title: Does pulse stacking improve the results of treatment with variable-pulse pulsed-dye lasers?
abstract: BACKGROUND
  It has been suggested that multiple stacked pulses of lower fluence may have a similar effect on targets as a single pulse of higher fluence. When treating vascular lesions, increasing the fluence beyond a certain point will increase the risk of purpura given a constant pulse duration. Stacking pulses of lower fluence may have the advantage of heating vessels to a critical temperature without creating purpura.
  
  
  OBJECTIVE
  To determine whether stacking low-fluence pulses of a variable-pulse pulsed-dye laser would improve clinical results without significantly increasing side and adverse effects.
  
  
  METHODS
  Twenty-five patients between the ages of 18 and 65 years with facial telangiectasia and skin types I-IV were enrolled in the study. For each subject, the cheek or nasal ala areas on either side of the facial midline with similar telangiectasia density ratings were randomized to single pulse and multiple stacked pulse groups. One side of the cheek or nasal ala was treated with single nonoverlapping pulses with the Candela Vbeam 595-nm pulsed-dye laser. The opposite side of the cheek or nose was treated with the same parameters but with three or four pulses stacked on top of each other at a 1.5-Hz repetition rate. Patients were asked to rate the pain of the procedure on each side on a 0 to 3 scale. Investigators rated the erythema and edema after the procedure as well as vessel clearing and overall telangiectasia density scale at 1 and 6 weeks after the procedure.
  
  
  RESULTS
  Twenty-three patients completed the study. The mean pain rating was 1.58 for the pulse stacked side and 1.38 for the single-pass side. The mean erythema score after the procedure was 1.17 for the pulsed stacked side and 1.09 for the single pulsed side. The mean vessel clearing 1 week after the treatment was 74.3% for the pulse stacked side and 58.5% for the single pulsed side. The mean vessel clearing 6 weeks after the treatment was 87.6% for the pulse stacked side and 67.4% for the single pulsed side. The mean telangiectasia density scale score before treatment was 2.67 for the pulse stacked side and 2.59 for the single pulsed side. At 1 week after treatment, the mean telangiectasia density scale score was 1.06 for the pulsed stacked side and 1.5 for the single pulsed side. At 6 weeks after treatment, the mean telangiectasia density scale score was 0.72 for the pulsed stacked side and 1.30 for the single pulsed side. No patients experienced purpura in either group, and there were no cases of hyperpigmentation, hypopigmentation, or scar formation. One patient experienced significant edema on the side of the cheeks treated with pulse stacking.
  
  
  CONCLUSIONS
  Treating superficial facial telangiectasia with a pulse stacking technique may improve clinical results without significantly increasing adverse effects.
authors.affiliation: SkinCare Physicians of Chestnut Hill, Chestnut Hill Boston University Dermatology, Boston, Massachusetts, USA. trohrer@skincarephysicians.net
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Rohrer
authors.forename: Vandana
authors.initials: V
authors.lastname: Chatrath
authors.forename: Vivek
authors.initials: V
authors.lastname: Iyengar
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005145:Face; D005260:Female; D006801:Humans; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013684:Telangiectasis / Q000532:radiotherapy*; D016896:Treatment Outcome