title: Measuring transepidermal water loss: a comparative in vivo study of condenser-chamber, unventilated-chamber and open-chamber systems.
abstract: OBJECTIVE
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Dermatology, School of Medicine, University of California, San Francisco, CA, USA. farahmands@derm.ucsf.edu
authors.forename: Sara
authors.initials: S
authors.lastname: Farahmand
authors.forename: Lilian
authors.initials: L
authors.lastname: Tien
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Hui
authors.forename: Howard I
authors.initials: HI
authors.lastname: Maibach
mesh_terms: D000328:Adult; D000368:Aged; D002138:Calibration; D003880:Dermatology / Q000295:instrumentation*; D003902:Detergents / Q000008:administration & dosage; D019937:Diagnostic Techniques and Procedures / Q000295:instrumentation / Q000592:standards*; D004643:Emollients / Q000008:administration & dosage; D004817:Epidermis / Q000378:metabolism*; D005260:Female; D005542:Forearm; D006801:Humans; D008297:Male; D008875:Middle Aged; D010577:Petrolatum / Q000008:administration & dosage; D012680:Sensitivity and Specificity; D012879:Skin Physiological Phenomena; D053832:Surgical Tape; D014867:Water / Q000378:metabolism*; D014870:Water Loss, Insensible / Q000187:drug effects / Q000502:physiology*
chemical_list: D003902:Detergents; D004643:Emollients; D014867:Water; D010577:Petrolatum