Document Detail

Ventilation-perfusion ratio in perflubron during partial liquid ventilation.
MedLine Citation:
PMID:  20448078     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Functional magnetic resonance imaging (fMRI) of fluorine-19 allows for the mapping of oxygen partial pressure within perfluorocarbons in the alveolar space (Pao(2)). Theoretically, fMRI-detected Pao(2) can be combined with the Fick principle approach, i.e., a mass balance of oxygen uptake by ventilation and delivery by perfusion, to quantify the ventilation-perfusion ratio (Va/Q) of a lung region: The mixed venous blood and the inspiratory oxygen fraction, which are equal for all lung regions, are measured. In addition, the local expiratory oxygen fraction and the end capillary oxygen content, both of which may differ between the lung regions, are calculated using the fMRI-detected Pao(2). We investigated this approach by numerical simulations and applied it to quantify local Va/Q in the perfluorocarbons during partial liquid ventilation. METHODS: Numerical simulations were performed to analyze the sensitivity of the Va/Q calculation and to compare this approach with another one proposed by Rizi et al. in 2004 (Magn Reson Med 2004;52:65-72). Experimentally, the method was used during partial liquid ventilation in 7 anesthetized pigs. The Pao(2) distribution in intraalveolar perflubron was measured by fluorine-19 MRI. Respiratory gas fractions together with arterial and mixed venous blood samples were taken to quantify oxygen partial pressure and content. Using the Fick principle, the local Va/Q was estimated. The impact of gravity (nondependent versus dependent) of perflubron dose (10 vs 20 mL/kg body weight) and of inspired oxygen fraction (Fio(2)) (0.4-1.0) on Va/Q was examined. RESULTS: In numerical simulations, the Fick principle proved to be appropriate over the Va/Q range from 0.02 to 2.5. Va/Q values were in acceptable agreement with the method published by Rizi et al. In the experimental setting, low mean Va/Q values were found in perflubron (confidence interval [CI] 0.08-0.29 with 20 mL/kg perflubron). At this dose, Va/Q in the nondependent lung was higher (CI 0.18-0.39) than in the dependent lung regions (CI 0.06-0.16; P = 0.006; Student t test). Differences depending on Fio(2) or perflubron dose were, however, small. CONCLUSION: The results show that derivation of Va/Q from local Po(2) measurements using fMRI in perflubron is feasible. The low detected Va/Q suggests that oxygen transport into the perflubron-filled alveolar space is significantly restrained.
Alexander-Wigbert K Scholz; Balthasar Eberle; Claus P Heussel; Matthias David; Marc D Schmittner; Michael Quintel; Laura M Schreiber; Norbert Weiler
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-05-06
Journal Detail:
Title:  Anesthesia and analgesia     Volume:  110     ISSN:  1526-7598     ISO Abbreviation:  Anesth. Analg.     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-05-26     Completed Date:  2010-06-15     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  1310650     Medline TA:  Anesth Analg     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1661-8     Citation Subset:  AIM; IM    
Department of Anesthesiology, Johannes Gutenberg-University, Langenbeckstrasse 1, 55131 Mainz, Germany. ascholz@uni-mainz.d
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MeSH Terms
Blood Gas Monitoring, Transcutaneous
Body Temperature
Computer Simulation
Contrast Media / diagnostic use*
Fluorine Radioisotopes / diagnostic use
Fluorocarbons / diagnostic use*
Hemodynamics / physiology
Liquid Ventilation*
Magnetic Resonance Imaging / methods*
Oxygen / blood
Pulmonary Alveoli / metabolism,  physiology*
Pulmonary Diffusing Capacity
Ventilation-Perfusion Ratio / physiology*
Reg. No./Substance:
0/Contrast Media; 0/Fluorine Radioisotopes; 0/Fluorocarbons; 423-55-2/perflubron; 7782-44-7/Oxygen

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

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