Document Detail

Interaction between brain chemistry and physiology after traumatic brain injury: impact of autoregulation and microdialysis catheter location.
MedLine Citation:
PMID:  21488707     Owner:  NLM     Status:  MEDLINE    
Bedside monitoring of cerebral metabolism in traumatic brain injury (TBI) with microdialysis is gaining wider clinical acceptance. The objective of this study was to examine the relationship between the fundamental physiological neuromonitoring modalities intracranial pressure (ICP), cerebral perfusion pressure (CPP), brain tissue oxygen (P(bt)O(2)), and cerebrovascular pressure reactivity index (PRx), and cerebral chemistry assessed with microdialysis, with particular focus on the lactate/pyruvate (LP) ratio as a marker of energy metabolism. Prospectively collected observational neuromonitoring data from 97 patients with TBI, requiring neurointensive care management and invasive cerebral monitoring, were analyzed. A linear mixed model analysis was used to account for individual patient differences. Perilesional tissue chemistry exhibited a significant independent relationship with ICP, P(bt)O(2) and CPP thresholds, with increasing LP ratio in response to decrease in P(bt)O(2) and CPP, and increase in ICP. The relationship between CPP and chemistry depended upon the state of PRx. Within the studied physiological range, tissue chemistry only changed in response to increasing ICP or drop in P(bt)O(2)<1.33 kPa (10 mmHg). In agreement with previous studies, significantly higher levels of cerebral lactate (p<0.001), glycerol (p=0.013), LP ratio (p<0.001) and lactate/glucose (LG) ratio (p=0.003) were found in perilesional tissue, compared to "normal" brain tissue (Mann-Whitney test). These differences remained significant following adjustment for the influences of other important physiological parameters (ICP, CPP, P(bt)O(2), P(bt)CO(2), PRx, and brain temperature; mixed linear model), suggesting that they may reflect inherent tissue properties related to the initial injury. Despite inherent biochemical differences between less-injured brain and "perilesional" cerebral tissue, both tissue types exhibited relationships between established physiological variables and biochemistry. Decreases in perfusion and oxygenation were associated with deteriorating neurochemistry and these effects were more pronounced in perilesional tissue and when cerebrovascular reactivity was impaired.
Ivan Timofeev; Marek Czosnyka; Keri L H Carpenter; Jurgens Nortje; Peter J Kirkpatrick; Pippa G Al-Rawi; David K Menon; John D Pickard; Arun K Gupta; Peter J Hutchinson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of neurotrauma     Volume:  28     ISSN:  1557-9042     ISO Abbreviation:  J. Neurotrauma     Publication Date:  2011 Jun 
Date Detail:
Created Date:  2011-06-21     Completed Date:  2012-05-14     Revised Date:  2014-02-20    
Medline Journal Info:
Nlm Unique ID:  8811626     Medline TA:  J Neurotrauma     Country:  United States    
Other Details:
Languages:  eng     Pagination:  849-60     Citation Subset:  IM    
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MeSH Terms
Brain Chemistry / physiology*
Brain Injuries / diagnosis,  metabolism*,  physiopathology*
Catheters, Indwelling / standards
Homeostasis / physiology*
Microdialysis / instrumentation,  methods*
Middle Aged
Monitoring, Physiologic / instrumentation,  methods
Prospective Studies
Young Adult
Grant Support
G0600986//Medical Research Council; G0600986 ID79068//Medical Research Council; G0601025//Medical Research Council; G9439390//Medical Research Council; G9439390 ID 65883//Medical Research Council

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

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