Document Detail

Noninvasive autoregulation monitoring with and without intracranial pressure in the naive piglet brain.
MedLine Citation:
PMID:  20519421     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Cerebrovascular autoregulation monitoring is often desirable for critically ill patients in whom intracranial pressure (ICP) is not measured directly. Without ICP, arterial blood pressure (ABP) is a substitute for cerebral perfusion pressure (CPP) to gauge the constraint of cerebral blood flow across pressure changes. We compared the use of ABP versus CPP to measure autoregulation in a piglet model of arterial hypotension.
METHODS: Our database of neonatal piglet (5-7 days old) experiments was queried for animals with naïve ICP that were made lethally hypotensive to determine the lower limit of autoregulation (LLA). Twenty-five piglets were identified, each with continuous recordings of ICP, regional cerebral oximetry (rSo2), and cortical red cell flux (laser Doppler). Autoregulation was assessed with the cerebral oximetry index (COx) in 2 ways: linear correlation between ABP and rSo2 (COx(ABP)) and between CPP and rSo2 (COx(CPP)). The lower limits of autoregulation were determined from plots of red cell flux versus ABP. Averaged values of COx(ABP) and COx(CPP) from 5 mm Hg ABP bins were used to show receiver operating characteristics for the 2 methods.
RESULTS: COx(ABP) and COx(CPP) yielded identical receiver operating characteristic curve areas of 0.91 (95% confidence interval [CI], 0.88-0.95) for determining the LLA. However, the thresholds for the 2 methods differed: a threshold COx(ABP) of 0.5 was 89% sensitive (95% CI, 81%-94%) and 81% specific (95% CI, 73%-88%) for detecting ABP below the LLA. A threshold COx(CPP) of 0.42 gave the same 89% sensitivity (95% CI, 81%-94%) with 77% specificity (95% CI, 69%-84%).
CONCLUSIONS: The use of ABP instead of CPP for autoregulation monitoring in the naïve brain with COx results in a higher threshold value to discriminate ABP above from ABP below the LLA. However, accuracy was similar with the 2 methods. These findings support and refine the use of near-infrared spectroscopy to monitor autoregulation in patients without ICP monitors.
Ken M Brady; Jennifer O Mytar; Kathleen K Kibler; Charles W Hogue; Jennifer K Lee; Marek Czosnyka; Peter Smielewski; R Blaine Easley
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review     Date:  2010-06-02
Journal Detail:
Title:  Anesthesia and analgesia     Volume:  111     ISSN:  1526-7598     ISO Abbreviation:  Anesth. Analg.     Publication Date:  2010 Jul 
Date Detail:
Created Date:  2010-06-25     Completed Date:  2010-07-12     Revised Date:  2014-02-19    
Medline Journal Info:
Nlm Unique ID:  1310650     Medline TA:  Anesth Analg     Country:  United States    
Other Details:
Languages:  eng     Pagination:  191-5     Citation Subset:  AIM; IM    
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MeSH Terms
Blood Pressure / physiology
Brain / physiology*
Cerebrovascular Circulation / physiology
Data Interpretation, Statistical
Homeostasis / physiology*
Intracranial Pressure / physiology*
Likelihood Functions
Linear Models
Monitoring, Physiologic / methods*
Oxygen / blood
ROC Curve
Grant Support
G9439390//Medical Research Council
Reg. No./Substance:

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

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