Carbon Dioxide Laser Treatment in Burn-related Scarring

This study evaluates the effect effect of ablative fractional CO2 laser (AFCO2L) on burns scar appearance and dermal architecture at 6 weeks and up to 3-years post-treatment. Half of the scar will receive AFCO2L and half the scar will receive standard care.

Ablative fractional CO2 laser (AFCO2L) is emerging as a promising scar treatment for burns patients. Fractionated delivery of CO2 laser treatment leaved columns of undamaged skin to quickly re-epithelialize and has reduced the previously higher risk profile of unfractionated ablative laser delivery in terms of permanent pigmentation changes, higher rates of infection and scarring. The exact mechanisms of CO2 laser action are still unclear, but likely involve a combination of macroscopic ablative fenestration, microscopic thermal collagen alteration and molecular profile alterations. Use of AFCO2L for scar management is increasing amongst burn clinicians; consensus opinion and several large series have demonstrated safe and effective result, however robust randomised controlled evidence for the efficacy of CO2 laser on burns scarring is still lacking.

Scar area (10x10cm square) randomly assigned a square vector 'map' which split the scar into a control and treatment half along one of 4 vectors: vertical, horizontal, and along both diagonals. The envelope revealing the vector map and treatment zones was opened by the treating laser clinician immediately prior to the first treatment. The same treating clinician performed all laser treatments to minimise inter-user variability.

Patient and treating clinician were aware of which scar half had been treated, however investigator and assessor were blinded

Each treatment half of the scar received three standardised CO2 laser treatments using the DeepFX setting hand piece (Ultrapulse, Lumenis), performed under general anaesthetic at 4-6 week intervals. All treatments consisted of a single pass of 300Hz, 5% density and 50mJ energy with minimal overlapping. Post-operatively all laser treatment and control zones had emollient applied and silicone dressings which were removed at 48 hours. Further emollient was applied twice daily for 2 weeks to all areas of the scar. Standard care scar management (including silicone, massage and pressure garments) was directed by burn occupational therapists and was continued for all areas of scar.

Each control half of the scar received emollient applied twice daily for 2 weeks to all areas of the scar after each treatment. Standard care scar management (including silicone, massage and pressure garments) was directed by burn occupational therapists and was continued for all areas of scar.

Fractional CO2 laser treatment using the DeepFX setting hand piece (Ultrapulse, Lumenis), performed under general anaesthetic at 4-6 week intervals. All treatments consisted of a single pass of 300Hz, 5% density and 50mJ energy with minimal overlapping

The Modified Vancouver Scar Scale requires an assessor to rate the patient's scars in 4 domains, each assigning a score to the scar for different qualities (pliability, height, vascularity and pigmentation) from 0 to 4 in pliability and height; and 0 to 3 in vascularity and pigmentation, where 0 is a 'normal' score as close to normal skin as possible and a score of 3 or 4 would indicate a poor outcome, dissimilar to normal skin. The minimum total score is 0 (very good scar) and maximum score is 14 (very bad scar)

Change in Patient Scar Assessment Scale (patient element of the POSAS scale) from baseline at 6 weeks post-final treatment

Patient element of the POSAS scale (Patient and Observer Scar Assessment Scale) version 2.0. The scale asks the patient to rate their scars in 6 domains, each assigning a score to the scar for different qualities (pain, itch, colour, stiffness, thickness irregularity and overall opinion) from 1 to 10, where 1 is a very good score and 10 is a very poor score. The minimum total score is 7 (very good scar) and maximum score is 70 (very bad scar)

3mm punch biopsies from treatment and control segments of scar looking at dermal architecture in terms of collagen fibre thickness and orientation

3mm punch biopsies from treatment and control segments of scar looking at dermal architecture in terms of collagen fibre thickness and orientation

The Modified Vancouver Scar Scale requires an assessor to rate the patient's scars in 4 domains, each assigning a score to the scar for different qualities (pliability, height, vascularity and pigmentation) from 0 to 4 in pliability and height; and 0 to 3 in vascularity and pigmentation, where 0 is a 'normal' score as close to normal skin as possible and a score of 3 or 4 would indicate a poor outcome, dissimilar to normal skin. The minimum total score is 0 (very good scar) and maximum score is 14 (very bad scar)

Change in Patient Scar Assessment Scale (patient element of the POSAS scale) from baseline at 6 weeks post-final treatment

Patient element of the POSAS scale (Patient and Observer Scar Assessment Scale) version 2.0. The scale asks the patient to rate their scars in 6 domains, each assigning a score to the scar for different qualities (pain, itch, colour, stiffness, thickness irregularity and overall opinion) from 1 to 10, where 1 is a very good score and 10 is a very poor score. The minimum total score is 7 (very good scar) and maximum score is 70 (very bad scar)

3mm punch biopsies from treatment and control segments of scar looking at dermal architecture in terms of collagen fibre thickness and orientation

Inclusion Criteria: Minimum burn injury scar area of 10x10cm Vancouver Scar Scale (VSS) score of >5 ≥6 months following injury Patient age 18+ years Exclusion Criteria: Current pregnancy or lactation Patients unable to consent (dementia or another cognitive dysfunction) Non-English-speaking patients Scars on the face or hand (these anatomical areas were considered to be of significant aesthetic and functional importance and thus excluded from the trial )

De-identified individual participant data for primary and secondary outcome measures will be made available