Document Detail


Noninvasive monitoring of cerebral perfusion pressure in patients with acute liver failure using transcranial doppler ultrasonography.
MedLine Citation:
PMID:  18581484     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Elevated intracranial pressure (ICP) leads to loss of cerebral perfusion, cerebral herniation, and irreversible brain damage in patients with acute liver failure (ALF). Conventional techniques for monitoring ICP can be complicated by hemorrhage and infection. Transcranial doppler ultrasonography (TCD) is a noninvasive device which can continuously measure cerebral blood flow velocity, producing a velocity-time waveform that indirectly monitors changes in cerebral hemodynamics, including ICP. The primary goal of this study was to determine whether TCD waveform features could be used to differentiate ALF patients with respect to ICP or, equally important, cerebral perfusion pressure (CPP) levels. A retrospective study of 16 ALF subjects with simultaneous TCD, ICP, and CPP measurements yielded a total of 209 coupled ICP-CPP-TCD observations. The TCD waveforms were digitally scanned and seven points corresponding to a simplified linear waveform were identified. TCD waveform features including velocity, pulsatility index, resistive index, fraction of the cycle in systole, slopes, and angles associated with changes in the slope in each region, were calculated from the simplified waveform data. Paired ICP-TCD observations were divided into three groups (ICP < 20 mmHg, n = 102; 20 < or = ICP < 30 mmHg, n = 74; and ICP > or = 30 mmHg, n = 33). Paired CPP-TCD observations were also divided into three groups (CPP > or = 80 mmHg, n = 42; 80 > CPP > or = 60 mmHg, n = 111; and CPP < 60 mmHg, n = 56). Stepwise linear discriminant analysis was used to identify TCD waveform features that discriminate between ICP groups and CPP groups. Four primary features were found to discriminate between ICP groups: the blood velocity at the start of the Windkessel effect, the slope of the Windkessel upstroke, the angle between the end systolic downstroke and start diastolic upstroke, and the fraction of time spent in systole. Likewise, 4 features were found to discriminate between the CPP groups: the slope of the Windkessel upstroke, the slope of the Windkessel downstroke, the slope of the diastolic downstroke, and the angle between the end systolic downstroke and start diastolic upstroke. The TCD waveform captures the cerebral hemodynamic state and can be used to predict dynamic changes in ICP or CPP in patients with ALF. The mean TCD waveforms for corresponding, correctly classified ICP and CPP groups are remarkably similar. However, this approach to predicting intracranial hypertension and CPP needs to be further refined and developed before clinical application is feasible.
Authors:
Shushma Aggarwal; David M Brooks; Yoogoo Kang; Peter K Linden; John F Patzer
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Liver transplantation : official publication of the American Association for the Study of Liver Diseases and the International Liver Transplantation Society     Volume:  14     ISSN:  1527-6473     ISO Abbreviation:  Liver Transpl.     Publication Date:  2008 Jul 
Date Detail:
Created Date:  2008-07-10     Completed Date:  2008-09-08     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100909185     Medline TA:  Liver Transpl     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1048-57     Citation Subset:  IM    
Affiliation:
Department of Anesthesiology, University of Pittsburgh Medican Center, Pittsburgh 15213, PA. aggarwals@anes.upmc.edu
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Adult
Aged
Blood Pressure*
Cerebrovascular Circulation*
Female
Humans
Intracranial Pressure*
Liver Failure, Acute / physiopathology*
Male
Middle Aged
Middle Cerebral Artery / ultrasonography
Retrospective Studies
Ultrasonography, Doppler, Transcranial*
Comments/Corrections
Comment In:
Liver Transpl. 2008 Jul;14(7):915-6   [PMID:  18581486 ]

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


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