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A dynamic nonlinear relationship between the static and pulsatile components of intracranial pressure in patients with subarachnoid hemorrhage.

ABSTRACT: In the search for optimal monitoring and predictive tools in neurocritical care, the relationship of the pulsatile component of intracranial pressure (ICP) and the pressure itself has long been of great interest. Higher pressure often correlates with a higher pulsatile response to the heartbeat, interpreted as a type of compliance curve. Various mathematical approaches have been used, but regardless of the formula used, it is implicitly assumed that a reproducible curve exists. The authors investigated the stability of the correlation between static and pulsatile ICPs in patients with subarachnoid hemorrhage (SAH) who were observed for several hours by using data sets large enough to allow such calculations to be made.The ICP recordings were obtained in 39 patients with SAH and were parsed into 6-second time windows (1,998,944 windows in 197 recordings). The ICP parameters were computed for each window as follows: static ICP was defined as the mean ICP, and pulsatile ICP was characterized by mean ICP wave amplitude, rise time, and rise time coefficient.The mean ICP and ICP wave amplitudes were simultaneously high or low (the expected correlation) in only approximately 60% of observations. Furthermore, static and pulsatile ICP correlated well only over short intervals; the degree of correlation weakened over periods of hours and was inconsistent across patients and within individual patients over time. Decorrelation originated with abrupt shifting and gradual drifting of mean ICP and ICP wave amplitude over several hours.The relationship between the static and pulsatile components of ICPs changes over time. It evolves, even in individual patients, over a number of hours. This can be one reason the observation of high pulsatile ICP (indicative of reduced intracranial compliance) despite normal mean ICP that is seen in some patients with SAH. The meaning and potential clinical usefulness of such changes in the curves is uncertain, but it implies that clinical events result not only from moving further out on a compliance curve; in practice, the curve, and the biological system that underlies the curve, may itself change.

SUBMITTER: Eide PK

PROVIDER: S-EPMC4046835 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature

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A dynamic nonlinear relationship between the static and pulsatile components of intracranial pressure in patients with subarachnoid hemorrhage.

Eide Per K PK Rapoport Benjamin I BI Gormley William B WB Madsen Joseph R JR

Journal of neurosurgery 20100301 3

<h4>Object</h4>In the search for optimal monitoring and predictive tools in neurocritical care, the relationship of the pulsatile component of intracranial pressure (ICP) and the pressure itself has long been of great interest. Higher pressure often correlates with a higher pulsatile response to the heartbeat, interpreted as a type of compliance curve. Various mathematical approaches have been used, but regardless of the formula used, it is implicitly assumed that a reproducible curve exists. Th ...[more]

PMID: 19731984

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Project description:ObjectiveElevated ICP is a well-recognized phenomenon in aneurysmal subarachnoid hemorrhage (aSAH) that has been demonstrated to lead to poor outcomes. Delayed cerebral ischemia (DCI) is the most important reason for a poor clinical outcome after a subarachnoid hemorrhage. DCI is understood as a multifactorial process that evolves over time, largely caused by the sequelae of increased intracranial pressure (ICP). The study aimed to assess how to better define the association between ICP and DCI, and whether rational ICP management can improve the outcome of aSAH patients.MethodsWe prospectively reviewed patients diagnosed with aSAH and received microsurgery clipping at our department from December 2019 to January 2021. Subdural ICP monitoring devices were kept to monitor the ICP. The ICP values were recorded every 1-h epochs. ICP -guided dehydration treatments were routinely performed to control the ICP level of patients after surgery. To evaluate whether the subdural ICP-directed management improved the prognosis of the aSAH patients, we compared the outcome data of the patients in our cohort with those treated at another ward of our hospital at the same period.ResultsIn total, 144 consecutive aSAH patients received microsurgery clipping at our department, 68 of whom underwent ICP monitoring. A total of 11,424 1-h ICP measurements were recorded for the included patients (1.30 years of recordings). Of 68 patients with ICP monitoring, 27 (27/68, 39.7%) patients developed DCI. Univariate analysis showed that higher Hunt-Hess grade (OR 2.138, 95% CI 1.025-4.459, p = 0.043), higher preoperative modified Rankin Scale score (OR 1.534, 95% CI 1.033-2.276, p = 0.034), and the max ICP value of each day value >28.5 mmHg (OR 4.442, 95% CI 1.509-13.082, p = 0.007) were associated with DCI. Also, patients with ICP-directed treatment showed a significantly lower DCI incidence than patients without ICP monitoring.ConclusionOur study suggests that I less than 15 mmHg possibly constitute normal values and that 28.5 mmHg is the ICP threshold most strongly associated with the occurrence of DCI in aSAH patients. Patients who received the ICP-directed treatment presented a lower incidence of DCI. Our findings provide a basis for the recommendation of ICP-directed treatment after aSAH.Trial registration numberNCT04785976.

Project description:IntroductionObservational studies suggest that different classes of antihypertensive drugs may have different effects on the occurrence of intracranial aneurysms (IA) and subarachnoid hemorrhage (SAH). However, the reported results in previous studies are inconsistent, and randomized data are absent. We performed a two-sample Mendelian randomization (MR) analysis to study the causal effects of genetically determined blood pressure (BP) and genetic proxies for antihypertensive drug classes on the risk of IA and SAH.Materials and methodsGenetic instruments and outcome data were obtained from independent genome-wide association studies (GWAS) or published data, which were exclusively restricted to European ancestry. Causal relationships were identified using inverse-variance weighted MR analyses and a series of statistical sensitivity analyses. The FinnGen consortium was used for repeated analysis to verify results obtained from the above GWAS.ResultsTwo-sample MR analysis showed that genetically determined Systolic BP, Dystolic BP, and Pulse Pressure were related to a higher risk of IA and SAH. Based on identified single nucleotide polymorphisms (SNPs) that influence the effect of calcium channel blockers (CCB, 42 SNPs), beta-blockers (BB, 8 SNPs), angiotensin-converting enzyme inhibitors (ACEI, 2 SNPs), angiotensin receptor blockers (ARB, 1 SNPs), and thiazides (5 SNPs), genetically determined effect of CCBs was associated with a higher risk of IA (OR, 1.07 [95% CI, 1.03-1.10], p = 5.02 × 10-5) and SAH (OR, 1.06 [95% CI, 1.03-1.09], p = 1.84 × 10-3). No associations were found between other antihypertensive drugs and the risk of IA or SAH. The effect of CCBs on SAH was confirmed in FinnGenconsortium samples (OR, 1.04 [95% CI, 1.00-1.08], p = 0.042).Discussion and conclusionThis MR analysis supports the role of elevated blood pressure in the occurrence of intracranial aneurysms and subarachnoid hemorrhage. However, genetic proxies for calcium channel blockers were associated with an increased risk of intracranial aneurysms and subarachnoid hemorrhage. Further studies are required to confirm these findings and investigate the underlying mechanisms.

Project description:BackgroundThe options of surgical approach and treatment stage are two challenging treatment strategy issues with multiple intracranial aneurysmal subarachnoid hemorrhage (MIA-SAH).MethodsWe retrospectively analyzed data from patients with MIA-SAH who underwent surgery in our center between January 1, 2014 and September 1, 2022. To define "zone classification", the cranial cavity was divided into four zones by the planes of cerebral falx and tentorium cerebelli. Aneurysms isolated to one zone were defined as zone classification I; those crossing two zones were defined as zone classification II; those crossing three zones were defined as zone classification III; and those crossing four zones were defined as zone classification IV. General and aneurysmal-related characteristics of patients with different zone classifications were collected and compared between two surgical approaches. Multivariate logistic regression analysis was used to identify factors independently associated with multistage treatment options.ResultsA total of 226 patients with 523 aneurysms were included. The proportion of patients undergoing endovascular treatment increased with higher zone classification (I: 85.4%; II: 94.0%; III: 100.0%; IV: 100.0%). The proportion of patients receiving one-stage treatment decreased with higher zone classification (I: 60.2%; II: 33.6%; III: 0.0%; IV: 0.0%). Compared with patients undergoing microsurgical clipping, more patients undergoing endovascular treatment had zone classification II-IV (56.9% vs. 31.8%, p = 0.025). Zone classification II-IV (odds ratio [OR] = 3.821, 95% confidence interval [CI]: 2.041-7.154, p < 0.001), endovascular treatment (OR = 8.756, 95% CI: 2.589-29.609, p < 0.001), and size of all unruptured aneurysms <3 mm (OR = 4.531, 95% CI: 2.315-8.871, p < 0.001) were each independently associated with multistage treatment.ConclusionsZone classification provides a new idea in MIA-SAH treatment strategies, especially regarding surgical approach and treatment stage options.

Project description:BackgroundThe aim was to study the course of body temperature in the acute phase of poor-grade aneurysmal subarachnoid hemorrhage (aSAH) in relation to the primary brain injury, cerebral physiology, and clinical outcome.MethodsIn this observational study, 166 patients with aSAH treated at the neurosurgery department at Uppsala University Hospital in Sweden between 2008 and2018 with temperature, intracranial pressure (ICP), and microdialysis (MD) monitoring were included. The first 10 days were divided into the early phase (days 1-3) and the vasospasm phase (days 4-10).ResultsNormothermia (temperature = 36-38 °C) was most prevalent in the early phase. A lower mean temperature at this stage was univariately associated with a worse primary brain injury, with higher Fisher grade and higher MD glycerol concentration, as well as a worse neurological recovery at 1 year. There was otherwise no association between temperature and cerebral physiological variables in the early phase. There was a transition toward an increased burden of hyperthermia (temperature > 38 °C) in the vasospasm phase. This was associated with concurrent infections but not with neurological or radiological injury severity at admission. Elevated temperature was associated with higher MD pyruvate concentration, lower rate of an MD pattern indicative of ischemia, and higher rate of poor neurological recovery at 1 year. There was otherwise no association between temperature and cerebral physiological variables in the vasospasm phase. The associations between temperature and clinical outcome did not hold true in multiple logistic regression analyses.ConclusionsSpontaneously low temperature in the early phase reflected a worse primary brain injury and indicated a worse outcome prognosis. Hyperthermia was common in the vasospasm phase and was more related to infections than primary injury severity but also with a more favorable energy metabolic pattern with better substrate supply, possibly related to hyperemia.

Project description:Invasive monitoring of pulsatile intracranial pressure can accurately predict shunt response in patients with idiopathic normal pressure hydrocephalus, but may potentially cause complications such as bleeding and infection. We tested how a proposed surrogate parameter for pulsatile intracranial pressure, the phase-contrast magnetic resonance imaging derived pulse pressure gradient, compared with its invasive counterpart. In 22 patients with suspected idiopathic normal pressure hydrocephalus, preceding invasive intracranial pressure monitoring, and any surgical shunt procedure, we calculated the pulse pressure gradient from phase-contrast magnetic resonance imaging derived cerebrospinal fluid flow velocities obtained at the upper cervical spinal canal using a simplified Navier-Stokes equation. Repeated measurements of the pulse pressure gradient were also undertaken in four healthy controls. Of 17 shunted patients, 16 responded, indicating high proportion of "true" normal pressure hydrocephalus in the patient cohort. However, there was no correlation between the magnetic resonance imaging derived pulse pressure gradient and pulsatile intracranial pressure (R = -.18, P = .43). Pulse pressure gradients were also similar in patients and healthy controls (P = .26), and did not differ between individuals with pulsatile intracranial pressure above or below established thresholds for shunt treatment (P = .97). Assessment of pulse pressure gradient at level C2 was therefore not found feasible to replace invasive monitoring of pulsatile intracranial pressure in selection of patients with idiopathic normal pressure hydrocephalus for surgical shunting. Unlike invasive, overnight monitoring, the pulse pressure gradient from magnetic resonance imaging comprises short-term pressure fluctuations only. Moreover, complexity of cervical cerebrospinal fluid flow and -pulsatility at the upper cervical spinal canal may render the pulse pressure gradient a poor surrogate marker for intracranial pressure pulsations.

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A dynamic nonlinear relationship between the static and pulsatile components of intracranial pressure in patients with subarachnoid hemorrhage.

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A dynamic nonlinear relationship between the static and pulsatile components of intracranial pressure in patients with subarachnoid hemorrhage.

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