Effect of Supine Versus Sitting Positions on Facial Tissue Dielectric Constant Values in Young Adult Men

Background Assessing facial skin epidermal and dermal water provides information about the skin's water content, which is relevant to its barrier function and may be associated with conditions such as psoriasis, eczema, and rosacea. One method that permits quantitative assessment of facial skin dermal water is via measurements of the tissue dielectric constant (TDC), but such data are sparse in the literature, especially as it applies to assessment in men's facial skin. The general lack of such data may limit the use of dermal water measurements to assess or track facial skin conditions. As an initial step toward improving this situation, this study aimed to evaluate facial TDC values in healthy adult males measured while supine and in the sitting position. These different positions were chosen to assess the potential impact of gravitational forces on the water content of facial tissue. Methodology TDC was measured bilaterally in triplicate to a 1.5 mm depth on the forehead, cheek, and jowl areas of 30 skin-healthy men after 15 minutes of supine lying and then after 15 minutes of upright sitting. Subject ages (mean ± SD) were 25.37 ± 2.59 years. TDC values on the right and left sides at corresponding sites were compared while the subjects were supine and seated. For each site, the right- and left-side TDC values were averaged and used to evaluate the changes associated with shifts in position. To account for the use of multiple right-left side comparisons, statistical acceptance of side differences was based on a p-value less than 0.01. Results While supine, left-right TDC values did not statistically differ at any site. The right-left average TDC values for forehead, cheek, and jowl (mean ± SD) were 41.38 ± 2.99, 39.24 ± 3.99, and 43.23 ± 4.13, respectively. While seated, all site average values were slightly lower: 40.36 ± 2.24, 38.76 ± 3.96, and 42.48 ± 3.47, but only the forehead difference was statistically significant (p = 0.001). Although statistically significant, the forehead difference was less than 1% and not likely to be of clinical significance. Conclusions For this group of young adults, facial skin TDC values were nearly symmetrical side-to-side, differed slightly among facial sites, and varied minimally between supine and sitting positions. If similar features exist in older men or in patients with the various skin conditions cited, then TDC values may be measured in either position, whichever is more convenient for the patient and examiner. Although the positional differences herein were small, further research into these differences in the presence of skin conditions is warranted. The currently determined TDC values, as indices of dermal water, may still serve as healthy-skin reference values for males that could make TDC measurements a useful modality for assessing and tracking changes in facial skin water across various skin conditions. However, the fact that the data from the present study were obtained via measurements on only 30 young adult men should be considered when applying the findings to other populations.