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Using Bioimpedance Spectroscopy to Prevent Progression of Lymphedema


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Surveillance of women at risk for breast cancer–related lymphedema using bioimpedance spectroscopy was more effective in preventing lymphedema progression than traditional measurement of arm circumference, when each is combined with immediate compression therapy. These findings came from the multicenter randomized PREVENT trial, which is among the first to show superiority for bioimpedance spectroscopy, according to Sheila Ridner, PhD, RN, FAAN, of Vanderbilt University School of Nursing, Nashville.1


These findings mean that women could potentially avoid this debilitating condition [lymphedema] if bioimpedance spectroscopy screening were the norm.
— Sheila Ridner, PhD, RN, FAAN

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At the 2019 American Society of Breast Surgeons Annual Meeting, Dr. Ridner reported on an interim analysis of 508 patients that compared the detection of early lymphatic impairment using bioimpedance spectroscopy, which directly measures extracellular fluid, with conventional tape measure assessment. The study found that fewer women progressed to clinical lymphedema when referred for therapy using bioimpedance spectroscopy.

“This study suggests that bioimpedance spectroscopy is a highly effective tool for pinpointing patients at risk,” Dr. Ridner said. “These findings mean that women could potentially avoid this debilitating condition if bioimpedance spectroscopy screening were the norm.”

Key Study Findings

The prospective study enrolled patients planned for mastectomy, lymph node–related breast cancer surgery, and/or radiation therapy. They were randomly assigned to bioimpedance spectroscopy or the control group (conventional tape measure). Regular assessments began 90 days after surgery.

Intervention was triggered by the finding of subclinical lymphedema, defined by an increase in arm circumference of at least 5% and up to 10% in the tape measure group and an increase of at least 6.5 L-Dex units in the bioimpedance spectroscopy group (see sidebar below). Therapy consisted of arm compression with a precisely fitted sleeve and chest gauntlet for 12 hours daily for 28 days. Lymphedema progression was indicated by at least a 10% volume change from pretreatment size, as measured by tape measure.

BREAST CANCER–RELATED LYMPHEDEMA

  • The PREVENT trial was a multicenter randomized trial evaluating bioimpedance spectroscopy versus traditional tape measurement assessment of lymphedema after breast surgery.
  • Bioimpedance spectroscopy was more successful in detecting lymphedema and preventing progression to clinical disease.
  • Funding for the PREVENT trial was provided by ImpediMed, the maker of the L-Dex U400 Bioimpedance spectroscopy device.

Among all participants, 21% met the threshold for intervention: 68 patients in the control group (28.5%) and 41 patients in the bioimpedance spectroscopy group (15.8%). The mean time to reach thresholds was 2.8 months and 9.5 months, respectively. Ten patients (14.7%) triggered in the tape measure group later progressed to clinical lymphedema compared with 2 patients in the bioimpedance spectroscopy group (4.9%). This represents a 67% relative reduction and a 9.8% absolute reduction (P = .130) using bioimpedance spectroscopy measurement, she reported.

Interestingly, although more patients in the tape measure group received early intervention, more also went on to suffer clinical lymphedema, probably because the technique is less accurate than bioimpedance spectroscopy, according to Dr. Ridner. By relying on electrical current to gauge fluid resistance between cells, bioimpedance spectroscopy provides extremely specific and precise measurement, she added.

WHAT IS THE L-DEX INDEX?

  • The lymphedema index (L-Dex) is a noninvasive measurement tool used in the clinical assessment of unilateral lymphedema of the arm or leg in women and of the leg in men. The L-Dex value helps to determine whether a patient has built up excess extracellular fluid in the at-risk limb.
  • In the PREVENT trial, for patients in the bioimpedance spectroscopy group, an increase of 6.5 L-Dex units from baseline, which are reflective of subclinical lymphedema, triggered therapeutic intervention. Those in the conventional tape measure group who experienced an increase in arm circumference of 5% or more, reflective of subclinical lymphedema, were treated with compression therapy.

Sources: www.impedimed.com/what-is-l-dex and
www.breastsurgeons.org/meeting/2019/
press_releases/lymphedema
.

“The two measures assess different things. Tape measurement includes fat, muscle, water inside cells (not lymph fluid), and lymph; thus, it may be picking up generalized swelling, not lymphedema. Bioimpedance spectroscopy detects only lymph fluid change,” Dr. Ridner explained. “At the end of the study, we will know more about contributing factors.” 

DISCLOSURE: The lymphedema PREVENT study was funded by ImpediMed, the maker of the L-Dex U400 bioimpedance spectroscopy device. Dr. Ridner is a principal investigator for research funded by ImpediMed and Tactile Medical through contractual agreements with Vanderbilt University.

REFERENCE

1. Ridner SH, Dietrich MS, Cowher MS, et al: Interim analysis of the lymphedema PREVENT randomized trial. 2019 American Society of Breast Surgeons Annual Meeting. Presented May 2, 2019.


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