Ohki Tomohiro, Nakagawa Atsuhiro, Hirano Takayuki, Hashimoto Tokitada, Menezes Viren, Jokura Hidefumi, Uenohara Hiroshi, Sato Yasuhiko, Saito Tsutomu, Shirane Reizo, Tominaga Teiji, Takayama Kazuyoshi
Transdisciplinary Fluid Integration Research Center, Institute of Fluid Science, Tohoku University, Miyagi, Japan.
Lasers Surg Med. 2004;34(3):227-34. doi: 10.1002/lsm.20021.
Although water jet technology has been considered as a feasible neuroendoscopic dissection methodology because of its ability to perform selective tissue dissection without thermal damage, problems associated with continuous use of water and the ensuing fountain-effect-with catapulting of the tissue-could make water jets unsuitable for endoscopic use, in terms of safety and ease of handling. Therefore, the authors experimented with minimization of water usage during the application of a pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser-induced liquid jet (LILJ), while assuring the dissection quality and the controllability of a conventional water jet dissection device. We have developed the LILJ generator for use as a rigid neuroendoscope, discerned its mechanical behavior, and evaluated its dissection ability using the cadaveric rabbit ventricular wall.
STUDY DESIGN/MATERIALS AND METHODS: The LILJ generator is incorporated into the tip of a stainless steel tube (length: 22 cm; internal diameter: 1.0 mm; external diameter: 1.4 mm), so that the device can be inserted into a commercial, rigid neuroendoscope. Briefly, the LILJ is generated by irradiating an internally supplied water column within the stainless steel tube using the pulsed Ho:YAG laser (wave length: 2.1 microm, pulse duration time: 350 microseconds) and is then ejected through the metal nozzle (internal diameter: 100 microm). The Ho:YAG laser pulse energy is conveyed through optical quartz fiber (core diameter: 400 microm), while cold water (5 degrees C) is internally supplied at a rate of 40 ml/hour. The relationship between laser energy (range: 40-433 mJ/pulse), standoff distance (defined as the distance between the tip of the optical fiber and the nozzle end; range: 10-30 mm), and the velocity, shape, pressure, and average volume of the ejected jet were analyzed by means of high-speed camera, PVDF needle hydrophone, and digital scale. The quality of the dissection plane, the preservation of blood vessels, and the penetration depth were evaluated using five fresh cadaveric rabbit ventricular walls, under neuroendoscopic vision.
Jet velocity (7.0-19.6 m/second) and pressure (0.07-0.28 MPa) could be controlled by varying the laser energy, which determined the penetration depth in the cadaveric rabbit ventricular wall (0.07-1.30 mm/shot). The latter could be cut into desirable shapes-without thermal effects-under clear neuroendoscopic vision. The average volume of a single ejected jet could be confined to 0.42-1.52 microl/shot, and there was no accompanying generation of shock waves. Histological specimens revealed a sharp dissection plane and demonstrated that blood vessels of diameter over 100 microm could be preserved, without thermal damage.
The present pulsed LILJ system holds promise as a safe and reliable dissection device for deployment in a rigid neuroendoscope.
尽管水刀技术因其能够在不造成热损伤的情况下进行选择性组织切割，被视为一种可行的神经内镜解剖方法，但持续用水相关的问题以及随之而来的组织弹射喷泉效应，可能使水刀在安全性和操作便利性方面不适用于内镜使用。因此，作者在确保传统水刀解剖设备的切割质量和可控性的同时，尝试在应用脉冲钬：钇铝石榴石（Ho:YAG）激光诱导液体射流（LILJ）过程中尽量减少水的使用量。我们开发了用作刚性神经内镜的LILJ发生器，识别了其机械性能，并使用尸体兔心室壁评估了其切割能力。
研究设计/材料与方法：LILJ发生器安装在不锈钢管（长度：22厘米；内径：1.0毫米；外径：1.4毫米）的尖端，以便该设备能够插入商用刚性神经内镜。简要来说，通过使用脉冲Ho:YAG激光（波长：2.1微米，脉冲持续时间：350微秒）照射不锈钢管内内部供应的水柱来产生LILJ，然后通过金属喷嘴（内径：100微米）喷射出去。Ho:YAG激光脉冲能量通过光学石英纤维（芯径：400微米）传输，同时以40毫升/小时的速率内部供应冷水（5摄氏度）。通过高速摄像机、PVDF针式水听器和数字秤分析激光能量（范围：40 - 433毫焦/脉冲）、 standoff距离（定义为光纤尖端与喷嘴端部之间的距离；范围：10 - 30毫米）与喷射射流的速度、形状、压力和平均体积之间的关系。在神经内镜视野下，使用五具新鲜尸体兔心室壁评估切割平面的质量、血管的保留情况和穿透深度。
通过改变激光能量可以控制射流速度（7.0 - 19.6米/秒）和压力（0.07 - 0.28兆帕），这决定了在尸体兔心室壁中的穿透深度（0.07 - 1.30毫米/次射击）。在清晰的神经内镜视野下，后者可以切割成理想形状且无热效应。单次喷射射流的平均体积可以限制在0.42 - 1.52微升/次射击，并且没有伴随产生冲击波。组织学标本显示切割平面锐利，并表明直径超过100微米的血管可以得以保留且无热损伤。
当前的脉冲LILJ系统有望成为一种安全可靠的切割设备，可用于刚性神经内镜。
