Correlation Between the Severity of Subcutaneous Echo-Free Space and the Amount of Extracellular Fluid Determined by Bioelectrical Impedance Analysis of Leg Edema.

BACKGROUND

Both subcutaneous echo-free space (SEFS) observed by ultrasonography and the ratio of intracellular fluid resistance to extracellular fluid resistance (R/R) calculated from bioelectrical impedance analysis (BIA) represent extracellular edema status in the extremities. We tried to correlate these parameters.

METHODS AND RESULTS

In 70 legs with venous edema (VE) and 68 legs with lymphedema (LE), subcutaneous tissue ultrasonography to determine SEFS severity (range, 0-2) and BIA to calculate R/R were performed. In the calf, SEFS severity showed good linear correlation with R/R, particularly in the lower lateral calf where the mean R/R for LE (SEFS grade 0: 3.2 ± 0.8; SEFS grade 1: 4.0 ± 0.9; SEFS grade 2: 6.3 ± 3.6) and VE (SEFS grade 0: 3.6 ± 0.6; SEFS grade 1: 4.4 ± 1.6; SEFS grade 2: 5.3 ± 2.0) was similar. In the thigh, a mild correlation was confirmed only in LE.

CONCLUSIONS

It may be concluded that SEFS in the lower calf area well represents the local fluid status regardless of the type of edema, but not so in the thigh.