| This lecture examines the relationship
between transepidermal water loss (TEWL) and the skin barrier.
A fundamental difficulty is that TEWL cannot be measured directly.
TEWL is water loss through the intact stratum corneum. "TEWL
instruments" measure water vapour flux density in the air
above the stratum corneum. The two quantities are not necessarily
equal.
After an introduction to define the problem, the conditions
necessary for deducing the barrier property from water vapour
flux measurements are examined from the perspectives of measurement
methods, signal interpretation and mathematical modelling of
the skin + measurement head system. The main conclusion is that
you can measure
barrier resistance provided that certain conditions are satisfied.
|
