title: Dew point effect of cooled hydrogel pads on human stratum corneum biosurface.
abstract: BACKGROUND
  Cooled hydrogel pads are used to prevent overheating effects of laser therapy. They do not induce cold injuries to the skin, but their more subtle physiological effects have not been thoroughly studied.
  
  
  OBJECTIVE
  To describe the changes in transepidermal water loss and electrometric properties of the skin surface following application of cooled hydrogel pads. Measurements were performed on normal forearm skin of 27 healthy volunteers and on freshly excised skin from abdominoplasty.
  
  
  METHODS
  LaserAid hydrogel pads cooled to 4 degrees C were placed for 15 min on the forearm skin. Measurements of transepidermal water loss (TEWL) and electrometric properties (Corneometer, Nova DPM 900) were performed before application and after removal of the cooled pads.
  
  
  RESULTS
  A consistent increase in corneometer units, dermal phase meter (DPM) values and TEWL were recorded at removal of the cooled hydrogel pads. Both the in vivo and in vitro assessments brought similar information.
  
  
  CONCLUSIONS
  The similar changes disclosed in vitro and in vivo suggest that a common physical process is operating in these conditions. The observed phenomenon is opposite to the predicted events given by the Arrhenius law probably because of the combination of cooling and occlusion by the pads. A dew point effect (air temperature at which relative humidity is maximal) is likely involved in the moisture content of the stratum corneum. Thus, the biological impact of using cooling hydrogel pads during laser therapy is different from the effect of a cryogenic spray cooling procedure. The better preservation of the water balance in the stratum corneum by the cooled hydrogel pads could have a beneficial esthetic effect on laser treated areas.
authors.affiliation: Department of Dermatopathology, University Hospital of Liège, Liège, Belgium.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Xhauflaire-Uhoda
authors.forename: Philippe
authors.initials: P
authors.lastname: Paquet
authors.forename: Gérald E
authors.initials: GE
authors.lastname: Piérard
mesh_terms: D000328:Adult; D047070:Bandages, Hydrocolloid; D003080:Cold Temperature; D017097:Electric Impedance; D004817:Epidermis / Q000502:physiology*; D006801:Humans; D006813:Humidity; D066298:In Vitro Techniques; D012879:Skin Physiological Phenomena; D014870:Water Loss, Insensible / Q000502:physiology*