Department of Urology, Seoul National University Hospital, Seoul, South Korea.
Department of Urology, Cho Ray Hospital, Ho Chi Minh City, Viet Nam.
PLoS One. 2020 May 22;15(5):e0233135. doi: 10.1371/journal.pone.0233135. eCollection 2020.
'Double-firing effect' in which laser firing occurs in the fiber tip and its proximal part is caused by different breakdown rates between fiber jackets and cores. This study investigated a new safe distance concept to prevent scope damage by analyzing the breakdown of the laser fiber jacket and cores.
Laser fibers were fixed in a benchtop simulation model. The fiber tip was in contact with uniform phantom stones and submerged in saline. Four different energy settings (1.0 or 2.0J x 10Hz or 30Hz) and two different fiber sizes (200 μm and 365 μm) were tested. After three minutes of use at each energy setting, the length of fiber shortening and jacket burn were measured. The fibers were stripped to measure the length of core degradation.
Mean degradation lengths were 4.2 to 7.8 mm. There was no statistical difference in the mean lengths of fiber core degradation and jacket burn. However, core degradation was longer than the jacket burn in half of the samples. The mean difference in lengths between core degradation and jacket burn was 0.49 ± 0.90 mm. Lengths of core degradation and the jacket burn were longer at the setting of high-power energy and 200 μm fiber - 2J with 30 Hz.
To reduce 'double-firing'-induced damage, the authors recommend that laser fiber should be cut 1.0 mm longer than visible jacket burn at high-power settings after 3-min continuous fragmentation. After cutting the fiber, the laser should be checked whether 'double-firing' is no more seen.
“双点火效应”是指由于光纤护套和芯体之间的击穿率不同，导致激光在光纤尖端及其近端发生点火。本研究通过分析激光光纤护套和芯体的击穿情况，提出了一种新的安全距离概念，以防止内窥镜损坏。
将激光光纤固定在台式模拟模型中。光纤尖端与均匀的结石模拟体接触，并浸没在盐水中。测试了四种不同的能量设置（1.0 或 2.0J x 10Hz 或 30Hz）和两种不同的光纤尺寸（200μm 和 365μm）。在每种能量设置下使用三分钟后，测量光纤缩短的长度和护套烧伤的长度。将光纤剥开，测量芯体降解的长度。
平均降解长度为 4.2 至 7.8 毫米。光纤芯体降解的平均长度和护套烧伤的平均长度之间没有统计学差异。然而，在一半的样本中，芯体降解的长度长于护套烧伤的长度。芯体降解和护套烧伤之间的平均长度差异为 0.49±0.90 毫米。在高能量设置（2J 与 30Hz）和 200μm 光纤下，芯体降解的长度和护套烧伤的长度较长。
为了减少“双点火”引起的损伤，作者建议在高功率设置下连续碎 3 分钟后，将光纤比可见护套烧伤长 1.0 毫米切断。切断光纤后，应检查激光是否不再出现“双点火”现象。
