Local Echo-Free Space in a Limb with Lymphedema Represents Extracellular Fluid in the Entire Limb

Abstract

Background: We previously reported that local subcutaneous echo-free space (SEFS) in the leg was stirringly correlated with extracellular fluid (ECF) status in the same part of the leg when assessed using bioelectrical impedance analysis (BIA). In this study, we examined whether local SEFS represents the ECF status in the entire limb. Methods and Results: In 51 legs and 40 arms with lymphedema (LE), subcutaneous tissue ultrasonography was performed to determine SEFS severity (range, 0-2). BIA was also performed to calculate the L-Dex® score (LDS), which is a BIA-derived parameter to represent ECF status, for the arm and modified LDS (mLDS) for the leg (the right arm was used as a reference instead of the contralateral leg). SEFS severity in any part of the leg showed good correlation with mLDS, but that in the lateral lower calf showed the strongest correlation (ρ = 0.86). In contrast, only SEFS severity in the medial forearm showed good correlation with LDS (ρ = 0.74). Conclusions: Local SEFS may represent ECF status in the entire limb in both the leg and arm LE.