Tissue Tonometer

Developed in Australia at Flinders Biomedical Engineering in collaboration with the Lymphoedema Assessment Clinic at Flinders Medical Centre, the Tissue Tonometer is an easy-to-use, fast, accurate and reproducible method of assessing pitting edema and fibrotic changes in edematous and lymph- edematous tissues.

Pitting edema results when there is a displacement of extra cellular fluid and is present in stage 1 lymphedema (ISL 1995). Over time, chronic inflammatory changes result in the progressive fibrotic indurations of tissues (Stage 2 lymph edema –ISL Grade 2). Assessing the rate of this change and the impact of your treatment and the patient’s management of this fibrosis is crucial since fibrosis is one of the major factors that can lead to poor lymph drainage and poor treatment outcomes.

What is the Tonometer?

The Tonometer has a weight of 200 grams that gently pushes a plunger onto the skin. The depth of penetration of the plunger is accurately recorded on a dial, to a resolution of 0.01mm.

This tool is quick and easy to use in any clinic setting. It is a mechanical device and does not require electricity or batteries. It is approx.11 cm (4 inches) in height and 5cm (2 inches) wide. It is made of stainless steel with a plastic base and is easy to clean. It comes with a full set of instructions.

Flinders Biomedical Engineering will provide a limited warranty for one year against mechanical defect, including free return shipping for the first three months of the warranty period if defective.

Why use a Tonometer?

Monitoring Change

Appropriate treatment for lymphedema requires accurate objective, diagnosis of the pathophysiologic changes. These changes can be monitored by the use of tonometry.

Tonometry measures the resistance of tissues to compression, in the major lymphatic territories. This provides a sensitive measure of fluid and fibrous accumulation within the tissues and of the progress of the territory or the limb from the initial fluid-rich stage through the fatty middle stage to the fibrous end point stage.

Tonometry is able to monitor the effect of treatment and progression of lymphedema. With fibrosis, tissue resistance to compression increases, resulting in low plunger penetration and a low numerical indication.

Objective to Accurate Charting

Routine measurement through a course of treatment may indicate an increasing plunger penetration due to a softening of the sclerotic tissue. Accurate charting of lymphedema and the course of treatment is essential in order to provide objective data to patients, referring physicians, insurers and research projects and provides evidence for your actions.

Important Considerations

In using the Tonometer, there are two important points to be aware of:

Firstly, it does not measure absolute amounts of fiber or changes in it. The measure is a relative one. That is why its best information comes when you are able to get a baseline (pre-treatment) indication of tonometry of the affected lymph territories or limbs and track the changes as the patient is treated. Secondly, it also important to try to get a contralateral reference point on a normal limb. This will allow you to see how other apparently normal lymphatic territories are progressing and allow you to assess the progress of the affected limb against the non-affected limb.

Reference
1. Bates DO, Levick JR and Mortimer PS (1994), ‘Quantification of Rate and Depth of Pitting in Human Edema Using an Electronic Tonometer’, Lymphology 27, pp 159 – 172

Note: Prices do not include tax and shipping