Analysis of Depth of Ablation, Thermal Damage, Wound Healing, and Wound Contraction With Erbium YAG Laser in a Yorkshire Pig Model
November 2015 | Volume 14 | Issue 11 | Original Article | 1245 | Copyright © November 2015
Salman M.S. Alsaad MD,a E.Victor Ross MD,b Wiley J.Smith MD,c and Damian P.DeRienzo MDd
aDermatology Department, college of medicine, King Saud University, Saudi Arabia
bCosmetic and Laser Dermatology, Scripps Clinic, San Diego, CA
cDepartment of Dermatology, Naval Medical Center, San Diego, CA
dDepartment of Pathology, Scripps Clinic, San Diego, CA
MATERIALS AND METHODS: The laser delivered an ablative pulse followed by a heating pulse of variable duration using either the full coverage or fractional hand piece. Pulse durations for specific coagulation depths were selected based on existing heat transfer models. The bilateral flanks of a single Yorkshire pig were irradiated. There were 14 treatment groups. 3 sites were treated per group for a total of 42 sites. Two of the 3 sites were for observational assessments and the 3rd site served as a reservoir for biopsies. Biopsy specimens were collected on days 0, 1, 3, 7, 14, and 28. Bleeding, erythema, wound healing, and wound contraction (in the fractional hand piece groups) were assessed.
CONCLUSION: Wound healing is faster for fractional laser skin resurfacing compared with traditional contiguous resurfacing as demonstrated by textural changes and degree of erythema. The laser operator can be confident that the depth of ablation displayed on this system accurately reflects what is occurring in vivo for both confluent and fractional modes. Likewise, the measured degree of coagulation was consistent with panel display settings for the confluent mode. However, the degree of coagulation, as measured by the thickness of residual thermal damage, did not vary significantly between the fractional groups. In other words, the pulse duration of the second (heating) pulse did not impact the degree of coagulation in the fractional mode. There was a 2.3% wound contraction between some groups and a 6.5% wound contraction between other groups. A two way analysis of variance found a statistically significant difference in wound contraction based on ablation depth (P=0.012) but the degree of coagulation did not prove to be statistically significant for wound contraction (P=0.66).
J Drugs Dermatol. 2015;14(11):1245-1252.