Single- and multifrequency models for bioelectrical impedance analysis of body water compartments

The 1994 National Institutes of Health Technology Conference on bioelectric al impedance analysis (BIA) did not support the use of BIA under conditions that alter the normal relationship between the extracellular (ECW) and int racellular water (ICW) compartments. To extend applications of BLA to these populations, we investigated the accuracy and precision of seven previousl y published BIA models for the measurement of change in body water compartm entalization among individuals infused with lactated Ringer solution or adm inistered a diuretic agent. Results were compared with dilution by using de uterium oxide and bromide combined with short-term changes of body weight. BLA, with use of proximal, tetrapolar electrodes, was measured from 5 to 50 0 kHz, including 50 kHz. Single-frequency, 50-kHz models did not accurately predict change in total body water, but the 50-kHz parallel model did accu rately measure changes in ICW. The only model that accurately predicted cha nge in ECW, ICW, and total body water was the 0/infinity-kHz parallel (Cole -Cole) multifrequency model. Use of the Hanai correction for mixing was les s accurate. We conclude that the multifrequency Cole-Cole model is superior under conditions in which body water compartmentalization is altered from the normal state.