What are the basic features of the carbon dioxide (CO₂) laser?

The CO₂ laser emits radiation at 10,600 nm, in the far-infrared region. All water in tissue absorbs this wavelength of light, and this absorption is not dependent on selective absorption by any biologic tissue. As the water absorbs energy, the temperature rapidly rises, vaporizing the tissue. The amount of tissue damage is related to the energy setting and the amount of time the laser impacts on the target. There is some true ablation of tissue and this is surrounded by a zone of thermal damage. This area of thermal damage is used in resurfacing by causing immediate collagen contraction and later collagen remodeling.

The standard delivery system for the CO₂ laser is an articulated arm, which comprises a series of rigid tubes with mirrored joints capable of rotating in all directions. The CO₂ laser light is invisible and therefore must use a heliumneon laser as an aiming beam. The CO₂ laser operates in a range between 1 W and 30 W of power. The mechanical pulses are set between 0.01 sec and 0.1 sec, but the laser may also operate in a continuous-wave mode. CO₂ lasers are usually used in a focused or defocused mode, the former for high intensity use, such as cutting, and the latter for low-power destructive uses.

The new superpulsed and ultrapulsed CO₂ lasers have powers up to 60 W and pulse duration in the range of 250 µsec to 1 msec. There are now many fractional CO₂ lasers designed to reduce the side effects of CO₂ laser ablation (Table 54-3).