Nuutinen Jouni, Alanen Esko, Autio Pekka, Lahtinen Marjo-Riitta, Harvima Ilkka, Lahtinen Tapani
Department of Applied Physics, University of Kuopio, Kuopio, Finland.
Skin Res Technol. 2003 May;9(2):85-9. doi: 10.1034/j.1600-0846.2003.00025.x.
BACKGROUND/AIMS: Open chamber systems for measuring transepidermal water loss (TEWL) have limitations related to ambient and body-induced airflows near the probe, probe size, measurement sites and angles, and measurement range. The aim of the present investigation was to develop a closed chamber system for the TEWL measurement without significant blocking of normal evaporation through the skin. Additionally, in order to use the evaporimeter to measure evaporation rates through other biological and non-biological specimens and in the field applications, a small portable, battery-operated device was a design criteria.
A closed unventilated chamber (inner volume 2.0 cm(3) was constructed. For the skin measurement, the chamber with one side open (open surface area 1.0 cm(2) is placed on the skin. The skin application time was investigated at low and high evaporation rates in order to assess the blocking effect of the chamber on normal evaporation. From the rising linear part of the relative humidity (RH) in the chamber the slope was registered. The slope was calibrated into a TEWL value by evaporating water at different temperatures and measuring the water loss of heated samples with a laboratory scale. The closed chamber evaporation technique was compared with a conventional evaporimeter based on an open chamber method (DermaLab), Cortex Technology, Hadsund, Denmark). The reproducibility of the closed chamber method was measured with the water samples and with volar forearm and palm of the hand in 10 healthy volunteers.
The skin application time varied between 7 and 9 s and the linear slope region between 3 and 5 s at the evaporation rates of 3-220 g/m(2) h. A correlation coefficient between the TEWL value from the closed chamber measurements and the readings of the laboratory scale was 0.99 (P < 0.001). The reproducibility of the evaporation measurements with the water samples was 4.0% at the evaporation rate of 40 g/m(2) h. A correlation coefficient of the TEWL values between the closed chamber and open chamber measurements was 0.99 (P < 0.001) in the range where the response of a conventional evaporimeter was linear (until 120 g/m(2)h. With volar forearm and palm of the hand of 10 healthy volunteers the reproducibility of the measurements was 8.0 and 10.1%.
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.
背景/目的：用于测量经表皮水分流失（TEWL）的开放式腔室系统存在一些局限性，这些局限性与探头附近的环境气流和身体引起的气流、探头尺寸、测量部位和角度以及测量范围有关。本研究的目的是开发一种封闭腔室系统，用于测量TEWL，同时不会显著阻碍皮肤的正常蒸发。此外，为了使用蒸发仪测量其他生物和非生物样本的蒸发速率以及在现场应用中，设计标准是一种小型便携式电池供电设备。
构建了一个封闭的无通风腔室（内部体积2.0 cm³）。对于皮肤测量，将一侧开口的腔室（开口表面积1.0 cm²）放置在皮肤上。在低蒸发速率和高蒸发速率下研究了皮肤应用时间，以评估腔室对正常蒸发的阻碍作用。从腔室内相对湿度（RH）的上升线性部分记录斜率。通过在不同温度下蒸发水并用实验室天平测量加热样本的失水量，将斜率校准为TEWL值。将封闭腔室蒸发技术与基于开放式腔室方法的传统蒸发仪（DermaLab，丹麦哈松德的科特斯技术公司）进行了比较。在10名健康志愿者中，使用水样以及手掌和前臂掌侧对封闭腔室方法的重现性进行了测量。
在3 - 220 g/m²·h的蒸发速率下，皮肤应用时间在7至9秒之间变化，线性斜率区域在3至5秒之间。封闭腔室测量得到的TEWL值与实验室天平读数之间的相关系数为0.99（P < 0.001）。在40 g/m²·h的蒸发速率下，水样蒸发测量的重现性为4.0%。在传统蒸发仪响应呈线性的范围内（直至120 g/m²·h），封闭腔室和开放式腔室测量的TEWL值之间的相关系数为0.99（P < 0.001）。在10名健康志愿者的手掌和前臂掌侧进行测量时，测量的重现性分别为8.0%和10.1%。
封闭腔室技术解决了与开放式腔室蒸发仪相关的缺点。特别是，它将测量范围扩展到高蒸发速率，并且TEWL测量几乎可以在任何解剖部位和测量角度进行。通过使用封闭腔室，可以避免与外部或身体引起的气流对测量的干扰。
