Evaluation of barrier function of te stratumcorneum wit a portable device based on a closed camber system for measuring transepidermal water loss

摘要

Transepidermal water loss(TEWL) provides us accurate in vivo information about the integriety of the barrier function of the stratum corneum (SC).The largest drawback for using the conventional instruments is their high cost.Moreover,it is also required to conduct measurements in a special environment where there is no air turbulence because so far available instruments are based on an open chamber system that measures the water vapor pressure gradient produced above the skinsurface by te vapor passing through the SC barrier.Recnetly,we have had a chance to test a newly devised portable equipment (Model H4300-S;NIKKISO-YSI CO.,LTD.,Tokyo,Japan) with a closed chamber system whose measuring principleis based on a computed TEWL estimation from a time-wise increase in relative humidity in the space of the probe that is applied on the skin surface.We conducted an in vivo comparative study by using the new portable device and the conventional method using the DermaLab(Cortex Technology,Hadsund,Denmark) in healthy individuals and dermatological patients.We found that the sensitivity of the new device was not inferior to the conventional one because it could detect the poor SC barrier function of normalfacial skin as comparedtothe skin of the extremities.Moreover,barrier disruption that is present in the lesional skin of AD or psoriasis was demonstrable in a severity-dependent fashion.Only one difference from the conventionalone is that the obtained values measured with this new device were lower than those obtained with the DermaLab,probably due to the difference in the method ological principles. It was also unalbe to measure TEWL at the sites with measured values less than 1 g/sq-m/h.However,there was a good correlation betwen the data obtained with different methods (p<0.001).The biggest advantage to use the closed system is that,because water evaporation from the skintakes place in any position,we canperform TEWL measurements without paying attention to the position of the skin surface in contrast to the conventional opensystem that requires the position of the skinsurface to be horizontal.Thus,we can conclude that the closed chamer systemis much more practical than the conventional open cylinder system.It can be carried easily to any palce and enables us to conduct TEWL measurements without requiring any special environment preventive against air turbulence in addition to its cheaper price.