Measures of Tissue Property Changes in Lymphedema

Depending on the stage to which lymphedema has progressed, affected tissues may become 'harder' in the sense that if you push on the affected tissue it is more difficult to indent. This is the case for example when accumulated protein in the tissue, together with other factors, results in fibrosis. On the other hand, sometimes in the earlier phases of lymphedema development, accumulating fluid in the tissue results in the 'pitting' edema situation, in which tissue fairly easily indents when force is applied, but it takes an abnormally long time for the tissue deformation to return to its original state. Quantitative measures of these features and their changes with either time or treatment can be very useful in both research studies and clinical outcomes assessments.

One of the earliest methods of quantitatatively assessing changes in lymphedematous tissue properties was based on the use of a tonometer developed by Clodius and co-workers1 in 1976. Described as measuring resistance of tissues to compression, the device was first used to measure long standing lymphedma patients and then again after a treatment sequence. The long standing lymphedema was recorded as having increased resistance, which after treatment was greatly reduced. About the same time, the device was used by
Piller and Clodius2 to objectify drug treatment effects. Subsequently, variants of this technique3 have been used by researchers to assess upper4-6 and lower7-8 extremity tissue changes in response to various therapies or interventions. Bates and co-workers9 extended this approach by also including measurements of the rate at which tissue deformed. Tonometry has also been used in an attempt to select patients for therapeutic liposuction based on tissue hardness10. All have generally reported good results with respect to the utility of tonometry for their intended purposes. However, the reliabilty of tonometry as a clinical tool in comparsion with other methods has recently be questioned based on interrater reliability estimates11.

For the most part the individual tonometer devices that have been used in the various studies were specially designed by the researchers. At present there is only one tonometer that is widely available commercially. It is essentially the one that was used by Chen et al. in the reliability study previously cited11. One of the major problems with this type of device is that its operation depends on loading it with a weight and then depending on gravity to produce penetration into the tissue under test. Thus it can only be accurately used if it vertical with respect to the tissue plane being tested. Further, because of its rather wide base plate,which is needed to support the device, its stability is poor on body parts that are not sufficienly flat and large. These may be severe limitations for its use in many situations.

A different and newer approach to assessing local tissue resistance to deformation that is independent of gravity and can be emplyed at any body site uses a hand held device in which the tissue is indented to a known distance and the corresponding force to cause that indentation is measured12
 

REFERENCES

1. Clodius L, Deak L, Piller NB. A new instrument for the evaluation fo tissue tonicity in lymphoedema. Lymphology. Mar 1976;9(1):1-5

2. Piller NB, Clodius L. The use of a tissue tonometer as a diagnostic aid in extremity lymphoedema: a determination of its conservative treatment with benzo-pyrones. Lymphology. Dec 1976;9(4):127-132.

3. Casley-Smith JR. A tissue tonometer for use in the field. Lymphology. Dec 1985;18(4):192-194.

4. Chen HC, O'Brien BM, Pribaz JJ, Roberts AH. The use of tonometry in the assessment of upper extremity lymphoedema. Br J Plast Surg. Jul 1988;41(4):399-402.

5. Szuba A, Achalu R, Rockson SG. Decongestive lymphatic therapy for patients with breast carcinoma-associated lymphedema.
    A randomized, prospective study of a role for adjunctive intermittent pneumatic compression. Cancer. Dec 1 2002;95(11):2260-2267.

6. Carati CJ, Anderson SN, Gannon BJ, Piller NB. Treatment of postmastectomy lymphedema with low-level laser therapy:
    A double blind, placebo-controlled trial. Cancer. Sep 15 2003;98(6):1114-1122.

7. Kar SK, Kar PK, Mania J. Tissue tonometry: a useful tool for assessing filarial lymphedema. Lymphology. Jun 1992;25(2):55-61.

8. Liu NF, Olszewski W. Use of tonometry to assess lower extremity lymphedema. Lymphology. Dec 1992;25(4):155-158.

9. Bates DO, Levick JR, Mortimer PS. Quantification of rate and depth of pitting in human edema using an electronic tonometer. Lymphology. Dec 1994;27(4):159-172.

10. Bagheri S, Ohlin K, Olsson G, Brorson H. Tissue tonometry before and after liposuction of arm lymphedema following breast cancer. Lymphat Res Biol. Summer 2005;3(2):66-80.

11. Chen YW, Tsai HJ, Hung HC, Tsauo JY. Reliability study of measurements for lymphedema in breast cancer patients. Am J Phys Med Rehabil. Jan 2008;87(1):33-38.

12. Mayrovitz HN.
Assessing Lymphedema by Tissue Indentation Force and Local Tissue Water   Lymphology 2009;42:88-98