Abstract
Introduction
Studies examining the histopathological changes that occur in human skin following fractional laser treatment have been performed mainly in animals or abdominal tissue prior to abdominoplasty. This study looks at the effect of double pulse fractional CO~2~ laser compared to single pulse treatments to assess differences in tissue injury in the face and abdomen.
Methods
Twelve healthy subjects randomized into two groups, had two 1โcm^2^ areas (infraumbilical and forehead) treated with the fractional CO~2~ laser (Deep Fx, Lumenis). Settings used were 15โmJ double pulse, and 30โmJ single pulse, 300โHz, 10% density and compared to the historic control of 15 patients treated at 15โmJ single pulse [Bailey et al. (2011), Lasers Surg Med 43: 99โ107]. Treated sites were biopsied and analyzed with H&E and TUNEL staining to measure width and depth of the microthermal zones (MTZ) of ablation.
Results
When comparing 15โmJ double pulse to single pulse there were significant differences both in depth (abdominal skin, Pโ=โ0.002 and facial skin, Pโ=โ0.001) and width (facial skin, Pโ=โ0.0002) of MTZ. When comparing double pulsing at 15โmJ with single pulsing at 30โmJ there were significant differences between MTZ depths in the abdomen (Pโ<โ0.01) but not in either the MTZ depth (Pโ=โ0.69) or the width in the face (Pโ=โ0.502).
Discussion
This study demonstrates the differences between histopathological laser injury patterns in the face compared to the abdomen when single pulsing is used. It also demonstrates that double pulsing at 15โmJ is statistically similar to single pulsing at 30โmJ in the face. We think this could have ramifications for clinical practice where by double pulsing at lower energies may result in better clinical outcomes than increasing energies or using multiple passes at single pulse. Clinical studies needs to be performed to investigate this further. Lasers Surg. Med. 44:4โ10, 2012. ยฉ 2012 Wiley Periodicals, Inc.