The Importance of Optimal Hydration in Patients with Heart Failure—Not Always Too Much Fluid

Figures

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  Figure 1. Simplified representation of the relationship between euvolemia, dehydration, and overhydration (congestion) in heart failure; TBW—total body water; *—Dehydration can be defined as a complex condition resulting in a reduction in total body water, however, the problem is more complex (see Section 4).

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  Figure 2. (a) Graphical definition of electrical impedance; (b) Equivalent circuit of human tissues according to Hayden model: CM—capacitance of cell membrane, RM—resistance of cell membrane, RICF—resistance of intracellular fluid, RECF—resistance of extracellular fluids; (c) Schematic of the flow of current through tissues for signal in range of kHz; (d) Schematic of the flow of current through tissues for signal in range of MHz, which according to simulations is more “direct” than in kHz frequencies.

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  Figure 3. Khajuria and Krahn equation, recommended for calculating plasma osmolality. All variables have to be input in mmol/L. Abbreviations: pOsmc—calculated plasma osmolality; [Na+]—serum sodium concentration; [K+]—serum potassium concentration; [glucose]—serum glucose concentration; [urea]—serum urea concentration.

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  Figure 4. Possible causes of dehydration in heart failure.

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  Figure 5. PRISMA flow diagram for the databases search.

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  Figure 6. The graphical representation of relationships between euvolemia, overhydration, dehydration, and fluid input/output.