FXCO2 laser therapy of existing burn scars does not significantly improve outcomes in a porcine model

"Living Well" After Burn Injury: Using Case Reports to Illustrate Significant Contributions From the Burn Model System Research Program

The Burn Model System (BMS) program of research has been funded since 1993 by the National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR). The overarching aim of this program is to improve outcomes and quality of life for people with burns in the areas of health and function, employment, and community living and participation. This review reports on BMS contributions that have affected the lives of individuals with a significant burn injury using case reports to associate BMS contributions with recovery. In January 2020, current BMS grantee researchers assessed peer-reviewed BMS publications from 1994 to 2020. Using case report methodology, contributions were linked to three individuals treated at one of the four Burn Model System institutions. With over 25 years of NIDILRR funding, unique BMS contributions to patient recovery were identified and categorized into one of several domains: treatment, assessment measures, sequelae, peer support, employment, and long-term functional outcomes. A second review for significant results of BMS research that add to the understanding of burn injury, pathophysiology, and recovery research was identified and categorized as injury recovery research. The case study participants featured in this review identified select NIDILRR research contributions as having direct, personal benefit to their recovery. The knowledge generation and clinical innovation that this research program has contributed to our collective understanding of recovery after burn injury is considerable. Using case study methodology with three adult burn survivors, we highlight the impact and individual significance of program findings and reinforce the recognition that the value of any clinical research must have relevance to the lives of the study population.

Fractional CO2 laser ablation of porcine burn scars after grafting: Is deeper better?

INTRODUCTION

Fractional CO₂ lasers have been used in clinical settings to improve scarring following burn injury. Though used with increasing frequency, the appropriate laser settings are not well defined and overall efficacy of this therapy has not been definitively established. As it has been proposed that for thick hypertrophic scars proportionally greater fluence and thus deeper ablation into the scar tissue would be most effective, the goal of this study was to examine the role of ablation depth on scar outcomes in a highly-controlled porcine model for burn scars-after grafting.

METHODS

Properties of laser ablated wells were quantified on ex vivo pig skin as a function of laser energy (20, 70 or 150mJ). Full-thickness burn wounds were created on the dorsum of red Duroc pigs with the eschar excised and grafted with a split-thickness autograft meshed and expanded 1.5:1. After four weeks of healing, sites were treated with either 20, 70, or 150mJ pulse energy from a fractional CO₂ laser at 5% density or left untreated as a control. Sites were treated every four weeks with three total sessions. Scar area, pigmentation, erythema, roughness, histology, and biomechanics were evaluated prior to each laser treatment at day 28, 56, and 83, as well as four weeks after the final laser treatment, day 112. Additional biopsies were collected at day 112 for gene expression analysis.

RESULTS

The depth of the laser ablated wells increased with increasing pulse energy while the width of the wells was smaller in the 20mJ group and not significantly different in the 70 and 150mJ groups. Scar properties (area, color, biomechanics) were not significantly altered by laser therapy at any of the laser energies tested versus controls. Average scar roughness was improved by laser therapy in a dose dependent manner with scars treated with 150mJ of energy having the smoothest surface; however, these changes were not statistically significant. Assessment of matrix metalloproteinase 9 gene expression showed a slight upregulation in scars treated with 70 or 150mJ versus control scars and scars treated with 20mJ pulse energy.

CONCLUSION

The current study demonstrated that the properties of the ablative well (depth and width) are not linearly correlated with laser pulse energy, with only a small increase in well depth at energies between 70 and 150mJ. Overall, the study suggests that there is little difference in outcomes as a function of laser energy. Fractional CO₂ laser therapy did not result in any statistically significant benefit to scar properties assessed by quantitative, objective measures, thus highlighting the need for additional clinical investigation of laser therapy efficacy with non-treated controls and objective measures of outcome.