Laubach Hans, Chan Henry H, Rius Francisca, Anderson R Rox, Manstein Dieter
Wellman Laboratories for Photomedicine and Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA.
Lasers Surg Med. 2007 Jan;39(1):14-8. doi: 10.1002/lsm.20453.
Fractional photothermolysis is a new concept in cutaneous re-modeling whereby laser-induced microscopic zones of thermal injury (MTZ-Microscopic Treatment Zones) are surrounded by normal, viable tissue. This unique thermal damage pattern allows re-epithelialization in less than 24 hours. To increase patient comfort level during the procedure of fractional photothermolysis, simultaneous skin cooling has been proposed and is now extensively used. The purpose of this in vitro study was to examine the influence of skin temperature on the diameter of the epidermal microthermal zone and the extent of thermal injury per unit area. The determination of the changes in these parameters that are due to skin temperature will allow the better control and understanding of fractional photothermolysis at different skin temperatures.
Fractional photothermolysis was performed with a 1,550 nm fiber laser (Fraxel SR Laser) with 10 mJ per pulse on full-thickness cadaver skin. The skin samples were brought prior to exposure to temperatures that ranged from 0 to 45 degrees C. The epidermis of the skin samples was separated by dispase treatment, stained for thermal damage by NBTC stain, and lesion diameter was assessed by a blinded investigator.
The average MTZ diameter exhibits a positive, linear relationship with skin temperature (R(2) = 0.904, P < 0.0001). As the skin temperature increases from 0 to 45 degrees C. The MTZ diameter increases from 93 to 147 microm (58%), and the MTZ area from 6,870 to 17,050 microm(2) (148%).
The skin temperature affects the size of epidermal MTZs during fractional photothermolysis and is an important variable factor. The use of simultaneous skin cooling increases patient comfort; however, as it also decreases MTZ size, it may interfere with treatment efficacy. The control of skin temperature is necessary to provide a consistent outcome and to be able to compare treatments.
点阵式光热溶解术是皮肤重塑领域的一个新概念，即激光诱导的微小热损伤区域（MTZ - 微观治疗区）被正常的、有活力的组织所包围。这种独特的热损伤模式使得上皮再形成可在不到24小时内完成。为了在点阵式光热溶解术过程中提高患者的舒适度，人们提出并广泛采用了同步皮肤冷却技术。本体外研究的目的是探讨皮肤温度对表皮微热区直径以及单位面积热损伤程度的影响。确定这些因皮肤温度而产生的参数变化，将有助于更好地控制和理解不同皮肤温度下的点阵式光热溶解术。
使用波长为1550nm的光纤激光器（飞梭SR激光），对全层尸体皮肤进行每脉冲10mJ的点阵式光热溶解术。在照射前，将皮肤样本加热至0至45摄氏度的不同温度。通过Dispase处理分离皮肤样本的表皮，用NBTC染色评估热损伤情况，由一位不知情的研究者测量损伤直径。
平均MTZ直径与皮肤温度呈正线性关系（R(2) = 0.904，P < 0.0001）。当皮肤温度从0摄氏度升至45摄氏度时，MTZ直径从93微米增加至147微米（增加了58%），MTZ面积从6870平方微米增加至17050平方微米（增加了148%）。
在点阵式光热溶解术中，皮肤温度会影响表皮MTZ的大小，是一个重要的可变因素。同步皮肤冷却的使用提高了患者的舒适度；然而，由于它也会减小MTZ的大小，可能会干扰治疗效果。控制皮肤温度对于获得一致的治疗结果以及能够比较不同治疗方法是必要的。
