title: Relationship of energy settings and impedance in different anatomic areas using a radiofrequency device.
abstract: BACKGROUND
  Radiofrequency (RF) used for volumetric heating into the deep dermis has been used effectively for rejuvenation of the face. The delivery of the RF energy depends on several variables, including the electrical impedance of the underlying tissue.
  
  
  OBJECTIVE
  To describe the effects of impedance on energy delivery into the treated site.
  
  
  METHODS
  We report four patients who underwent treatment using the ThermaCool TC system (Thermage, Inc, Hayward, CA, USA). Five sites on each patient were selected for impedance evaluation at two treatment levels.
  
  
  RESULTS
  Impedance levels varied only slightly between treatment levels. The impedance levels varied greatly between patients and from site to site in each patient. The impedance levels for each of the patients were greatest on the arm, followed by the forehead, cheeks, and back.
  
  
  CONCLUSIONS
  Energy delivery to a treated area is directly related to the impedance of the tissue. The impedance is shown to vary by site and can be changed by manipulation of the tissue, such as by injection of local anesthesia. Alteration of the impedance may have an effect on the uniform delivery of the selected energy.
authors.affiliation: The Center for Liposculpture and Cosmetic Laser Surgey, Chicago, Illinois, USA.
authors.forename: Edward B
authors.initials: EB
authors.lastname: Lack
authors.forename: John D
authors.initials: JD
authors.lastname: Rachel
authors.forename: Lisa
authors.initials: L
authors.lastname: D'Andrea
authors.forename: Jennifer
authors.initials: J
authors.lastname: Corres
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology*; D001415:Back / Q000502:physiology*; D017097:Electric Impedance; D005145:Face / Q000502:physiology*; D006801:Humans; D006979:Hyperthermia, Induced / Q000295:instrumentation*; D008875:Middle Aged; D000078702:Radiofrequency Therapy