Segmental Impedance Thresholds for Early Detection of Unilateral Upper Limb Swelling.

BACKGROUND: Detection of early lymphedema is important for effective treatment outcome and reduction of disease burden. The aims of this study were to determine normal inter-limb variance in the hand and four segments of the arm using bioimpedance spectroscopy (BIS) to provide diagnostic thresholds for detection of early lymphedema development, to determine the intra-rater reliability of these measurements, and to compare the inter-limb BIS ratios to differences based on arm circumference measures.

METHODS AND RESULTS: One hundred women, aged 49.1 (SD 13.8) years without history of breast cancer or lymphedema participated. Impedance measures for the hand and four 10 cm length arm segments were used to determine the inter-limb segment BIS ratios. Circumference difference and segment volumes were calculated from circumference measures obtained with a tape measure. A subgroup of women was measured on two occasions, one week apart. Thresholds were determined for the dominant and nondominant limb, based on two and three standard deviations (SD) above the mean. The 2SD and 3SD thresholds for the dominant arm ranged from 1.121 to 1.150 and 1.172 to 1.209, respectively, and for the nondominant limb ranged from 1.057 to 1.107 and 1.103 to 1.169, respectively. Intra-rater reliability was high (ICC: 0.945-0.983). BIS ratio and circumference-based measures did not identify the same segments as being over threshold.

CONCLUSIONS: BIS diagnostic thresholds for the hand and four segments of the arm, based on normative data, taking into consideration arm dominance have been developed. Segmental BIS has been shown to be highly reliable.