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Proceedings Paper

Determination Of Central Blood Volume And Extravascular Lung Water By A Double Fiberoptic Device
Author(s): H. Korb; J. Bock; A. Hoeft; R. DeVivie
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Paper Abstract

In patients undergoing thoracic surgery central blood volume is subject to large variations and extravascular lung water (EVLW) may change critically due to fluid shifts. Therefore, an accurate monitoring of these parameters, in particular under perioperative conditions, seems to be desirable. The conventional method for determination of EVLW uses a bolus injection of cold indocyanine green dye into the right atrium and indicator detection on the arterial site. However, this technique is known to overestimate extravascular lung water to a considerable amount. In order to investigate the underlying mechanisms of this overestimation, an experimental study was performed with simultaneous measurements of indicator kinetics in the pulmonary artery and the aortic root by a specially designed double fiberoptic device. Experiments were carried out in 9 mongrel dogs under piritramide-N20 anesthesia. Pulmonary edema was induced by application of oleic acid. Cold indocyanine green dye was injected into the v. cava and indicator kinetics were recorded from the pulmonary artery and aorta using thermistor-fiberoptic catheters. The transport functions of cold and dye were computed by deconvolution of the corresponding pairs of dilution curves. The mean transit times of the intravascular (dye) and diffusible (cold) indicator were determined by transport functions. Then central blood volume and extravascular lung water could be calculated from these mean transit times together with cardiac output. Results: The average overestimation by the conventional analysis of curves (monoexponetial extrapolation) amounts to 55% under control conditions as well as in oleic acid edema. This overestimation is due to indicator recirculation (39%) and a reversible exchange of heat with prepulmonary structures (16%). More accurate measurements of ETLV can be obtained by deconvolution analysis, if pre- and postpulmonary indicator kinetics are recorded by fiberoptic catheters.

Paper Details

Date Published: 15 June 1989
PDF: 6 pages
Proc. SPIE 1067, Optical Fibers in Medicine IV, (15 June 1989); doi: 10.1117/12.952103
Show Author Affiliations
H. Korb, University of Gottingen (Germany)
J. Bock, University of Gottingen (Germany)
A. Hoeft, University of Gottingen (Germany)
R. DeVivie, University of Gottingen (Germany)

Published in SPIE Proceedings Vol. 1067:
Optical Fibers in Medicine IV
Abraham Katzir, Editor(s)

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