The BCM measures the electrical responses at 50 different frequencies between 5 and 1000 kHz.
OH is derived from the impedance data based on a 3-compartment model developed by Chamney et al12 The 3 compartments are lean tissue mass, adipose tissue mass, and OH.
OH is the difference between the amount of ECW in tissue that is detected by the BCM and the amount of water present in tissue predicted using physiological models under normal (euvolemic) conditions.
Therefore, the OH value obtained from the BCM can be compared directly with that of the normal population.
Volume overload was defined as a relative OH value (OH normalized to ECW or OH/ECW) ≥7%, corresponding to the value of the 90th percentile for the reference cohort.
The BCM device has been validated in a study involving 350 healthy people with the same ethnic background in Taiwan.
Both investigators and patients were blinded to the OH results.
We performed a repeat body composition measurement 6 months after enrollment and found no significant changes in the OH levels over time (paired t test, P=0.563).
Anemia was defined in accordance with the World Health Organization as hemoglobin concentrations