Fluid doesn’t need feet

Fluid management is a crucial part of managing dialysis patients. Historically, this was based on clinical assessments that are “notoriously subjective”, recount two English researchers from Leeds Teaching Hospitals NHS Trust. Now, a recently introduced body composition monitor (BCM) is able to objectively quantify the volume of excess or deficient fluid in a patient; and in addition to extra- and intracellular water (ECW/ICW), the model also maps the calculated ECW, ICW and weight to a “unique combination” of normally hydrated lean tissue mass (LTM), normally hydrated adipose tissue mass (ATM) and the volume of excess or deficient fluid, explain the authors.

This measure of fluid excess or deficiency, defined as the hydration status (HS), is crucial: It gives an “easily interpretable value” that can be used next to traditional clinical assessments to guarantee an optimal fluid management. One hitch: The models used by the BCM were developed and validated using standard wrist-to-ankle bioimpedance measurements, made between electrodes on the hand and foot – which would exclude the not insignificant number of dialysis patients with ulcerated (and therefore bandaged) or amputated feet, due to the lack of accessible sites for electrodes.

But the hitch seems to have been overcome: The present study compared hydration measurements made with ‘hand-to-hand’ (H-H) to ‘hand-to-foot’ (H-F) configurations, and came to the conclusion that H-H measurements seem to be as appropriate as those with H-F: 101 patients were measured with both methods, and compared with H-F, H-H measurements showed a bias of -0.1l. For 61% of patients the difference between the readings was within 0.5 L; for 81% it was within 1.0 L.

Hand-to-hand measurements constitute an acceptable alternative protocol for BCM measurements in patients with inaccessible, sore, bandaged or amputated feet.