Measurement of transepidermal water loss in localized scleroderma

Localized scleroderma (LS) is a disease characterized by fibrotic changes in the dermis. Connective tissue growth factor and transforming growth factor β2 are the main mediators of fibrogenesis; this, along with excessive connective tissue production, affects epidermal keratinocytes, and thereby contributes to the changed quality of skin barrier. The objective of this article was to study the objective measurement of the skin barrier quality in LS with transepidermal water loss (TEWL) meter. The measurements of TEWL were performed on LS plaques in all three stages of various body locations. Control measurements were made on the contralateral side of healthy skin. The difference between TEWL in LS area and the contralateral side of the healthy skin was evaluated. A higher average TEWL 7.86 g/m²/h (SD 5.29) was observed on LS plaques compared with the control measurements on healthy skin 6.39 g/m²/h (SD 2.77). TEWL average values decreased from the inflammatory stage, through the sclerotic and to the atrophic stage. The mean difference 1.301 g/m²/h (SD 5.16) was found between TEWL on LS plaques and on the contralateral healthy skin in 82 measurements, i.e., a higher TEWL was observed in LS. The difference was statistically significant with p = 0.0250. Although fibrogenesis in scleroderma is localized in dermis, the skin barrier changes can be detected.     

Correlation of transepidermal water loss with skin barrier properties in vitro: comparison of three evaporimeters

Aim: This study investigates the relationship between transepidermal water loss (TEWL) and skin permeability to tritiated water as a rapid assessment of the integrity of the barrier properties of skin as part of in vitro skin permeation studies.
Methods: TEWL values before and during the experimental period were measured using three evaporimeters (A, B, and C) representing different measuring principles and technologies. Single application of tritiated water was dosed on dermatomed human skin samples in a flow-through diffusion cell system. Radioactivity of the absorbed dose and the removable dose residues was counted to determine percent dose and flux rate. These data were further combined with TEWL values to analyze the correlation.
Results: Evaporimeter C, a closed chamber–condenser technology, had higher measurement capacity than other instruments, evaporimeter A, an open chamber, and evaporimeter B, a closed chamber ( P <0.001). The baseline TEWL value correlated with tritiated water flux ( r =0.34, P =0.04). The pattern of tritiated water expressed as percent dose permeated into receptor fluid was similar to that of TEWL values.
Conclusion: These data indicate that TEWL can be ascribed to be a measure of skin water barrier function. Further work should be conducted to interpret the significance of measuring TEWL by evaporimetry.     

Side‐by‐side comparison of an open‐chamber (TM 300) and a closed‐chamber (Vapometer™) transepidermal water loss meter

Background: The measurement of transepidermal water loss (TEWL) is used to monitor changes in the stratum corneum's permeability to water vapor. This measurement is widely used in the cosmetics industry and in dermatology research. However, only limited work has been undertaken to assess the comparability of results from different TEWL meters over an extended range of measurements. Methods: This study compared the results of TEWL measurements between two commonly used open‐chamber and closed‐chamber TEWL devices. Five hundred and forty measurements were taken in 17 participants on the dorsum and palm of both hands on two different days and the order of the devices was randomized. Results: The results showed that the open TEWL meter's capacity for measuring high values of TEWL was restricted, and that the closed‐chamber TEWL meter was less sensitive to differences in the lower range of measurements. Conclusion: Both devices have their strengths for different applications, but their results cannot be directly compared. We were unable to find a statistical model that would allow us to transform the measurements made on one device for a comparison with the results generated by the other device.     

Comparison of closed chamber and open chamber evaporimetry

Background: Recently it has been asserted that a closed chamber evaporimeter, the VapoMeter, offers advantages over standard open chamber devices in measuring transepidermal water loss (TEWL). Purported improvements include the ability to take measurements at any angle, short reading times and insensitivity to external air currents. These claims are compelling, considering that measuring TEWL at diverse skin sites can be tedious, especially with children. The primary aim of this study was to compare the performance of closed and open chamber instruments when they were held at various angles and, secondly to evaluate the ability of the devices to discriminate between test conditions. Methods: The performance of closed chamber (VapoMeter) and open chamber (DermaLab^®) evaporimeters were compared by measuring water vapor emitted from IMS Vitro‐skin^® that had been hydrated to a predetermined level. Measurements were taken at three angles from vertical – 0°, 45°, and 90°. Vitro‐skin^® samples were weighed periodically throughout the experimental phase to verify water loss rates. Results: Both the VapoMeter and the DermaLab^® yielded significantly lower water loss values when held at angles that varied from the vertical (0°) position, indicating that the closed chamber device is no more capable of accurately measuring TEWL at any angle than an open chamber instrument. The DermaLab^® provided better discrimination than the VapoMeter when the instruments were held vertically, as is the only prescribed testing position for open‐chamber instruments. The VapoMeter was easier to use than the DermaLab^®; however, there was evidence that the sealed chamber could become saturated under high water loss conditions. Conclusions: Previous assertions that the VapoMeter closed chamber evaporimeter is capable of measuring TEWL regardless of angle were not validated. Each device appeared capable of accurately estimating water loss rates only in the vertical position. Although the VapoMeter was easier to use than the open chamber device, its tendency to become saturated under high water loss conditions could be a disadvantage when assessing dynamic TEWL.     

Validation of the VapoMeter, a closed unventilated chamber system to assess transepidermal water loss vs. the open chamber Tewameter®

BACKGROUND/AIM: Transepidermal water loss (TEWL) is one of the most important biophysical parameters for evaluating the efficiency of the human skin water barrier. Different approaches exist to measure TEWL. The most commonly used methodology consists of the open chamber diffusion technique in which the water vapor pressure gradient is measured in g/h m2 according to Fick's law. A typical apparatus is the Tewameter. Recently, a portable device--the VapoMeter--became available with a humidity sensor in a closed chamber. METHODS: In the present work, the closed chamber VapoMeter is compared with the open chamber Tewameter for its applicability to assess TEWL. A comparative study--including parallel in vivo measurements with both devices--was carried out on human forearm skin. RESULTS: It could be concluded that both instruments are reliable tools. A good correlation between recordings (r=0.503-0.966) was found with a consistent feature of measuring higher TEWL values for the Tewameter than for the VapoMeter. Probe pressure, probe temperature and relative humidity were revealed to be important parameters inducing significant differences in data outcome. CONCLUSIONS: From skin barrier damage experiments it became clear that the Tewameter is able to detect significantly smaller differences than the VapoMeter. In addition, the closed chamber device is currently not sensitive enough to discriminate for the effects induced by diurnal rhythm and fluctuations as a function of time. On the other hand, the small and handy VapoMeter allows more flexibility in measuring protocols and in in-use performance.     

EIectrical impedance and transepidermal water loss of healthy human skin under different conditions

Background/aims: The skin barrier function is a multidimensional quality, which can be defined by a combination of noninvasive measurements, including EIectrical impedance (EI) and transepidermal water loss (TEWL). Methods: TEWL and EI were determined on in five different areas of the body in 25 healthy volunteers. The effects of hydration (a 15 min water bath, a 1 h occlusion and application of an oil-in-water emulsion combined with occlusion) were measured on the volar forearm. Results: EI was highest in the axillary region, followed by the cheek, spinal region, presternal area and upper arm. TEWL was highest in the axillary region, followed by the cheek. Lowest levels were detected in the spinal region, the presternal region and the upper arm. The water bath increased EI but not TEWL. After 1 h occlusion TEWL was not increased and EI decreased, which corresponds to stratum corneum hydration. After a single application of an oil-in-water emulsion, we observed a reduction of EI and an increase of TEWL. The simultaneous use of occlusion and application of an emulsion led to the most significant reduction of EI. TEWL was increased during the following 30 min. Conclusions: EI and TEWL show a topological variability. Acute hydration increased EI but occlusion and/or moisturizing decreased EI. Acute hydration and occlusion alone did not significantly affect TEWL, but moisturizing in combination caused a longer lasting TEWL increase. To examine the stratum corneum function, the use of different noninvasive techniques seem to provide more complex information.     

A comparison of techniques for the measurement of transepidermal water loss

Summary An Evaporimeter and a ventilated chamber technique have been compared in their ability to measure transepidermal water loss (TEWL) through rat skin. These techniques measure TEWL under very different conditions; the Evaporimeter measures the net TEWL under ambient relative humidity (RH) whereas the ventilated chamber employs a constant atmosphere, usually of low RH and thus measured the uni-directional diffusion of water. Paired Evaporimeter and ventilated chamber measurements were made of TEWL through normal skin and through skin whose barrier properties had been altered by tape-stripping (15 applications) or single applications of n-hexadecane (28.4 mol cm^–2). Both measuring techniques indicated the same level of TEWL through normal skin (mean 0.3 mg cm^–2 h^–1) and during increases in TEWL induced by n-hexadecane (max TEWL c 3.5 mg cm^–2 h^–1). However, the Evaporimeter was found to underestimate the higher rates of TEWL induced by tape-stripping, ie above TEWL rates of 7.5 mg cm^–2 h^–1. The Evaporimeter is portable, easy to use and suitable for measurements of net water loss up to 7.5 mg cm^–2 h^–1; it can only be used for comparative assessments of epidermal barrier function if used at a particular ambient RH. The more cumbersome ventilated chamber is to be preferred for accurate assessments of barrier function where high rates of TEWL occur.At this address during a period of industrial training     

Guidelines for transepidermal water loss (TEWL) measurement

This report reviews individual-related variables, environment-related variables and instrument-related variables, with a focus on the Evaporimeter EP1 (ServoMed). Start-up and use is described, and guidelines for good laboratory practice given.     

Measuring transepidermal water loss: a comparative in vivo study of condenser-chamber, unventilated-chamber and open-chamber systems

Background/aims: Two main systems have been utilized for measuring transepidermal water loss (TEWL): open chamber and closed chamber. Yet, further validation and standardization studies may be necessary to reveal the sensitivity, precision, and robustness of these instruments. Methods: Three instruments are compared for their applicability to assess TEWL: unventilated chamber, open chamber and condenser chamber. The comparative study was performed on human forearm skin (n=6), in the normal condition (baseline), and after (1) 10 tape strippings on both arms, (2) moisturizer cream (Eucerin^®) and petrolatum application for 1 h, and (3) 1% sodium lauryl sulfate (SLS) aqueous solution and distilled water (as control) application for 20 min. Results: The condenser‐chamber system, was the only device among these three that could show the effect of tape stripping on TEWL values as compared with baseline (P<0.001). The effect of moisturization, in terms of % change of TEWL values after application of cream and petrolatum, did not show significant difference between devices (P>0.05). However, only the values obtained from condenser‐chamber device revealed a highly significant change as compared with baseline (P<0.001). Condenser‐chamber system could also discriminate between the effect of moisturizer and petrolatum on TEWL values (P<0.05). The change of TEWL values after SLS application was shown to be significant by unventilated and condenser‐chamber systems (P<0.05). However, none of the devices differentiated between the effect of water and 1% SLS solution applied for 20 min. The values obtained from all three instruments correlate well with each other (P<0.001). Conclusion: Our results highlight the differences between two closed‐chamber TEWL measurement instruments, which are designed based on different measurement principles. This may provide insights to find the best practice to improve the quality, precision and sensitivity of the measurements.     

The effect of bilayer and hexagonal H(II) phase lipid films on transepidermal water loss

The common membrane phospholipids tend to adopt either the familiar bilayer phase or the less familiar hexagonal H(II) phase when isolated and hydrated in excess water. The objective of this study was to compare the effects of these very different macroscopic lipid structures on transepidermal water loss (TEWL) when they are applied to the surface of pig skin mounted in Franz diffusion cells. First, a novel in vitro method for monitoring TEWL was developed and characterized in which the flux of water from the subphase through skin was measured through the absorption of (3H)-water by lyophilized polyethylene glycol (PEG) mounted above the skin surface. TEWL was varied by disrupting the skin barrier to different degrees by tape stripping or solvent extraction. Bilayer-forming egg phosphatidylcholine (EPC) or hexagonal H(II)-forming dioleoyl phosphatidylethanolamine (DOPE) were applied topically as solutions in ethanol and subsequently dried to films. The molecular configuration adopted by each lipid at the skin surface was confirmed by phosphorus NMR. TEWL for normal skin was approximately 2 g H2O/h/m2, increasing to a maximum of 80 g H2O/h/m2 after the stratum corneum was completely removed by tape stripping. On tape-stripped skin, films of lipid doses as low as 10 mg/cm2 significantly reduced TEWL, and DOPE (hexagonal H(II)) was approximately twofold more effective than EPC (bilayer). Furthermore, the effects of EPC and Vaseline on reducing TEWL from damaged skin were readily reversed by a simple aqueous wash, whereas the DOPE effect was unaltered even by vigorous washing. Similar results were obtained with lipid films applied to solvent-extracted skin. The data are consistent with the formation of extensive hydrophobic interactions between the skin and the outwardly facing acyl chains of the inverted, hexagonal H(II) phase adopted by DOPE. This results in the formation of a durable surface barrier capable of significantly reducing TEWL from damaged skin.     

经表皮水分流失与皮肤屏障的遗传学研究

经表皮水分流失（Transepidermal water loss?,TEWL）测量的是水分从真皮和表皮的水合层向皮肤表面扩散的通量密度,是用于评估皮肤屏障功能的一项成熟无创的方法,最新的一项研究发现TEWL值与9号染色体9q34.3基因突变密切相关,本文总结了TEWL与皮肤屏障功能的遗传学研究进展。     

面部糖皮质激素依赖性皮炎患者经皮水分丢失和皮肤含水量分析

目的 分析面部糖皮质激素依赖性皮炎患者的皮肤屏障功能。方法 将面部分为额部、鼻尖、下颌、双面颊、双侧口角的皮损区及左耳后无皮损区共8个点，分别测量95例面部糖皮质激素依赖性皮炎患者及25例健康对照者的经皮水分丢失（TEWL）和皮肤含水量。结果 与健康组相比，面部糖皮质激素依赖性皮炎组下颌、双侧口角、双面颊TEWL值均显著升高（t值分别为4.90，2.60，2.57，2.54，3.77，P < 0.01）；双侧口角、右面颊及额部的皮肤含水量均显著降低（t值分别为3.27，3.81，2.02，2.78，P < 0.05）。在8个测量点中，面部糖皮质激素依赖性皮炎组与健康组TEWL值均为下颌及双侧口角 > 双面颊及额部 > 耳后无皮损区；皮肤含水量降低均为下颌及双侧口角 > 双面颊及额部 > 耳后无皮损区。结论 面部糖皮质激素依赖性皮炎患者下颌、双侧口角、双面颊区域皮肤屏障功能受损，口周区域TEWL值较高，而面颊皮肤水分含量较少。     

Loss of contact sensitization evaluated by laser Doppler blood flowmetry and transepidermal water loss measurement

Allergic contact dermatitis, which is mediated by activated T cells through a Type IV reaction, is usually believed to persist throughout life. There have been several reports of spontaneous loss of sensitization, e.g., loss of previous patch test reaction or loss of allergic contact dermatitis withal continuous exposure to the allergens. However, these have not been well quantified. The aim of this study was to confirm the development of desensitization or hyposensitization with the aid of objective measurements. A total of 18 patients with alopecia areata, who had received 4 months diphenylcyclopropenone (DPCP) contact immunotherapy, were patch tested and the responses were measured by laser Doppler blood flowmetry (LDF) and transepidermal water loss (TEWL). Patch tests were performed 2X, before and after 4 months of immunotherapy. To determine whether local desensitization developed, we compared change of DPCP concentrations producing mild contact dermatitis on the scalp. Our results showed that systemic and local hyposensitization occurred in human subjects by weekly applications of low concentrations of DPCP for 4 months. LDF seems to be more correlated with visual scores than TEWL measurement.     

Time course of occlusive effects on skin evaluated by measurement of transepidermal water loss (TEWL) Including patch tests with sodium lauryl sulphate and water

The time course for transepidermal water loss (TEWL) for a period of 3 h after removal of occlusive patch tests with sodium lauryl sulphate (SLS), water and empty chambers was studied in healthy volunteers. Patches were applied to the upper arm for 24 h, TEWL was measured immediately after removal of the patches, and every 30 min up to 3 h. For SLS and water patches, TEWL remained significantly increased for 3 h. as compared to normal adjacent skin, while for empty chamber patches. TEWL was only significantly increased for 30 min. A significant decrease from 0 to 30 min and from 30 to 60 min was observed for all patches, and for water patches, a significant decrease in TEWL was found from 60 to 180 min, while SLS patches remained constant. The prolonged increase in TEWL observed after SLS exposure is a well-known occurrence. The prolonged increase in TEWL after exposure to water is interpreted as transient damage to the water harrier of the skin.