Monitoring of skin response to sodium lauryl sulphate: clinical scores versus bioengineering methods

Abstract

The present trial was designed to evaluate clinical scores (single observer) of sodium lauryl sulphate (SLS)‐induced skin irritation in a group of subjects (n =10) over a 10‐day period along with various skin function parameters. In order to avoid significant variations due to secondary phenomena, the following parameters were recorded with non‐invasive instruments in this order: skin capacitance (Cl; arbitrary units; CM420 Corneometer), transepidermal water loss (TEWL:, g/m2. H: Evaporimeter) and laser Doppler fowmetry (CBFV: cutaneous blood flow values; Periflux. All examinations were performed during water on reclined relaxed subjects present for at least 10 min in a test, room with controlled temperature und relative humidity (to: 19.5–20.70 C and RH: 47.3 60.3%). The analysis of differential data (∂=value at tx‐value before test; 2‐way ANOVA) was made on single parameters as a function of site (volar forearm versus neck) and time (from 24 h after 48‐h occlusion with 5% SLS up to 10 days later). The profile of erythema scores over time differed between neck and forearm, but the ∂CBFV readings with the laser Doppler instrument did not detect significant site‐time interactions. Roughness (blind evaluation with palpating finger) and capacitance readings (∂CI) showed significant differences between sites, but the profile over time was similar in both locations. ∂TEWL did not differ according to anatomical location. The reason (or different erythema scores on neck and forearm might be related to inherent regional variation of optical properties of the skin or to a substantial contribution of SLS‐induced roughness to the readings of erythema. Indeed, such a discrepancy has already been reported with 10% SLS, and a significant dose effect was observed between 5 and 10% SLS. indicating that these observations were not due to a saturation of the skin vascular response quantified as CBFV. Hence, the influence of optical phenomena on clinical scorings might be worth further consideration.

Full-Body Skin Mapping for Six Biophysical Parameters: Baseline Values at 16 Anatomical Sites in 125 Human Subjects

“…In the present study, the low values can be considered in the range of a normal barrier function while the medium values were slightly higher than those considered to reflect a normal epidermal function and are usually assessed on the volar forearm. The highest TEWL values were registered on the the palms and soles as well as on the axilla, in accordance with former studies [36][37][38] . Cofactors like occlusion and the impact of eccrine sweat gland activity might have largely contributed to the elevated TEWL values.…”

Sodium Lauryl Sulfate-Induced Irritation in the Human Face: Regional and Age-Related Differences

“…Various protocols (concentrations, application time) use SLS in water solution to induce skin irritation [10,11] . In our study, since the face was suspected to be more sensitive than the remaining regions of the body, and for a practical purpose, SLS 2% was applied only for 1 h under occlusion.…”

Objective interpretation of severity of SLS induced edema by stereoimaging

“…These measurement methods, which rely on additional physiologic phenomenon related to skin surface changes have been researched for many years, because they are non-invasive and objective [1][2][3][4][5][6]. Furthermore, high-frequency pulsed ultrasound and MRI are also being investigated as skin thickness measuring tools [7,8].…”

“…Various bioengineering methods (colorimeter, transepidermal water loss, corneometer, laser Doppler velocimeter, reflectance spectrophotometer and ultrasound) [1][2][3][4][5][6][7][8] have been used for Summary Background: In the evaluation of the severity of skin inflammations, visual scoring system is widely being used as a subjective method. However, it is well known that interobserver variations occur even between the interpretations of experienced dermatologists.…”

“…the objective quantification of SLS induced edema. These measurement methods observing the additional physiologic phenomenon developed according to skin surface changes were sought after by researchers for many years recently since they are non-invasive and objective, and could be used to compare with each other [2][3][4][5][6][7][8]. Furthermore, highfrequency pulsed ultrasound and MRI are also being used to observe edema by measuring skin thickness [7,8].…”