Correlation of L-Dex Bioimpedance Spectroscopy with Limb Volume and Lymphatic Function in Lymphedema

Christopher J. Coroneos, MD, MSc, FRCSC,1 Franklin C. Wong, MD, PhD, JD,2 Sarah M. DeSnyder, MD, FACS,3 Simona F. Shaitelman, MD, EdM,4 and Mark V. Schaverien, MBChB, MSc, MEd, MD, FRCS (Plast)1/ Lymphatic Research Biology 2018

Click to read the abstract

Correlation of L-Dex Bioimpedance Spectroscopy with Limb Volume and Lymphatic Function in Lymphedema

Christopher J. Coroneos, MD, MSc, FRCSC,1 Franklin C. Wong, MD, PhD, JD,2 Sarah M. DeSnyder, MD, FACS,3 Simona F. Shaitelman, MD, EdM,4 and Mark V. Schaverien, MBChB, MSc, MEd, MD, FRCS (Plast)1/ Lymphatic Research Biology 2018

Background: Bioimpedance spectroscopy (BIS) is an established tool for the measurement of extracellular fluid in lymphedema. This study assesses the validity of BIS measurements using the l-Dex for evaluating the effectiveness of interventions to treat lymphedema. Measurements are correlated with limb volume, assessment of pitting edema, physiologic measures of lymphatic function, and response to surgical intervention. Three l-Dex BIS metrics are compared.

Methods and Results: This retrospective study of prospectively collected data identified consecutive patients with lymphedema. l-Dex BIS measurements, limb volume measurements using perometry, transport index (TI) evaluation using radioisotope lymphoscintigraphy, staging using indocyanine green(ICG) fluorescent lymphography, and clinical evaluation of degree of pitting edema were compared to examine correlations. l-Dex BIS metrics included the l-Dex ratio, absolute difference between the affected and unaffected extremities, and their unadjusted ratio. The study included 26 patients with 70 sets of evaluations. There were significant correlations between the l-Dex ratio and limb volume ratio (LVR) using perometry, the degree of pitting edema, TI evaluation using lymphoscintigraphy, and staging using ICG lymphography. Of the l-Dex BIS metrics, the l-Dex ratio correlated most closely with all measures (q=0.71–0.94, p<0.0001). Following complete decongestive therapy, the mean decrease in the l-Dex ratio was 48.3% whereas the corresponding mean reduction in limb volume was 13.8% (q=0.19; p=0.65); subsequent physiological surgery including lymphovenous bypass and vascularized lymph node transfer resulted in an average reduction in l-Dex ratio of 36.1% and mean limb volume reduction of 25.2% (q=0.38; p=0.27).

Conclusions: L-Dex BIS measurements demonstrate face, construct, and criterion validity, and correlate with clinical assessment, LVR, physiologic measures of lymphatic function, and response to conservative and surgical intervention. The L-Dex ratio correlates most closely with all measures and is the recommended metric when using BIS.

Main findings

  • This study compared L- dex, limb volume measurement using perometry, clinical evaluation of degree of pitting, lymphoscintigraphy and ICG fluoroscopy.
  • All 21 patients with upper extremity involvement had lymphedema secondary breast cancer treatment; 13 patients underwent mastectomy, and 8 segmental mastectomy. All of these patients underwent axillary lymphadenectomy, radiation, and chemotherapy; 19 patients received regional nodal irradiation. Among the five patients with lower extremity lymphedema, etiologies included radical hysterectomy, radical prostatectomy, and abdominoperineal resection, all with pelvic lymph node dissection.
  • L-Dex ratio demonstrated face, construct, and criterion validity; it correlated significantly with all measures, including a strong correlation with limb volume ratio (LVR) using perometry (q=0.71; p<0.001). Second, the l-Dex ratio correlated more closely with all measures than both the unadjusted ratio and the absolute differences in the impedance at R0 between the affected and unaffected extremities. Third, LVR using perometry correlated with the TI using lymphoscintigraphy, but not with staging using ICG fluorescent lymphography. Fourth, following nonsurgical or surgical intervention, there were no significant correlations between the reduction in the l-Dex ratio and limb volume.
  • This study has the following limitations: First, all analysis are retrospective, though data were obtained from a prospectively maintained database. Second, the majority of patients, and all included upper extremity cases, were secondary to breast cancer treatment. Further, data were obtained from a single surgeon; results may therefore not be generalizable to all forms of lymphedema and all practice settings. Finally, construct validity was limited to concurrent validity, where l-Dex BIS was correlated to other existing measures; future study will analyze its predictive validity and association with patient-reported outcome measures.