elastance/compliance. We employed a novel approach investigating longitudinal/dynamic intracranial pressure patterns in traumatic brain injury. In a risk adjusted model, six groups were identified and predicted outcomes. If validated, trajectory modeling may be a first step toward developing a new, granular approach for intracranial pressure phenotyping in conjunction with other phenotyping tools like biomarkers and neuroimaging. This may be particularly relevant in light of changing traumatic brain injury demographics toward the elderly.

The Influence of Sedation Level Guided by Bispectral Index on Therapeutic Effects for Patients with Severe Traumatic Brain Injury.

Sedation therapy is vital for treating severe traumatic brain injury (TBI). Yet, types of sedation assessment tools and sedation levels that are suitable for sedation treatment have not been investigated. To investigate the influence of different sedation levels guided by the Bispectral Index (BIS) on the therapeutic effects for severe TBI. According to inclusion, exclusion, and rejection criteria, 35 patients were prospectively included and divided into Richmond Agitation Sedation Scale (RASS), BIS(I), and BIS(II) groups. The RASS group was controlled the level of sedation to within -2 or -3, and the BIS(I) and (II) groups within the range of 40-50 and 50-60, respectively. In addition to clinical data, RASS, BIS, and intracranial pressure (ICP) values were collected. RASS and ICP variability were introduced to investigate the different of sedative control effect with or without BIS monitor, and the control effect of ICP between different sedation levels. Statistical analysis was performed to estimate the effectiveness of different sedation levels guided by BIS in sedation treatment within 72 hours. There were no significant differences in demographics among the 3 groups. RASS variability of the BIS(I) and (II) groups was significantly lower than that of the RASS group (P < 0.05), and in the BIS(I) group it was insignificantly lower than in the BIS(II) group. The ICP of the BIS(I) and (II) groups declined to <13.5 mm Hg significantly earlier than that of the RASS group (P < 0.05), and the difference between BIS(I) and (II) was insignificant. ICP variability of RASS group was higher than those of the BIS(I) and (II) groups (P < 0.05), and ICP variability of the BIS(I) group was significantly lower than that of the BIS(II) group (P < 0.05). Differences in days in the neurosurgery intensive care unit and outcomes among the 3 groups were insignificant. BIS is more reliable than RASS for maintaining a stable sedation status and ICP. Deeper sedation levels (BIS 40-50) cause ICP to decrease more quickly, with lower ICP variability.

186 Predicting the Requirement for Intracranial Pressure Monitoring in Pediatric Traumatic Brain Injury

Abstract INTRODUCTION Each year, the annual hospitalization rates of traumatic brain injury (TBI) in children in the US are 57.7/100K less than 5 years of age and 23.1/100K in the 5–14 year age group. Although technological advances in multi-modality monitoring allow for high frequency monitoring of the physiological pressure variables, a recent randomised-control trial in adults has questioned the requirement for invasive monitoring. Here in, we describe an objective, non-invasive, quantitative means of stratifying which patients are likely to benefit from invasive monitoring. METHODS Radiological biomarkers of TBI (optic nerve sheath diameter; ONSD, basal cistern size, ventricular volume, volume of extra-axial masses, parenchymal oedema) were measured by independent observers and quantified by automatic software (3D slicer, Boston, MA) and correlated with epochs of continuous high frequency variables of pressure monitoring around the time of imaging, in pediatric TBI patients admitted to Cambridge University Hospital (CUH) between January 2009 and December 2016. RESULTS &gt;42 patients with a mean age of 10.3 years were admitted to CUH with a TBI and required invasive monitoring. The ICP was 19.6? ±?7.8 mmHg (median±IQR). The presence of subarachnoid blood was related to higher ICP, higher arterial blood pressure, and a trend toward dysfunctional cerebrovascular autoregulation (PRx). Smaller basal cisterns were related to increased ICP (R = −0.42, P = 0.02), impaired PRx (R = −0.5, P = 0.003). The correlation of mean ONSD and max ONSD with ICP was 0.725 (P &lt; 0.0001) and 0.698 (P &lt; 0.0001), respectively. CONCLUSION Here we define a set of radiological criteria to help predict the development of unfavourable intracranial pressure variables after a pediatric TBI. The use of objective radiological markers in this model can be tested on an external database to validate the relationship with intracranial pressure.

Clinical observation of the time course of raised intracranial pressure after subarachnoid hemorrhage.

The time course of intracranial pressure (ICP) after subarachnoid hemorrhage (SAH) is not well known. This retrospective study was conducted to investigate the occurrence and the dynamic variation of raised ICP post-SAH. ICP was prospectively studied in 120 patients with SAH who were admitted to neurocritical care within 24 h of hemorrhage. Patients underwent continuous ICP monitoring for at least 7 days, unless they died. Clinical status on admission, radiographic tests, treatment details and neurological outcome on discharge were analyzed in relation to ICP. The highest daily mean ICP and the day when ICP reduced to normal levels were assessed. Of the 120 patients studied, 112 (93.3 %) encountered ICP elevation whilst in hospital. The daily mean ICP was higher in Hunt and Hess grades IV-V patients than grades I-III patients (P = 0.01). The elevated ICP remained at a higher level for the initial 3 days (grades I-III patients) or 4 days (grades IV-V patients), after which the pressure decreased towards normal levels. The in-patient mortality was significantly increased in the high ICP variability group (P = 0.001), which was divided by the cutoff point using receiver operating characteristic curve analysis. Raised ICP mainly occurs within 8 days post-SAH, especially the initial 3-4 days. Those highlight the need for earlier management of ICP after SAH.

Association of intracranial pressure with outcome in comatose patients with intracerebral hemorrhage

BackgroundTherapeutic targets for intracranial pressure (ICP) in patients with severe intracerebral hemorrhage (ICH) are approximated from data of traumatic brain injury. However, specific data for ICH are lacking. Here, we aimed to investigate the association between ICP, mortality and functional outcome following severe ICH. MethodsWe analyzed consecutive comatose patients with ICH in whom ICP monitoring was applied. Outcome at 3months was assessed using the modified Rankin scale (mRS). Multivariate logistic regression including pre-defined predictors was used in order to identify the effects of ICP on outcome. Results121 patients with ICH and ICP monitoring were analyzed. Mean ICP (OR 1.2, CI 1.08–1.45, p=0.003), ICP variability (OR 1.3, CI 1.03–1.73, p=0.03) and relative frequency of ICP values >20mmHg (OR 1.1, CI 1.02– 1.15, p=0.008) were independently associated with mortality at 3months. Relative frequency of ICP values >20mmHg (OR 1.1, CI 1.001–1.3, p=0.04) was associated also with poor functional outcome at 3months. ConclusionsOur data suggest that in the context of other predictors as age, admission clinical status, hemorrhage volume and intraventricular hemorrhage, average ICP, ICP variability and the frequency of ICP values >20mmHg are independently associated with mortality and poor outcome after ICH. Further studies and prospective validations of ICP thresholds for ICH patients are highly warranted.

Intracranial pressure variability predicts short-term outcome after intracerebral hemorrhage: A retrospective study

IntroductionElevated intracranial pressure (ICP) is generally observed in brain injury and intracerebral hemorrhage (ICH) patients and is consistently associated with poor neurological outcome. Intracranial pressure variability (IPV) is a better predictor of long-term neurological outcome than mean ICP in traumatic brain injury patients. However, whether IPV regulates functional outcome in ICH patients has not been investigated. In the present study, we investigated the relationship between IPV and functional outcome in ICH patients and determined whether IPV is a valid predictor of neurological outcome in ICH patients. MethodsA consecutive series of 56 patients with ICH were enrolled in this study. These patients underwent surgical treatments and were planted with an ICP monitor. The ICP was continuously recorded for 7days at one-hour intervals. The mean arterial blood pressure (MAP) and cerebral perfusion pressure (CPP) were also calculated. We used successive variation (SV) to represent IPV, which was calculated by averaging the difference in ICP between successive parameters. The short-term outcome was dichotomized into improved and deteriorated groups based on the changes in their Glasgow Coma Scale (GCS) score between admission and 30days after admission. The long-term outcome was evaluated by Glasgow Outcome Scale (GOS) at 12months after discharge from the hospital, and the patients were dichotomized into independent and dependent groups. ResultsThe results showed that IPV was lower in the improved patient group and higher in patients with poorer outcome at 30days after ICH. There was a significant positive correlation between SV and short-term neurological outcome. We also found the in-patient mortality was significantly increased in the high IPV patient group (P=0.02), which was divided by the cutoff point using receiver operating characteristic (ROC) curve analysis. The univariate correlation analysis demonstrated that the IPV levels were positively correlated with mean ICP (R2=0.652, P=0.000), while were negatively correlated with CPP (R2=0.426, P=0.000). Increases in SV of ICP were a predictor of 30-day poor short-term outcome, but not for 12-month long-term outcome after adjusting for the potential confounders in a multivariable logistic regression model. ConclusionsThe results suggest that high IPV is correlated with poorer outcome in ICH patients. Managing the ICP at an appropriate level during the early phase after ICH may improve functional outcome in ICH patients.

An Approach to Determining Intracranial Pressure Variability Capable of Predicting Decreased Intracranial Adaptive Capacity in Patients With Traumatic Brain Injury

Nurses caring for traumatic brain injury (TBI) patients with intracranial hypertension (ICH) recognize that patients whose intracranial adaptive capacity is reduced are susceptible to periods of disproportionate increase in intracranial pressure (DIICP) in response to a variety of stimuli. It is possible that DIICP signals potential secondary brain damage due to sustained or intermittent ICH. However, there are few clinically accessible intracranial pressure (ICP) measurement parameters that allow nurses and other critical care clinicians to identify patients at risk of DIICP. The purpose of this study was to investigate whether there are specific minute-to-minute trends in ICP variability during the first 48 hr of monitoring that might accurately predict DIICP in patients with severe TBI. A total of 38 patients with severe TBI were sampled from the data set of a randomized controlled trial testing bedside monitoring displays and cerebral perfusion pressure management in individuals with TBI or sub-arachnoid hemorrhage. The investigators retrospectively examined the rates of change (slope) in mean, standard deviation, and variance of ICP on a 1-min basis for 30 consecutive min prior to a specified DIICP event. There was a significantly increasing linear and quadratic slope in mean ICP prior to the development of DIICP, compared with the comparison data set (p < .05). It is feasible to display moving averages in modern bedside monitoring. Such an arrangement may be useful to provide visual displays that provide immediate clinically relevant information regarding the patients with decreased adaptive capacity and therefore increased risk of DIICP.