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Evaluation of Volume Kinetic Modelling and Analysis for the Assessment of Acute Fluid Shifts in Cats

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Title: Evaluation of Volume Kinetic Modelling and Analysis for the Assessment of Acute Fluid Shifts in Cats
Author: Yiew, Xiu Ting
Department: Department of Clinical Studies
Program: Veterinary Science
Advisor: Bateman, Shane
Abstract: Fluid therapy is a rapidly evolving yet imprecise clinical practice based upon broad assumptions, species-to-species extrapolations, outdated experimental evidence, and individual preferences. Fluid therapy can cause significant harm through fluid overload which increases morbidity and mortality. With limited evidence to support our current fluid administration practices in cats, greater understanding of the volume kinetics (pharmacokinetics) of intravenous fluid and body water physiology in this species would provide valuable data to support safer effective fluid therapy practices. This research project explored the potential of volume kinetic modelling analysis as determined by hemoglobin dilution and estimated urine output in unveiling the distribution, elimination, plasma volume expansion, half-life, and comparative potency of three commonly prescribed intravenous fluids in healthy cats. The feasibility of a novel non-invasive 3-dimensional bladder volume estimation method utilizing bladder circumference tracings obtained from point-of-care bladder ultrasonographic images was also investigated. Approximately equipotent doses of blinded balanced crystalloid solution (Plasma-Lyte A, 20 mL/kg), hypertonic saline solution (5% sodium chloride, 3.3 mL/kg), and synthetic colloid solution (6% tetrastarch 130/0.4, 5 mL/kg) infused over 15 minutes on separate random occasions revealed similar peak plasma volume expansion. The half-life and potency of these solutions were consistent with reports from human and canine studies. Intriguingly, the distribution of all infusions from the central compartment was rapid while the elimination was slow in comparison to other species; suggesting that cats may have different physiological responses to intravenous fluid infusion, which may explain their susceptibility to fluid overload. Computer simulations of hypothetical fluid infusions to achieve and maintain plasma volume expansion at steady state revealed the need for substantial reduction in the infusion rate following initial fluid bolus. Lastly, non-invasive 3-dimensional bladder volume estimation was achieved and showed promising potential in terms of feasibility and agreement with a recently published feline geometric linear bladder dimension formula. Bladder circumference tracings were easy to perform, reliable, and reproducible among individuals with limited point-of-care ultrasonography experience and remained robust when dealing with images of various diagnostic qualities. Additional work on volume kinetics and non-invasive bladder volume estimation are warranted for further investigation of acute fluid shifts in cats.
Date: 2019-07
Rights: Attribution-NonCommercial-NoDerivatives 4.0 International
Terms of Use: All items in the Atrium are protected by copyright with all rights reserved unless otherwise indicated.
Embargoed Until: 2020-09-01

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Attribution-NonCommercial-NoDerivatives 4.0 International Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivatives 4.0 International