Janda Philip, Sroka Ronald, Mundweil Boris, Betz Christian S, Baumgartner Reinhold, Leunig Andreas
Department of Oto-Rhino-Laryngology/Head & Neck Surgery, Ludwig-Maximilians-University, 81377 Munich, Germany.
Lasers Surg Med. 2003;33(2):93-101. doi: 10.1002/lsm.10199.
Laser light of various wavelengths is being used for surgical procedures in otolaryngology. Apart from well-known fiber guided laser systems such as Nd:YAG- and Ho:YAG-lasers, newly developed diode-laser systems of different wavelengths have recently become popular in surgery. In order to compare the effects of fiber guided laser light with respect to their induced tissue effects, these laser systems have been studied and compared under reproducible test conditions.
STUDY DESIGN/MATERIALS AND METHODS: The laser fibers of four common medical laser systems (Ho:YAG- (lambda = 2,080 nm), Nd:YAG- (lambda = 1,064 nm), and diode-laser (lambda = 830 and 940 nm)) were fixed to a computer controlled stepper motor. The laser light was applied in contact mode onto ex vivo muscle tissue, using identical power settings and a reproducible application procedure (application velocity, application angle) under constant conditions (temperature of tissue and volume). The size of the thermal effects on the tissue (e.g., coagulation, ablation, and carbonization zones) were measured and photographed via optical microscopy.
Depending on the laser wavelength used, the experimental results proved different degrees of tissue responses. Nd:YAG- and diode-lasers provided for only low coagulation effects in the depth of the tissue, but produced severe carbonization at the surface. Ho:YAG-laser light revealed the highest ablation capabilities of the lasers investigated in addition to large coagulation zones which were of larger extent than those produced by Nd:YAG- and diode-laser light.
Contact treatment by Ho:YAG-laser light might provide for a precise and effective tissue reduction in a bloodless manner because of its high ablation and coagulation capabilities, especially if large volumes are treated and structures beneath are non-critical. In comparison, Nd:YAG- and diode-laser treatment in contact application showed low thermal tissue effects (i.e., coagulation) in the depth, resulting from a high power loss caused by the development of large carbonization zones at the surface of the tissue. Therefore, the degree of blood-perfusion and the capability of vessel-closure induced by these lasers should be taken into account. The presented investigation also revealed that in contact mode, the tested laser systems produced tissue effects, which were highly different from those already described for applications in non-contact mode. Physicians who are performing laser treatments in close boundaries must be aware that changing from non-contact to contact mode in laser application greatly influences the resulting tissue effects.
各种波长的激光正被用于耳鼻喉科的外科手术。除了众所周知的光纤引导激光系统，如Nd:YAG激光和Ho:YAG激光，最近新开发的不同波长的二极管激光系统在外科手术中也变得很受欢迎。为了比较光纤引导激光在诱导组织效应方面的作用，在可重复的测试条件下对这些激光系统进行了研究和比较。
研究设计/材料与方法：将四种常见医用激光系统（Ho:YAG（波长=2080nm）、Nd:YAG（波长=1064nm）以及二极管激光（波长=830nm和940nm））的激光光纤固定到计算机控制的步进电机上。在恒定条件（组织温度和体积）下，使用相同的功率设置和可重复的应用程序（应用速度、应用角度），以接触模式将激光照射到离体肌肉组织上。通过光学显微镜测量并拍摄组织上热效应的大小（如凝固、消融和碳化区域）。
根据所使用的激光波长，实验结果证明了不同程度的组织反应。Nd:YAG激光和二极管激光在组织深度仅产生较低的凝固效应，但在表面产生严重的碳化。Ho:YAG激光除了具有比Nd:YAG激光和二极管激光产生的更大范围的凝固区域外，还显示出所研究的激光中最高的消融能力。
Ho:YAG激光的接触治疗可能因其高消融和凝固能力而以无血方式提供精确有效的组织切除，特别是在处理大体积组织且下方结构不重要时。相比之下，Nd:YAG激光和二极管激光的接触应用在深度上显示出较低的热组织效应（即凝固），这是由于组织表面形成大的碳化区域导致高功率损耗所致。因此，应考虑这些激光引起的血液灌注程度和血管闭合能力。本研究还表明，在接触模式下，测试的激光系统产生的组织效应与已描述的非接触模式应用有很大不同。在近距离进行激光治疗的医生必须意识到，激光应用从非接触模式转变为接触模式会极大地影响最终的组织效应。
