Bioimpedance for Lymphedema Management

Courtesy of Impedimed

Introduction

Measurement is one of the major challenges related to lymphedema diagnosis and treatment. New technology, through the use of bioimpedance, brings the hope of being a simplified and practical technique for obtaining these essential measurements.

Why Measurement is Important

Measurement is one of the major challenges related to lymphedema diagnosis and treatment and it is important for these reasons:

• Diagnosing or confirming a diagnosis of lymphedema. Early detection and intervention prior to irreversible skin changes is especially important. Research on the effectiveness of lymphedema treatment and self-care.
• Justifying continued treatment under certain reimbursement plans.

Traditional Measurement Techniques

Edema, or swelling, is not as simple to measure as it appears. Limb volume may be estimated or measured in several ways:

• Volumeter: a mechanical device that measures limb volume based on the amount of water displaced.
• Perometer: an electromechanical device that electronically measures limb cross section at multiple intervals; this data is then used to calculate limb volume.
• Tape measure: a mechanical device used to measure the circumference of the limb at multiple intervals. Approximate limb volume may be calculated from circumference measurements or circumference measurements may be compared directly.

Each of These Techniques has Its Disadvantages:

• Volumeter is seldom used in clinics because the water displacement process is cumbersome and messy.
• Perometer devices are expensive and some models are very bulky.
• Tape measure is time consuming and requires considerable experience.

All share some common drawbacks:

• Limited sensitivity: for water displacement any difference of less than 5 ounces (150 ml) is considered to be a measurement error.
• Reliance on limb volume differences or baseline measurement comparison. Differences in right and left limb volume occur for many reasons unrelated to lymphedema and are not useful for people with lymphedema in both limbs. Changes relative to a baseline measurement are only possible if there is an established baseline, and may occur for other reasons.

Bioimpedance

A new approach to evaluating tissue changes related to lymphedema is based on measuring the bioimpedance of potentially affected tissues. This technique is also known as known as bioelectrical impedance analysis (BIA.)

Bioimpedance is a painless non-invasive diagnosic method that measures the composition of body tissues particularly the presence of body fluids such as lymph.

In association with lymphedema it is a valuable tool in the early detection of fluid build-up and the ongoing measurement of the quantity of fluid present in affected tissues.

Low frequency electrical currents travel through the extracellular fluid in the spaces between the cells without penetrating the cell membrane. Higher frequency signals penetrate the cell walls and pass through both intracellular and extracellular fluid. Impedance can be calculated based on current flows at different signal frequencies and used to estimate how much extracellular fluid is present.

Bioimpedance can be measured using a hand-held device and electrodes attached to one foot, each hand and wrist (for upper extremity). The process is fast and painless.

• Sensitivity for early detection of lymphedema and monitoring small changes.
• Accuracy and repeatability.
• Speed: measure both right and left limbs in five minutes.
• Ability to detect lymphedema without relying on comparison. This will help in cases of lymphedema in both limbs (bilateral) and for lymphedema in areas other than the limbs.

Volume measurements provide diagnostic information for lymphedema in one arm or one leg where the difference in volume between limbs indicates swelling. Measurements taken before treatment for a condition such as breast cancer, provide a valuable baseline that facilitates early diagnositic sign of developing lymhedema before clinical symptoms are visible.

What does this mean?

• Breast cancer patients and others who are at risk for developing lymphedema can be monitored more closely, lymphedema can be detected earlier using bioimpedance, and treated early to reduce or delay the long term effects including infection, fibrosis, and the accumulation of excess adipose tissue. In one study, bioimpedance predicted the onset of lymphedema up to 10 months before clinical diagnosis [1].
• Lymphedema therapists can save time and reduce frustration by using bioimpedance instead of tape measure measurements. Reducing the time required for measurement frees up time that can be used for other reimbursable procedures and seeing additional patients.
• Lymphedema patients can spend less time being measured by their therapists and more time on things they would rather be doing.
• Better data on the effectiveness of lymphedema treatment and self-care options ultimately leading to better care.

More Information

The FDA has cleared the Impedimed XCA (see image) device and L-Dex system for the clinical assessment of unilateral lymphedema of the arm. (It has not been cleared for use on the legs.) More information on bioimpedance devices and measurement is available from the Impedimed website.

References

[1] “Early Diagnosis of Lymphedema Using Multiple Frequency Bioimpedance” by B. H. Cornish et. al. Lymphology, No 34, 2001.

[2] “A New Technique for the Quantification of Peripheral Edema with Application in Both Unilateral and Bilateral Cases” by Bruce Cornish, PhD et. al. Angiology, Vol 53, No 1, 2002.

[3] “Measurement Techniques in Assessment of Lymphedema” by Jane Armer, RN, PhD and Sheila Ridner, RN, PhD. Lymph Link, Vol 18 No 3, July 2006.

[4] “A Simple and Innovative Device to Measure Arm Volume at Home for Patients With Lymphedema After Breast Cancer” by Jean Lette, MD. Journal of Clinical Oncology, Vol 24, No 34, December 1, 2006.

[5] “The Use of Bioimpedance Analysis to Evaluate Lymphedema” by Anne Warren et. al. Annals of Plastic Surgery, Vol 58, No 5, May 2007.

[6] “Bioimpedance Analysis in the Assessment of Lymphoedema Diagnosis and Management” by Stanley Rockson, MD. Journal of Lymphoedema, 2007, Vol 2, No 1.

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Category: How Lymphedema is Treated Updated: 2008-04-04