The Whiteley Clinic, Stirling House, Guildford, UK.
The Whiteley Clinic, Stirling House, Guildford, UK; Faculty of Health and Biomedical Sciences, University of Surrey, Surrey, UK.
J Vasc Surg Venous Lymphat Disord. 2021 Jul;9(4):1051-1056. doi: 10.1016/j.jvsv.2020.10.018. Epub 2020 Dec 2.
International guidelines recommend endovenous laser ablation as one of the first-line treatments for truncal venous reflux associated with varicose veins. Clinicians use linear endovenous energy density to measure the energy used during treatment. The aim of this study was to investigate the power output from the fiber tip and to see if this changed with use.
We placed 15 mL of water in a thermally insulated 25-mL beaker. Two thermocouples were placed equidistantly adjacent to the laser fiber tip. A 1470-nm laser was fired at 5W for 2 minutes and the temperature change was measured. Three fibers were used on different days to allow the laser to cool for 24 hours between fibers. Each fiber was tested three times in a row. We also tested the "first treatment" effect by comparing the power output when the fiber was fired immediately after the laser was switched on, compared with treatments when the laser had been switched on for 1 hour. To assess whether this was due to the console being "cold" on the first firing of the day, we repeated the experiment having switched on the laser console 1 hour before firing to "prewarm" the console. However, the diode was not fired during this hour. To measure fiber degradation, three runs of the experiment were performed successively before firing the laser continuously for 20 minutes, then three more runs were conducted, resulting in delivery of approximately 10,000 J.
The actual power output seemed to be lower than the console suggested. The power output from the first fiber used in a succession of three with the same laser had a significantly lower power output than the following two runs (P = .0004 and P < .0001, respectively). When the laser was prewarmed for 1 hour without firing, no change in this output pattern was noted (P = .293). Fiber degradation was not found in any of the fibers that were tested within the maximum recommended for the fiber (10,000 J).
The first use of a fiber in a treatment session has a significantly lower power output from the treatment tip than subsequent uses, even if the machine is prewarmed and the console displays the same power for each. The authors believe that this phenomenon is due to the diode being less efficient when first used after switching it on. Clinicians need to be aware that the true power output at the fiber tip may not be as indicated by the console display and may be variable during a treatment session.
国际指南推荐静脉内激光消融术作为与静脉曲张相关的主干静脉反流的一线治疗方法之一。临床医生使用线性静脉内能量密度来测量治疗过程中使用的能量。本研究的目的是研究光纤尖端的输出功率，并观察其是否随使用而变化。
我们将 15 毫升水放入一个隔热的 25 毫升烧杯中。将两个热电偶等距放置在激光光纤尖端的旁边。用 1470nm 激光以 5W 照射 2 分钟，并测量温度变化。在不同的日子使用三根光纤，以便在光纤之间冷却 24 小时。每根光纤连续测试三次。我们还通过比较光纤在激光打开后立即点火时的功率输出与激光打开 1 小时后的治疗效果，来测试“初次治疗”效果。为了评估这是否是由于当天第一次点火时控制台较“冷”，我们在点火前 1 小时打开激光控制台以“预热”控制台，重复了该实验。但是，在这 1 小时内，二极管没有点火。为了测量光纤退化，我们在连续点火 20 分钟之前，连续进行了三次实验，然后再进行了三次实验，总共输送了大约 10000J 的能量。
实际输出功率似乎低于控制台显示的功率。连续三次使用同一台激光器的第一根光纤的输出功率明显低于后两次（分别为 P=0.0004 和 P<0.0001）。当激光预热 1 小时而不点火时，没有注意到这种输出模式的变化（P=0.293）。在测试的光纤中，没有发现任何一根光纤的退化超过光纤的最大推荐值（10000J）。
在治疗过程中，第一次使用光纤时，从治疗尖端的输出功率明显低于随后的使用，即使机器预热且控制台显示每个都具有相同的功率。作者认为，这种现象是由于二极管在首次打开后效率较低所致。临床医生需要意识到，光纤尖端的实际输出功率可能与控制台显示的不一致，并且在治疗过程中可能会发生变化。
