Document Detail

Transcranial Doppler pulsatility index: not an accurate method to assess intracranial pressure.
MedLine Citation:
PMID:  20495421     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Transcranial Doppler sonography (TCD) assessment of intracranial blood flow velocity has been suggested to accurately determine intracranial pressure (ICP).
OBJECTIVE: We attempted to validate this method in patients with communicating cerebrospinal fluid systems using predetermined pressure levels.
METHODS: Ten patients underwent a lumbar infusion test, applying 4 to 5 preset ICP levels. On each level, the pulsatility index (PI) in the middle cerebral artery was determined by measuring the blood flow velocity using TCD. ICP was simultaneously measured with an intraparenchymal sensor. ICP and PI were compared using correlation analysis. For further understanding of the ICP-PI relationship, a mathematical model of the intracranial dynamics was simulated using a computer.
RESULTS: The ICP-PI regression equation was based on data from 8 patients. For 2 patients, no audible Doppler signal was obtained. The equation was ICP = 23*PI + 14 (R = 0.22, P < .01, N = 35). The 95% confidence interval for a mean ICP of 20 mm Hg was -3.8 to 43.8 mm Hg. Individually, the regression coefficients varied from 42 to 90 and the offsets from -32 to +3. The mathematical simulations suggest that variations in vessel compliance, autoregulation, and arterial pressure have a serious effect on the ICP-PI relationship.
CONCLUSIONS: The in vivo results show that PI is not a reliable predictor of ICP. Mathematical simulations indicate that this is caused by variations in physiological parameters.
Anders Behrens; Niklas Lenfeldt; Khalid Ambarki; Jan Malm; Anders Eklund; Lars-Owe Koskinen
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Neurosurgery     Volume:  66     ISSN:  1524-4040     ISO Abbreviation:  Neurosurgery     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-05-24     Completed Date:  2010-12-23     Revised Date:  2010-12-28    
Medline Journal Info:
Nlm Unique ID:  7802914     Medline TA:  Neurosurgery     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1050-7     Citation Subset:  IM    
Department of Clinical Neuroscience, Umeå University, Umeå, Sweden.
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MeSH Terms
Blood Pressure / physiology*
Cerebrospinal Fluid Pressure / physiology
Cerebrovascular Circulation / physiology*
Hemodynamics / physiology
Hydrocephalus, Normal Pressure / complications,  physiopathology,  ultrasonography
Intracranial Hypertension / etiology,  physiopathology*,  ultrasonography*
Intracranial Pressure / physiology*
Middle Cerebral Artery / physiopathology,  ultrasonography
Predictive Value of Tests
Pulsatile Flow / physiology*
Sensitivity and Specificity
Ultrasonography, Doppler, Transcranial / methods*
Comment In:
Neurosurgery. 2010 Dec;67(6):E1863-4; author reply E1864   [PMID:  21107156 ]
Neurosurgery. 2011 Jan;68(1):E289-92   [PMID:  21099711 ]

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