Effects of Extremity Elevation and Health Factors On Soft Tissue Electrical Conductivity

Abstract

Two clinical studies were completed using an auto-tuned induction coil conductivity sensor (ICCS) to determine the effects of a variety of factors on the electrical conductivity of soft tissue. In addition to fifteen "subject variables" such as blood pressure and others, we have specifically focused on considering the role of such factors as gender, age, BMI, smoking and elevation of extremities. Measurements were made at seven sites on either side of the body for a total of fourteen. Higher conductivities were obtained for women than men at all sites. At five sites, where age was a significant factor, conductivity was found to decline with increased age. Interestingly, smokers as a group tended to have reduced conductivity, suggesting that aging and smoking have similar effects on the microvasculature of soft tissue. Generally speaking, electrical conductivity is observed to increase in response to increased elevation at sites located on extremities. Considering just healthy adults, a definite pattern of elevation-induced electrical conductivity displacement emerges when subjects are flagged according to high, low or moderate blood pressure. We suggest that violations of this pattern may provide a method for identifying those individuals in an early stage of peripheral vascular disease.

Auto-Tuned Induction Coil Conductivity Sensor for In-Vivo Human Tissue Measurements

“…A valid concern may be raised regarding the tightness of phase lock, which could produce unrealistically high conductivities if not well controlled. In all clinical work thus far [19], phase angle lock was maintained to within 0.37 ± 0.12 degrees, regardless of body location. Clearly, no errors were incurred due to inadequate control of phase lock.…”