Correspondence

Dehydration versus Volume Depletion — and the Importance of Getting it Right

The Body Composition Monitor (BCM) (Fresenius Medical Care) measures body impedances in alternating currents to subsequently calculate fat and lean tissue mass, fluid compartments, and overhydration (OH). The aim of this study was to investigate differences between two versions of the BCM (an older version, 3.2.5, and a newer version, 3.3.3).

Between September 2021 and December 2021, 28 hemodialysis patients were included to undergo BCM measurements before each of 14 consecutive dialysis sessions with versions 3.2.5 and 3.3.3 devices. Measurements were performed according to instructions provided by the manufacturer. Differences between BCM devices were tested for statistical significance using paired Wilcoxon tests, neglecting clustering.

A total of 288 measurement pairs of 27 patients were left after exclusion of 43 flawed data points. The mean difference in OH between both BCM devices was 0.548 L (higher for version 3.2.5). Analysis of impedance data revealed differences in the high-frequency spectrum, quantifiable by the intracellular resistance, R_i (median R_{i version 3.2.5} = 1750.3 Ω; R_{i version 3.3.3} = 1612.45 Ω; P < 0.001), and the time delay, T_d (median T_{d version 3.2.5} = 1.85 ns; T_{d version 3.3.3} = 8.88 nanoseconds; P < 0.001).

This study finds that results between the two versions of the BCM differed in a clinically meaningful fashion and that the newer version 3.3.3 device had a bias toward less OH. Circulating BCM devices should be checked for versions and only devices of the same version should be used for each patient to ensure better within-patient consistency.

The use of intravenous fluids in out-of-hospital settings has evolved from the practices used by military and emergency response teams. When used in the elite sporting environment, IV fluid use must comply with the World Anti-Doping Code. Uncertainty can arise as clinicians seek to balance the appropriate use of IV fluids in delivering athlete care against the need for World Anti-Doping Code compliance.

This position statement reviews the current literature and incorporates clinical experiences to present best-practice recommendations on the clinical use of Intravenous fluids in the elite sport environment, framing recommendations in the context of the World Anti-Doping Code.

The World Anti-Doping Code restricts the use of Intravenous fluids in athletes under certain conditions. This report takes into account the World Anti-Doping Code and the risks of Intravenous fluid administration to provide guidelines around the judicious use of IV fluids for:

1. Treatment of severe dehydration in an athlete,

2. Management of exertional heat illness in an athlete,

3. Hypovolaemia because of trauma in sport,

4. Administering medications.