Easily applicable and inexpensive water-specific techniques to evaluate local oedema, swollen tissue problems and fluid retention in humans are not available. In the present investigation a recently constructed non-invasive device for a local measurement of changes in tissue water in human skin and subcutaneous fat (SSF) was validated. The instrument transmits an ultra high-frequency electromagnetic (EM) wave of 300 MHz into a coaxial line and further into an open-ended coaxial probe which is in contact with the skin. Due to the dimensions of the applied probe the penetration of the EM field extends to subcutaneous fat. A major part of the EM energy is absorbed by tissue water while the rest is reflected back into a coaxial line. From the information of the reflected wave an electrical parameter, directly proportional to tissue water content, called a dielectric constant of SSF, was calculated. For system validation, the decrease of water content in SSF measured with the dielectric technique in the volar forearm of seven patients during haemodialysis treatment was compared with the decrease of the circumference of the forearm and the amount of fluid removed. Statistically highly significant correlations were obtained between the decreasing dielectric constant (i.e. water content) of the SSF and the fluid removed during haemodialysis treatment (r = -0.99, p < 0.01) and between the decreasing dielectric constant and the circumference of the arm (r = 0.97, p < 0.05). The sensitivity of the dielectric method was four-fold compared with the circumferential measurement. The repeatability 3.0% was not dependent on the phase of haemodialysis. The new device allows an easy and non-invasive measurement technique to assess changes of tissue water in SSF.

The closed chamber technique solves the drawbacks related to open chamber evaporimeters. Especially, it extends the measurement range to high evaporation rates and TEWL measurements can be performed practically at any anatomical sites and measurement angle. By the use of a closed chamber the disturbance related to external or body-induced air flows on the measurement can be avoided.

The capacitive measuring principle of the MoistureMeter was demonstrated in an experimental arrangement. Although both instruments yielded equivalent data with the base formulation, the MoistureMeter was a more sensitive device than the Corneometer CM 820 and independent of added salt in the formulations.

Endovascular interventions with antegrade brachial arterial access are highly effective in restoring function in failing Brescia-Cimino fistulas.

We have performed a series of experiments which demonstrate the effect of open-ended coaxial diameter on the depth of penetration. We used a two layer configuration of a liquid and movable cylindrical piece of either Teflon or acrylic. The technique accurately demonstrates the depth in a sample for which a given probe diameter provides a reasonable measure of the bulk dielectric properties for a heterogeneous volume. In addition we have developed a technique for determining the effective depth for a given probe diameter size. Using a set of simulations mimicking four 50 Ω coaxial cable diameters, we demonstrate that the penetration depth in both water and saline has a clear dependence on probe diameter but is remarkably uniform over frequency and with respect to the intervening liquid permittivity. Two different 50 Ω commercial probes were similarly tested and confirm these observations. This result has significant implications to a range of dielectric measurements, most notably in the area of tissue property studies.