Hoffman W L, Anvari B, Said S, Tanenbaum B S, Liaw L H, Milner T, Nelson J S
Department of Dermatology, University of California, Irvine 92612, USA.
Dermatol Surg. 1997 Aug;23(8):635-41. doi: 10.1111/j.1524-4725.1997.tb00381.x.
Successful laser treatment of hemangiomas requires selective photothermal destruction of dilated cutaneous vessels without damaging the overlying epidermis. Delivering a short cryogen spurt, on the order of milliseconds, has been shown to result in localized cooling of the superficial skin structures during laser irradiation.
The purpose of this study was to examine the effectiveness of cryogen spray cooling (CSC) in protecting superficial tissue structures during continuous Nd:YAG laser irradiation of an in vivo model hemangioma.
The highly vascularized chicken comb was selected as the animal model for hemangiomas. The Nd:YAG laser irradiation ranged from 2.6 to 35.1 J/mm2. A feedback system utilizing infrared radiometry monitored the comb surface temperature and controlled delivery time of the cryogen spurt. When comb surface temperature during laser irradiation reached 36-42 degrees C, a 30-100 msec cryogen spurt was delivered. Animals were euthanized 1 hour to 21 days following each experiment. Gross and histologic analyses were performed.
Nd:YAG laser irradiation resulted in deep (up to 6.1 mm) tissue photocoagulation, while CSC preserved the overlying epidermis and papillary dermis.
The results demonstrate that CSC is effective in protecting the epidermis and papillary dermis, while achieving deep tissue photocoagulation during Nd:YAG laser irradiation. Further pilot studies in humans appear warranted.
成功地用激光治疗血管瘤需要对扩张的皮肤血管进行选择性光热破坏，同时不损伤覆盖其上的表皮。已证明，进行持续约毫秒级的短时间冷冻剂喷射，可在激光照射期间使浅表皮肤结构局部冷却。
本研究的目的是检验在对体内模型血管瘤进行连续Nd:YAG激光照射期间，冷冻剂喷雾冷却（CSC）对保护浅表组织结构的有效性。
选择血管高度丰富的鸡冠作为血管瘤的动物模型。Nd:YAG激光照射剂量范围为2.6至35.1 J/mm²。利用红外辐射测量的反馈系统监测鸡冠表面温度并控制冷冻剂喷射的输送时间。当激光照射期间鸡冠表面温度达到36 - 42摄氏度时，进行30 - 100毫秒的冷冻剂喷射。每次实验后1小时至21天对动物实施安乐死。进行大体和组织学分析。
Nd:YAG激光照射导致深度（达6.1毫米）的组织光凝，而CSC保护了覆盖其上的表皮和乳头层真皮。
结果表明，CSC在Nd:YAG激光照射期间对保护表皮和乳头层真皮有效，同时能实现深度组织光凝。似乎有必要在人体中进一步开展初步研究。
