title: Influence of body water distribution on skin thickness: measurements using high-frequency ultrasound.
abstract: BACKGROUND
  Although it is known that the skin acts as a water reservoir and participates in the fluid content of the whole body, no method has been established to quantify the fluid shifts in superficial tissue.
  
  
  OBJECTIVE
  The aim of this study was to investigate changes in dermal and subcutis thickness and echodensity at the forehead and lower leg by high-frequency (20 MHz) ultrasound under various physiological conditions influencing water balance.
  
  
  METHODS
  These parameters were measured in the skin of 20 healthy male volunteers at baseline and successively at 30 min after lying down, in a head-down position, after physical activity and after infusion of 10 mL kg-1 body weight of Ringer's solution.
  
  
  RESULTS
  Dermal thickness at the forehead showed a significant increase from baseline to a horizontal position and a further increase in the head-down position. Physical activity did not lead to further changes, whereas after fluid infusion the dermal thickness also increased markedly. The echodensity showed inverse changes, with decreasing values. The thickness of the subcutis increased slightly from baseline to a lying position and decreased in the head-down position and after fluid infusion. At the lower leg, skin thickness decreased slightly in the head-down position with elevated legs, and increased after fluid infusion.
  
  
  CONCLUSIONS
  Our results show that slight changes in the water distribution of the body influence the thickness and the echodensity of the dermis. Changes are more pronounced at the forehead than on the lower legs. Further, the fluid storage takes place mainly in the dermis and not in the subcutis. High-frequency ultrasound is able to quantify these effects and is a sensitive method for measuring fluid intake and balance during anaesthesia and therapy.
authors.affiliation: Department of Dermatology, Medical University of Lübeck, Ratzeburger Allee 160, D-23538 Lübeck, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Eisenbeiss
authors.forename: J
authors.initials: J
authors.lastname: Welzel
authors.forename: W
authors.initials: W
authors.lastname: Eichler
authors.forename: K
authors.initials: K
authors.lastname: Klotz
mesh_terms: D000328:Adult; D001834:Body Water / Q000378:metabolism*; D015444:Exercise / Q000502:physiology; D018495:Fluid Shifts; D005546:Forehead; D006801:Humans; D007866:Leg / Q000000981:diagnostic imaging; D008297:Male; D011187:Posture / Q000502:physiology; D012867:Skin / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D014463:Ultrasonography