| A dynamic nonlinear relationship between the static and pulsatile components of intracranial pressure in patients with subarachnoid hemorrhage. | |
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MedLine Citation:
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PMID: 19731984 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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OBJECT: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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. |
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Authors:
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Per K Eide; Benjamin I Rapoport; William B Gormley; Joseph R Madsen |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Journal of neurosurgery Volume: 112 ISSN: 1933-0693 ISO Abbreviation: J. Neurosurg. Publication Date: 2010 Mar |
Date Detail:
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Created Date: 2010-03-02 Completed Date: 2010-04-08 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0253357 Medline TA: J Neurosurg Country: United States |
Other Details:
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Languages: eng Pagination: 616-25 Citation Subset: AIM; IM |
Affiliation:
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Department of Neurosurgery, Rikshospitalet University Hospital, Oslo, Norway. per.kristian.eide@rikshospitalet.no |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Aged Databases, Factual Female Humans Intracranial Pressure* Linear Models Male Middle Aged Models, Neurological* Multivariate Analysis Nonlinear Dynamics* Periodicity* Signal Processing, Computer-Assisted Subarachnoid Hemorrhage / physiopathology* Time Factors |
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