Document Detail


Positive end-expiratory pressure oscillation facilitates brain vascular reactivity monitoring.
MedLine Citation:
PMID:  22984248     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The pressure reactivity index (PRx) identifies optimal cerebral perfusion pressure after traumatic brain injury. We describe a method to improve PRx precision by induced variations in arterial blood pressure (ABP) using positive end-expiratory pressure (PEEP) modulation (iPRx). Neonatal swine (n = 10) were ventilated with static PEEP and then with PEEP oscillated between 5 and 10 cmH(2)O at a frequency of 1/min. PRx was recorded as a moving correlation coefficient between ABP and intracranial pressure (ICP) from spontaneous ABP activity (0.05-0.003 Hz) during static PEEP. iPRx was similarly recorded with PEEP oscillation-induced ABP waves. The lower limit of autoregulation (LLA) was delineated with continuous cortical laser Doppler flux monitoring. PEEP oscillation increased autoregulation-monitoring precision. The ratios of median absolute deviations to range of possible values for the PRx and iPRx were 9.5% (8.3-13.7%) and 6.2% (4.2-8.7%), respectively (P = 0.006; median, interquartile range). The phase-angle difference between ABP and ICP above LLA was 161° (150°-166°) and below LLA, -31° (-42° to 12°, P < 0.0001). iPRx above LLA was -0.42 (-0.67 to -0.29) and below LLA, 0.32 (0.22-0.43, P = 0.0004). A positive iPRx was 97% specific and 91% sensitive for perfusion pressure below LLA. PEEP oscillation caused stable, low-frequency ABP oscillations that reduced noise in the PRx. Safe translation of these findings to clinical settings is expected to yield more accurate and rapid delineation of individualized optimal perfusion-pressure goals for patients.
Authors:
Ken M Brady; R Blaine Easley; Kathleen Kibler; David W Kaczka; Dean Andropoulos; Charles D Fraser; Peter Smielewski; Marek Czosnyka; Gerald J Adams; Christopher J Rhee; Craig G Rusin
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Publication Detail:
Type:  Journal Article     Date:  2012-09-13
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  113     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-05     Completed Date:  2013-04-12     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1362-8     Citation Subset:  IM    
Affiliation:
Anesthesiology, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas 77030, USA. kbrady@texaschildrens.org
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MeSH Terms
Descriptor/Qualifier:
Animals
Animals, Newborn
Arterial Pressure / physiology
Brain / blood supply
Brain Injuries / physiopathology
Cerebrovascular Circulation / physiology
Homeostasis
Humans
Intracranial Pressure / physiology
Models, Animal
Monitoring, Physiologic
Positive-Pressure Respiration*
Swine

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