Kautzky M, Fitzgerald R, Dechtyar I, Schenk P
Second Department of Otorhinolaryngology, University of Vienna Medical School, Austria.
ORL J Otorhinolaryngol Relat Spec. 1993 Mar-Apr;55(2):105-9. doi: 10.1159/000276391.
Endotracheal tube (ET) fire is the most frequent complication arising with laser surgery in the upper aerodigestive tract. No data are available about the safety of commonly used ETs when used with recently developed high-energy pulsed lasers, working with only a minimal thermal component but mainly photoablative. A comparative in vitro study was performed with three types of endotracheal tubes to assess their resistance to wall and cuff damage by the laser beams of two pulsed infrared solid-state lasers. ET perforation was attempted with the erbium:YAG (lambda = 2,930 nm) and holmium:YAG (lambda = 2,120 nm) lasers. For all experiments, a repetition rate of 5 Hz was used. The 2.5-microseconds holmium:YAG pulses were coupled into a nylon fibre of 400 microns diameter. The 2.0-microseconds erbium:YAG laser pulses were applied to ETs through a lens system providing a spot size diameter of 200 microns. Polyvinyl chloride and silicon ET segments were exposed to laser pulse energies from 97 to 500 mJ in the presence of different anaesthetic gas mixtures. The time from the onset of exposure to tube perforation was recorded. Thermal gradients following laser application were measured. Laser exposure was continued for up to 90 s, unless tube ignition occurred. At all energy levels tested, the photo-ablative mechanism of laser-tube interaction, with few thermal components, led to laser-induced tube ignition if an FiO2 > 21% for the holmium:YAG and 34% for the erbium:YAG laser was established. With increasing pulse energies, ET segments ignited sooner. MLT tubes performed best in the present safety test.
气管内导管（ET）起火是上呼吸道激光手术最常见的并发症。目前尚无关于常用气管内导管与最近开发的高能脉冲激光配合使用时安全性的数据，这些激光主要起光蚀作用，热成分极少。我们对三种类型的气管内导管进行了一项体外对比研究，以评估它们对两种脉冲红外固态激光束造成的管壁和套囊损伤的抵抗能力。我们尝试用铒：钇铝石榴石（波长 = 2930纳米）和钬：钇铝石榴石（波长 = 2120纳米）激光造成气管内导管穿孔。在所有实验中，重复频率均为5赫兹。2.5微秒的钬：钇铝石榴石脉冲被耦合到一根直径400微米的尼龙纤维中。2.0微秒的铒：钇铝石榴石激光脉冲通过一个提供200微米光斑尺寸直径的透镜系统施加到气管内导管上。在不同麻醉气体混合物存在的情况下，将聚氯乙烯和硅胶气管内导管节段暴露于97至500毫焦的激光脉冲能量下。记录从开始暴露到导管穿孔的时间。测量激光照射后的热梯度。除非发生导管着火，激光照射持续长达90秒。在所有测试的能量水平下，如果钬：钇铝石榴石激光的FiO2 > 21%，铒：钇铝石榴石激光的FiO2 > 及34%，激光与导管相互作用的光蚀机制（热成分极少）会导致激光引发的导管着火。随着脉冲能量增加，气管内导管节段着火更快。在本次安全性测试中，MLT导管表现最佳。
