Fig. 5.7. Informed consent for nonablative resurfacing
3 J/cm2 with a 7-mm spot size does not effectively target vasculature. When the laser is used with a 5-mm spot size and higher fluences, vas-culature can also be treated.
The most commonly used 1320-nm Nd:YAG laser is used with a spray cooling device that provides not only pre-, but also mid- and post-cooling of the epidermis to allow for a more superficial level of skin treatment. A temperature sensor reads the surface heat generated by a test pulse and the goal is to keep it in the 40°C to 45°C range. Energy settings are then set accordingly. Although originally done with a single pass, three passes are now recommended utilizing a precooling pass, a midcooling pass, and a postcooling pass. The precooling pass is performed at 30 ms cooling duration with a flu-ence range of 14-18 J/cm2, which is based on temperature sensor readings. The midcooling pass is used in combination with pre- and post-cooling at the following settings: 5-ms precool, 5-ms midcool, and 20-ms postcool at 17 J/cm2. The postcooling pass fluences are adjusted based on temperature sensor readings and range from 13 to 17 J/cm2 with a 30-ms postcool duration.
The 1450-nm midinfrared laser has greater water absorption so changes noted are more superficial. This may be more advantageous in targeting dermal solar damage, which typically involves the superficial dermis. It is used with a similar dynamic cooling device that protects the epidermis while depositing the heat in the dermis. When used for nonablative rejuvenation, the larger 6-mm hand piece is used typically at 10-16 J/cm2 with cooling at 25-35 ms. To target a specific lesion, as in sebaceous hyper-plasia, the 4-mm spot is used and the fluence is increased to 17-18 J/cm2 and cooling is decreased to 30 ms. Larger lesions can even be double pulsed.
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