Can bioimpedance spectroscopy (BIS) tell us about the form of lymphoedema?

Bioimpedance spectroscopy (BIS) has proved useful for the rapid accurate and quantification of lymphoedema. The underlying principle is that the impedance of a limb to an applied low frequency alternating electric current is inversely proportional to the quantity of extracellular fluid, including lymph. While many studies have shown a high degree of concordance between impedance and limb volume measurements, the question has often been asked: "How is this influenced by the form of lymphoedema?" Lymphoedema may present in various forms, e.g. primarily fluid, fibrotic etc. Broadly, these may be envisaged to represent a continuum from "purely" fluid through gel-like to a pseudo-membraneous tissue-like structure. BIS allows estima-tion of tissue capacitance which for biological structures is a characteristic of the cell membrane and tissue inter-faces. This study tested the hypothesis that membrane capacitance (Cm) would differentiate limbs with lym-phoedema from normal. Cm was measured (SFB3, Im-pediMed Ltd, Brisbane) for both arms of 116 women with no history of lymphoedema and 41 women with clinically affirmed unilateral post-mastectomy lymphoe-dema. Mean Cm for the controls were 4.2 +/- 1.7 nF (mean +/- SD) and 3.7 +/- 1.5 nF for the dominant and non-dominant arm respectively. Corresponding values were 4.1 +/- 3.7 nF and 6.2 +/- 7.1 nF for the unaffected and affected limbs re-spectively. While limb dominance significantly (

Early diagnosis of lymphedema in postsurgery breast cancer patients

Lymphedema is an accumulation of lymph fluid in the limb resulting from an insufficiency of the lymphatic system. It is commonly associated with surgical or radiotherapy treatment for breast cancer. As with many progressively debilitating disorders, the effectiveness of treatment is significantly improved by earlier intervention. Multiple frequency bioelectrical impedance analysis (MFBIA) previously was shown to provide accurate relative measures of lymphedema in the upper limb in patients after treatment for breast cancer, This presentation reports progress to date on a three-year prospective study to evaluate the efficacy of MFBIA to predict the early onset of lymphedema in breast cancer patients following treatment. Bioelectrical impedance measurements of each upper limb were recorded in a group of healthy control subjects (n = 50) to determine the ratio of extracellular limb-fluid volumes. From this population, the expected normal range of asymmetry (99.7% confidence) between the limbs was determined, Patients undergoing surgery to treat breast cancer were recruited into the study, and MFBIA measurements were recorded presurgery, at one month and three months after surgery, and then at two-month intervals for up to 24 months postsurgery, When patients had an MFBIA measure outside the 99.7% range of the control group, they were referred to their physician for clinical assessment. Results to date: Over 100 patients were recruited into the study over the past two years; at present, 19 have developed lymphedema and, of these, 12 are receiving treatment. In each of these 19 cases, MFBIA predicted the onset of the condition up to four months before it could be clinically diagnosed. The false-negative rate currently is zero, The study will continue to monitor patients over the remaining year to accurately ascertain estimates of specificity and sensitivity of the procedure

A comparison of the Siconolfi and Cole-Cole procedures for multifrequency impedance data analysis

The established Cole-Cole and newer Siconolfi methods for analysis of multifrequency impedance data were compared in a group of normal healthy individuals studied under bedside conditions. Impedance quotients derived from each procedure Here similarly well correlated with independent dilutional estimates of total body water. Although both methods estimated resistance at zero frequency, were highly correlated. and provided impedance quotients with very similar correlations with extracellular water, these estimates were significantly different and thus mag not be used interchangeably. The Siconolfi procedure demonstrated no significant advantage over the Cole-Cole method. In view of the sound theoretical basis for the latter, it is concluded that analysis of MFBIA data by the Cole-Cole method is to be preferred