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

Kotaro Suehiro, Noriyasu Morikage, Koshiro Ueda, Makoto Samura, Yuriko Takeuchi, Takashi Nagase, Takahiro Mizoguchi, Kaori Nakamura, and Kimikazu Hamano. Lymphatic Research and Biology, 2017

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

Kotaro Suehiro, Noriyasu Morikage, Koshiro Ueda, Makoto Samura, Yuriko Takeuchi, Takashi Nagase, Takahiro Mizoguchi, Kaori Nakamura, and Kimikazu Hamano. Lymphatic Research and Biology, 2017

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-Dexscore (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 (q=0.86). In contrast, only SEFS severity in the medial forearm showed good correlation with LDS (q=0.74).

Conclusions:

Local SEFS may represent ECF status in the entire limb in both the leg and arm LE.

Main findings

  • Small sample size.
  • Ultrasonography using a 10MHz transducer is a noninvasive and inexpensive technique and is probably available in most clinics.
  • Immediately following BIA, a B-mode scan of the subcutaneous tissue was recorded using an ultrasound system. The leg was scanned at eight points (upper, lower, medial, and lateral thigh and leg) and the arm was scanned at four points (medial, lateral, upper arm, and forearm) as reported previously. Then, the subcutaneous echo-free space (SEFS) was graded as follows: grade 0, no echo-free space; grade 1, horizontally oriented echo-free space (at <45 degrees to the skin) only; and grade 2, vertically oriented echo-free space (at > 45 degrees to the skin) bridging the horizontally oriented spaces.
  • Strongest correlation in the lateral lower calf and no correlation in the upper arm compared with LDex.
  • The authors suggest the results suggest that estimating oedema severity in the entire leg by examining SEFS in a specific local area is justified and may be useful in daily medical practices where BIA is not available. This appears to be a premature claim.