Modeling the impact of thoracic pressure on intracranial pressure.
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ABSTRACT:
SUBMITTER: Munster DW
PROVIDER: S-EPMC11006658 | biostudies-literature | 2024 Apr
REPOSITORIES: biostudies-literature
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Modeling the impact of thoracic pressure on intracranial pressure.
Munster Drayton W DW Lewandowski Beth E BE Nelson Emily S ES Prabhu R K RK Myers Jerry G JG
NPJ microgravity 20240410 1
A potential contribution to the progression of Spaceflight Associated Neuro-ocular Syndrome is the thoracic-to-spinal dural sac transmural pressure relationship. In this study, we utilize a lumped-parameter computational model of human cerebrospinal fluid (CSF) systems to investigate mechanisms of CSF redistribution. We present two analyses to illustrate potential mechanisms for CSF pressure alterations similar to those observed in microgravity conditions. Our numerical evidence suggests that th ...[more]
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Project description:Introduction: We investigated the effect of hematoma volume reduction with minimally invasive surgery (MIS) on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in patients with large spontaneous intracerebral hemorrhage (ICH). Methods: Post-hoc analysis of the Minimally Invasive Surgery Plus Alteplase for Intracerebral Hemorrhage Evacuation (MISTIE III) study, a clinical trial with blinded outcome assessments. The primary outcome was the proportion of ICP readings ≥20 and 30 mmHg, and CPP readings <70 and 60 mm Hg. Secondary outcomes included major disability (modified Rankin scale >3) and mortality at 30 and 365 days. We assessed the relationship between proportion of high ICP and low CPP events and MIS using binomial generalized linear models, and outcomes using multiple logistic regression. Results: Of 499 patients enrolled in MISTIE III, 72 patients had guideline based ICP monitors placed, 34 in the MIS group and 38 in control (no surgery) group. Threshold ICP and CPP events ≥20/ <70 mmHg occurred in 31 (43.1%) and 52 (72.2%) patients respectively. On adjusted analyses, proportion of ICP readings ≥20 and 30 mmHg were significantly lower in the MIS group vs. control group [Odds Ratio (OR) 0.27, 95% Confidence Interval [CI] 0.11-0.63 (p = 0.002); OR = 0.18, 0.04-0.75, p = 0.02], respectively. Proportion of CPP readings <70 and 60 mm Hg were also significantly lower in MIS patients [OR 0.31, 95% CI 0.15-0.63 (p = 0.001); OR 0.30, 95% CI 0.11-0.83 (p = 0.02)], respectively. Higher proportions of CPP readings <70 and 60 mm were significantly associated with short term mortality (p = 0.04), and (p = 0.006), respectively. Long term mortality was significantly associated with higher proportion of time with ICP ≥ 20 (p = 0.04), ICP ≥ 30 (p = 0.04), and CPP <70 mmHg (p = 0.01). Conclusion: Our results are consistent with the hypothesis that surgical reduction of ICH volume decreases proportion of high ICP and low CPP events and that these variables are associated with short- and long-term mortality.
| S-EPMC8427275 | biostudies-literature
Project description:ObjectivesIntracranial pressure (ICP) monitors have been used in some patients with spontaneous intracranial hemorrhage (ICH) to provide information to guide treatment without clear evidence for its use in this population. We assessed the impact of ICP monitor placement, including external ventricular drains and intraparenchymal monitors, on neurologic outcome in this population.Materials and methodsIn this secondary analysis of the Minimally Invasive Surgery Plus Alteplase for Intracerebral Hemorrhage Evacuation III trial, the primary outcome was poor outcome (modified Rankin Scale score 4-6) and the secondary outcome was death, at 1 year from onset. We compared outcomes in patients with or without an ICP monitor using unadjusted and adjusted logistic regression models. The analyses were repeated in a balanced cohort created with propensity score matching.ResultsSeventy patients underwent ICP monitor placement and 424 did not. Poor outcome was seen in 77.1% of patients in the ICP-monitor subgroup compared with 53.8% in the no-monitor subgroup (p<0.001). Of patients in the ICP-monitor subgroup, 31.4% died, compared with 21.0% in the no-monitor subgroup (p=0.053). In multivariate models, ICP monitor placement was associated with a >2-fold greater risk of poor outcome (odds ratio 2.76, 95% CI 1.30-5.85, p=0.008), but not with death (p=0.652). Our findings remained consistent in the propensity score-matched cohort.ConclusionThese results question whether ICP monitor-guided therapy in patients with spontaneous nontraumatic ICH improves outcome. Further work is required to define the causal pathway and improve identification of patients that might benefit from invasive ICP monitoring.
| S-EPMC8080544 | biostudies-literature
Project description:Elevated intracranial pressure (ICP) is observed in many brain disorders. Obesity has been linked to ICP pathogenesis in disorders such as idiopathic intracranial pressure (IIH). We investigated the effect of diet induced obesity (DIO) on ICP and clinically relevant sequelae. Rats were fed either a control or high fat diet. Following weight gain long term ICP, headache behavior, body composition and retinal outcome were examined. Post-hoc analysis of retinal histology and molecular analysis of choroid plexus and trigeminal ganglion (TG) were performed. DIO rats demonstrated raised ICP by 55% which correlated with the abdominal fat percentage and increased non-respiratory slow waves, suggestive of altered cerebral compliance. Concurrently, DIO rats demonstrated a specific cephalic cutaneous allodynia which negatively correlated with the abdominal fat percentage. This sensitivity was associated with increased expression of headache markers in TG. Additionally, DIO rats had increased retinal nerve fiber layer thickness in vivo associated with raised ICP with a subsequent post-hoc demonstration of neuroretinal degeneration. This study demonstrates for the first time that DIO leads to raised ICP and subsequent clinically relevant symptom development. This novel model of non-traumatic raised ICP could expand the knowledge regarding disorders with elevated ICP such as IIH.
| S-EPMC9160066 | biostudies-literature
Project description:Spreading depolarization (SD) develops after stroke and traumatic brain injury and may contribute to secondary brain damage. These diseases are often accompanied by intracranial hypertension, but little is known about the effects of intracranial pressure (ICP) on SD. Here, we study the effect of increased ICP on hemodynamic and metabolic response to SD in rats. SDs were triggered at different ICPs and cerebral perfusion pressures (CPP). The regional cerebral blood flow (rCBF), partial pressure of brain tissue oxygen (PbtO2), cerebral extracellular glucose and lactate concentrations were recorded. Fluoro-Jade staining was used to quantify neuronal injury in cortex. At high ICP (50 mmHg) with low CPP (30 mmHg), rCBF and PbtO2 were monophasically decreased in contrast to a monophasically increased pattern under normal conditions. Neuronal death increased in both hemispheres but much more on the side where SDs were triggered. At high ICP (50 mmHg) with normal CPP (70 mmHg), CBF and metabolism during SD did not differ from baseline, and neuronal death did not increase even on the side of SD induction. These data suggest that maintaining CPP at 70 mmHg, even when the ICP is as high as 50 mmHg, preserves normal blood flow and metabolism during SD events and prevents neuronal degeneration.
| S-EPMC11563493 | biostudies-literature
Project description:Idiopathic intracranial hypertension (IIH) is a disease characterised by elevated intracranial pressure (ICP). The impact of straining and exercise on ICP regulation is poorly understood yet clinically relevant to IIH patient care. We sought to investigate the impact of Valsalva manoeuvres (VMs) and exercise on ICP and cerebrovascular haemodynamics in IIH. People with IIH were prospectively enrolled and had an intraparenchymal telemetric ICP sensor inserted. Three participants (age [mean ± standard deviation]: 40.3 ± 13.9 years) underwent continuous real-time ICP monitoring coupled with cerebrovascular haemodynamic assessments during VMs and moderate exercise. Participants had IIH with supine ICP measuring 15.3 ± 8.7 mmHg (20.8 ± 11.8 cm cerebrospinal fluid (CSF)) and sitting ICP measuring -4.2 ± 7.9 mmHg (-5.7 ± 10.7 cmCSF). During phase I of a VM ICP increased by 29.4 ± 13.5 mmHg (40.0 ± 18.4 cmCSF) but returned to baseline within 16 seconds from VM onset. The pattern of ICP changes during the VM phases was associated to that of changes in blood pressure, the middle cerebral artery blood velocity and prefrontal cortex haemodynamics. Exercise led to minimal effects on ICP. In conclusion, VM-induced changes in ICP were coupled to cerebrovascular haemodynamics and showed no sustained impact on ICP. Exercise did not lead to prolonged elevation of ICP. Those with IIH experiencing VMs (for example, during exercise and labour) may be reassured at the brief nature of the changes. Future research must look to corroborate the findings in a larger IIH cohort.
| S-EPMC10936629 | biostudies-literature
Project description:BackgroundMorphological analysis of intracranial pressure (ICP) pulse waveforms provides indirect information on cerebrospinal compliance, which might be reduced by space-occupying lesions but also by intracranial hypertension and aging. This study investigates the impact of age and mean ICP on the shape and amplitude of ICP pulse waveform in traumatic brain injury (TBI). Additionally, it explores the association between morphological parameters and mortality after TBI.MethodsICP recordings from 183 TBI patients (median age: 50 (30, 61) years) from the CENTER-TBI database were retrospectively analyzed. ICP morphology was assessed using the artificial intelligence-based pulse shape index (PSI) and peak-to-peak amplitude of ICP pulse waveform (AmpICP). The impact of mean ICP, age, and their interaction on PSI and AmpICP were estimated using factorial ANOVA. To account for influence of disturbance in the intracranial volume on AmpICP and PSI, a multiple regression analysis was performed using age, mean ICP, and the Rotterdam CT score as explanatory variables. The associations of AmpICP and PSI with six-month mortality were assessed using the area under the ROC curve (AUC).ResultsAge had a predominant influence on PSI (p < 0.01), accounting for 33.1% of its variance, while mean ICP explained 6.6% (p < 0.01). Conversely, mean ICP primarily affected AmpICP (p < 0.01), explaining 22.8% of its variance, with age contributing 8.0% (p < 0.01). A combined effect of age and mean ICP on AmpICP (p = 0.01) explained 11.7% of its variance but did not influence PSI. After accounting for Rotterdam CT score, the results remained consistent, indicating that advanced age has the strongest impact on PSI (β = 0.342, p < 0.01) while elevated mean ICP has dominant influence on AmpICP (β = 0.522, p < 0.01). Both AmpICP and PSI were moderately associated with mortality (AUC: 0.76 and 0.71, respectively).ConclusionsAmpICP and PSI capture distinct aspects of cerebrospinal compliance. PSI appears to reflect age-related stiffening of the cerebrovascular system, while AmpICP, influenced by mean ICP, indicates acute volume compensatory changes. Combined, they provide a more comprehensive assessment of cerebrospinal volume-pressure compensation. Both morphological metrics are associated with mortality after TBI. As cerebrospinal compliance declines with age, older TBI patients become more susceptible to uncontrolled rises in ICP, which can worsen their outcome.
| S-EPMC11834513 | biostudies-literature
Project description:OBJECTIVES:The lower limit of cerebral blood flow autoregulation is the critical cerebral perfusion pressure at which cerebral blood flow begins to fall. It is important that cerebral perfusion pressure be maintained above this level to ensure adequate cerebral blood flow, especially in patients with high intracranial pressure. However, the critical cerebral perfusion pressure of 50 mm Hg, obtained by decreasing mean arterial pressure, differs from the value of 30 mm Hg, obtained by increasing intracranial pressure, which we previously showed was due to microvascular shunt flow maintenance of a falsely high cerebral blood flow. The present study shows that the critical cerebral perfusion pressure, measured by increasing intracranial pressure to decrease cerebral perfusion pressure, is inaccurate but accurately determined by dopamine-induced dynamic intracranial pressure reactivity and cerebrovascular reactivity. DESIGN:Cerebral perfusion pressure was decreased either by increasing intracranial pressure or decreasing mean arterial pressure and the critical cerebral perfusion pressure by both methods compared. Cortical Doppler flux, intracranial pressure, and mean arterial pressure were monitored throughout the study. At each cerebral perfusion pressure, we measured microvascular RBC flow velocity, blood-brain barrier integrity (transcapillary dye extravasation), and tissue oxygenation (reduced nicotinamide adenine dinucleotide) in the cerebral cortex of rats using in vivo two-photon laser scanning microscopy. SETTING:University laboratory. SUBJECTS:Male Sprague-Dawley rats. INTERVENTIONS:At each cerebral perfusion pressure, dopamine-induced arterial pressure transients (~10 mm Hg, ~45 s duration) were used to measure induced intracranial pressure reactivity (? intracranial pressure/? mean arterial pressure) and induced cerebrovascular reactivity (? cerebral blood flow/? mean arterial pressure). MEASUREMENTS AND MAIN RESULTS:At a normal cerebral perfusion pressure of 70 mm Hg, 10 mm Hg mean arterial pressure pulses had no effect on intracranial pressure or cerebral blood flow (induced intracranial pressure reactivity = -0.03 ± 0.07 and induced cerebrovascular reactivity = -0.02 ± 0.09), reflecting intact autoregulation. Decreasing cerebral perfusion pressure to 50 mm Hg by increasing intracranial pressure increased induced intracranial pressure reactivity and induced cerebrovascular reactivity to 0.24 ± 0.09 and 0.31 ± 0.13, respectively, reflecting impaired autoregulation (p < 0.05). By static cerebral blood flow, the first significant decrease in cerebral blood flow occurred at a cerebral perfusion pressure of 30 mm Hg (0.71 ± 0.08, p < 0.05). CONCLUSIONS:Critical cerebral perfusion pressure of 50 mm Hg was accurately determined by induced intracranial pressure reactivity and induced cerebrovascular reactivity, whereas the static method failed.
| S-EPMC6395276 | biostudies-literature
Project description:Morphological alterations in intracranial pressure (ICP) pulse waveform (ICPW) secondary to intracranial hypertension (ICP >20 mmHg) and a reduction in intracranial compliance (ICC) are well known indicators of neurological severity. The exclusive exploration of modifications in ICPW after either the loss of skull integrity or surgical procedures for intracranial hypertension resolution is not a common approach studied. The present study aimed to assess the morphological alterations in ICPW among neurocritical care patients with skull defects and decompressive craniectomy (DC) by comparing the variations in ICPW features according to elevations in mean ICP values. Patients requiring ICP monitoring because of acute brain injury were included. A continuous record of 10 min-length for the beat-by-beat analysis of ICPW was performed, with ICP elevation produced by means of ultrasound-guided manual internal jugular vein compression at the end of the record. ICPW features (peak amplitude ratio (P2/P1), time interval to pulse peak (TTP) and pulse amplitude) were counterweighed between baseline and compression periods. Results were distributed for three groups: intact skull (exclusive burr hole for ICP monitoring), craniotomy/large fractures (group 2) or DC (group 3). 57 patients were analyzed. A total of 21 (36%) presented no skull defects, 21 (36%) belonged to group 2, whereas 15 (26%) had DC. ICP was not significantly different between groups: ±15.11 for intact, 15.33 for group 2 and ±20.81 mmHg for group 3, with ICP-induced elevation also similar between groups (p = 0.56). Significant elevation was observed for the P2/P1 ratio for groups 1 and 2, whereas a reduction was observed in group 3 (elevation of ±0.09 for groups 1 and 2, but a reduction of 0.03 for group 3, p = 0.01), and no significant results were obtained for TTP and pulse amplitudes. In the present study, intracranial pressure pulse waveform analysis indicated that intracranial compliance was significantly more impaired among decompressive craniectomy patients, although ICPW indicated DC to be protective for further influences of ICP elevations over the brain. The analysis of ICPW seems to be an alternative to real-time ICC assessment.
| S-EPMC8392489 | biostudies-literature
Project description:ObjectivesElevated intracranial pressure is one of the proposed mechanisms leading to poor outcomes in patients with intraventricular hemorrhage. We sought to characterize the occurrence and significance of intracranial hypertension in severe intraventricular hemorrhage requiring extraventricular drainage.DesignProspective analysis from two randomized, multicenter, clinical trials.SettingIntensive care units of 23 academic hospitals.PatientsOne hundred patients with obstructive intraventricular hemorrhage and intracerebral hemorrhage volume <30 mL requiring emergency extraventricular drainage from two randomized multicenter studies comparing intraventricular recombinant tissue plasminogen activator (n=78) to placebo (n=22).InterventionsIntracranial pressure was recorded every 4 hrs in all patients and before and after a 1-hr extraventricular drainage closure period after injection. Intracranial pressure readings were analyzed at predefined thresholds and compared between treatment groups, before and after injection of study agent, and before and after opening of third and fourth ventricles on computed tomography. Impact on 30-day outcomes was assessed.Measurements and main resultsInitial intracranial pressure ranged from -2 to 60 mm Hg (median; interquartile range, 11;10). Of 2576 intracranial pressure readings, 91.5% (2359) were ≤20 mm Hg, 1.6% were >30, 0.5% were >40, and 0.2% were >50 mm Hg. In a multivariate analysis, threshold events>20 mm Hg and >30 mm Hg were more frequent in placebo vs. recombinant tissue plasminogen activator-treated groups (p=.03 and p=.08, respectively). Intracranial pressure elevation>20 mm Hg occurred during a required 1-hr extraventricular drainage closure interval in 207 of 868 (23.8%) injections of study agent, although early reopening of the extraventricular drainage only occurred in 7.9%. After radiographic opening of the lower ventricular system, intracranial pressure events>20 mm Hg remained significantly associated with initial intraventricular hemorrhage volume (p=.002) and extraventricular drainage placement ipsilateral to the largest intraventricular hemorrhage volume (p=.001), but not with thrombolytic treatment (p=.05) or intracerebral hemorrhage volume (p=.14). Ventriculoperitoneal shunts were required in 13.6% of placebo and 6.4% of recombinant tissue plasminogen activator-treated patients (p=.37). Percentage of intracranial pressure readings per patient>30 mm Hg and initial intracerebral hemorrhage and intraventricular hemorrhage volumes were independent predictors of 30-day mortality after adjustment for other outcome predictors (p=.003, p=.03, and p<.001, respectively). Independent predictors of poor modified Rankin Scale score at 30 days were percent of intracranial pressure events>30 mm Hg per patient (p=.01; but not >20 mm Hg), both intracerebral hemorrhage and intraventricular hemorrhage volume, and pulse pressure.ConclusionsIntracranial pressure is not frequently elevated during monitoring and drainage with an extraventricular drainage in patients with severe intraventricular hemorrhage, although intracranial pressure >30 mm Hg predicts higher short-term mortality. Thrombolytic therapy may reduce the frequency of high intracranial pressure events. Intracranial pressure elevation appears to be significantly correlated with extraventricular drainage placement in the ventricle with greatest clot volume.
| S-EPMC4365868 | biostudies-literature
Project description:Clinicians frequently observe hemodynamic changes preceding elevated intracranial pressure events. We employed a machine learning approach to identify novel and differentially expressed features associated with elevated intracranial pressure events in children with severe brain injuries. Statistical features from physiologic data streams were derived from non-overlapping 30-min analysis windows prior to 21 elevated intracranial pressure events; 200 records without elevated intracranial pressure events were used as controls. Ten Monte Carlo simulations with training/testing splits provided performance benchmarks for 4 machine learning approaches. XGBoost yielded the best performing predictive models. Shapley Additive Explanations analyses demonstrated that a majority of the top 20 contributing features consistently derived from blood pressure data streams up to 240 min prior to elevated intracranial events. The best performing prediction model was using the 30-60 min analysis window; for this model, the area under the receiver operating characteristic window using XGBoost was 0.82 (95% CI 0.81-0.83); the area under the precision-recall curve was 0.24 (95% CI 0.23-0.25), above the expected baseline of 0.1. We conclude that physiomarkers discernable by machine learning are concentrated within blood pressure and intracranial pressure data up to 4 h prior to elevated intracranial pressure events.
| S-EPMC9744906 | biostudies-literature