Lymphedema is swelling of a body part due to excess accumulation of lymphatic fluid. In most cases, lymphedema is the result of lymphatic vessel damage caused by surgery, trauma, infection or filariasis. There are two main goals to measure lymphedema with high accuracy: 1) early diagnosis which may prevent clinically significant lymphedema to develop by early treatment, and 2) evaluate changes in volume (lymphedema) as measure of treatment effects. Besides for clinical environments high accuracy volume measurements also have important applications in sport sciences and technical/industrial environments and others. As limb volume changes over time are generally small, a reliable and objective method is needed. All methods used to date have challenges to achieve a usable clinical accuracy1. We have developed and patented a new volumetric device, the Peracutus Aqua Meth (PAM) (picture)2. Pumping water in or out of the measuring unit at a nearly constant flow rate renders a continuous profile of cross sectional areas along the length of the limb (or any other object). Based on the profile, the volume of any chosen segment of a limb can be determined. A demonstration and an Measuring unit animation are available: https://www.peracutus.com/products-and-results/peracutus-aqua-meth/.The first prototype of the PAM was used in a clinical study including 39 healthy test subjects to demonstrate correct volume measurements3. The figure below shows the profiles of 3 subsequent measurements. In order to correct for differences in stretching the fingers and holding the arm at different depths in the measuring unit a new reference point, the hand median, was mathematically defined4. Aligning profiles in this way greatly enhanced the accuracy of the measurements. Standard deviations of around 1.5% and less are obtained for cross sectional area measurements as well as for arm volume determinations and segments thereof.
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