title: Evaluation of pulse-duration on purpuric threshold using extended pulse pulsed dye laser (cynosure V-star).
abstract: OBJECTIVE
  Pulsed dye lasers (PDL) with extended pulse-durations create new opportunities in the treatment of vascular lesions. Development of extended pulse methods requires understanding of tissue effects of extended pulse-durations. We evaluated tissue effects of extended pulse-duration PDL (EPDL) with cooling. Effects of increasing pulse-duration, fluence, and multiple passes were evaluated to determine purpuric threshold and delayed purpuric response.
  
  
  METHODS
  Ten patients were treated with EPDL and air-cooling on normal buttocks skin. Exposure pulse-durations of 0.5, 2, 20, and 40 milliseconds and increasing fluences 3-20 J/cm(2), pulse-duration dependent. Exposures were evaluated 0.5, 1, and 24 or 48 hours determining purpuric threshold and side effects.
  
  
  RESULTS
  Immediate purpuric threshold increased from 6.2 to 8, 10.4, and 13.8 J/cm(2) at pulse-durations of 0.5, 2, 20, and 40 milliseconds, respectively. Purpuric threshold dropped after 24 hours to 5.2, 7.1, 9.3, and 11.9 J/cm(2), respectively. Multi-pass treatment lowered purpuric threshold by 1 J/cm(2). EPDL purpura resolved in less time than traditional PDL. No side effects were noted.
  
  
  CONCLUSIONS
  EPDL exhibits increasing purpuric threshold with increasing pulse-durations, and risk of delayed onset of purpura.
authors.affiliation: et@mgci.com
authors.forename: Emil
authors.initials: E
authors.lastname: Tanghetti
authors.forename: Rafael A
authors.initials: RA
authors.lastname: Sierra
authors.forename: Evan A
authors.initials: EA
authors.lastname: Sherr
authors.forename: Mirko
authors.initials: M
authors.lastname: Mirkov
mesh_terms: D004334:Drug Administration Schedule; D006801:Humans; D007834:Lasers / Q000009:adverse effects*; D020551:Pulse Therapy, Drug; D011693:Purpura / Q000209:etiology* / Q000473:pathology; D011832:Radiation Injuries / Q000209:etiology* / Q000473:pathology; D012016:Reference Values; D012867:Skin / Q000293:injuries* / Q000473:pathology / Q000528:radiation effects*; D013997:Time Factors; D015599:Trauma Severity Indices