Document Detail

A dynamic nonlinear relationship between the static and pulsatile components of intracranial pressure in patients with subarachnoid hemorrhage.
MedLine Citation:
PMID:  19731984     Owner:  NLM     Status:  MEDLINE    
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.
Per K Eide; Benjamin I Rapoport; William B Gormley; Joseph R Madsen
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of neurosurgery     Volume:  112     ISSN:  1933-0693     ISO Abbreviation:  J. Neurosurg.     Publication Date:  2010 Mar 
Date Detail:
Created Date:  2010-03-02     Completed Date:  2010-04-08     Revised Date:  2014-06-08    
Medline Journal Info:
Nlm Unique ID:  0253357     Medline TA:  J Neurosurg     Country:  United States    
Other Details:
Languages:  eng     Pagination:  616-25     Citation Subset:  AIM; IM    
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MeSH Terms
Databases, Factual
Intracranial Pressure*
Linear Models
Middle Aged
Models, Neurological*
Multivariate Analysis
Nonlinear Dynamics*
Signal Processing, Computer-Assisted
Subarachnoid Hemorrhage / physiopathology*
Time Factors
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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