Document Detail

Wavelet assessment of cerebrospinal compensatory reserve and cerebrovascular reactivity.
MedLine Citation:
PMID:  17470981     Owner:  NLM     Status:  MEDLINE    
We introduce a wavelet transfer model to relate spontaneous arterial blood pressure (ABP) fluctuations to intracranial pressure (ICP) fluctuations. We employ a complex continuous wavelet transform to develop a consistent mathematical framework capable of parametrizing both cerebral compensatory reserve and cerebrovascular reactivity. The frequency-dependent gain and phase of the wavelet transfer function are introduced because of the non-stationary character of the ICP and ABP time series. The gain characterizes the dampening of spontaneous ABP fluctuations and is interpreted as a novel measure of cerebrospinal compensatory reserve. For a group of 12 patients who died as a result of cerebral lesions (Glasgow Outcome Scale (GOS) = 1) the average gain in the low-frequency (0.02- 0.07 Hz) range was 0.51 +/- 0.13 and significantly exceeded that of 17 patients with GOS = 2 having an average gain of 0.26 +/- 0.11 with p = 1x10(-4) (Kruskal-Wallis test). A time-averaged synchronization index (which may vary from 0 to 1) defined in terms of the wavelet transfer function phase yields information about the stability of the phase difference of the ABP and ICP signals and is used as a cerebrovascular reactivity index. A low value of synchronization index reflects a normally reactive vascular bed, while a high value indicates pathological entrainment of ABP and ICP fluctuations. Such entrainment is strongly pronounced in patients with fatal outcome (for this group the low-frequency synchronization index was 0.69 +/- 0.17). The gain and synchronization parameters define a cerebral hemodynamic state space (CHS) in which the patients with GOS = 1 are to large extent partitioned away from those with GOS = 2. The concept of CHS elucidates the interplay of vascular and compensatory mechanisms.
M Latka; W Kolodziej; M Turalska; D Latka; W Zub; B J West
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2007-04-05
Journal Detail:
Title:  Physiological measurement     Volume:  28     ISSN:  0967-3334     ISO Abbreviation:  Physiol Meas     Publication Date:  2007 May 
Date Detail:
Created Date:  2007-05-01     Completed Date:  2007-08-14     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9306921     Medline TA:  Physiol Meas     Country:  England    
Other Details:
Languages:  eng     Pagination:  465-79     Citation Subset:  IM    
Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, Wroclaw, Poland.
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MeSH Terms
Blood Pressure / physiology*
Cerebrovascular Circulation / physiology*
Intracranial Hemorrhages / physiopathology*
Intracranial Pressure / physiology*
Middle Aged
Models, Cardiovascular

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

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