CO₂ lasers have been used to treat skin since the 1960s. Traditional non-fractionated lasers deliver a continuous wave of thermal energy that ablates the entire epidermis without much penetration to the deeper dermis. This results in a longer downtime for the patient and slower healing.^1-3 Fractional CO2 lasers deliver energy to the skin in microscopic columns or thermal zones, resulting in ablation of the epidermis in these areas. The surrounding epidermis is left intact, which allows for faster re-epithelialization and quicker healing.¹

Currently, there are several fractional CO₂ lasers on the market, and differentiating them can be an arduous task. In this report, we compare and contrast 12 different fractional CO₂ laser resurfacing machines in terms of maximum power, pulse type, maximum fluence, spot size, heat index, incisional handpieces, and cost so that the surgeon will be able to make an educated decision as to which laser would be most suited for his/her practice.

Analysis
The 12 different laser resurfacing machines currently out on the market were studied. These include the Matrix LS-25 (Sandstone Medical Technologies, LLC), Pixel CO₂ (Alma Lasers, Inc.), Active Fx (Lumenis, Inc.), Deep and Total Fx (Lumenis Inc.), SmartXide DOT CO₂ (DEKA Laser), Affirm CO₂ (Cynosure, Inc.), Re:pair (Solta Medical, Inc.), MedArt A/S FRx (ASAH Medico), Juvia (Ellipse A/S), eCO₂ (Lutronic, Inc.), Mixto SX (Lasering USA), and Exel O₂ (Quantel Derma).

Each laser was compared in terms of maximum power, pulse type, maximum fluence, spot size, heat index, incisional handpiece, and cost. Findings for each laser are presented in Table 1.

Power ranged from 15 W to 60 W. All but three laser machines (Juvia, FRx, and Mixto SX) offered ultrapulse or superpulse technology. Maximum pulse fluence ranged from 17 J/cm² to 9554 J/cm². Spot sizes also varied per machine, but only three machines offered interchangeable spot size handpieces: the Re:pair offered 125 micron and 600 micron tips, the Mixto Sx offered 300 micron and 180 micron tips, and the eCO₂ offered five different spot size tips—120 micron, 300 micron, 1mm, 1.3mm, and 2mm tips. The greatest heat index was noted in the Exel O2, Mixto SX, and eCO₂. Every laser had an incisional handpiece except for the eCO₂ laser. Smaller spot size incisional handpieces were found with the Active and Deep Fx, Affirm, Re:pair, and Mixto Sx. Finally, prices ranged from $35,000 to $175,000.

Conclusions
With the many CO2 lasers on the market, it is difficult to decide which one to invest in. Ultrapulse (higher energy with shorter pulse) and superpulse (lower energy/ shorter pulses) technology offers deeper penetration with less surface ablation; this results in greater effective collagen penetration with less patient downtime. The superpulsed CO₂ laser produces significantly less lateral thermal spread at wound edges than previous CO² lasers.² The less powerful machines were continuous wave pulsed, while some of the more powerful ones were either superpulsed or ultrapulsed. Maximum fluence offered was a limitation of the less powerful machines.

Heat index is a relative value that measures a laser's ability to deposit heat in tissue. It is the maximum energy per pulse with maximum pulse width. It is not based on fluence or maximum power. It is both the energy and time that results in the greatest derivation of heat. The greatest heat index was noted in the Exel O2, Mixto SX, and eCO₂.

Interchangeable spot size handpieces are a great advantage of the Re:pair, Mixto Sx, and eCO₂. Different spots sizes can produce dramatic differences in terms of histologic evidence of thermal and coagulative effects. Depending on the patient's expectations and time restraints, the different handpieces can address many different clinical scenarios.

The lack of an incisional handpiece is a limitation of the eCO_{2. Incisional handpieces with smaller spot sizes, such as} the Active and Deep Fx, Affirm, Re:pair, and Mixto Sx, allow for finer incisions with less tissue charring. The ultimate clinical appearance of healed wounds after cutaneous surgery with a superpulsed CO₂ laser is generally impossible to differentiate from wounds following traditional cold steel surgery.² The finger attached to the incisional handpiece also facilitates dissection with orbital cases and lower lid blepharoplasties.

Finally, in terms of price, the more powerful lasers and the lasers offering interchangeable handpieces tended to be the more expensive, but also offer a wider range of resurfacing capabilities. Lumenis offers both the surface ablation of the Active Fx and the deeper penetration of the Deep Fx in their Total Fx machine.

Ultimately, the choice of fractional CO2 laser depends on the surgeon's practice and patient expectations. Newer technology has led to great advancements in laser resurfacing and the ability to tailor treatments toward the individual needs of patients.

Adapted from a presentation given at Cosmetic Dermatology Forum (cosmeticsurgeryforum.com) in Las Vegas, December 2009.

Section Editors: Asish Bhatia, MD and Jeffrey Hsu, MD

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