Estimation of acute fluid shifts using bioelectrical impedance analysis in horses.

This research article examines the usefulness of a method called multi-frequency bioelectrical impedance analysis (MF-BIA) in accurately assessing fast fluid changes in horses, particularly during dehydration and the expansion of the extracellular fluid volume (ECFV) which holds potential applications in equine critical care.

Understanding Multi-frequency Bioelectrical Impedance Analysis (MF-BIA)

• MF-BIA is a non-invasive method that has been used to measure the volume of extracellular fluid in different species. It operates by registering the resistance of body tissues to the passage of a small electrical signal.
• In this study, researchers aimed to determine whether it could detect acute, or sudden, changes in fluid levels within the bodies of horses. This is related to whether MF-BIA could be useful in monitoring fluid therapy, which is vital to maintaining an appropriate level of hydration in horses.

Experimental Methodology

• Three experiments were conducted on a group of six healthy mares to assess the methodology.
• The first experiment involved a crystalloid expansion of normally hydrated subjects (increasing the amount of fluid in the body with a solution that contains small molecules).
• The second experiment involved dehydration produced by a drug called furosemide, which increases urination, followed by the administration of a crystalloid.
• The third experiment emulated a condition of sudden blood loss and subsequent readministration of lost blood.
• Measurements were taken at different times before, during, and after each of these fluid shifts.
• The researchers then compared the MF-BIA measurements with the known changes in fluid volume, calculated based on the amount of intravenous fluids administered and the urinary fluid losses.

Results and Conclusion

• The study found that the MF-BIA measurement accurately registered changes in ECFV and total body water during crystalloid expansion and dehydration, demonstrating its application.
• However, the measurement did not produce significant results during blood loss and administration.
• The mean errors between MF-BIA results and measured net changes are small, further validating its reliable use in assessing acute fluid changes in horses.
• Providing a practical and accurate methodology, MF-BIA can be effectively utilized for assessing acute fluid changes during dehydration and expansion of ECFV using isotonic crystalloids, hence extending its applicability in equine critical care.