Comparative evaporimetry in man.
OBJECTIVE
Transepidermal water loss (TEWL) measurements are frequently used; the most widely utilized instrument has been the open chamber device. Traditional open-chamber systems for measuring TEWL have limitations related to ambient and body-induced airflows near the probe, probe size, measurement site and angles. Recent technology provides a portable and battery-operated closed chamber Evaporimeter. It is presumably less affected by external factors such as room- or body-induced airflows, breathing or heating of the probe by the operators' hand. This study compares this commercial instrument, a closed chamber device, with a traditional open-chamber device.


METHODS
Two open chamber devices and one closed chamber device were used in such a way that each instrument could simultaneously measure TEWL in an identical experimental environment with known relative humidity and temperature values. TEWL values of seven locations on healthy volunteers were measured simultaneously with each instrument in the same room according to the guidelines of the standardization group of the European society of contact dermatitis.


RESULTS
For TEWL values of all forearm locations, there was no statistically significant difference between the mean values measured by all three instruments. For TEWL values of forehead locations, there was a significant difference between the mean values of open chamber device and closed chamber device. For the forehead, values from closed chamber device were higher than the open one.


CONCLUSIONS
The TEWL values measured by all instruments were constant with small standard deviations. These instruments appear sufficiently robust that a standardization group could document similarities and differences with in vitro models. We suspect that both techniques will continue to be used and that the closed method will find increasing use because of its ease of use.
Department of Dermatology, University of California, San Francisco, CA 94143-0989, USA.
Jigna H
JH
Shah
Hongbo
H
Zhai
Howard I
HI
Maibach
D000328:Adult; D000368:Aged; D001834:Body Water / Q000502:physiology*; D003880:Dermatology / Q000295:instrumentation*; D005260:Female; D005542:Forearm; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012879:Skin Physiological Phenomena; D014870:Water Loss, Insensible / Q000502:physiology*